Merge remote-tracking branch 'upstream/master'

2018-07-23 22:21:30 -03:00
parent 40dde25b79 896a2d071a
commit 5142d0f0a5
224 changed files with 8092 additions and 1221 deletions
@@ -48,3 +48,12 @@ dependency-reduced-pom.xml
 *.so
 *.dylib
 *.dll
+
+xml/src/test/resources/example_dom4j_new.xml
+xml/src/test/resources/example_dom4j_updated.xml
+xml/src/test/resources/example_jaxb_new.xml
+core-java-io/hard_link.txt
+core-java-io/target_link.txt
+core-java/src/main/java/com/baeldung/manifest/MANIFEST.MF
+ethereum/logs/
+jmeter/src/main/resources/*-JMeter.csv
@@ -19,7 +19,7 @@ In additional to Spring, the following technologies are in focus: `core Java`, `

 Building the project
 ====================
-To do the full build, do: `mvn install -Dgib.enabled=false`
+To do the full build, do: `mvn install -Pdefault -Dgib.enabled=false`


 Working with the code in Eclipse
@@ -0,0 +1,88 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>apache-avro-tutorial</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <compiler-plugin.version>3.5</compiler-plugin.version>
+        <avro.version>1.8.2</avro.version>
+        <java.version>1.8</java.version>
+        <slf4j.version>1.7.25</slf4j.version>
+    </properties>
+	
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.10</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${slf4j.version}</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.avro</groupId>
+            <artifactId>avro</artifactId>
+            <version>${avro.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.avro</groupId>
+            <artifactId>avro-compiler</artifactId>
+            <version>${avro.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.avro</groupId>
+            <artifactId>avro-maven-plugin</artifactId>
+            <version>${avro.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${compiler-plugin.version}</version>
+                <configuration>
+                    <source>${java.version}</source>
+                    <target>${java.version}</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.avro</groupId>
+                <artifactId>avro-maven-plugin</artifactId>
+                <version>${avro.version}</version>
+                <executions>
+                    <execution>
+                        <id>schemas</id>
+                        <phase>generate-sources</phase>
+                        <goals>
+                            <goal>schema</goal>
+                            <goal>protocol</goal>
+                            <goal>idl-protocol</goal>
+                        </goals>
+                        <configuration>
+                            <sourceDirectory>${project.basedir}/src/main/resources/</sourceDirectory>
+                            <outputDirectory>${project.basedir}/src/main/java/</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>
@@ -0,0 +1,14 @@
+package com.baeldung.avro.util;
+
+import org.apache.avro.Schema;
+import org.apache.avro.compiler.specific.SpecificCompiler;
+
+import java.io.File;
+import java.io.IOException;
+
+public class AvroClassGenerator {
+    public void generateAvroClasses() throws IOException {
+        SpecificCompiler compiler = new SpecificCompiler(new Schema.Parser().parse(new File("src/main/resources/avroHttpRequest-schema.avsc")));
+        compiler.compileToDestination(new File("src/main/resources"), new File("src/main/java")); 
+    }
+}
@@ -0,0 +1,24 @@
+package com.baeldung.avro.util;
+
+
+import org.apache.avro.Schema;
+import org.apache.avro.SchemaBuilder;
+
+public class AvroSchemaBuilder {
+
+    public Schema createAvroHttpRequestSchema(){
+
+        Schema clientIdentifier = SchemaBuilder.record("ClientIdentifier").namespace("com.baeldung.avro.model")
+                .fields().requiredString("hostName").requiredString("ipAddress").endRecord();
+
+        Schema avroHttpRequest = SchemaBuilder.record("AvroHttpRequest").namespace("com.baeldung.avro.model").fields()
+                .requiredLong("requestTime")
+                .name("clientIdentifier").type(clientIdentifier).noDefault()
+                .name("employeeNames").type().array().items().stringType().arrayDefault(null)
+                .name("active").type().enumeration("Active").symbols("YES", "NO").noDefault()
+                .endRecord();
+        return avroHttpRequest;
+    }
+}
+
+
@@ -0,0 +1,13 @@
+/**
+ * Autogenerated by Avro
+ *
+ * DO NOT EDIT DIRECTLY
+ */
+package com.baeldung.avro.util.model;
+@SuppressWarnings("all")
+@org.apache.avro.specific.AvroGenerated
+public enum Active {
+  YES, NO  ;
+  public static final org.apache.avro.Schema SCHEMA$ = new org.apache.avro.Schema.Parser().parse("{\"type\":\"enum\",\"name\":\"Active\",\"namespace\":\"com.baeldung.avro.model\",\"symbols\":[\"YES\",\"NO\"]}");
+  public static org.apache.avro.Schema getClassSchema() { return SCHEMA$; }
+}
@@ -0,0 +1,33 @@
+package com.baeldung.avro.util.serealization;
+
+import com.baeldung.avro.util.model.AvroHttpRequest;
+import org.apache.avro.io.DatumReader;
+import org.apache.avro.io.Decoder;
+import org.apache.avro.io.DecoderFactory;
+import org.apache.avro.specific.SpecificDatumReader;
+
+import java.io.IOException;
+
+public class AvroDeSerealizer {
+
+public AvroHttpRequest deSerealizeAvroHttpRequestJSON(byte[] data){
+    DatumReader<AvroHttpRequest> reader = new SpecificDatumReader<>(AvroHttpRequest.class);
+    Decoder decoder = null;
+    try {
+        decoder = DecoderFactory.get().jsonDecoder(AvroHttpRequest.getClassSchema(), new String(data));
+        return reader.read(null, decoder);
+    } catch (IOException e) {
+        return null;
+    }
+}
+
+public AvroHttpRequest deSerealizeAvroHttpRequestBinary(byte[] data){
+    DatumReader<AvroHttpRequest> employeeReader = new SpecificDatumReader<>(AvroHttpRequest.class);
+    Decoder decoder = DecoderFactory.get().binaryDecoder(data, null);
+    try {
+        return employeeReader.read(null, decoder);
+    } catch (IOException e) {
+        return null;
+    }
+}
+}
@@ -0,0 +1,44 @@
+package com.baeldung.avro.util.serealization;
+
+import com.baeldung.avro.util.model.AvroHttpRequest;
+import org.apache.avro.io.*;
+import org.apache.avro.specific.SpecificDatumWriter;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+public class AvroSerealizer {
+
+public byte[] serealizeAvroHttpRequestJSON(AvroHttpRequest request){
+    DatumWriter<AvroHttpRequest> writer = new SpecificDatumWriter<>(AvroHttpRequest.class);
+    byte[] data = new byte[0];
+    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+    Encoder jsonEncoder = null;
+    try {
+        jsonEncoder = EncoderFactory.get().jsonEncoder(AvroHttpRequest.getClassSchema(), stream);
+        writer.write(request, jsonEncoder);
+        jsonEncoder.flush();
+        data = stream.toByteArray();
+    } catch (IOException e) {
+        data =null;
+    }
+    return data;
+}
+
+public byte[] serealizeAvroHttpRequestBinary(AvroHttpRequest request){
+    DatumWriter<AvroHttpRequest> writer = new SpecificDatumWriter<>(AvroHttpRequest.class);
+    byte[] data = new byte[0];
+    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+    Encoder jsonEncoder = EncoderFactory.get().binaryEncoder(stream,null);
+    try {
+        writer.write(request, jsonEncoder);
+        jsonEncoder.flush();
+        data = stream.toByteArray();
+    } catch (IOException e) {
+        data = null;
+    }
+
+    return data;
+}
+
+}
@@ -0,0 +1,47 @@
+{
+  "type":"record",
+  "name":"AvroHttpRequest",
+  "namespace":"com.baeldung.avro.model",
+  "fields":[
+    {
+      "name":"requestTime",
+      "type":"long"
+    },
+    {
+      "name":"clientIdentifier",
+      "type":{
+        "type":"record",
+        "name":"ClientIdentifier",
+        "fields":[
+          {
+            "name":"hostName",
+            "type":"string"
+          },
+          {
+            "name":"ipAddress",
+            "type":"string"
+          }
+        ]
+      }
+    },
+    {
+      "name":"employeeNames",
+      "type":{
+        "type":"array",
+        "items":"string"
+      },
+      "default":null
+    },
+    {
+      "name":"active",
+      "type":{
+        "type":"enum",
+        "name":"Active",
+        "symbols":[
+          "YES",
+          "NO"
+        ]
+      }
+    }
+  ]
+}
@@ -0,0 +1,75 @@
+package com.baeldung.avro.util.serealization;
+
+import com.baeldung.avro.util.model.Active;
+import com.baeldung.avro.util.model.AvroHttpRequest;
+import com.baeldung.avro.util.model.ClientIdentifier;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+import static org.junit.Assert.*;
+
+public class AvroSerealizerDeSerealizerTest {
+
+    AvroSerealizer serealizer;
+    AvroDeSerealizer deSerealizer;
+    AvroHttpRequest request;
+
+    @Before
+    public void setUp() throws Exception {
+        serealizer = new AvroSerealizer();
+        deSerealizer = new AvroDeSerealizer();
+
+        ClientIdentifier clientIdentifier = ClientIdentifier.newBuilder().
+                setHostName("localhost").setIpAddress("255.255.255.0").build();
+
+        List<CharSequence> employees = new ArrayList();
+        employees.add("James");
+        employees.add("Alice");
+        employees.add("David");
+        employees.add("Han");
+
+        request = AvroHttpRequest.newBuilder().setRequestTime(01l)
+                .setActive(Active.YES).setClientIdentifier(clientIdentifier)
+                .setEmployeeNames(employees).build();
+    }
+
+    @After
+    public void tearDown() throws Exception {
+    }
+
+@Test
+public void WhenSerialized_UsingJSONEncoder_ObjectGetsSerialized(){
+    byte[] data = serealizer.serealizeAvroHttpRequestJSON(request);
+    assertTrue(Objects.nonNull(data));
+    assertTrue(data.length > 0);
+}
+
+@Test
+public void WhenSerialized_UsingBinaryEncoder_ObjectGetsSerialized(){
+    byte[] data = serealizer.serealizeAvroHttpRequestBinary(request);
+    assertTrue(Objects.nonNull(data));
+    assertTrue(data.length > 0);
+}
+
+@Test
+public void WhenDeserialize_UsingJSONDecoder_ActualAndExpectedObjectsAreEqual(){
+    byte[] data = serealizer.serealizeAvroHttpRequestJSON(request);
+    AvroHttpRequest actualRequest = deSerealizer.deSerealizeAvroHttpRequestJSON(data);
+    assertEquals(actualRequest,request);
+    assertTrue(actualRequest.getRequestTime().equals(request.getRequestTime()));
+}
+
+@Test
+public void WhenDeserialize_UsingBinaryecoder_ActualAndExpectedObjectsAreEqual(){
+    byte[] data = serealizer.serealizeAvroHttpRequestBinary(request);
+    AvroHttpRequest actualRequest = deSerealizer.deSerealizeAvroHttpRequestBinary(data);
+    assertEquals(actualRequest,request);
+    assertTrue(actualRequest.getRequestTime().equals(request.getRequestTime()));
+}
+}
+
@@ -99,6 +99,16 @@
            <artifactId>joda-time</artifactId>
            <version>${joda.version}</version>
        </dependency>
+        <dependency>
+            <groupId>org.aspectj</groupId>
+            <artifactId>aspectjrt</artifactId>
+            <version>${asspectj.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.aspectj</groupId>
+            <artifactId>aspectjweaver</artifactId>
+            <version>${asspectj.version}</version>
+        </dependency>
    </dependencies>

    <build>
@@ -170,6 +180,7 @@
        <joda.version>2.10</joda.version>
        <!-- testing -->
        <assertj.version>3.6.1</assertj.version>
+        <asspectj.version>1.8.9</asspectj.version>
        <avaitility.version>1.7.0</avaitility.version>
        <jmh-core.version>1.19</jmh-core.version>
        <jmh-generator.version>1.19</jmh-generator.version>
@@ -0,0 +1,9 @@
+package com.baeldung.aspect;
+
+public aspect ChangeCallsToCurrentTimeInMillisMethod {
+    long around():
+            call(public static native long java.lang.System.currentTimeMillis())
+                    && within(user.code.base.pckg.*) {
+        return 0;
+    }
+}
@@ -1,6 +1,7 @@
 package com.baeldung.util;

 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;

 import java.time.Clock;
 import java.time.Instant;
@@ -9,6 +10,8 @@ import java.time.LocalTime;
 import java.time.ZoneId;
 import java.time.temporal.ChronoField;

+import org.joda.time.DateTime;
+import org.joda.time.DateTimeUtils;
 import org.junit.Test;

 public class CurrentDateTimeUnitTest {
@@ -39,5 +42,4 @@ public class CurrentDateTimeUnitTest {

        assertEquals(clock.instant().getEpochSecond(), now.getEpochSecond());
    }
-
 }
@@ -0,0 +1,27 @@
+package com.baeldung.convertlisttomap;
+
+public class Animal {
+    private int id;
+    private String name;
+
+    public Animal(int id, String name) {
+        this.id = id;
+        this.setName(name);
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}
@@ -0,0 +1,42 @@
+package com.baeldung.convertlisttomap;
+
+import com.google.common.collect.Maps;
+import org.apache.commons.collections4.MapUtils;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class ConvertListToMapService {
+
+    public Map<Integer, Animal> convertListBeforeJava8(List<Animal> list) {
+
+        Map<Integer, Animal> map = new HashMap<>();
+
+        for (Animal animal : list) {
+            map.put(animal.getId(), animal);
+        }
+        return map;
+    }
+
+    public Map<Integer, Animal> convertListAfterJava8(List<Animal> list) {
+        Map<Integer, Animal> map = list.stream().collect(Collectors.toMap(Animal::getId, animal -> animal));
+        return map;
+    }
+
+    public Map<Integer, Animal> convertListWithGuava(List<Animal> list) {
+
+        Map<Integer, Animal> map = Maps.uniqueIndex(list, Animal::getId);
+        return map;
+    }
+
+    public Map<Integer, Animal> convertListWithApacheCommons(List<Animal> list) {
+
+        Map<Integer, Animal> map = new HashMap<>();
+
+        MapUtils.populateMap(map, list, Animal::getId);
+
+        return map;
+    }
+}
@@ -0,0 +1,68 @@
+package com.baeldung.convertlisttomap;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsInAnyOrder;
+
+public class ConvertListToMapServiceUnitTest {
+    List<Animal> list;
+
+    private ConvertListToMapService convertListService;
+
+    @Before
+    public void init() {
+        this.convertListService = new ConvertListToMapService();
+        this.list = new ArrayList<>();
+
+        Animal cat = new Animal(1, "Cat");
+        list.add(cat);
+        Animal dog = new Animal(2, "Dog");
+        list.add(dog);
+        Animal pig = new Animal(3, "Pig");
+        list.add(pig);
+        Animal cow = new Animal(4, "Cow");
+        list.add(cow);
+        Animal goat = new Animal(5, "Goat");
+        list.add(goat);
+
+    }
+
+    @Test
+    public void givenAList_whenConvertBeforeJava8_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListBeforeJava8(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+    @Test
+    public void givenAList_whenConvertAfterJava8_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListAfterJava8(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+    @Test
+    public void givenAList_whenConvertWithGuava_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListWithGuava(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+    @Test
+    public void givenAList_whenConvertWithApacheCommons_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListWithApacheCommons(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+}
@@ -0,0 +1,68 @@
+package com.baeldung.convertlisttomap;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasItem;
+import static org.hamcrest.Matchers.hasSize;
+
+public class ConvertListWithDiplicatedIdToMapServiceUnitTest {
+    List<Animal> duplicatedIdList;
+
+    private ConvertListToMapService convertListService = new ConvertListToMapService();
+
+    @Before
+    public void init() {
+
+        this.duplicatedIdList = new ArrayList<>();
+
+        Animal cat = new Animal(1, "Cat");
+        duplicatedIdList.add(cat);
+        Animal dog = new Animal(2, "Dog");
+        duplicatedIdList.add(dog);
+        Animal pig = new Animal(3, "Pig");
+        duplicatedIdList.add(pig);
+        Animal cow = new Animal(4, "Cow");
+        duplicatedIdList.add(cow);
+        Animal goat = new Animal(4, "Goat");
+        duplicatedIdList.add(goat);
+
+    }
+
+    @Test
+    public void givenADupIdList_whenConvertBeforeJava8_thenReturnMapWithRewrittenElement() {
+
+        Map<Integer, Animal> map = convertListService.convertListBeforeJava8(duplicatedIdList);
+
+        assertThat(map.values(), hasSize(4));
+        assertThat(map.values(), hasItem(duplicatedIdList.get(4)));
+    }
+
+    @Test
+    public void givenADupIdList_whenConvertWithApacheCommons_thenReturnMapWithRewrittenElement() {
+
+        Map<Integer, Animal> map = convertListService.convertListWithApacheCommons(duplicatedIdList);
+
+        assertThat(map.values(), hasSize(4));
+        assertThat(map.values(), hasItem(duplicatedIdList.get(4)));
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void givenADupIdList_whenConvertAfterJava8_thenException() {
+
+        convertListService.convertListAfterJava8(duplicatedIdList);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void givenADupIdList_whenConvertWithGuava_thenException() {
+
+        convertListService.convertListWithGuava(duplicatedIdList);
+
+    }
+
+}
@@ -50,22 +50,9 @@ public class HashSetInitalizingUnitTest {

    @Test
    public void whenUsingJava8_usingCollectOnStream_thenCorrectSize() {
-        Set<String> set = Stream.of("a", "b", "c").collect(Collectors.toSet());
+        Set<String> set = Stream.of("a", "b", "c").collect(Collectors.toCollection(HashSet::new));
        assertEquals(3, set.size());
    }
-    @Test
-    public void whenUsingJava8_fromStringArray_thenCorrectSize() {
-        String[] stringArray = {"a","b","c"};
-        Set<String> set = Arrays.stream(stringArray).collect(Collectors.toCollection(HashSet::new));
-        assertEquals(3, set.size());
-    }
-
-    // Requires Java9 - uncomment if you are using Java 9 or higher
-    /*@Test
-    public void whenUsingJava9_usingCollectOnStream_thenCorrectSize() {
-        Set set = Set.of("a", "b", "c");
-        assertEquals(3, set.size());
-    }*/

    @Test
    public void whenUsingGoogleGuava_createMutableSet_thenCorrectSize() {
@@ -78,4 +65,6 @@ public class HashSetInitalizingUnitTest {
        Set<String> set = ImmutableSet.of("a", "b", "c");
        assertEquals(3, set.size());
    }
+  
 }
+
@@ -1,5 +1,5 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.baeldung</groupId>
    <artifactId>core-java</artifactId>
@@ -73,9 +73,10 @@
        <dependency>
            <groupId>org.assertj</groupId>
            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
+            <version>${assertj-core.version}</version>
            <scope>test</scope>
        </dependency>
+
        <dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
@@ -146,6 +147,45 @@
            <artifactId>icu4j</artifactId>
            <version>${icu4j.version}</version>
        </dependency>
+        <!-- Mime Type Resolution Libraries -->
+        <dependency>
+            <groupId>org.apache.tika</groupId>
+            <artifactId>tika-core</artifactId>
+            <version>${tika.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>net.sf.jmimemagic</groupId>
+            <artifactId>jmimemagic</artifactId>
+            <version>${jmime-magic.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-dbcp2</artifactId>
+            <version>${commons-dbcp2.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.zaxxer</groupId>
+            <artifactId>HikariCP</artifactId>
+            <version>${HikariCP.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.mchange</groupId>
+            <artifactId>c3p0</artifactId>
+            <version>${c3p0.version}</version>
+        </dependency>
+        <!-- instrumentation -->
+        <dependency>
+            <groupId>org.javassist</groupId>
+            <artifactId>javassist</artifactId>
+            <version>${javaassist.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.sun</groupId>
+            <artifactId>tools</artifactId>
+            <version>1.8.0</version>
+            <scope>system</scope>
+            <systemPath>${java.home}/../lib/tools.jar</systemPath>
+        </dependency>
    </dependencies>

    <build>
@@ -301,7 +341,7 @@
                    </arguments>
                </configuration>
            </plugin>
-
+            
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
@@ -348,6 +388,7 @@
                    <plugin>
                        <groupId>org.codehaus.mojo</groupId>
                        <artifactId>exec-maven-plugin</artifactId>
+                        <version>${exec-maven-plugin.version}</version>
                        <executions>
                            <execution>
                                <id>run-benchmarks</id>
@@ -372,9 +413,115 @@
                </plugins>
            </build>
        </profile>
+
+        <!-- java instrumentation profiles to build jars -->
+        <profile>
+            <id>buildAgentLoader</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-jar-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <phase>package</phase>
+                                <goals>
+                                    <goal>jar</goal>
+                                </goals>
+                                <configuration>
+                                    <classifier>agentLoader</classifier>
+                                    <classesDirectory>target/classes</classesDirectory>
+                                    <archive>
+                                        <manifest>
+                                            <addClasspath>true</addClasspath>
+                                        </manifest>
+                                        <manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
+                                    </archive>
+
+                                    <includes>
+                                        <include>com/baeldung/instrumentation/application/AgentLoader.class</include>
+                                        <include>com/baeldung/instrumentation/application/Launcher.class</include>
+                                    </includes>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+        <profile>
+            <id>buildApplication</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-jar-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <phase>package</phase>
+                                <goals>
+                                    <goal>jar</goal>
+                                </goals>
+                                <configuration>
+                                    <classifier>application</classifier>
+                                    <classesDirectory>target/classes</classesDirectory>
+                                    <archive>
+                                        <manifest>
+                                            <addClasspath>true</addClasspath>
+                                        </manifest>
+                                        <manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
+                                    </archive>
+
+                                    <includes>
+                                        <include>com/baeldung/instrumentation/application/MyAtm.class</include>
+                                        <include>com/baeldung/instrumentation/application/MyAtmApplication.class</include>
+                                        <include>com/baeldung/instrumentation/application/Launcher.class</include>
+                                    </includes>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+        <profile>
+            <id>buildAgent</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-jar-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <phase>package</phase>
+                                <goals>
+                                    <goal>jar</goal>
+                                </goals>
+                                <configuration>
+                                    <classifier>agent</classifier>
+                                    <classesDirectory>target/classes</classesDirectory>
+                                    <archive>
+                                        <manifest>
+                                            <addClasspath>true</addClasspath>
+                                        </manifest>
+                                        <manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
+                                    </archive>
+
+                                    <includes>
+                                        <include>com/baeldung/instrumentation/agent/AtmTransformer.class</include>
+                                        <include>com/baeldung/instrumentation/agent/MyInstrumentationAgent.class</include>
+                                    </includes>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
    </profiles>

    <properties>
+        
        <!-- marshalling -->
        <jackson.version>2.8.5</jackson.version>
        <gson.version>2.8.2</gson.version>
@@ -395,16 +542,23 @@
        <vavr.version>0.9.0</vavr.version>

        <!-- testing -->
-        <assertj.version>3.6.1</assertj.version>
+        <assertj-core.version>3.10.0</assertj-core.version>

+        <!-- JDBC pooling frameworks -->
+        <commons-dbcp2.version>2.4.0</commons-dbcp2.version>
+        <HikariCP.version>3.2.0</HikariCP.version>
+        <c3p0.version>0.9.5.2</c3p0.version>
+        
        <!-- maven plugins -->
        <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
        <springframework.spring-web.version>4.3.4.RELEASE</springframework.spring-web.version>
        <springframework.boot.spring-boot-starter.version>1.5.8.RELEASE</springframework.boot.spring-boot-starter.version>
+        
        <javamoney.moneta.version>1.1</javamoney.moneta.version>
        <h2database.version>1.4.197</h2database.version>
        <esapi.version>2.1.0.1</esapi.version>
        <jmh-core.version>1.19</jmh-core.version>
+       
        <jmh-generator-annprocess.version>1.19</jmh-generator-annprocess.version>
        <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
        <javax.mail.version>1.5.0-b01</javax.mail.version>
@@ -412,7 +566,13 @@
        <onejar-maven-plugin.version>1.4.4</onejar-maven-plugin.version>
        <maven-shade-plugin.version>3.1.1</maven-shade-plugin.version>
        <spring-boot-maven-plugin.version>2.0.3.RELEASE</spring-boot-maven-plugin.version>
+        <exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
        <icu4j.version>61.1</icu4j.version>
+        <!-- Mime Type Libraries -->
+        <tika.version>1.18</tika.version>
+        <jmime-magic.version>0.1.5</jmime-magic.version>
+        <!-- instrumentation -->
+        <javaassist.version>3.21.0-GA</javaassist.version>
    </properties>

-</project>
+</project>
@@ -0,0 +1,85 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BasicConnectionPool implements ConnectionPool {
+
+    private final String url;
+    private final String user;
+    private final String password;
+    private final List<Connection> connectionPool;
+    private final List<Connection> usedConnections = new ArrayList<>();
+    private static final int INITIAL_POOL_SIZE = 10;
+    private final int MAX_POOL_SIZE = 20;
+    
+    public static BasicConnectionPool create(String url, String user, String password) throws SQLException {
+        List<Connection> pool = new ArrayList<>(INITIAL_POOL_SIZE);
+        for (int i = 0; i < INITIAL_POOL_SIZE; i++) {
+            pool.add(createConnection(url, user, password));
+        }
+        return new BasicConnectionPool(url, user, password, pool);
+    }
+    
+    private BasicConnectionPool(String url, String user, String password, List<Connection> connectionPool) {
+        this.url = url;
+        this.user = user;
+        this.password = password;
+        this.connectionPool = connectionPool;
+    }
+    
+    @Override
+    public Connection getConnection() throws SQLException {
+        if (connectionPool.isEmpty()) {
+            if (usedConnections.size() < MAX_POOL_SIZE) {
+                connectionPool.add(createConnection(url, user, password));
+            } else {
+                throw new RuntimeException("Maximum pool size reached, no available connections!");
+            }
+        }
+
+        Connection connection = connectionPool.remove(connectionPool.size() - 1);
+        usedConnections.add(connection);
+        return connection;
+    }
+    
+    @Override
+    public boolean releaseConnection(Connection connection) {
+        connectionPool.add(connection);
+        return usedConnections.remove(connection);
+    }
+    
+    private static Connection createConnection(String url, String user, String password) throws SQLException {
+        return DriverManager.getConnection(url, user, password);
+    }
+    
+    public int getSize() {
+        return connectionPool.size() + usedConnections.size();
+    }
+
+    @Override
+    public String getUrl() {
+        return url;
+    }
+
+    @Override
+    public String getUser() {
+        return user;
+    }
+
+    @Override
+    public String getPassword() {
+        return password;
+    }
+
+    public void shutdown() throws SQLException {
+        usedConnections.forEach(this::releaseConnection);
+        for (Connection c : connectionPool) {
+            c.close();
+        }
+        connectionPool.clear();
+    }
+}
@@ -0,0 +1,28 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import com.mchange.v2.c3p0.ComboPooledDataSource;
+import java.beans.PropertyVetoException;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+public class C3poDataSource {
+
+    private static final ComboPooledDataSource cpds = new ComboPooledDataSource();
+
+    static {
+        try {
+            cpds.setDriverClass("org.h2.Driver");
+            cpds.setJdbcUrl("jdbc:h2:mem:test");
+            cpds.setUser("user");
+            cpds.setPassword("password");
+        } catch (PropertyVetoException e) {
+            e.printStackTrace();
+        }
+    }
+    
+    public static Connection getConnection() throws SQLException {
+        return cpds.getConnection();
+    }
+    
+    private C3poDataSource(){}
+}
@@ -0,0 +1,18 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.List;
+
+public interface ConnectionPool {
+
+    Connection getConnection() throws SQLException;
+    
+    boolean releaseConnection(Connection connection);
+    
+    String getUrl();
+    
+    String getUser();
+
+    String getPassword();
+}   
@@ -0,0 +1,25 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import org.apache.commons.dbcp2.BasicDataSource;
+
+public class DBCPDataSource {
+    
+    private static final BasicDataSource ds = new BasicDataSource();
+    
+    static {
+        ds.setUrl("jdbc:h2:mem:test");
+        ds.setUsername("user");
+        ds.setPassword("password");
+        ds.setMinIdle(5);
+        ds.setMaxIdle(10);
+        ds.setMaxOpenPreparedStatements(100);
+    }
+    
+    public static Connection getConnection() throws SQLException {
+        return ds.getConnection();
+    }
+    
+    private DBCPDataSource(){}
+}
@@ -0,0 +1,28 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import com.zaxxer.hikari.HikariConfig;
+import com.zaxxer.hikari.HikariDataSource;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+public class HikariCPDataSource {
+    
+    private static final HikariConfig config = new HikariConfig();
+    private static final HikariDataSource ds;
+    
+    static {
+        config.setJdbcUrl("jdbc:h2:mem:test");
+        config.setUsername("user");
+        config.setPassword("password");
+        config.addDataSourceProperty("cachePrepStmts", "true");
+        config.addDataSourceProperty("prepStmtCacheSize", "250");
+        config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
+        ds = new HikariDataSource(config);
+    }
+    
+    public static Connection getConnection() throws SQLException {
+        return ds.getConnection();
+    }
+    
+    private HikariCPDataSource(){}
+}
@@ -0,0 +1,70 @@
+package com.baeldung.instrumentation.agent;
+
+import javassist.CannotCompileException;
+import javassist.ClassPool;
+import javassist.CtClass;
+import javassist.CtMethod;
+import javassist.NotFoundException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.IllegalClassFormatException;
+import java.security.ProtectionDomain;
+
+public class AtmTransformer implements ClassFileTransformer {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(AtmTransformer.class);
+
+    private static final String WITHDRAW_MONEY_METHOD = "withdrawMoney";
+
+    /** The internal form class name of the class to transform */
+    private String targetClassName;
+    /** The class loader of the class we want to transform */
+    private ClassLoader targetClassLoader;
+
+    public AtmTransformer(String targetClassName, ClassLoader targetClassLoader) {
+        this.targetClassName = targetClassName;
+        this.targetClassLoader = targetClassLoader;
+    }
+
+    @Override
+    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
+            ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
+        byte[] byteCode = classfileBuffer;
+
+        String finalTargetClassName = this.targetClassName.replaceAll("\\.", "/"); //replace . with /
+        if (!className.equals(finalTargetClassName)) {
+            return byteCode;
+        }
+
+        if (className.equals(finalTargetClassName) && loader.equals(targetClassLoader)) {
+            LOGGER.info("[Agent] Transforming class MyAtm");
+            try {
+                ClassPool cp = ClassPool.getDefault();
+                CtClass cc = cp.get(targetClassName);
+                CtMethod m = cc.getDeclaredMethod(WITHDRAW_MONEY_METHOD);
+                m.addLocalVariable("startTime", CtClass.longType);
+                m.insertBefore("startTime = System.currentTimeMillis();");
+
+                StringBuilder endBlock = new StringBuilder();
+
+                m.addLocalVariable("endTime", CtClass.longType);
+                m.addLocalVariable("opTime", CtClass.longType);
+                endBlock.append("endTime = System.currentTimeMillis();");
+                endBlock.append("opTime = (endTime-startTime)/1000;");
+
+                endBlock.append("LOGGER.info(\"[Application] Withdrawal operation completed in:\" + opTime + \" seconds!\");");
+
+                m.insertAfter(endBlock.toString());
+
+                byteCode = cc.toBytecode();
+                cc.detach();
+            } catch (NotFoundException | CannotCompileException | IOException e) {
+                LOGGER.error("Exception", e);
+            }
+        }
+        return byteCode;
+    }
+}
@@ -0,0 +1,59 @@
+package com.baeldung.instrumentation.agent;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.lang.instrument.Instrumentation;
+
+public class MyInstrumentationAgent {
+    private static Logger LOGGER = LoggerFactory.getLogger(MyInstrumentationAgent.class);
+
+    public static void premain(String agentArgs, Instrumentation inst) {
+        LOGGER.info("[Agent] In premain method");
+
+        String className = "com.baeldung.instrumentation.application.MyAtm";
+        transformClass(className,inst);
+    }
+
+    public static void agentmain(String agentArgs, Instrumentation inst) {
+        LOGGER.info("[Agent] In agentmain method");
+
+        String className = "com.baeldung.instrumentation.application.MyAtm";
+        transformClass(className,inst);
+    }
+
+    private static void transformClass(String className, Instrumentation instrumentation) {
+        Class<?> targetCls = null;
+        ClassLoader targetClassLoader = null;
+        // see if we can get the class using forName
+        try {
+            targetCls = Class.forName(className);
+            targetClassLoader = targetCls.getClassLoader();
+            transform(targetCls, targetClassLoader, instrumentation);
+            return;
+        } catch (Exception ex) {
+            LOGGER.error("Class [{}] not found with Class.forName");
+        }
+        // otherwise iterate all loaded classes and find what we want
+        for(Class<?> clazz: instrumentation.getAllLoadedClasses()) {
+            if(clazz.getName().equals(className)) {
+                targetCls = clazz;
+                targetClassLoader = targetCls.getClassLoader();
+                transform(targetCls, targetClassLoader, instrumentation);
+                return;
+            }
+        }
+        throw new RuntimeException("Failed to find class [" + className + "]");
+    }
+
+    private static void transform(Class<?> clazz, ClassLoader classLoader, Instrumentation instrumentation) {
+        AtmTransformer dt = new AtmTransformer(clazz.getName(), classLoader);
+        instrumentation.addTransformer(dt, true);
+        try {
+            instrumentation.retransformClasses(clazz);
+        } catch (Exception ex) {
+            throw new RuntimeException("Transform failed for class: [" + clazz.getName() + "]", ex);
+        }
+    }
+
+}
@@ -0,0 +1,46 @@
+package com.baeldung.instrumentation.application;
+
+import com.sun.tools.attach.VirtualMachine;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.util.Optional;
+
+/**
+ * Created by adi on 6/10/18.
+ */
+public class AgentLoader {
+    private static Logger LOGGER = LoggerFactory.getLogger(AgentLoader.class);
+
+    public static void run(String[] args) {
+        String agentFilePath = "/home/adi/Desktop/agent-1.0.0-jar-with-dependencies.jar";
+        String applicationName = "MyAtmApplication";
+
+        //iterate all jvms and get the first one that matches our application name
+        Optional<String> jvmProcessOpt = Optional.ofNullable(VirtualMachine.list()
+          .stream()
+          .filter(jvm -> {
+              LOGGER.info("jvm:{}", jvm.displayName());
+              return jvm.displayName().contains(applicationName);
+          })
+          .findFirst().get().id());
+
+        if(!jvmProcessOpt.isPresent()) {
+            LOGGER.error("Target Application not found");
+            return;
+        }
+        File agentFile = new File(agentFilePath);
+        try {
+            String jvmPid = jvmProcessOpt.get();
+            LOGGER.info("Attaching to target JVM with PID: " + jvmPid);
+            VirtualMachine jvm = VirtualMachine.attach(jvmPid);
+            jvm.loadAgent(agentFile.getAbsolutePath());
+            jvm.detach();
+            LOGGER.info("Attached to target JVM and loaded Java agent successfully");
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}
@@ -0,0 +1,14 @@
+package com.baeldung.instrumentation.application;
+
+/**
+ * Created by adi on 6/14/18.
+ */
+public class Launcher {
+    public static void main(String[] args) throws Exception {
+        if(args[0].equals("StartMyAtmApplication")) {
+            new MyAtmApplication().run(args);
+        } else if(args[0].equals("LoadAgent")) {
+            new AgentLoader().run(args);
+        }
+    }
+}
--- a/Show More
+++ b/Show More