initial structure and tests

logging-modules/logging-techniques/src/main/java/com/baeldung/structuredlogging/User.java

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+package com.baeldung.structuredlogging;
+
+public class User {
+
+    private String id;
+    private String name;
+    private String password;
+
+    public User(String id, String name, String password) {
+        this.id = id;
+        this.name = name;
+        this.password = password;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+}

logging-modules/logging-techniques/src/main/resources/logback.xml

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+<configuration>
+    <appender name="jsonConsoleAppender" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder class="net.logstash.logback.encoder.LogstashEncoder">
+            <includeCallerData>true</includeCallerData>
+            <jsonGeneratorDecorator class="net.logstash.logback.decorate.CompositeJsonGeneratorDecorator">
+                <decorator class="net.logstash.logback.decorate.PrettyPrintingJsonGeneratorDecorator"/>
+                <decorator class="net.logstash.logback.mask.MaskingJsonGeneratorDecorator">
+                    <defaultMask>XXXX</defaultMask>
+                    <path>password</path>
+                </decorator>
+            </jsonGeneratorDecorator>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="jsonConsoleAppender"/>
+    </root>
+
+</configuration>

logging-modules/logging-techniques/src/test/java/StructuredLog4jExampleUnitTest.java

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+
+import com.baeldung.structuredlogging.User;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static net.logstash.logback.argument.StructuredArguments.kv;
+
+public class StructuredLog4jExampleUnitTest {
+
+    Logger logger = LoggerFactory.getLogger("logger_name_example");
+
+    @Test
+    void whenInfoLoggingData_thenFormatItCorrectly() {
+        User user = new User("1", "John Doe", "123456");
+
+        logger.atInfo().setMessage("Processed user succesfully")
+                .addKeyValue("user_info", user)
+                .log();
+    }
+
+    @Test
+    void givenStructuredLog_whenUseLog4j_thenExtractCorrectInformation() {
+        User user = new User("1", "John Doe", "123456");
+
+        try {
+            throwExceptionMethod();
+        } catch (RuntimeException ex) {
+            logger.atError().addKeyValue("user_info", user)
+                    .setMessage("Error processing given user")
+                    .addKeyValue("exception_class", ex.getClass().getSimpleName())
+                    .addKeyValue("error_message", ex.getMessage())
+                    .log();
+        }
+    }
+
+    private void throwExceptionMethod() {
+        throw new RuntimeException("Error saving user data", new AssertionError());
+    }
+}

logging-modules/logging-techniques/src/test/resources/log4j.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="INFO">
+    <Appenders>
+        <Console name="ConsoleAppender" target="SYSTEM_OUT">
+            <JsonLayout compact="true" eventEol="true" objectMessageAsJsonObject="true" properties="true"/>
+        </Console>
+    </Appenders>
+
+    <Loggers>
+        <Root level="INFO">
+            <AppenderRef ref="stdout"/>
+        </Root>
+    </Loggers>
+</Configuration>