BAEL-1818 - A Guide to Connection Pools in Java (#4735)

* Strange git issue with README.MD, wouldn't revert the file * Initial Commit * Initial Commit * Update pom.xml * Update pom.xml * Initial Commit * Update pom.xml * Update source files * Update source files * Update source files * Update source files * Update Application.java * Update pom.xml * Update HikariCPDataSourceUnitTest class * Update HikariCPDataSourceUnitTest.java * Update pom.xml * Update unit test classes * Update BasicConnectionPoolUnitTest.java * Fix indentation in DBCDDataSource class * Update DBCPDataSource.java * Update BasicConnectionPool class * Update BasicConnectionPool class * Update BasicConnectionPool.java * Update BasicConnectionPool.java * Update pom.xml * Update pom.xml * BAEL-1818 Refactored getConnection(), added shutdown(), cleaned up pom.xml * BAEL-1818 Removed getConnectionPool(), upgraded c3po version * BAEL-1818 Deleted obsolete connectionpool module * BAEL-1818 Deleted obsolete connectionpool module
2018-07-20 20:28:01 -03:00
parent 86daa854d2
commit ac801b4319
10 changed files with 328 additions and 5 deletions
@@ -0,0 +1,87 @@
+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.size() == 0) {
+            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 {
+        for (Connection c : usedConnections) {
+            this.releaseConnection(c);
+        }
+        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(){}
+}