同过增强Connection类[重写了close的方法]实现的从连接池取出连
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2022-05-18 09:40:32
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package tk.dong.connection.util;import java.io.IOException;import java.io.InputStream;import java.io.PrintWriter;import java.sql.Array;import java.sql.Blob;import java.sql.CallableStatement;import java.sql.Clob;import java.sql.Connection;i
package tk.dong.connection.util; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.sql.Array; import java.sql.Blob; import java.sql.CallableStatement; import java.sql.Clob; import java.sql.Connection; import java.sql.DatabaseMetaData; import java.sql.DriverManager; import java.sql.NClob; import java.sql.PreparedStatement; import java.sql.SQLClientInfoException; import java.sql.SQLException; import java.sql.SQLFeatureNotSupportedException; import java.sql.SQLWarning; import java.sql.SQLXML; import java.sql.Savepoint; import java.sql.Statement; import java.sql.Struct; import java.util.LinkedList; import java.util.Map; import java.util.Properties; import java.util.concurrent.Executor; import java.util.logging.Logger; import javax.sql.DataSource; //这是同过增强Connection类[重写了close的方法]实现的从连接池取出连接并放回连接 public class JdbcPool implements DataSource { // 创建连接池,用的是LinkList, private static LinkedList测试代码connections = new LinkedList (); // 通过静态初始化块创建,当程序进行初始化的时候就会触发 static { // 将连接数据库的配置文件读入到流中 InputStream inStream = JdbcPool.class.getClassLoader().getResourceAsStream( "jdbc.properties"); Properties properties = new Properties(); try { properties.load(inStream); // 获取连接数据库的驱动(根据property属性文件中的属性获取驱动) Class.forName(properties.getProperty("driverClassName")); for (int i = 0; i 0){ //取出链表中的第一个对象赋值给临时的连接对象 conn=connections.removeFirst(); System.out.println("又一个连接对象被拿走:::::::连接池还有"+connections.size()+"个连接对象"); } return conn; } @Override public Connection getConnection(String username, String password) throws SQLException { // TODO Auto-generated method stub return null; } @Override public PrintWriter getLogWriter() throws SQLException { // TODO Auto-generated method stub return null; } @Override public void setLogWriter(PrintWriter out) throws SQLException { // TODO Auto-generated method stub } @Override public void setLoginTimeout(int seconds) throws SQLException { // TODO Auto-generated method stub } @Override public int getLoginTimeout() throws SQLException { // TODO Auto-generated method stub return 0; } @Override public Logger getParentLogger() throws SQLFeatureNotSupportedException { // TODO Auto-generated method stub return null; } @Override public T unwrap(Class iface) throws SQLException { // TODO Auto-generated method stub return null; } @Override public boolean isWrapperFor(Class> iface) throws SQLException { // TODO Auto-generated method stub return false; } } // 增强的Connection 连接对类 // 装饰器模式 // 1.首先看需要被增强对象继承了什么接口或父类,编写一个类也去继承这些接口或父类。 class MyConnection implements Connection { // 2.在类中定义一个变量,变量类型即需增强对象的类型。 // 用来接收连接池 private LinkedList connections; // 用来接收连接对象 private Connection conn; // 构造器为 public MyConnection(Connection conn, LinkedList connections) { this.conn = conn; this.connections = connections; } // 我只用到这个方法所以我只写这个方法 @Override public void close() throws SQLException { // 将不用的连接再次放入连接池 connections.add(conn); System.out.println("有一个连接对象用完了,已经返回连接池,现在连接池中还有==="+connections.size()); } // 下面的方法用不到,所以就不写内容了 @Override public T unwrap(Class iface) throws SQLException { // TODO Auto-generated method stub return null; } @Override public boolean isWrapperFor(Class> iface) throws SQLException { // TODO Auto-generated method stub return false; } @Override public Statement createStatement() throws SQLException { // TODO Auto-generated method stub return null; } @Override public PreparedStatement prepareStatement(String sql) throws SQLException { // TODO Auto-generated method stub return null; } @Override public CallableStatement prepareCall(String sql) throws SQLException { // TODO Auto-generated method stub return null; } @Override public String nativeSQL(String sql) throws SQLException { // TODO Auto-generated method stub return null; } @Override public void setAutoCommit(boolean autoCommit) throws SQLException { // TODO Auto-generated method stub } @Override public boolean getAutoCommit() throws SQLException { // TODO Auto-generated method stub return false; } @Override public void commit() throws SQLException { // TODO Auto-generated method stub } @Override public void rollback() throws SQLException { // TODO Auto-generated method stub } @Override public boolean isClosed() throws SQLException { // TODO Auto-generated method stub return false; } @Override public DatabaseMetaData getMetaData() throws SQLException { // TODO Auto-generated method stub return null; } @Override public void setReadOnly(boolean readOnly) throws SQLException { // TODO Auto-generated method stub } @Override public boolean isReadOnly() throws SQLException { // TODO Auto-generated method stub return false; } @Override public void setCatalog(String catalog) throws SQLException { // TODO Auto-generated method stub } @Override public String getCatalog() throws SQLException { // TODO Auto-generated method stub return null; } @Override public void setTransactionIsolation(int level) throws SQLException { // TODO Auto-generated method stub } @Override public int getTransactionIsolation() throws SQLException { // TODO Auto-generated method stub return 0; } @Override public SQLWarning getWarnings() throws SQLException { // TODO Auto-generated method stub return null; } @Override public void clearWarnings() throws SQLException { // TODO Auto-generated method stub } @Override public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return null; } @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return null; } @Override public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return null; } @Override public Map > getTypeMap() throws SQLException { // TODO Auto-generated method stub return null; } @Override public void setTypeMap(Map > map) throws SQLException { // TODO Auto-generated method stub } @Override public void setHoldability(int holdability) throws SQLException { // TODO Auto-generated method stub } @Override public int getHoldability() throws SQLException { // TODO Auto-generated method stub return 0; } @Override public Savepoint setSavepoint() throws SQLException { // TODO Auto-generated method stub return null; } @Override public Savepoint setSavepoint(String name) throws SQLException { // TODO Auto-generated method stub return null; } @Override public void rollback(Savepoint savepoint) throws SQLException { // TODO Auto-generated method stub } @Override public void releaseSavepoint(Savepoint savepoint) throws SQLException { // TODO Auto-generated method stub } @Override public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return null; } @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return null; } @Override public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return null; } @Override public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException { // TODO Auto-generated method stub return null; } @Override public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException { // TODO Auto-generated method stub return null; } @Override public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException { // TODO Auto-generated method stub return null; } @Override public Clob createClob() throws SQLException { // TODO Auto-generated method stub return null; } @Override public Blob createBlob() throws SQLException { // TODO Auto-generated method stub return null; } @Override public NClob createNClob() throws SQLException { // TODO Auto-generated method stub return null; } @Override public SQLXML createSQLXML() throws SQLException { // TODO Auto-generated method stub return null; } @Override public boolean isValid(int timeout) throws SQLException { // TODO Auto-generated method stub return false; } @Override public void setClientInfo(String name, String value) throws SQLClientInfoException { // TODO Auto-generated method stub } @Override public void setClientInfo(Properties properties) throws SQLClientInfoException { // TODO Auto-generated method stub } @Override public String getClientInfo(String name) throws SQLException { // TODO Auto-generated method stub return null; } @Override public Properties getClientInfo() throws SQLException { // TODO Auto-generated method stub return null; } @Override public Array createArrayOf(String typeName, Object[] elements) throws SQLException { // TODO Auto-generated method stub return null; } @Override public Struct createStruct(String typeName, Object[] attributes) throws SQLException { // TODO Auto-generated method stub return null; } @Override public void setSchema(String schema) throws SQLException { // TODO Auto-generated method stub } @Override public String getSchema() throws SQLException { // TODO Auto-generated method stub return null; } @Override public void abort(Executor executor) throws SQLException { // TODO Auto-generated method stub } @Override public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException { // TODO Auto-generated method stub } @Override public int getNetworkTimeout() throws SQLException { // TODO Auto-generated method stub return 0; } }
package tk.dong.connectionPool.test; import java.sql.Connection; import java.sql.SQLException; import org.junit.Test; import tk.dong.connection.util.JdbcPool; public class TestJdbcPool { @Test public void jdbcPool() throws SQLException { // 创建连接池对象 JdbcPool jdbcPool = new JdbcPool(); // 从连接池中获取连接对象 jdbcPool.getConnection(); // 多次获取连接对象 jdbcPool.getConnection(); jdbcPool.getConnection(); Connection conn = jdbcPool.getConnection(); // 归还用完的连接对象 conn.close(); // 再次获取连接对象 jdbcPool.getConnection(); jdbcPool.getConnection(); jdbcPool.getConnection(); jdbcPool.getConnection(); } }测试输出结果
连接池已经加入了::::::::::1::::::::::个链接对象 连接池已经加入了::::::::::2::::::::::个链接对象 连接池已经加入了::::::::::3::::::::::个链接对象 连接池已经加入了::::::::::4::::::::::个链接对象 连接池已经加入了::::::::::5::::::::::个链接对象 连接池已经加入了::::::::::6::::::::::个链接对象 连接池已经加入了::::::::::7::::::::::个链接对象 连接池已经加入了::::::::::8::::::::::个链接对象 连接池已经加入了::::::::::9::::::::::个链接对象 连接池已经加入了::::::::::10::::::::::个链接对象 又一个连接对象被拿走:::::::连接池还有9个连接对象 又一个连接对象被拿走:::::::连接池还有8个连接对象 又一个连接对象被拿走:::::::连接池还有7个连接对象 又一个连接对象被拿走:::::::连接池还有6个连接对象 有一个连接对象用完了,已经返回连接池,现在连接池中还有===7 又一个连接对象被拿走:::::::连接池还有6个连接对象 又一个连接对象被拿走:::::::连接池还有5个连接对象 又一个连接对象被拿走:::::::连接池还有4个连接对象 又一个连接对象被拿走:::::::连接池还有3个连接对象