数据库连接池的创建与运用

//数据库连接池，用集合保存一大批connection,用户-servlet-dao-db
//-->改为用户-servlet-dao-connectionpool--db
public class jdbcpool implements DataSource {

	//连接池里面先保存多个连接，供dao取出连接，要增删改查连接用linkedlist
	private static LinkedList<Connection>list=new LinkedList<Connection>();
	
	static{
		Properties p=new Properties();
		InputStream in=jdbcpool.class.getClassLoader().getResourceAsStream("db.properties");
		try {
			p.load(in);
			for(int i=0;i<10;i++)//为数据库创建10个连接，放到连接池
			{
				Class.forName(p.getProperty("driver"));
				Connection con=DriverManager.getConnection(p.getProperty("url"), p.getProperty("username"), p.getProperty("password"));
				list.add(con);
			}
		}  catch (Exception e) {
			e.printStackTrace();
		}
	}
	@Override
	public Connection getConnection() throws SQLException {

		//从连接池里面取出数据
		if(list.size()<=0)
		{
			throw new RuntimeException();
		}
		Connection con=list.removeFirst();
		//每次都移除第一个连接，连接池里减少一个，相当于取出了一个连接
		
		//conn.Close();这样释放资源的话只会释放到数据库中，不会释放到连接池中
		//相当于我们可以增强con.close()方法，当close()的时候，归还到连接池中去
		
		MyConnection my=new MyConnection(con);
	
		return my;
	}
	//增强方法有3种方法
	//1:写一个connction子类，覆盖close()方法，增强close()方法
	//2:用包装设计模式
	//3:动态代理
	

	//使用包装设计模式增强才，close()方法，包装设计模式步奏
		/*
		 * 1:定义一个类，实现与增强相同的接口
		 * 2:在类中定义一个变量，记住被增强对象
		 * 3:定义一个构造函数，接受被增强对象
		 * 4:覆盖想增强方法
		 * 5:对于不想增强的方法，直接调用目标对象的方法
		 */
		class MyConnection implements Connection
		{
			private Connection con;
			public MyConnection(Connection con)
			{
				this.con=con;
			}
			@Override
			public void close() throws SQLException {

		
				list.add(con);//释放数据库资源的时候，直接释放到连接池中去
				
			}

		@Override
		public <T> T unwrap(Class<T> 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 this.con.prepareStatement(sql);
		}

		@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<String, Class<?>> getTypeMap() throws SQLException {
			// TODO Auto-generated method stub
			return null;
		}

		@Override
		public void setTypeMap(Map<String, Class<?>> 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 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 <T> T unwrap(Class<T> 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;
	}
}

　　

package com.mysql;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import org.junit.Test;

public class insertData {

	@Test
	public void testInsert() throws SQLException 
	{
		Connection con=null;
		try{
		jdbcpool p=new jdbcpool();
		con=p.getConnection();
		String sql="insert into login value('jack','456')";
		PreparedStatement ps=con.prepareStatement(sql);
		int i=ps.executeUpdate();
		if(i>0)
		{
			System.out.println("insert success");
		}
		}
		catch (Exception e) {
		}
		finally{
			con.close();//释放资源到连接池
		}
		
	}
}