工具类--JDBCUtils

工具类–JDBCUtils

1、代码

public class JDBCUtils {
	private static ComboPooledDataSource ds = new ComboPooledDataSource();
	private static ThreadLocal<Connection> tl=new ThreadLocal<>();
	public static Connection getConnection() throws SQLException {
		//从线程中获取conneciton
		Connection conn = tl.get();
		if(conn==null){
			conn=ds.getConnection();
			//和当前线程绑定
			tl.set(conn);
		}
		return conn;
	}
	// 获取数据源
	public static DataSource getDataSource() {
		return ds;
	}
	// 释放资源
	public static void closeResource( Statement st, ResultSet rs) {
		closeResultSet(rs);
		closeStatement(st);
	}
	
	// 释放资源
	public static void closeResource(Connection conn, Statement st, ResultSet rs) {
		closeResource(st, rs);
		closeConn(conn);
	}

	// 释放 connection
	public static void closeConn(Connection conn) {
		if (conn != null) {
			try {
				conn.close();
				//和线程解绑
				tl.remove();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			conn = null;
		}
	}
	public static void closeStatement(Statement st) {
		if (st != null) {
			try {
				st.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			st = null;
		}
	}
	public static void closeResultSet(ResultSet rs) {
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			rs = null;
		}
	}

	public static void startTransaction() throws SQLException{
		getConnection().setAutoCommit(false);
	}
	public static void commitAndClose(){
		Connection conn = null;
		try {
			conn=getConnection();
			//事务提交
			conn.commit();
			//关闭资源
			conn.close();
			//解除版定
			tl.remove();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
	public static void rollbackAndClose(){
		Connection conn = null;
		try {
			conn=getConnection();
			//事务回滚
			conn.rollback();
			//关闭资源
			conn.close();
			//解除版定
			tl.remove();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
}

2、c3p0-config.xml
(1)代码

<c3p0-config>
	<default-config>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/kunkun</property>
		<property name="user">root</property>
		<property name="password">admin</property>
		<property name="checkoutTimeout">30000</property>
		<property name="idleConnectionTestPeriod">30</property>
		<property name="initialPoolSize">10</property>
		<property name="maxIdleTime">30</property>
		<property name="maxPoolSize">100</property>
		<property name="minPoolSize">10</property>
		<property name="maxStatements">200</property>
		<user-overrides user="test-user">
			<property name="maxPoolSize">10</property>
			<property name="minPoolSize">1</property>
			<property name="maxStatements">0</property>
		</user-overrides>
	</default-config> 
	<named-config name="itcast">
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/kunkun</property>
		<property name="user">root</property>
		<property name="password">admin</property>
		<property name="acquireIncrement">5</property>
		<property name="initialPoolSize">20</property>
		<property name="minPoolSize">10</property>
		<property name="maxPoolSize">40</property>
		<property name="maxStatements">0</property>
		<property name="maxStatementsPerConnection">5</property>
	</named-config>
</c3p0-config>

(2)必须有默认配置，否则不能成功连接数据库

3、注意
连接数据库后可以进行测试，测试是否可以正常连接数据库