java常用工具类之数据库连接类（可以连接多种数据库）

依赖包下载：http://xiazai.jb51.net/201407/tools/java-db-dependency(jb51.net).rar

数据库连接类源码：

package com.itjh.javaUtil;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetmetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.dbcp.ConnectionFactory;
import org.apache.commons.dbcp.DriverManagerConnectionFactory;
import org.apache.commons.dbcp.PoolableConnectionFactory;
import org.apache.commons.dbcp.PoolingDriver;
import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.pool.ObjectPool;
import org.apache.commons.pool.impl.GenericObjectPool;



public class DBUtil {

	private String dri = null;
	private String url = null;
	private String username = null;
	private String password = null;
	private String poolName = null; // 连接池名称
	private ObjectPool connectionPool = null; // 连接池
	// 对应的定时查询类
	private QueryThread queryThread = null;

	
	public DBUtil(String dri, String url, String userName, String password,
			String poolName) {
		this.dri = dri;
		this.url = url;
		this.username = userName;
		this.password = password;
		this.poolName = poolName;
	}

	
	public int execute(Connection conn, PreparedStatement pstm)
			throws SQLException {
		try {
			return pstm.executeUpdate();
		} finally {
			Close(conn);
		}
	}

	
	public List> query(Connection conn,
			PreparedStatement pstm) throws SQLException {
		try {
			return resultSetToList(pstm.executeQuery());
		} finally {
			Close(conn);
		}
	}

	
	private List> resultSetToList(ResultSet rs)
			throws java.sql.SQLException {
		if (rs == null)
			return Collections.EMPTY_LIST;

		ResultSetmetaData md = rs.getmetaData(); // 得到结果集(rs)的结构信息，比如字段数、字段名等
		int columnCount = md.getColumnCount(); // 返回此 ResultSet 对象中的列数
		List> list = new ArrayList>();
		Map rowData = new HashMap();
		while (rs.next()) {
			rowData = new HashMap(columnCount);
			for (int i = 1; i <= columnCount; i++) {
				rowData.put(md.getColumnName(i), rs.getObject(i));
			}
			list.add(rowData);
		}
		return list;
	}

	
	public List> query(String sql) throws SQLException {
		List> results = null;
		Connection conn = null;
		try {
			conn = getConnection();
			QueryRunner qr = new QueryRunner();
			results = qr.query(conn, sql, new MapListHandler());
		} finally {
			Close(conn);
		}
		return results;
	}

	
	public List> query(String sql, Object param)
			throws SQLException {
		List> results = null;
		Connection conn = null;
		try {
			conn = getConnection();
			QueryRunner qr = new QueryRunner();
			results = (List>) qr.query(conn, sql, param,
					new MapListHandler());
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			Close(conn);
		}
		return results;
	}

	
	public int execute(String sql) throws Exception {
		Connection conn = getConnection();
		int rows = 0;
		try {
			QueryRunner qr = new QueryRunner();
			rows = qr.update(conn, sql);
		} finally {
			Close(conn);
		}
		return rows;
	}

	
	public int execute(String sql, Object[] params) throws Exception {
		Connection conn = getConnection();
		int rows = 0;
		try {
			QueryRunner qr = new QueryRunner();
			rows = qr.update(conn, sql, params);
		} finally {
			Close(conn);
		}
		return rows;
	}

	
	public void Close(Connection conn) throws SQLException {
		if (conn != null) {
			conn.close();
		}
		DbUtils.closeQuietly(conn);
	}

	
	private void StartPool() {
		try {
			Class.forName(dri);
		} catch (ClassNotFoundException e1) {
			e1.printStackTrace();
		}
		if (connectionPool != null) {
			ShutdownPool();
		}
		try {
			connectionPool = new GenericObjectPool(null);
			ConnectionFactory connectionFactory = new DriverManagerConnectionFactory(
					url, username, password);
			PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(
					connectionFactory, connectionPool, null, "SELECT 1", false,
					true);
			Class.forName("org.apache.commons.dbcp.PoolingDriver");
			PoolingDriver driver = (PoolingDriver) DriverManager
					.getDriver("jdbc:apache:commons:dbcp:");
			driver.registerPool(poolName, poolableConnectionFactory.getPool());

		} catch (Exception e) {
			e.printStackTrace();
		}
		// 开启查询程序
		queryThread = new QueryThread(this);
		queryThread.start();
	}

	
	private void ShutdownPool() {
		try {
			PoolingDriver driver = (PoolingDriver) DriverManager
					.getDriver("jdbc:apache:commons:dbcp:");
			driver.closePool(poolName);
			// 关闭定时查询
			queryThread.setStartQuery(false);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	
	public synchronized Connection getConnection() {
		Connection conn = null;
		try {
			if (connectionPool == null)
				StartPool();
			conn = DriverManager.getConnection("jdbc:apache:commons:dbcp:"
					+ poolName);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return conn;
	}
}


class QueryThread extends Thread {

	private DBUtil dbUtil = null;
	// 是否开启查询
	private boolean startQuery = true;

	
	public QueryThread(DBUtil dbUtil) {
		this.dbUtil = dbUtil;
	}

	public void run() {
		while (true) {
			try {
				if (startQuery) {
					this.dbUtil.query("select 1");
				}
				// System.out.println(startQuery+"  123");
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				try {
					Thread.sleep(120000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}

	public void setStartQuery(boolean startQuery) {
		// System.out.println("startQuery shut:"+startQuery);
		this.startQuery = startQuery;
	}
}