万变不离其宗。。持久层怎么变也是JDBC，框架怎么新也是反射机制。。

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今天刚好复习一下JDBC，顺便对MySql进行一个入门的学习。

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环境：MySql 5.5 + Navicat for MySql 10.0.5 + MyEclipse 9.0

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从MySql官方：http://www.mysql.com/?下载了 mysql-connector-java-5.1.17-bin.jar

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从MyEclipse的DB Browser中得到测试成功后的

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驱动类：com.mysql.jdbc.Driver

链接URL：jdbc:mysql://localhost:3306/accp

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准备的差不多了，实例就是 简单粗暴，直接有效 直接上代码。。

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---------------------------------------我是华丽的无所不在的分割线-------------------------------------------

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用户实体类：

package com.accp.jdbc.entity;

/**
 * 
 * @author Maxpin on 2011-10-04
 * 
 *         用户实体类
 */
public class Userinfo {
	private int userid; // 编号
	private String loginid; // 用户名
	private String loginpwd; // 密码
	private String username; // 姓名

	/**
	 * 构造方法
	 */
	public Userinfo() {
	}

	/**
	 * @param loginid
	 * @param loginpwd
	 * @param username
	 */
	public Userinfo(String loginid, String loginpwd, String username) {
		this.loginid = loginid;
		this.loginpwd = loginpwd;
		this.username = username;
	}

	/**
	 * @param userid
	 * @param loginid
	 * @param loginpwd
	 * @param username
	 */
	public Userinfo(int userid, String loginid, String loginpwd, String username) {
		this.userid = userid;
		this.loginid = loginid;
		this.loginpwd = loginpwd;
		this.username = username;
	}

	//getter & setter methods 略?

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Dao基类：包含了数据库链接、关闭、CRUD操作及MySql分页查询

package com.accp.jdbc.base;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.accp.jdbc.entity.Userinfo;

/**
 * 
 * @author Maxpin on 2011-10-04
 * 
 *         Dao基类：包含了数据库链接、关闭、CRUD操作及MySql分页查询
 */
public class BaseDao {

	// 连接地址
	private static final String url = "jdbc:mysql://localhost:3306/accp";
	// 驱动类
	private static final String driverClass = "com.mysql.jdbc.Driver";
	// 用户名
	private static final String uname = "root";
	// 密码
	private static final String pwd = "admin";

	/**
	 * 获取数据库连接
	 * 
	 * @return 连接对象
	 */
	protected static Connection getConnection() {
		Connection conn = null;
		try {
			Class.forName(driverClass);
			conn = DriverManager.getConnection(url, uname, pwd);
		} catch (ClassNotFoundException e) {
			System.out.println("找不到驱动类");
		} catch (SQLException e) {
			System.out.println("建立连接错误！");
		}
		return conn;
	}

	/**
	 * 关闭数据库连接
	 * 
	 * @param conn
	 *            数据库连接
	 * @param rs
	 *            结果集
	 * @param pstmt
	 *            命令对象
	 */
	public static void closeAll(Connection conn, ResultSet rs, Statement pstmt) {
		try {
			if (null != rs && !rs.isClosed()) {
				rs.close();
				rs = null;
			}
		} catch (SQLException e) {
			System.out.println("关闭结果集出错！");
		}
		try {
			if (null != pstmt && !pstmt.isClosed()) {
				pstmt.close();
				pstmt = null;
			}
		} catch (SQLException e) {
			System.out.println("关闭命令对象出错！");
		}
		try {
			if (null != conn && !conn.isClosed()) {
				conn.close();
				conn = null;
			}
		} catch (SQLException e) {
			System.out.println("关闭链接出错");
		}
	}

	/**
	 * 保存指定用户信息
	 * 
	 * @param user
	 *            用户对象
	 * @throws Exception
	 *             抛出异常
	 */
	public static void saveUserinfo(Userinfo user) throws Exception {
		if (null != user) {
			Connection conn = getConnection();
			PreparedStatement pstmt = null;
			String sql = "insert into USERINFO values(null,?,?,?)";
			try {
				pstmt = conn.prepareStatement(sql);
				pstmt.setString(1, user.getLoginid());
				pstmt.setString(2, user.getLoginpwd());
				pstmt.setString(3, user.getUsername());
				pstmt.executeUpdate();
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				closeAll(conn, null, pstmt);
			}
		} else {
			throw new Exception("用户信