数据库：

create table t1(id int primary key not null auto_increment,name varchar(32),password varchar(32));

insert into t1(name,password) values('admin','123');
insert into t1(name,password) values('zhangsan','123');
insert into t1(name,password) values('lisi','123');

Java代码：

mysqlDao.java：

package com.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import org.junit.Test;

public class mysqlDao {
	
	private static String driver="com.mysql.jdbc.Driver";     //驱动
	private String url="jdbc:mysql://localhost:3306/test";    //数据库连接地址
	private String user="root";     //数据库账户
	private String password="11";      //数据库密码
	
	private Connection connection=null;      //连接
	private Statement stmt=null;      //声明
	private ResultSet rs=null;     //结果集
	
	private int i=-1;
	
	/*
	 * 创建驱动
	 * */
	static{
		try {
			Class.forName(driver);
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	/*
	 * 加载驱动
	 * */
	@Test
	public void connect() {
		// TODO Auto-generated method stub
		try {
			
			connection=DriverManager.getConnection(url, user, password);
			
			if(connection!=null){
				System.out.println("数据库连接成功！");
			}else{
				System.out.println("数据库连接失败！");
			}
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	/*
	 * 执行sql语句
	 * */
	public void doSql(String sql) {
		// TODO Auto-generated method stub
		
		System.out.println("This Is mysqlDao.doSql() Method!");
		
		if(sql!=null){
			connect();
			
			try {
				
				stmt=connection.createStatement();
				stmt.execute(sql);
				
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
		
	}
	
	/*
	 * 获取影响行数
	 * */
	public int getUpCount() {
		// TODO Auto-generated method stub
		
		try {
			i=stmt.getUpdateCount();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return i;
	}
	
	/*
	 * 获取结果集
	 * */
	public ResultSet getRs() {
		
		try {
			rs=stmt.getResultSet();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return rs;
	}
	
	/*
	 * 执行关闭方法
	 * */
	public void close() {
		// TODO Auto-generated method stub
		
			try {
				if(rs!=null){
				rs.close();
				}
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}finally{
				
					try {
						
						if(stmt!=null){
						stmt.close();
						}
					} catch (SQLException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}finally{
						if(connection!=null){
							try {
								connection.close();
							} catch (SQLException e) {
								// TODO Auto-generated catch block
								e.printStackTrace();
							}
						}
					}
				}
				
	}

}