JDBC连接MYSQL,JDBC增删改查 经典 范例

一切详情请看代码：绝对经典，注视写的很清楚

package cn.csdn.dao;import java.util.List;import cn.csdn.domain.User;public interface UserDao {	boolean insert(User entity);	boolean checkUser(String name);	public boolean delete(User entity);	public boolean update(User entity);	User findById(Integer id);	List findAll();}
package cn.csdn.dao;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;import cn.csdn.domain.User;public class UserDaoImpl implements UserDao{	/*声明操作数据的对象*/	private static Connection conn;	private PreparedStatement pstmt;	private ResultSet rs;	/*静态块*/	static{		/*准备驱动程序,加载驱动*/		try {			Class.forName("com.mysql.jdbc.Driver");			/*面试必考题*/			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/job?user=root&password=admin&useUnicode=true&characterEncoding=UTF-8");			} catch (ClassNotFoundException e) {			// TODO Auto-generated catch block			e.printStackTrace();		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}					}		@Override	public boolean checkUser(String name) {		/*第一步：声明返回变量*/		boolean flag=false;		/*第二步：获取连接对象 conn */		/*第三步：定义sql语句 "select * from user where name='"+name+"'";*/		String sql = "select * from user where name=?";				try {			/*第四步：根据sql语句创建预处理对象*/			pstmt = conn.prepareStatement(sql);			/*第五步：为站位符 赋值*/			int index = 1;			pstmt.setString(index++, name);			/*第六步:执行查询*/			rs = pstmt.executeQuery();			/*第七步:判断*/			if(rs.next()){				flag = true;			}					} catch (SQLException e) {			e.printStackTrace();		}		/*第八步：关闭*/		if(rs!=null){			try {				rs.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(pstmt!=null){			try {				pstmt.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(conn!=null){			try {				conn.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}		return flag;	}	@Override	public boolean insert(User entity) {		/*第一步：声明返回变量*/		boolean flag=false;		/*第二步：获取连接对象 conn */		/*第三步：定义sql语句 ;insert  into user(name,sex,age)values('"+entity.getName()+"','"+entity.getSex()+"',"+entity.getAge()+");"*/		String sql = "insert  into user(name,sex,age)values(?,?,?);";				try {			/*第四步：根据sql语句创建预处理对象*/			pstmt = conn.prepareStatement(sql);			/*第五步：为站位符 赋值*/			int index = 1;			pstmt.setObject(index++, entity.getName());			pstmt.setObject(index++, entity.getSex());			pstmt.setObject(index++, entity.getAge());			/*第六步:执行更新*/			int i = pstmt.executeUpdate();			/*第七步:判断*/			if(i>0){				flag = true;			}					} catch (SQLException e) {			e.printStackTrace();		}		/*第八步：关闭*/				if(pstmt!=null){			try {				pstmt.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(conn!=null){			try {				conn.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}		/*记得一定要把返回的值，修改成返回的变量*/		return flag;	}	@Override	public boolean delete(User entity) {		/*第一步：声明返回变量*/		boolean flag=false;		/*第二步：获取连接对象 conn */		/*第三步：定义sql语句 ;insert  into user(name,sex,age)values('"+entity.getName()+"','"+entity.getSex()+"',"+entity.getAge()+");"*/		String sql = "delete from user where id=?";				try {			/*第四步：根据sql语句创建预处理对象*/			pstmt = conn.prepareStatement(sql);			/*第五步：为站位符 赋值*/			int index = 1;			pstmt.setInt(index++, entity.getId());			/*第六步:执行更新*/			int i = pstmt.executeUpdate();			/*第七步:判断*/			if(i>0){				flag = true;			}					} catch (SQLException e) {			e.printStackTrace();		}		/*第八步：关闭*/				if(pstmt!=null){			try {				pstmt.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(conn!=null){			try {				conn.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}		/*记得一定要把返回的值，修改成返回的变量*/		return flag;	}	public static void main(String[] args) {		/*看明白了嘛*/		UserDao userDao = new UserDaoImpl();		/*boolean flag = userDao.checkUser("redarmy");		if(flag){			System.out.println("用户名已经被占用了");		}else{			System.out.println("用户名还没有被使用,你可以使用此用户名");		}*/				/*boolean flag = userDao.insert(new User(null, "红军12", "男", 20));		if(flag){			System.out.println("注册成功");		}else{			System.out.println("注册失败");		}*/				/*List users = userDao.findAll();		for (int i = 0; i < users.size(); i++) {			User entity = (User) users.get(i);			System.out.println(entity.getId()+"  "+entity.getName());		}*/				//userDao.update(new User(7,"孙悟空","女",10000));		User entity = userDao.findById(7);        System.out.println(entity.getId()+"  "+entity.getName());					}	@Override	public List findAll() {		/*第一步:定义返回结果*/		List allentities = new ArrayList();		/*第二步:获取连接对象*/		/*第三步：定义sql语句*/		String sql ="select * from user";		try {			/*第四步：根据sql语句创建预处理对象*/			pstmt = conn.prepareStatement(sql);			/*第五步：为站位符 赋值*/								/*第六步:执行查询*/			rs = pstmt.executeQuery();			/*第七步:判断*/			while(rs.next()){				User entity = new User();				entity.setId(rs.getInt("id"));				entity.setName(rs.getString("name"));				entity.setSex(rs.getString("sex"));				entity.setAge(rs.getInt("age"));				allentities.add(entity);			}					} catch (SQLException e) {			e.printStackTrace();		}		/*第八步：关闭*/		if(rs!=null){			try {				rs.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(pstmt!=null){			try {				pstmt.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(conn!=null){			try {				conn.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}		return allentities;	}				@Override	public boolean update(User entity) {		/*第一步：声明返回变量*/		boolean flag=false;		/*第二步：获取连接对象 conn */		/*第三步：定义sql语句 ;insert  into user(name,sex,age)values('"+entity.getName()+"','"+entity.getSex()+"',"+entity.getAge()+");"*/		String sql = "update user set name=?,sex=?,age=? where id=?";				try {			/*第四步：根据sql语句创建预处理对象*/			pstmt = conn.prepareStatement(sql);			/*第五步：为站位符 赋值*/			int index = 1;			pstmt.setObject(index++, entity.getName());			pstmt.setObject(index++, entity.getSex());			pstmt.setObject(index++, entity.getAge());			pstmt.setInt(index++, entity.getId());			/*第六步:执行更新*/			int i = pstmt.executeUpdate();			/*第七步:判断*/			if(i>0){				flag = true;			}					} catch (SQLException e) {			e.printStackTrace();		}		/*第八步：关闭*/				if(pstmt!=null){			try {				pstmt.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(conn!=null){			try {				conn.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}		/*记得一定要把返回的值，修改成返回的变量*/		return flag;	}	@Override	public User findById(Integer id) {		/*第一步:定义返回结果*/		User entity = new User();		/*第二步:获取连接对象*/		/*第三步：定义sql语句*/		String sql ="select * from user where id=?";		try {			/*第四步：根据sql语句创建预处理对象*/			pstmt = conn.prepareStatement(sql);			/*第五步：为站位符 赋值*/			int index = 1;			pstmt.setInt(index++, id);			/*第六步:执行查询*/			rs = pstmt.executeQuery();			/*第七步:判断*/			if(rs.next()){								entity.setId(rs.getInt("id"));				entity.setName(rs.getString("name"));				entity.setSex(rs.getString("sex"));				entity.setAge(rs.getInt("age"));							}					} catch (SQLException e) {			e.printStackTrace();		}		/*第八步：关闭*/		if(rs!=null){			try {				rs.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(pstmt!=null){			try {				pstmt.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				if(conn!=null){			try {				conn.close();			} catch (SQLException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}		return entity;	}}
package cn.csdn.domain;import java.io.Serializable;/*业务Bean*/public class User implements Serializable{	/**	 * 	 */	private static final long serialVersionUID = 2646300928284173726L;	/**递增序列*/	private Integer id;	/**姓名*/	private String name;	/*性别*/	private String sex;	/*年龄*/	private Integer age;	public User() {		super();		// TODO Auto-generated constructor stub	}	public User(Integer id, String name, String sex, Integer age) {		super();		this.id = id;		this.name = name;		this.sex = sex;		this.age = age;	}	public Integer getId() {		return id;	}	public void setId(Integer id) {		this.id = id;	}	public String getName() {		return name;	}	public void setName(String name) {		this.name = name;	}	public String getSex() {		return sex;	}	public void setSex(String sex) {		this.sex = sex;	}	public Integer getAge() {		return age;	}	public void setAge(Integer age) {		this.age = age;	}		}





----------------代码源自于redarmychen