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(); }<pre class="java" name="code">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; } } </pre> 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