基于mybatis的增删改查

基于mybatis的增删改查

上代码
1，创建User实体类，产生set，get，方法，实例化，toString

```java
public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", pwd='" + pwd + ''' +
                '}';
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
}

2,方法层UserDao`

```java
public interface UserDao {
    //模糊查询
    ListgetUserLike(String value);


    //查询全部用户
    List getUserList();
    //根据ID查询用户
    User getUserById(int id);
    
    User getUserById2(Mapmap);
    //增加用户
    int addUser(User user);
    //万能增加用户
    int addUser2(Mapmap);
    //修改用户
    int upDateUser(User user);
    //删除用户
    int deleteUser(int id);
}

3,在UserMapper.xml写出相应的SQL语句，供数据库调用

```java

    select * from  mybatis.user where name like #{value};


    select * from mybatis.user;


    
        select * from mybatis.user where id =#{2};
    
    
        select * from mybatis.user where id =#{id} ;
    
    
        insert into mybatis.user(id,name,pwd) values (#{id},#{name},#{pwd});
    
    
        insert into mybatis.user(id,name,pwd) values (#{userid},#{username},#{password});
    
    
        update mybatis.user set name=#{name},pwd=#{pwd}  where id=#{id};
    
    
        delete from mybatis.user where id =#{id};
    

4，在测试类写入方法， *** 作数据库并返回结果集

  @Test
    public void getUserLike(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();//数据库连接
        UserDao mapper = sqlSession.getMapper(UserDao.class);//接口 *** 作
        List userList = mapper.getUserLike("%李%");//执行通配符或者拼接字符串
        for (User user : userList) {
            System.out.println(user);
        }
        sqlSession.close();
    }
    @Test
    public void Test(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List userList = userDao.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }
        sqlSession.close();
    }
    @Test
    public void getUserById(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();//数据库连接
        UserDao mapper = sqlSession.getMapper(UserDao.class);//接口 *** 作
        User user = mapper.getUserById(2);
        System.out.println(user);
        sqlSession.close();
    }
    @Test
    public void getUserById2(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();//数据库连接
        UserDao mapper = sqlSession.getMapper(UserDao.class);//接口 *** 作
        HashMap map = new HashMap();
        map.put("id",1);
        mapper.getUserById2(map);
        User user= mapper.getUserById2(map);
        System.out.println(user);
        sqlSession.close();
    }
    @Test
    public void addUser(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);
       int i= mapper.addUser(new User(4,"哈哈","123333"));
        if(i>0){
            System.out.println(i);
        }
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void addUser2(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        Map map = new HashMap();
        map.put("userid",5);
        map.put("username","Hello");
        map.put("password","123321");
        mapper.addUser2(map);
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void upDateUser(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        mapper.upDateUser(new User(4,"呵呵","123456"));
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void deleteUser(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        mapper.deleteUser(4);
        sqlSession.commit();
        sqlSession.close();
    }

5，结果展示
（1）模糊查询

（2）查询id=2的所有信息

（3）增加id为4 的信息
（4）修改id=4的信息

（5）删除id=4的全部信息

增删改查全部讲解清楚，最后小编提一句，查询不用向数据库提交事务，删除、修改、添加均需要向数据库添加commit(),否则代码不报错，但产生不了你想要的结果。今天就到这里吧。