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MyBatis——MyBatis实现增、删、改、查

1.创建数据库

   
       
    
     4.0.0
        
    
     com.muan
        
    
     MyBatis练习
        
    
     1.0-SNAPSHOT
        
            
             
                 
      
       junit
                  
      
       junit
                  
      
       4.11
              
             
             
                 
      
       org.mybatis
                  
      
       mybatis
                  
      
       3.5.1
              
             
             
                 
      
       mysql
                  
      
       mysql-connector-java
                  
      
       5.1.47
              
             
             
                 
      
       log4j
                  
      
       log4j
                  
      
       1.2.17
              
         
        
            
             
                 
                      
       
        src/main/java
                       
                           
        
         **/*.properties
                            
        
         **/*.xml
                        
                       
       
        false
                   
                  
                      
       
        src/main/resources
                       
                           
        
         **/*.properties
                            
        
         **/*.xml
                        
                       
       
        false
                   
              
         
    
   

4.在pojo包下编写实体类User

package com.muan.pojo;public class User {    private int id;    private String name;    private String password;    public User() {    }    public User(int id, String name, String password) {        this.id = id;        this.name = name;        this.password = password;    }    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 getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    @Override    public String toString() {        return "User{" +                "id=" + id +                ", name='" + name + '\'' +                ", password='" + password + '\'' +                '}';    }}

5.编写dao层接口

package com.muan.dao;import com.muan.pojo.User;import java.util.List;public interface UserMapper {    //获取全部用户    List
   
     getAllUser();    //通过id获取用户    User getUserById(int id);    //添加一个用户    int addUser(User user);    //通过id删除用户    int deleteUserById(int id);    //修改用户    int modify(User user);}
   

6.编写对应的xml文件，并编写SQL

   
   
       
        
        
            
             
             
         
        
        
            select * from user        
        
        
            select * from user where id=#{id}        
        
        
    
             insert into user(id,name,pwd) values (#{id},#{name},#{password})    
        
        
    
             delete from user where id=#{id}    
            
        
    
             update user set name=#{name},pwd=#{password} where id=#{id}    
       
   

7.编写JDBC配置文件database.properties

driver = com.mysql.jdbc.Driverusername = rootpassword = 123456url = jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=UTF-8

8.配置mybatis-config.xml

9.编写mybatis工具类

package com.muhan.utils;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import java.io.IOException;import java.io.InputStream;public class MyBatisUtils {    //类变量不需要设置默认值；    private static SqlSession sqlSession;    static {        //在maven中，所有的资源文件一般都放在resources目录下，我们可以直接拿到。        try {            String resource = "mybatis-config.xml";            InputStream inputStream = Resources.getResourceAsStream(resource);            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);            sqlSession= sqlSessionFactory.openSession();        } catch (IOException e) {            e.printStackTrace();        }    }    //设置SqlSessionFactory公共的方法    public static SqlSession getSqlSession(){        return sqlSession;    }}

10.测试：在Test目录下的编写测试类

• 获取全部用户

@Test    public void getAllUserTest(){        //通过工具类获取sqlSessionFactory对象        SqlSession sqlSession = MyBatisUtils.getSqlSession();        //获取mapper队形，参数传入的是接口类的class对象        UserMapper mapper = sqlSession.getMapper(UserMapper.class);        //通过mapper对象调用方法        List
   
     allUser = mapper.getAllUser();        for (User user : allUser) {            System.out.println(user);        }    }
   

效果展示：

• 通过id获取用户

@Test    public void getUserById(){        SqlSession sqlSession = MyBatisUtils.getSqlSession();        UserMapper mapper = sqlSession.getMapper(UserMapper.class);        User userById = mapper.getUserById(1);        System.out.println(userById);    }

效果展示：

• 添加用户：注意事务提交和关闭事务

//添加用户    @Test    public void addUser(){        SqlSession sqlSession = MyBatisUtils.getSqlSession();        UserMapper mapper = sqlSession.getMapper(UserMapper.class);        User user = new User(4, "小可爱", "123456");        mapper.addUser(user);        sqlSession.commit();        sqlSession.close();    }

效果展示：

• 通过id删除用户：注意事务提交和关闭事务

@Test    public void deleteUserById(){        SqlSession sqlSession = MyBatisUtils.getSqlSession();        UserMapper mapper = sqlSession.getMapper(UserMapper.class);        mapper.deleteUserById(4);        sqlSession.commit();        sqlSession.close();    }

效果展示：

• 修改用户：注意事务提交和关闭事务

@Test    public void modify(){        SqlSession sqlSession = MyBatisUtils.getSqlSession();        UserMapper mapper = sqlSession.getMapper(UserMapper.class);        User user = new User(4, "小可爱", "5678");        mapper.modify(user);        sqlSession.commit();        sqlSession.close();    }

效果展示：

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