mybatis1

MyBatis框架简单使用

1.添加mybatis包

        
        
            mysql
            mysql-connector-java
            8.0.15
        

        
        
            org.mybatis
            mybatis
            3.5.5
        
        
        
            org.projectlombok
            lombok
            1.18.12
            provided
        
        
        
            log4j
            log4j
            1.2.17
        

 

2.添加db.properties

这里后面没有使用这种方式，因为解析不了，不知道为啥

# 数据库配置文件
db.driver=com.mysql.cj.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=Asia/Shanghai
db.username=root
db.password=123456

这里有两点需要注意的地方

1.driver的写法：com.mysql.cj.jdbc.Driver和com.mysql.jdbc.Driver的区别

https://blog.csdn.net/superdangbo/article/details/78732700

2.serverTimezone=Asia/Shanghai千万不要大小写写错，否则...

3.创建SqlMapConfig.xml

这里注意两点：

1.没有使用解析的方式，而是直接写的数据库连接配置信息

2.下面mapper的写法

写法不一样

报错：Could not find resource com.mybatis.mapper

com/mybatis/mapper/UserMapper.xml

之前写的是com.mybatis.mapper是错的会找不到mapper对应的xml文件

https://www.cnblogs.com/mkl7/p/10745371.html

4.创建Mapper以及Mapper.xml

UserMapper

package com.mybatis.mapper;

import com.mybatis.entity.User;

import java.util.List;

public interface UserMapper {

    User selectUserById(Long id);

    List selectAllUsers();

    void delectUserById(Long id);
}

UserMapper.xml

    
    
        select * from mybatis_user where id=#{value}
    
    
    
        select * from mybatis_user
    
    

    
        delete from mybatis_user where id=#{value}
    

entity包下User实体

package com.mybatis.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private Long id;
    private String username;
    private String password;
}

5.log4j配置文件

log4j.properties

### 设置###
log4j.rootLogger = debug,stdout,D,E

### 输出信息到控制抬 ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

### 输出DEBUG 级别以上的日志到=D://Projects/java/Mybatis/logs/log.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = D://Projects/java/Mybatis/logs/log.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = DEBUG 
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

### 输出ERROR 级别以上的日志到=D://Projects/java/Mybatis/logs/log.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =D://Projects/java/Mybatis/logs/log.log
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR 
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

6.测试类

package com.mybatis.mapper;

import com.mybatis.entity.User;
import junit.framework.TestCase;
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 org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.Reader;

public class UserMapperTest extends TestCase {
    private SqlSession sqlSession;
    private UserMapper mapper;

    @Before
    public void setup() {
        System.out.println("begin:before");
        try {
            //mybatis连接工厂
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader("SqlMapConfig.xml"));
            //mybatis连接对象
            SqlSession sqlSession = sqlSessionFactory.openSession();
            //mybatis的mapper的代理对象
            mapper = sqlSession.getMapper(UserMapper.class);
            System.out.println("#######################");
            System.out.println(mapper);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Test
    public void testSelectAllUsers() {
        SqlSessionFactory sqlSessionFactory = null;
        try {
            Reader r=Resources.getResourceAsReader("SqlMapConfig.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(r);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //mybatis连接对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //mybatis的mapper的代理对象
        mapper = sqlSession.getMapper(UserMapper.class);
        System.out.println(mapper);
        System.out.println(sqlSession);
        mapper.selectAllUsers().forEach(System.out::println);
    }

    @Test
    public void testSelectUserById() {
        User user = mapper.selectUserById(1L);
        System.out.println(user);
    }

    @Test
    public void testDelectUserById() {
        mapper.delectUserById(3L);
        //  mybatis默认情况是手动提交事务的
        sqlSession.commit();
    }

    @After
    public void tearDown() {
        if (sqlSession != null) {
            sqlSession.close();
        }
    }
}

这里有个问题就是我的@Before没有起作用，所以我把连接先写在函数中

运行结果只有查询

中间碰到的一切爆红的错误，都是因为书写不正确的粗心导致，仔细检查

在pom文件中需要注意添加

        
        
            
                src/main/java
                
                    **/*.xml
                    **/*.properties
                
                true