MyBatis(日志,常用操作,循环遍历,参数传递)

1.Log日志

 日志级别: debug< info < Warning < error 

 2.logback

   1.导入jar包

	
   
     ch.qos.logback
     logback-classic
     1.2.3
   

    @Test
    public void testLogger(){
        Logger logger = LoggerFactory.getLogger(MyBatisTest.class);
        logger.debug("我是debug日志");
        logger.info("我是info日志");
        logger.warn("我是警告日志");
        logger.error("我是错误日志");
    }

  info == System.out

2.添加配置文件 logback.xml

    logback日志默认加载resources中的logback.xml

    
    
        
            
            
            [%d{HH:mm:ss.SSS}] [%-5level] [%thread] [%logger] [%msg]%n
            UTF-8
        
    

    
    
    
        
        
    

    
    

3.MyBatis动态加载数据源

1.编辑jdbc.propertoes配置文件 

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/top_news?serverTimezone=UTC&rewriteBatchedStatements=true&characterEncoding=utf-8
jdbc.username=root
jdbc.password=123456

2.mybatis-config.xml中动态加载配置文件

     注意properties标签位置

4.MyBatis简化操作

编辑mybatis的核心配置文件

  注意标签位置

别名定义

定义别名包 :指定公共前缀

sql标签

    
    
        select id,name,age,sex from user
    

5.MyBatis参数传递(重点)

  1.#{} 和${}取值说明

         ${xxxx}取值

                $符取值  没有引号  需要自己手动添加

                $符取值 没有预编译的效果 ,有sql注入的风险

                $符只是字符串的拼接

        #{}取值

               #有预编译的效果

               #会为字符串自动添加引号

               

    @Test
    public void test02() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        String name = "星期一";
        List userList = mapper.findName(name);
        userList.forEach(System.out::println);
    }

    
        select * from user where name = #{name}
    

2.$ 的用处

模糊查询时使用

    @Test
    public void test03() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        String name = "节";
        List userList = mapper.findLikeName(name);
        userList.forEach(System.out::println);
    }

    
        select id,name,age,sex from user where name like "%${name}%"
    

以字段为参数时

    @Test
    public void test04() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        String column = "age";
        List userList = mapper.findOrderBy(column);
        userList.forEach(System.out::println);
    }

    
        select id,name,age,sex from user order by "${age}"
    

3.单值传递

  原则:

单值传递与名无关,只与下标有关 args,param

1. 使用#号和$符时,如果只有一个参数时,使用任意名称都可以获取参数
2. 但是使用${} 时 不能以数字为参数

3.使用$ 不能写NULL

使用$不能写数字,但是#可以

4.多值传递

说明:接口中的参数个数有多个

取值规则:arg0,arg1     param1,param2

    @Test
    public void test06() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int age = 18;
        String sex = "女";
        List userList = mapper.findByAS(age,sex);
        userList.forEach(System.out::println);
    }

    
        select * from user where age = #{param1} and sex = #{param2}
    

5.Map封装数据

 说明: 基于mybatis的原则,可以把多值封装为单值对象

    @Test
    public void test05() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int age = 18;
        String sex = "女";
        Map map = new HashMap();
        map.put("age",age);
        map.put("sex",sex);
        List userList = mapper.findByAS(map);
        userList.forEach(System.out::println);
    }

  

    
        select * from user where age = #{age} and sex = #{sex}
    

6.@Param注解

mybatis针对Map封装数据提供了注解的支持

    List findByAnno(@Param("age") int age,
                          @Param("sex") String sex);

    
        select * from user where age = #{age} and sex = #{sex}
    

6.MyBatis增删改查相关用法

增删改需要开启事务

增加

    @Test
    public void testInsert(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User(null,"刘谦",30,"男");
        int rows=  mapper.insertUser(user);
        System.out.println("影响的行数" + rows);
    }

    
        insert into user values (null,#{name},#{age},#{sex})
    

修改

    @Test
    public void testUpdate(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User(41,"宋江",30,"男");
        int rows = mapper.updateUser(user);
        System.out.println("影响的行数"+rows);
    }  
    @Test
    public void testUpdate1(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int rows = mapper.updateUser(new User(2,"吴用",10,"男"));
        System.out.println("影响的行数"+rows);
    }

    
        update user
        set name = #{name},
            age  = #{age},
            sex  = #{sex}
        where id = #{id}
    

删除

    @Test
    public void testDelete(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int id = mapper.deleteUser(1);
        System.out.println("影响的行数"+id);
    }

    
        delete from user where id = #{id}
    

7.MyBatis中包扫描机制

说明:MyBatis默认条件下使用mappers标签引入映射文件

优化:采用package标签优化属性

注意事项:

mapper.xml映射文件的路径必须与接口的包路径一致     用 / 创建包

target包里面接口和xml在一个包下

8.MyBatis常用操作

1.如果属性名称一样,需要传递参数,首选使用Map集合

    @Test
    public void test08(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        Map map = new HashMap();
        map.put("minage",18);
        map.put("maxage",100);
        List userlist =mapper.findByAge(map);
        userlist.forEach(System.out::println);
    }

CDATA标签:

在sql语句中 当大于或者小于号或者其他符号被当做标签使用,则使用转义字符

    

        = #{minage} and age <= #{maxage}
]]>
    

2.利用Map返回数据

   有时查询的数据可能只返回部分结果,没有返回全部数据,用map返回

MyBatis针对与类型有两种写法   

                                        1. 包名.类型  java.util.Map

                                         2.小写字符   map    (要配置别名包)

    @Test
    public void test09(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        String sex = "男";
        List userlist =mapper.findBySex(sex);
        System.out.println(userlist);
    }

    
        select name,age from user where sex = #{sex}
    

      

9.MyBatis中主键自增回显

useGeneratedKeys = "true" 开启主键自增

keyColumn = "id"    指定自增的字段   主键自增 一张表只有一个   可以不写

keyProperty= "id"        制定映射的属性

    @Test
    public void testInsert(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User(null,"刘谦",30,"男");
//        int rows=  mapper.insertUser(user);
//        System.out.println("影响的行数" + rows);
        mapper.insertUser(user);
        System.out.println(user);
    }

    
        insert into user
        values (null, #{name}, #{age}, #{sex})
    

10.MyBatis中的循环遍历写法

  1.foreach循环遍历

    @Test
    public void test10(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        Integer[] array = {1,3,4,5,7};
        List list = Arrays.asList(array);//利用get方法获取参数
        List userList = mapper.getArray(list);
        System.out.println(userList);
    }

    

        select * from user where id in
                           
                           #{item}
                           
    

如果循环遍历时,参数是Map集合,则collection  写map中的key  也就是数组的名称

    要求:map.value是一个可遍历的值 例如是一个list,array

    //要求: 查询id= 1,3,4,5,同时sex = "男"

    @Test
    public void test11(){
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        Map map = new HashMap();
        map.put("ids",new Integer[]{1,3,4,5});
        map.put("sex","男");
        List userList = mapper.selectArray(map);
        System.out.println(userList);
    }

    
    

        select * from user where sex = #{sex} and id in
        
            #{item}