Mybatis学习 分页的实现,使用注解开发,使用注解实现CURD

2022-08-27 14:29:27

分页的实现此处有两种思路:

1.使用SQL的 limit ?,?

2.使用limit分页

方式一 (步骤:):

(1).dao层中UserMapper接口的编写:

//分页的sql实现
  List<User>getUserByLimit(Map<String,Integer> map);

(2).dao层中UserMapper接口的userMapper.xml编写

<selectid="getUserByLimit"parameterType="map"resultType="study.com.pojo.User">
        select * from mybatis.user limit #{startIndex},#{pageSize}</select>

(3).测试

@org.junit.Testpublicvoidtest4(){
    SqlSession sqlSession= MybatisUtils.getsqlsession();
    UserDao userDao= sqlSession.getMapper(UserDao.class);

    HashMap<String, Integer> map=newHashMap<String, Integer>();//从该索引处开始检索
    map.put("startIndex",1);//检索长度为2,也就是只展示两条数据
    map.put("pageSize",2);
    List<User> userList= userDao.getUserByLimit(map);for(User user: userList){
        System.out.println(user);}
    sqlSession.close();}

使用注解开发

(1) 注解在接口上实现

@Select("select * from user")
List<User>getUsers();

(2)需要在核心配置文件中绑定接口

<!--绑定接口--><mappers><mapperclass="com.kuang.dao.UserMapper"/></mappers>

(3)测试

使用注解实现CURD

(1).dao层的UserMapper的编写:

publicinterfaceUserMapper{@Select("select * from user")
    List<User>getAllUser();//增@Insert("insert into user (id,name,pwd) values (#{id},#{name},#{pwd})")intaddUser(User u);//删@Delete("delete from user where id=#{id}")intdelete(int id);//改@Update("update user set pwd=#{pwd},name=#{name} where id=#{id}")intupdate(User u);//查@Select("select * from user where id=#{id}")public Userselect(int id);}

(2).mybatis核心文件的编写(映射器):

<mappers><mapperclass="com.kuang.dao.UserMapper"></mapper></mappers>

(3).实现事务的自动提交:

publicstatic SqlSessionFactorygetSqlSessionFactory(){return sqlSessionFactory;}publicstatic SqlSessiongetSqlSession(){//开启事物的自动提交return sqlSessionFactory.openSession(true);}

(4).测试类的编写:

publicclassUserTest{@TestpublicvoidgetAllUser(){

        SqlSession sqlSession= MybatisUtils.getSqlSession();
        UserMapper mapper= sqlSession.getMapper(UserMapper.class);
        List<User> users= mapper.getAllUser();
        System.out.println(users);
        sqlSession.close();}@TestpublicvoidaddUser(){

        SqlSession sqlSession= MybatisUtils.getSqlSession();
        UserMapper mapper= sqlSession.getMapper(UserMapper.class);
        User u=newUser(5,"劳务","567");int i= mapper.addUser(u);
        System.out.println(i);}@Testpublicvoiddelete(){

        SqlSession sqlSession= MybatisUtils.getSqlSession();
        UserMapper mapper= sqlSession.getMapper(UserMapper.class);//        User u=new User(5,"劳务","567");int i= mapper.delete(5);
        System.out.println(i);}@Testpublicvoidupdate(){

        SqlSession sqlSession= MybatisUtils.getSqlSession();
        UserMapper mapper= sqlSession.getMapper(UserMapper.class);
       User u=newUser(5,"老五","666");int i= mapper.update(u);
        System.out.println(i);}@Testpublicvoidselect(){

        SqlSession sqlSession= MybatisUtils.getSqlSession();
        UserMapper mapper= sqlSession.getMapper(UserMapper.class);

        User i= mapper.select(5);
        System.out.println(i);}}
  • 作者:一点莹
  • 原文链接:https://blog.csdn.net/jingli456/article/details/114228832
    更新时间:2022-08-27 14:29:27