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);}}