7、分页
思考：为什么要分页？
减少数据的处理量
7.1使用Limit分页
SELECT * from user limit startIndex,pageSize 使用Mybatis实现分页，核心SQL
1.接口
//分页
List<User> getUserByLimit(Map<String,Integer> map);2.Mapper.XML
<!--分页查询-->
<select id="getUserByLimit" parameterType="map" resultMap="UserMap">
select * from mybatis.user limit #{startIndex},#{pageSize}
</select>
3.测试
@Test
public void getUserBylimit(){
SqlSession sqlSesssion = MybatisUtils.getSqlSesssion();
UserMapper mapper = sqlSesssion.getMapper(UserMapper.class);
HashMap<String, Integer> map = new HashMap<String, Integer>();
map.put("startIndex",0);
map.put("pageSize",2);
List<User> userlist = mapper.getUserByLimit(map);
for (User user: userlist) {
System.out.println(user);
}
sqlSesssion.close();
}
7.2、RowBounds
不再使用SQL实现分页
1.接口
//分页2
List<User> getUserByRowBounds();
2.mapper.xml
<!--分页查询2-->
<select id="getUserByRowBounds">
select * from user limit #{startIndex},#{pageSize}
</select>
3.测试
public void getUserByRowBounds(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
//RowBounds实现
RowBounds rowBounds = new RowBounds(1, 2);
//通过Java代码层面实现分页
List<User> userList = sqlSession.selectList("com.jiang.dao.UserMapper.getUserByRowBounds", null, rowBounds);
for (User user : userList) {
System.out.println(user);
}
sqlSession.close();
}
7.3、分页插件
