七、分页
7.1
//分页
@PostMapping("/listPage")
// public List<Login00> listhu(@RequestBody HashMap map){
public List<Login00> listhu(@RequestBody QueryPageParam queryPageParam){
//hashmap
// System.out.println(map);//会获取到postman里面的发送数据
// System.out.println("pagesize="+map.get("pageSize"));
//自定义的方法
System.out.println(queryPageParam);
System.out.println("pagesize="+queryPageParam.getPageSize());
return null;
}
测试：
前端传入参数如下：
对于使用HashMap：
对于自定义的：
对于map，前端不管传入多少，都可以接收到，但是对于自己定义的，可以通过这样子处理：
获取param里面的值：
可以直接用HashMap也可以封装，封装的话比较统一吧。
7.2添加分页拦截器
官网代码:https://baomidou.com/pages/97710a/#配置方法
@PostMapping("/listPage")
public List<Login00> listhu(@RequestBody QueryPageParam queryPageParam){
//分页拦截器
// Page<Login00> page = new Page<>(1,2);//当前页1，每页2条
//也可以这样子对当前页和每页条数进行设置
Page<Login00> page = new Page<>();
page.setCurrent(queryPageParam.getPageNum());
page.setSize(queryPageParam.getPageSize());
//进行查询
HashMap param = queryPageParam.getParam();
String uname = (String) param.get("uname");
LambdaQueryWrapper<Login00> lambdaQueryWrapper = new LambdaQueryWrapper<>();
lambdaQueryWrapper.like(Login00::getUname,uname);
IPage result=iLogin00Service.page(page,lambdaQueryWrapper);
System.out.println("total="+result.getTotal());
return result.getRecords();
}
控制台输出total=3，因为数据库里面是有3条符合的数据。
7.3 编写分页mapper
contorller:
@PostMapping("/listPageC")
// public List<Login00> listhu(@RequestBody HashMap map){
public List<Login00> listPageC(@RequestBody QueryPageParam queryPageParam){
HashMap param = queryPageParam.getParam();
String uname = (String) param.get("uname");
Page<Login00> page = new Page<>();
page.setCurrent(queryPageParam.getPageNum());
page.setSize(queryPageParam.getPageSize());
//进行查询
// LambdaQueryWrapper<Login00> lambdaQueryWrapper = new LambdaQueryWrapper<>();
// lambdaQueryWrapper.like(Login00::getUname,uname);
IPage result=iLogin00Service.pageC(page);
System.out.println("total="+result.getTotal());
return result.getRecords();
}
service:
IPage pageC(IPage<Login00> page);
serviceimpl
@Override
public IPage pageC(IPage<Login00> page) {
return login00Mapper.pageC(page);
}
mapper
IPage pageC(IPage<Login00> page);
mapper配置文件xml
<select id="pageC" resultType="com.example.entity.Login00">
select * from login00
</select>
运行结果：
虽然是添加了uname的限制，但是还是查询了全部，因为在xml文件中写的是select * from login00
要实现添加uname限制，可以直接在xml的查询语句里面添加限制，也可以使用mybatis-plus提供的Wrapper（官网查找）
controller
LambdaQueryWrapper<Login00> lambdaQueryWrapper = new LambdaQueryWrapper<>();
lambdaQueryWrapper.like(Login00::getUname,uname);
IPage result2=iLogin00Service.pageCC(page,lambdaQueryWrapper);
在mapper中(注意是@Pama..这样子的格式)：
IPage pageCC(Page<Login00> page,@Param(Constants.WRAPPER) Wrapper wrapper);
在mapper.xml（注意是${ew.customSqlSegment}这样子的格式）中
<select id="pageCC" resultType="com.example.entity.Login00">
select * from login00 ${ew.customSqlSegment}
</select>
后台total是1
后台total是3
分页涉及的代码：
comment层分页拦截器代码：
package com.example.comment;
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
//分页拦截器
@Configuration
public class MybatisPlusConfig {
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));//如果配置多个插件,切记分页最后添加
//interceptor.addInnerInterceptor(new PaginationInnerInterceptor()); 如果有多数据源可以不配具体类型 否则都建议配上具体的DbType
return interceptor;
}
}
自定义的分页参数：
package com.example.comment;
import lombok.Data;
import java.util.HashMap;
//分页参数
@Data
public class QueryPageParam {
//默认值
private static int PAGE_SIZE=20;
private static int PAGE_NUM=1;
private int pageSize=PAGE_SIZE;
private int pageNum=PAGE_NUM;
private HashMap param;
}
controller
package com.example.controller;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.comment.QueryPageParam;
import com.example.entity.Login00;
import com.example.service.ILogin00Service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.HashMap;
import java.util.List;
@RestController
@RequestMapping("/login00")
public class Login00Controller {
@Autowired
private ILogin00Service iLogin00Service;
//分页
@PostMapping("/listPage")
// public List<Login00> listhu(@RequestBody HashMap map){
public List<Login00> listhu(@RequestBody QueryPageParam queryPageParam){
//hashmap
// System.out.println(map);//会获取到postman里面的发送数据
// System.out.println("pagesize="+map.get("pageSize"));
//自定义的方法
// System.out.println(queryPageParam);
// System.out.println("pagesize="+queryPageParam.getPageSize());
//
// HashMap param = queryPageParam.getParam();
// String uname = (String) param.get("uname");
// String utype = (String) param.get("utype");
// System.out.println("uname: "+uname+" utype: "+utype);
//分页拦截器
// Page<Login00> page = new Page<>(1,2);//当前页1，每页2条
//也可以这样子对当前页和每页条数进行设置
Page<Login00> page = new Page<>();
page.setCurrent(queryPageParam.getPageNum());
page.setSize(queryPageParam.getPageSize());
//进行查询
HashMap param = queryPageParam.getParam();
String uname = (String) param.get("uname");
LambdaQueryWrapper<Login00> lambdaQueryWrapper = new LambdaQueryWrapper<>();
lambdaQueryWrapper.like(Login00::getUname,uname);
IPage result=iLogin00Service.page(page,lambdaQueryWrapper);
System.out.println("total="+result.getTotal());
return result.getRecords();
}
@PostMapping("/listPageC")
public List<Login00> listPageC(@RequestBody QueryPageParam queryPageParam){
HashMap param = queryPageParam.getParam();
String uname = (String) param.get("uname");
Page<Login00> page = new Page<>();
page.setCurrent(queryPageParam.getPageNum());
page.setSize(queryPageParam.getPageSize());
//进行查询
IPage result=iLogin00Service.pageC(page);
System.out.println("total="+result.getTotal());
return result.getRecords();
}
@PostMapping("/listPageCC")
public List<Login00> listPageCC(@RequestBody QueryPageParam queryPageParam){
HashMap param = queryPageParam.getParam();
String uname = (String) param.get("uname");
Page<Login00> page = new Page<>();
page.setCurrent(queryPageParam.getPageNum());
page.setSize(queryPageParam.getPageSize());
//进行查询
//使用Wrapper自定义SQL 添加限制
//注意，mybatis-plus版本要>=3.0.7
LambdaQueryWrapper<Login00> lambdaQueryWrapper = new LambdaQueryWrapper<>();
lambdaQueryWrapper.like(Login00::getUname,uname);
IPage result2=iLogin00Service.pageCC(page,lambdaQueryWrapper);
System.out.println("total2="+result2.getTotal());
return result2.getRecords();
}
}
service
public interface ILogin00Service extends IService<Login00> {
IPage pageC(Page<Login00> page);
IPage pageCC(Page<Login00> page, Wrapper lambdaQueryWrapper);
}
serviceimpl
@Service
public class Login00ServiceImpl extends ServiceImpl<Login00Mapper, Login00> implements ILogin00Service {
@Autowired
private Login00Mapper login00Mapper;
@Override
public IPage pageC(Page<Login00> page) {
return login00Mapper.pageC(page);
}
@Override
public IPage pageCC(Page<Login00> page, Wrapper lambdaQueryWrapper) {
return login00Mapper.pageCC(page,lambdaQueryWrapper);
}
}
mapper
@Mapper
public interface Login00Mapper extends BaseMapper<Login00> {
IPage pageC(Page<Login00> page);
IPage pageCC(Page<Login00> page,@Param(Constants.WRAPPER) Wrapper wrapper);
}
mapper的xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.mapper.Login00Mapper">
<select id="pageC" resultType="com.example.entity.Login00">
select * from login00
</select>
<select id="pageCC" resultType="com.example.entity.Login00">
select * from login00 ${ew.customSqlSegment}
</select>
</mapper>