解决Mybatis-Plus操作分页后数据失效问题

业务场景

我们知道在使用PageHelper分页插件时，会对执行PageHelper.startPage(pageNum, pageSize);方法后的第一条查询语句进行分页操作。在开发中总会遇到这样的业务情景，在进行分页查询后，需要对获得的列表数据包装成另一种类型，此时需要对新类型的列表进行分页，然而由于PageInfo<T>因为泛型的原因，导致处理后的列表不能加入到该类中。

如，我在数据库分页后查询到的类为PageInfo<User>，此时改类中的list属性为User，在当前的业务场景下，我需要将User类型替换为UserVo类型。

当我们对list属性进行操作时，会同时导致PageInfo类中的其他属性发生改变，如total等。

解决方法

//从数据库获得的Users分页列表
//当我们打印users时，会发现打印出来的数据除了列表数据还有分页属性
List<User> users = this.list();
//操作users获得的需要的列表
List<UserVo> userVos = this.list2(users);
//创建User的info类，此时page中的属性已生成
PageInfo<User> userPage = new PageInfo<>(users);
//创建UserVo的info类
PageInfo<UserVo> userVoPage= new PageInfo<>(userVos );
//将userPage中除看list外的其他属性复制到userVoPage中
PageInfoUtil pageInfoUtil = new PageInfoUtil();
pageInfo = pageInfoUtil.getPageVo(userPage ,userVoPage);

pageInfoUtil
public class PageInfoUtil {
public PageInfo getPageVo(PageInfo pageInfoPo,PageInfo pageInfoVo){
 pageInfoVo.setTotal(pageInfoPo.getTotal());
 pageInfoVo.setEndRow(pageInfoPo.getEndRow());
 pageInfoVo.setHasNextPage(pageInfoPo.isHasNextPage());
 pageInfoVo.setHasPreviousPage(pageInfoPo.isHasPreviousPage());
 pageInfoVo.setIsFirstPage(pageInfoPo.isIsFirstPage());
 pageInfoVo.setIsLastPage(pageInfoPo.isIsLastPage());
 pageInfoVo.setNavigateFirstPage(pageInfoPo.getNavigateFirstPage());
 pageInfoVo.setNavigateLastPage(pageInfoPo.getNavigateLastPage());
 pageInfoVo.setNavigatePages(pageInfoPo.getNavigatePages());
 pageInfoVo.setNavigatepageNums(pageInfoPo.getNavigatepageNums());
 pageInfoVo.setNextPage(pageInfoPo.getNextPage());
 pageInfoVo.setPageNum(pageInfoPo.getPageNum());
 pageInfoVo.setPages(pageInfoPo.getPages());
 pageInfoVo.setPageSize(pageInfoPo.getPageSize());
 pageInfoVo.setPrePage(pageInfoPo.getPrePage());
 pageInfoVo.setSize(pageInfoPo.getSize());
 pageInfoVo.setStartRow(pageInfoPo.getStartRow());
 pageInfoVo.setFirstPage(pageInfoPo.getFirstPage());
 pageInfoVo.setLastPage(pageInfoPo.getLastPage());
 return pageInfoVo;
}
}

End

想使用秀一点的方法，结果能力有限，没有成功，只能使用这种笨方法，如果有更好的方法，欢迎各位指导。

补充知识：mybatis-plus分页无效, total=0问题(springmvc)

前言

项目中(springmvc)分页采用mybatis-plus, 头一回用, 就遇到了如题问题

pom.xml

<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus</artifactId>
<version>3.2.0</version>
</dependency>

mapper继承了BaseMapper

@Repository
public interface UserMapper extends BaseMapper<UserPo>{
// 这里代码没用, 查询采用的BaseMapper中的 IPage<T> selectPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);
}

service层

@Override
public SysUserVo list(UserQo qo) {
 QueryWrapper<UserPo> queryWrapper = new QueryWrapper<>();
 queryWrapper.like("name", qo.getKeyword())
   .or().
   like("code", qo.getKeyword());
 Page<UserPo> page = new Page<>(qo.getPageNo(), qo.getPageSize());
 IPage<UserPo> userPoIPage = userMapper.selectPage(page, queryWrapper);
 List<UserPo> records = userPoIPage.getRecords();
 long total = userPoIPage.getTotal();// 总记录数
 long pages = userPoIPage.getPages();// 查询结果数
 long pageNo = userPoIPage.getCurrent();// 当前页
 long pageSize = userPoIPage.getSize();// 每页条数
 List<UserVo> userVos = Lists.newArrayList();
 for (UserPo userPo : records) {
  Integer userId = userPo.getId();
  List<RolePo> roles = userMapper.selectRoles(userId);
  UserVo userVo = UserVo.builder().code(userPo.getCode())
    .name(userPo.getName())
    .rolePo(roles)
    .status(userPo.getStatus())
    .build();
  userVos.add(userVo);
 }
 SysUserVo sysUserVo = SysUserVo.builder()
   .list(userVos)
   .total(total)
   .build();
 return sysUserVo;
}

结果分页并没有生效, 于是添加 *

package com.cebbank.api.config;

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.pagination.optimize.JsqlParserCountOptimize;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@EnableTransactionManagement
@MapperScan("com.cebbank.api.mapper")
public class MybatisPlusConfig {
@Bean
public PaginationInterceptor paginationInterceptor() {
 PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
 // 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求 默认false
 paginationInterceptor.setOverflow(true);
 // 设置最大单页限制数量，默认 500 条，-1 不受限制
 paginationInterceptor.setLimit(100);
 // 开启 count 的 join 优化,只针对部分 left join
 paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
 paginationInterceptor.setDialectType("mysql");
 return paginationInterceptor;
}
}

还是没生效

最后找到解决方案, 在数据源配置中显式添加分页插件

@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
 MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
 sqlSessionFactoryBean.setDataSource(dataSource());
 MybatisConfiguration configuration = new MybatisConfiguration();
 configuration.setMapUnderscoreToCamelCase(true);
 configuration.setDefaultEnumTypeHandler(EnumOrdinalTypeHandler.class);
 sqlSessionFactoryBean.setConfiguration(configuration);
//  sqlSessionFactoryBean.setMapperLocations(resolveMapperLocations());
 sqlSessionFactoryBean.setPlugins(new Interceptor[]{new PaginationInterceptor()});

return sqlSessionFactoryBean.getObject();
}

完整配置

package com.cebbank.api.config;

import com.alibaba.druid.pool.DruidDataSource;
import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.type.EnumOrdinalTypeHandler;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

/**
* @author linyong
* @date 2020/7/30 16:38
* @description 数据源配置
**/
@Configuration
@EnableAspectJAutoProxy
@MapperScan("com.cebbank.api.mapper")
public class DBConfig {

@Value("${spring.datasource.url}")
private String url;

@Value("${spring.datasource.driver-class-name}")
private String driverClassName;

@Value("${spring.datasource.username}")
private String username;

@Value("${spring.datasource.password}")
private String password;

@Value("${spring.datasource.initialSize:5}")
private Integer initialSize;

@Value("${spring.datasource.maxActive:50}")
private Integer maxActive;

@Value("${spring.datasource.maxWait:60000}")
private Integer maxWait;

@Value("${spring.datasource.minIdle:5}")
private Integer minIdle;

@Value("${spring.datasource.testWhileIdle:true}")
private Boolean testWhileIdle;

@Value("${spring.datasource.testOnBorrow:true}")
private Boolean testOnBorrow;

@Value("${spring.datasource.testOnReturn:true}")
private Boolean testOnReturn;

@Value("${spring.datasource.validationQuery:select 1}")
private String validationQuery;

// @Value("${mybatis.mapper-locations}")
// private String mapperLocations;

@Bean
public DataSource dataSource(){
 DruidDataSource druidDataSource = new DruidDataSource();
 druidDataSource.setUrl(url);
 druidDataSource.setDriverClassName(driverClassName);
 druidDataSource.setUsername(username);
 druidDataSource.setPassword(password);
 druidDataSource.setInitialSize(initialSize);
 druidDataSource.setMaxActive(maxActive);
 druidDataSource.setMaxWait(maxWait);
 druidDataSource.setMinIdle(minIdle);
 druidDataSource.setTestWhileIdle(testWhileIdle);
 druidDataSource.setTestOnBorrow(testOnBorrow);
 druidDataSource.setTestOnReturn(testOnReturn);
 druidDataSource.setValidationQuery(validationQuery);
 return druidDataSource;
}

// private Resource[] resolveMapperLocations() {
//  ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
//  String[] arr = mapperLocations.split(",");
//  List<String> locations = Arrays.asList(arr);
//  List<Resource> resources = new ArrayList();
//  if (locations != null) {
//   for (String mapperLocation : locations) {
//    try {
//     Resource[] mappers = resourceResolver.getResources(mapperLocation);
//     resources.addAll(Arrays.asList(mappers));
//    } catch (IOException e) {
//     // ignore
//    }
//   }
//  }
//  return resources.toArray(new Resource[resources.size()]);
// }

@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
 MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
 sqlSessionFactoryBean.setDataSource(dataSource());
 MybatisConfiguration configuration = new MybatisConfiguration();
 configuration.setMapUnderscoreToCamelCase(true);
 configuration.setDefaultEnumTypeHandler(EnumOrdinalTypeHandler.class);
 sqlSessionFactoryBean.setConfiguration(configuration);
//  sqlSessionFactoryBean.setMapperLocations(resolveMapperLocations());
 sqlSessionFactoryBean.setPlugins(new Interceptor[]{new PaginationInterceptor()});

return sqlSessionFactoryBean.getObject();
}

@Bean
public DataSourceTransactionManager transactionManager(){
 DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
 transactionManager.setDataSource(dataSource());
 return transactionManager;
}

}

问题解决！

来源：https://blog.csdn.net/Acceleactor/article/details/88237620