SpringBoot系列之基于MongoRepository实现分页

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2023-01-10
Java基础面试题
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标签   SpringBoot

Spring Data MongoDB项目提供了与MongoDB文档数据库的集成。是Spring Data项目的一个分支。本博客基于Spring Data MongoDB实现，引入项目spring-boot-starter-data-mongodb实现MongoDB的分页，仅供参考

环境准备

  • 开发环境
  • JDK 1.8
  • SpringBoot2.2.1
  • Maven 3.2+
  • 开发工具
  • IntelliJ IDEA
  • smartGit
  • Navicat15

Maven配置

新建一个SpringBoot下面，在pom配置文件里加上，dependencyManagement进行Springboot统一的版本控制

<properties> 
    <java.version>1.8</java.version> 
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> 
    <spring-boot.version>2.2.1.RELEASE</spring-boot.version>
</properties>
 
<dependencyManagement> 
    <dependencies> 
        <dependency> 
            <groupId>org.springframework.boot</groupId> 
            <artifactId>spring-boot-dependencies</artifactId> 
            <version>${spring-boot.version}</version> 
            <type>pom</type> 
            <scope>import</scope> 
        </dependency> 
    </dependencies>
</dependencyManagement>

加上mongoDB的starter配置，加上spring-boot-starter-data-mongodb封装好的starter

<dependency> 
    <groupId>org.springframework.boot</groupId> 
    <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>

也可以加上PageHelper的配置，非必须

<dependency> 
    <groupId>com.github.pagehelper</groupId> 
    <artifactId>pagehelper-spring-boot-starter</artifactId> 
    <version>1.2.10</version>
</dependency>

MongoDB配置

有些版本启动可能会报错，所以可以先exclude数据库的自动配置，在Application类加上@SpringBootApplication(exclude= {DataSourceAutoConfiguration.class})

加上MongoDB的一些自定义配置

package com.example.mongodb.configuration;
 
import com.mongodb.ConnectionString;
import com.mongodb.MongoClientSettings;
import com.mongodb.client.MongoClient;
import com.mongodb.client.MongoClients;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.config.AbstractMongoClientConfiguration;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
 
import java.util.Collection;
import java.util.Collections;
 
@Configuration
@EnableMongoRepositories(basePackages = "com.example.mongodb.repository")
public class MongoConfiguration extends AbstractMongoClientConfiguration {
 
    private static final String DB_NAME = "test";
    private static final String IP = "127.0.0.1";
    private static final String PORT = "27017";
 
    @Override 
    public MongoClient mongoClient() {
        ConnectionString str = new ConnectionString("mongodb://"+ IP + ":"+ PORT + "/" + getDatabaseName());
        MongoClientSettings mongoClientSettings = MongoClientSettings.builder()
                .applyConnectionString(str)
                .build();
        return MongoClients.create(mongoClientSettings);
    }
 
 
    @Override 
    public MongoTemplate mongoTemplate() throws Exception {
        return new MongoTemplate(mongoClient() , getDatabaseName());
    }
 
    @Override 
    protected String getDatabaseName() {
        return DB_NAME;
    }
 
    @Override 
    protected Collection<String> getMappingBasePackages() {
        return Collections.singleton("com.example.mongodb");
    }
}

代码实现

加上Document类，collection 对应数据库对应的文档

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import lombok.experimental.SuperBuilder;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.data.mongodb.core.mapping.MongoId;
 
import java.io.Serializable;
 
@Data
@SuperBuilder(toBuilder = true)
@AllArgsConstructor
@NoArgsConstructor
@ToString
@Document(collection = "user")
public class User implements Serializable {
    @MongoId 
    private Long id;
    private String name;
    private Integer age;
    private String email;
 
}

加上接口实现MongoRepository<User, Long> ，一个User是对应的文档类，Long是对应的主键id

import com.example.mongodb.model.User;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.data.mongodb.repository.Query;
import org.springframework.stereotype.Repository;
 
import java.util.Optional;
 
@Repository
public interface UserRepository extends MongoRepository<User, Long> {
 
    @Query("{ 'email' : ?0 }")
    User findByEmail(String email);
 
    @Query("{'_id' : ?0 }")
    Optional<User> findById(Long id);
 
}

业务实现类：基于ExampleMatcher 实现业务参数的加入，Pageable封装分页的参数

@Override
public org.springframework.data.domain.Page<User> mongoPageList(PageBean pageBean, User queryParam) {
    User param = new User();
    if (StrUtil.isNotBlank(queryParam.getName())) {
        param.setName(queryParam.getName());
    }
    ExampleMatcher matcher = ExampleMatcher.matching()
            .withMatcher("name", ExampleMatcher.GenericPropertyMatchers.contains());
    Example<User> example = Example.of(param, matcher);
    Sort sort = Sort.by(Sort.Direction.DESC, "_id");
    Pageable pageable = PageRequest.of(pageBean.getPageIndex() - 1, pageBean.getPageRowNum(), sort);
    org.springframework.data.domain.Page<User> page = userRepository.findAll(example, pageable);
    return new PageImpl<User>(page.getContent() , pageable , page.getTotalElements());
}

拓展

分页基于MongoRepository实现比较容易，不过发现index是从0开始的，返回的参数比较少，比如总页数，虽然也可以前端自己计算，不过为了统一规范，可以自己再根据需要进行封装

定义一个ResultBean，返回给前端

package com.example.mongodb.common.rest;
 
import lombok.Data;
import org.springframework.http.HttpStatus;
 
@Data
public class ResultBean<T> {
 
	/**
	 * 状态
	 * */
	private int status;
	/**
	 * 描述
	 * */
	private String desc;
	/**
	 * 数据返回
	 * */
	private T data;
 
	public ResultBean(int status, String desc, T data) {
		this.status = status;
		this.desc = desc;
		this.data = data;
	}
 
	public ResultBean(T data) {
		this.status = HttpStatus.OK.value();
		this.desc = "处理成功";
		this.data = data;
	}
 
	public static <T> ResultBean<T> ok(T data) {
		return new ResultBean(data);
	}
 
	public static <T> ResultBean<T> ok() {
		return new ResultBean(null);
	}
 
	public static <T> ResultBean<T> badRequest(String desc,T data) {
		return new ResultBean(HttpStatus.BAD_REQUEST.value(), desc, data);
	}
 
	public static <T> ResultBean<T> badRequest(String desc) {
		return new ResultBean(HttpStatus.BAD_REQUEST.value(), desc, null);
	}
 
	public static <T> ResultBean serverError(String desc, T data){
		return new ResultBean(HttpStatus.INTERNAL_SERVER_ERROR.value(),"服务器内部异常:"+desc,data);
	}
 
	public static <T> ResultBean serverError(String desc){
		return new ResultBean(HttpStatus.INTERNAL_SERVER_ERROR.value(),"服务器内部异常:"+desc,null);
	}
 
}

分页的对象

package com.example.mongodb.common.page;
 
import lombok.Data;
 
@Data
public class PageObject {
    // 当前页 
    private long pageIndex;
    // 当前页数 
    private long pageRowNum;
    // 总页数 
    private long totalPage;
    // 总数量 
    private long totalRow;
 
}

分页查询类

package com.example.mongodb.common.page;
 
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
 
import java.util.List;
import java.util.Optional;
 
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class PageBean {
 
    // 当前页 
    private Integer pageIndex = 1;
    // 一页的条数 
    private Integer pageRowNum = 10;
 
    @JsonIgnore 
    private Page pages;
 
    public void initPage() {
        this.pages = PageHelper.startPage(pageIndex , pageRowNum);
    }
 
    public PageDataBean loadData(List dataList) {
        return new PageDataBean(dataList , pages.getTotal() , pageIndex , pageRowNum);
    }
 
    public PageBean setPageBean(org.springframework.data.domain.Page page) {
        PageBean pageBean = new PageBean();
        pageBean.setPageRowNum(pageRowNum);
        pageBean.setPageIndex(pageIndex);
        Optional.ofNullable(page).ifPresent(e->{
            Page<?> pageHelper = new Page<>();
            pageHelper.setTotal(page.getTotalElements());
            pageHelper.setPageNum(pageRowNum);
            pageHelper.setPageSize(pageIndex);
            pageBean.setPages(pageHelper);
        });
        return pageBean;
    }
 
}

分页数据返回类：

package com.example.mongodb.common.page;
 
 
import lombok.Data;
 
import java.util.ArrayList;
import java.util.List;
 
@Data
public class PageDataBean<T> {
 
    private List<T> dataList = new ArrayList<>();
 
    private PageObject pageObj = new PageObject();
 
    public PageDataBean(List<T> dataList , Long totalRow , Integer pageIndex , Integer pageRowNum) {
        this.dataList = dataList;
        pageObj.setPageIndex(pageIndex);
        pageObj.setPageRowNum(pageRowNum);
        pageObj.setTotalRow(totalRow);
        pageObj.setTotalPage(totalRow / pageRowNum + (totalRow % pageRowNum == 0 ? 0 : 1));
    }
 
}

基于上面的封装类，Controller类进行调用：

@GetMapping(value = "/user/mongoPageList")
public ResultBean<PageDataBean<List<User>>> mongoPageList(PageBean pageBean , User param) {
    Page<User> pageDataBean = userService.mongoPageList(pageBean, param);
    pageBean = pageBean.setPageBean(pageDataBean);
    return ResultBean.ok(pageBean.loadData(pageDataBean.getContent()));
}
Java基础面试题
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