SpringBoot分页查询

前期准备

依赖添加

	<parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>1.5.3.RELEASEversion>
        <relativePath/>
    parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>
    <repositories>
        
        <repository>
            <id>spring-snapshotsid>
            <name>Spring Snapshotsname>
            <url>https://repo.spring.io/snapshoturl>
            <snapshots>
                <enabled>trueenabled>
            snapshots>
        repository>
        <repository>
            <id>spring-milestonesid>
            <name>Spring Milestonesname>
            <url>https://repo.spring.io/milestoneurl>
            <snapshots>
                <enabled>falseenabled>
            snapshots>
        repository>
    repositories>

    <pluginRepositories>
        
        <pluginRepository>
            <id>spring-snapshotsid>
            <name>Spring Snapshotsname>
            <url>https://repo.spring.io/snapshoturl>
            <snapshots>
                <enabled>trueenabled>
            snapshots>
        pluginRepository>
        <pluginRepository>
            <id>spring-milestonesid>
            <name>Spring Milestonesname>
            <url>https://repo.spring.io/milestoneurl>
            <snapshots>
                <enabled>falseenabled>
            snapshots>
        pluginRepository>
    pluginRepositories>

统一json返回值类型

1. 设置json返回值类型

@Data
public class Result {
    /**
     * json返回值
     *   {
     *      "code": 0,
     *      "flag": true,
     *      "message": "string",
     *      "data": [
     *          {
     *          "id": "string",
     *          "labelname": "string",
     *          "state": "string",
     *          "count": 0,
     *          "recommend": "string"
     *          }
     *       ]
     *   }
    * */
    private int code;
    private String message;
    private boolean flag;
    private Object data;
}

2. 自定义状态码

//项目自己约定的状态码，定义成常量方便使用
public class StatusCode {

    //成功
    public static final int OK=20000;
    //失败
    public static final int ERROR =20001;
    //用户名或密码错误
    public static final int LOGINERROR =20002;
    //权限不足
    public static final int ACCESSERROR =20003;
    //远程调用失败
    public static final int REMOTEERROR =20004;
    //重复操作
    public static final int REPERROR =20005;
}

springBoot配置文件

server:
  port: 9001
spring:
  application:
    #不推荐写下划线
    name: tensquare-base
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://192.168.200.157:3306/tensquare_base?characterEncoding=utf-8
    username: root
    password: cqrjxk39
  jpa:
    database: mysql
    show-sql: true

springBoot启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import util.IdWorker;

//springBoot的启动类，所有springBoot项目都是靠main方法启动，自带服务器容器
@SpringBootApplication
public class BaseApplication {
    public static void main(String[] args) {
        SpringApplication.run(BaseApplication.class);
    }
    //如果这个项目中需要用到IdWord的类，需要将该类纳入spring管理成一个Bean
    @Bean
    public IdWorker idWorker(){
        return new IdWorker();
    }
}

核心代码

设置分页返回值的数据类型

@Data
public class PageResult<T> {
    /**
    * 分页返回
    *"data": {
            "total": 0,
            "rows": [
                {
                    "id": "string",
                    "labelname": "string",
                    "state": "string",
                    "count": 0,
                    "recommend": "string"
                }
             ]
          }
    * */
    private long totle;
    private List<T> rows;
}

pojo层

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

//标签实体类
@Entity
//指定表格
@Table(name = "tb_label")
@Data
public class Label {
    @Id
    private String id;
    private String labelname;
    private String state;
    private Long count;
    private String recommend;
    private Long fans;

}

dao层

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface LabelDao extends JpaRepository<Label,String>, JpaSpecificationExecutor<Label> {
    //JpaRepository实现简单的增删改查，Label是实体类，String是主键的类型
    //JpaSpecificationExecutor实现复杂,带条件的增删改查
}

service层

import com.tensquare.search.dao.ArticleDao;
import com.tensquare.search.pojo.Article;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service
@Transactional
public class ArticleService {
    @Autowired
    private ArticleDao articleDao;

    public void addArticle(Article article){
        articleDao.save(article);
    }

    public Page<Article> findByTitleOrContentLike(String title,String content,int page,int size){
        PageRequest of = PageRequest.of(page - 1, size);
        Page<Article> byTitleOrContentLike = articleDao.findByTitleOrContentLike(title, content, of);
        return byTitleOrContentLike;
    }
}

controller层

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.web.bind.annotation.*;

@RestController
@CrossOrigin
@RequestMapping("/article")
public class ArticleController {
    @Autowired
    private ArticleService articleService;
    
    @RequestMapping(value = "/{key}/{page}/{size}",method =RequestMethod.GET)
    public Result findByTitleOrContentLike(@PathVariable String key,@PathVariable int page,@PathVariable int size){
        Page<Article> byTitleOrContentLike = articleService.findByTitleOrContentLike(key, key, page, size);
        return new Result(true,StatusCode.OK,"查询成功",new PageResult<Article>(byTitleOrContentLike.getTotalElements(),byTitleOrContentLike.getContent()));
    }

}