需求分析:

?具體返回如下JSON格式數(shù)據(jù)

含有四個屬性列:id 和 username 和photo 和followerCount

第一步:

?首先按照下面文章創(chuàng)建一個模板項目

SpingBoot——SB整合MB的web項目模板_北嶺山腳鼠鼠的博客-CSDN博客

?第二步:

使用如下的建表語句在一個數(shù)據(jù)庫中新建一個用戶表

CREATE TABLE `users` (
                         `id` int NOT NULL AUTO_INCREMENT,
                         `username` char(20) DEFAULT NULL,
                         `photo` varchar(200) DEFAULT NULL,
                         `followerCount` int DEFAULT NULL,
                         PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

并在pojo層中新建一個與之對應(yīng)的實體類Users

package com.example.backbound.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Users {
    private int id;
    private String username;
    private String photo;
    private int followerCount;
}

第三步:

解決跨域訪問的問題:

新建一個config包，在里面新建一個CorsConfig類，填充以下內(nèi)容，然后在前后端聯(lián)調(diào)時就不會出現(xiàn)跨域訪問報錯了。

package com.example.backbound.config;

import org.springframework.context.annotation.Configuration;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Configuration
public class CorsConfig implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        HttpServletRequest request = (HttpServletRequest) req;

        String origin = request.getHeader("Origin");
        if(origin!=null) {
            response.setHeader("Access-Control-Allow-Origin", origin);
        }

        String headers = request.getHeader("Access-Control-Request-Headers");
        if(headers!=null) {
            response.setHeader("Access-Control-Allow-Headers", headers);
            response.setHeader("Access-Control-Expose-Headers", headers);
        }

        response.setHeader("Access-Control-Allow-Methods", "*");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Credentials", "true");

        chain.doFilter(request, response);
    }

    @Override
    public void init(FilterConfig filterConfig) {

    }

    @Override
    public void destroy() {
    }
}

?第四步:

準備三層架構(gòu)各個類

controller層:

新建一個userlistcontroller

package com.example.backbound.controller.userlist;


import com.example.backbound.pojo.Users;
import com.example.backbound.service.userlist.impl.userlistservice;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/userlist/")
public class userlistcontroller {


    @Autowired
    private userlistservice  userlistservice;

    @GetMapping
    public List<Users> getuserlist(){
        List<Users> usersList=userlistservice.getuserlist();
        return usersList;
    }
}

service層：

先新建一個userlistservice接口

package com.example.backbound.service.userlist;

import com.example.backbound.pojo.Users;

import java.util.List;

public interface userlist {
    public List<Users> getuserlist();

}

在新建一個該接口的實現(xiàn)類

package com.example.backbound.service.userlist.impl;

import com.example.backbound.mapper.userlist.UserlistMapper;
import com.example.backbound.pojo.Users;
import com.example.backbound.service.userlist.userlist;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class userlistservice implements userlist {
    @Autowired
    private UserlistMapper userlistMapper;
    @Override
    public List<Users> getuserlist() {
        return userlistMapper.getuserlist();
    }
}

?Mapper層:

實現(xiàn)一個userlistMapper接口如下

package com.example.backbound.mapper.userlist;

import com.example.backbound.pojo.Users;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

@Mapper
public interface UserlistMapper {

    @Select("select * from users")
    List<Users> getuserlist();
}

最后項目文件結(jié)構(gòu)如下所示

?文章來源地址http://www.zghlxwxcb.cn/news/detail-446953.html

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