一、新建项目

1、选择Spring Initializr，点击next。

2、输入项目组名及项目名称，java version版本选择8，点击next。

3、选择Spring Web，然后finish

二、编码

1、创建如图所示的类

2、Count

package com.example.demo;

public class Count {
    private int count;
    public int getCount() {
        return count;
    }
    public void setCount(int count) {
        this.count = count;
    }
}

3、DemoApplication

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

4、ResourceController

package com.example.demo;

import com.example.demo.Count;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import com.example.demo.ResourceService;
@RestController

public class ResourceController {

    @Autowired
    ResourceService resourceService;

    @RequestMapping(value = "/count", method = RequestMethod.PUT)
    @ResponseBody
    public void initCount(@RequestBody Count count){
        resourceService.initCount(count);
    }

    @RequestMapping(value = "/count", method = RequestMethod.POST)
    @ResponseBody
    public void modifyCount(@RequestBody Count count){
        resourceService.addCount(count);
    }

    @RequestMapping(value = "/count", method = RequestMethod.GET)
    @ResponseBody
    public  Count getCount()
    {
        return resourceService.getCount();
    }
}

5、ResourceManager

package com.example.demo;

public class ResourceManager {
    private int count = 0;

    private static ResourceManager instance = new ResourceManager();

    private ResourceManager(){}

    public static ResourceManager getInstance(){
        return instance;
    }

    public synchronized void addCount(int i){
        count = count + i;
    }

    public synchronized  void minusCount(int i){
        count = count -i;
    }

    public int getCount(){
        return count;
    }

    public void initCount(int i){
        count = i;
    }
}

6、ResourceService

package com.example.demo;

import com.example.demo.Count;
import com.example.demo.ResourceManager;
import org.springframework.stereotype.Service;

@Service
public class ResourceService {
    public void addCount(Count count){
        if (count != null){
            ResourceManager.getInstance().addCount(count.getCount());
        }
    }

    public void minusCount(Count count){
        if (count != null) {
            ResourceManager.getInstance().minusCount(count.getCount());
        }
    }

    public Count getCount()
    {
        Count count = new Count();
        count.setCount(ResourceManager.getInstance().getCount());
        return count;
    }

    public void initCount(Count count){
        if (count != null) {
            ResourceManager.getInstance().initCount(count.getCount());
        }
    }
}

7、运行程序

8、在浏览器地址栏上输入localhost:8080/count

三、测试

本文采用Postman 8.12.2 版本进行测试。
服务提供三个接口，URL均为：http://localhost:8080/count
put进行初始化，post用于修改（这里修改是累加），get用于查询。

1、如何处理get请求

在Postman的工作区中：
1、选择HTTP请求方式为GET
2、在URL区域输入链接
3、点击 “Send”按钮
4、你将看到下方返回200状态码
5、在正文中出现相应结果，表明您的测试已经成功运行。

2、如何处理post请求

（1）创建一个新请求

（2）在新请求中

1、选择HTTP请求方式为post
2、在URL区域输入链接：http://localhost:8080/count
3、切换到Body选项
4、选中raw选项
5、选择JSON

6、复制前面GET请求返回的json内容，并将“0”改为“10”，点击send

7、查询

3、如何处理put请求

1、选择HTTP请求方式为put
2、在URL区域输入链接：http://localhost:8080/count
3、切换到Body选项
4、选中raw选项
5、选择JSON

6、复制前面GET请求返回的json内容，并将“0”改为“140”，点击send

7、查询