SpringCloud——接口互相调用(RestTemplate+Ribbon)

小灰灰 2022-05-10 02:14 240阅读 0赞

我之前写过两个接口服务user和student，现在将它完善一下

user，创建一个接口 localhost:12003/getUserList 返回一个json数据，用来做测试

![70][]

UserApi.java

package com.springcloud.demo.api;
    
    import java.util.List;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;
    
    import com.springcloud.demo.domain.BaseJSON;
    import com.springcloud.demo.domain.po.UserPO;
    import com.springcloud.demo.server.UserService;
    
    @RestController
    public class UserApi {
    	
    	@Autowired
    	public UserService userService;
    	
    	@RequestMapping(value="/test",method=RequestMethod.GET)
    	public String test() {
    		return "Hello World";
    	}
    	
    	@RequestMapping(value="/getUserList",method=RequestMethod.GET)
    	public BaseJSON getUserList() {
    		BaseJSON json = new BaseJSON();
    		List<UserPO> list = userService.getUserList();
    		if(list.size()<0||list==null) {
    			json.setCode(11);
    			json.setMessage("失败");
    		}else {
    			json.setResult(list);
    		}
    		return json;
    	}
    	
    }

Service层实现

package com.springcloud.demo.server.imp;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import org.springframework.stereotype.Service;
    
    import com.springcloud.demo.domain.po.UserPO;
    import com.springcloud.demo.server.UserService;
    
    @Service
    public class UserServiceImp implements UserService{
    
    	@Override
    	public List<UserPO> getUserList() {
    		List<UserPO> list = new ArrayList<>();
    		UserPO user = new UserPO();
    		
    		user.setId(1);
    		user.setUsername("lg");
    		user.setPassword("123456");
    		list.add(user);
    		
    		user.setId(2);
    		user.setUsername("lxy");
    		user.setPassword("123456");
    		list.add(user);
    		return list;
    	}
    
    	
    }

Student 调用 user的restFul接口，获取数据，然后将数据重新封装

![70 1][]

首先我们需要注入RestTemplate，这里我们图方便加载BootMain中了，使用@LoadBalanced注解标明

package com.springcloud.demo;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.cloud.netflix.feign.EnableFeignClients;
    import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
    import org.springframework.context.annotation.Bean;
    import org.springframework.scheduling.annotation.EnableScheduling;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.client.RestTemplate;
    
    import springfox.documentation.annotations.ApiIgnore;
    import springfox.documentation.swagger2.annotations.EnableSwagger2;
    
    @Controller
    @SpringBootApplication
    @ApiIgnore
    @EnableScheduling 
    @EnableDiscoveryClient
    @EnableFeignClients
    @EnableSwagger2
    @EnableHystrixDashboard
    public class BootMain {
    	public static void main(String[] args) {
    		SpringApplication.run(BootMain.class, args);
    	}
    	
    	@RequestMapping("/help")
    	public String help() {
    		return "redirect:swagger-ui.html";
    	}
    	/**
        重点看这里
        */
    	@Bean
        @LoadBalanced
        RestTemplate restTemplate() {
            return new RestTemplate();
        }
    }

service调用实现

【注】：

1、RestTemplate 访问的URL不能携带ip和端口号，不然会报错,改成你所调用的服务在注册中心注册的名字

报错 
    No instances available for 192.168.xx.xx
    No instances available for [IP]

2、使用Entity接收RestTemplate获取到的值

@Autowired 
    private RestTemplate rt;

//ResponseEntity<BaseJSON> re = rt.getForEntity(url, BaseJSON.class);
    HttpEntity<BaseJSON> re = rt.getForEntity(url, BaseJSON.class);
    BaseJSON json = re.getBody();

获取到的json就是我门的目标json对象（BaseJSON自己封装的），里面拥有从user获取到的全部数据  
3、在获取对象时候，我们得到的Object无法直接转为目标对象StudentPO，我们可以先将其转为json字符串，然后再转为我们的目标对象，需要在pom.xml中加入jar包，具体java<——>操作可见：[json数据对象操作][json]

package com.springcloud.demo.service.imp;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.http.HttpEntity;
    import org.springframework.http.ResponseEntity;
    import org.springframework.stereotype.Service;
    import org.springframework.web.client.RestTemplate;
    
    import com.springcloud.demo.domain.BaseJSON;
    import com.springcloud.demo.domain.po.StudentPO;
    import com.springcloud.demo.domain.po.UserPO;
    import com.springcloud.demo.service.StudentService;
    
    import net.sf.json.JSONObject;
    
    @Service
    public class StudentServiceImp implements StudentService{
    	
    	@Autowired 
    	private RestTemplate rt;
    	
    	@Override
    	public List<StudentPO> getStudentList() {
    		//使用RestTemplate
    		String url = "http://user/getUserList";
    		/**
    		 * String url = "http://192.168.99.115:12001/user/getUserList";
    		  * 报错：No instances available for [IP]
    		 */
    		//ResponseEntity<BaseJSON> re = rt.getForEntity(url, BaseJSON.class);
    		HttpEntity<BaseJSON> re = rt.getForEntity(url, BaseJSON.class);
    		BaseJSON json = re.getBody();
    		
    		List<UserPO> userList = new ArrayList();
    		List<StudentPO> studentList = new ArrayList();
    		
    		if(json.getCode()==0) {
    			userList = (List<UserPO>) json.getResult();
    			for(Object obj:userList) {
    				JSONObject jsonObject = JSONObject.fromObject(obj);
    				
    				UserPO user = (UserPO)jsonObject.toBean(jsonObject,UserPO.class);
    				StudentPO student = new StudentPO();
    				student.setId(user.getId());
    				student.setName(user.getUsername());
    				student.setPassword(user.getUsername());
    				student.setGrade(1);
    				studentList.add(student);
    			}
    		}else {
    			studentList = null;
    		}
    		return studentList;
    	}
    	
    }

[70]: /images/20220510/47b849afe0cc44b58b54459652488b98.png
[70 1]: /images/20220510/6efc2ec5625a4d91871dedbc265494f3.png
[json]: https://blog.csdn.net/qq_34819372/article/details/82350402