SpringCloud的EureKaClient之间调用及负载均衡

本文通过订单服务OrderService调用用户服务UserService做案例

1.UserService

UserService的eurekaclient

@RestController
@SpringBootApplication
public class UserApp {
	@Value("${server.port}")
	private String port;
	public static void main(String[] args) {
		new SpringApplicationBuilder(UserApp.class).web(WebApplicationType.SERVLET).run(args);
	}
	@RequestMapping("/")
	public String findUserById(Integer id) {
		
		return port+"_"+id;
	}
}

UserService的yml

server:
  port: 8001
spring:
  application:
    name: user-service
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

2.OrderService 的eurekaclient,将会调用UserService的方法

2.1 OrderService 的RestTemplate

package com.cloud.erkcli1;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class OrderConfig {
	
	@LoadBalanced//负载均衡
	@Bean
	RestTemplate restTemplate() {
		return new RestTemplate();
	}
}

RestTemplate是一个HTTP客户端，使用它我们可以方便的调用HTTP接口，支持GET、POST、PUT、DELETE等方法。

GET请求方法

<T> T getForObject(String url, Class<T> responseType, Object... uriVariables);

<T> T getForObject(String url, Class<T> responseType, Map<String, ?> uriVariables);

<T> T getForObject(URI url, Class<T> responseType);

<T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Object... uriVariables);

<T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Map<String, ?> uriVariables);

<T> ResponseEntity<T> getForEntity(URI var1, Class<T> responseType);

getForObject方法
返回对象为响应体中数据转化成的对象，举例如下：

@GetMapping("/{id}")
public Result getUser(@PathVariable Long id) {
    return restTemplate.getForObject(userServiceUrl + "/user/{1}", Result.class, id);
}

getForEntity方法
返回对象为ResponseEntity对象，包含了响应中的一些重要信息，比如响应头、响应状态码、响应体等，举例如下：

@GetMapping("/getEntityByUsername")
public Result getEntityByUsername(@RequestParam String username) {
    ResponseEntity<Result> entity = restTemplate.getForEntity(userServiceUrl + "/user/getByUsername?username={1}", Result.class, username);
    if (entity.getStatusCode().is2xxSuccessful()) {
        return entity.getBody();
    } else {
        return new Result("操作失败", 500);
    }
}

POST请求方法

<T> T postForObject(String url, @Nullable Object request, Class<T> responseType, Object... uriVariables);

<T> T postForObject(String url, @Nullable Object request, Class<T> responseType, Map<String, ?> uriVariables);

<T> T postForObject(URI url, @Nullable Object request, Class<T> responseType);

<T> ResponseEntity<T> postForEntity(String url, @Nullable Object request, Class<T> responseType, Object... uriVariables);

<T> ResponseEntity<T> postForEntity(String url, @Nullable Object request, Class<T> responseType, Map<String, ?> uriVariables);

<T> ResponseEntity<T> postForEntity(URI url, @Nullable Object request, Class<T> responseType);

postForObject示例

@PostMapping("/insert")
public Result insert(@RequestBody User user) {
    return restTemplate.postForObject(userServiceUrl + "/user/insert", user, Result.class);
}

postForEntity示例

@PostMapping("/insert")
public Result insert(@RequestBody User user) {
    return restTemplate.postForEntity(userServiceUrl + "/user/insert", user, Result.class).getBody();
}

PUT请求方法

void put(String url, @Nullable Object request, Object... uriVariables);

void put(String url, @Nullable Object request, Map<String, ?> uriVariables);

void put(URI url, @Nullable Object request);

PUT请求示例

@PutMapping("/update")
public Result update(@RequestBody User user) {
    restTemplate.put(userServiceUrl + "/user/update", user);
    return new Result("操作成功",200);
}

DELETE请求方法

void delete(String url, Object... uriVariables);

void delete(String url, Map<String, ?> uriVariables);

void delete(URI url);

DELETE请求示例

@DeleteMapping("/delete/{id}")
public Result delete(@PathVariable Long id) {
   restTemplate.delete(userServiceUrl + "/user/delete/{1}", null, id);
   return new Result("操作成功",200);
}

2.2 OrderService的请求

@RestController
@SpringBootApplication
public class OrderApp {
	
	public static void main(String[] args) {
		new SpringApplicationBuilder(OrderApp.class).web(WebApplicationType.SERVLET).run(args);
	}
	@Autowired
	private RestTemplate restTemplate;
	
	@Value("${service-url.user-service}")
	private String userServiceUrl;
	@RequestMapping("/aaa")
	public String findOrder(Integer id) {
		
		ResponseEntity<String> responseEntity = restTemplate.getForEntity(userServiceUrl+"?id="+id, String.class);
		
		return "order["+responseEntity.getBody()+"]";
	}
}

2.3 OrderService的yml

server:
  port: 8101
spring:
  application:
    name: order-service
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
service-url:
  user-service: http://user-service

3测试

开启两个UserService,端口分别开启为8001/8002然后开启一个OrderService去调用.然后多次访问http://localhost:8101/aaa?id=3 .

结果分别是:order[8002_3]/order[8001_3]
可以看到服务调用及其负载均衡

标签：负载,String,EureKaClient,SpringCloud,Object,url,user,public,Result
来源： https://blog.csdn.net/dmw412724/article/details/115523534