Spring Boot - Rest Template

Rest Template是用来创建使用RESTful Web服务的应用程序，你可以使用exchange()方法来使用所有HTTP相关的web服务，如下代码展示如何注入Rest Template 对象。

package com.restfulapio.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
public class DemoApplication {

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

    @Bean
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

GET

通过使用RestTemplate的exchange方法来使用GET API（http://localhost:8080/products）
你将按照如下步骤来使用API：
自动装配Rest Template 对象

使用HttpHeaders设置Request头信息

使用HttpEntity来封装request请求内容
指定URL,HTTPMethod,和Exchange()返回的类型
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@RestController
public class ConsumeWebService {
    @Autowired
    RestTemplate restTemplate;

    @RequestMapping(value = "/template/products")
    public String getProductList(){
        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        HttpEntity<String> entity = new HttpEntity<String>(headers);
        return restTemplate.exchange("http://localhost:8080/products", HttpMethod.GET, entity, String.class).getBody();
    }
}

POST,DELETE,PUT

步骤都是相同，不同的细节在于：

POST自动封装了Product对象，进一步与headers封装至HttpEnitity对象中
Update获取到id参数，以及自动封装Porduct对象，进一步转发请求
DELETE获取到id参数，进一步转发请求

代码如下：

package com.restfulapio.demo.controller;

import com.restfulapio.demo.bean.Product;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

import java.lang.reflect.Array;
import java.util.Arrays;

@RestController
public class ConsumeWebService {
    @Autowired
    RestTemplate restTemplate;

    @RequestMapping(value = "/template/products")
    public String getProductList(){
        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        HttpEntity<String> entity = new HttpEntity<String>(headers);
        return restTemplate.exchange("http://localhost:8080/products", HttpMethod.GET, entity, String.class).getBody();
    }

    @RequestMapping(value = "/template/products",method = RequestMethod.POST)
    public String createProducts(@RequestBody Product product){
        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        HttpEntity<Product> entity = new HttpEntity<Product>(product, headers);
        return restTemplate.exchange("http://localhost:8080/products",HttpMethod.POST,entity,String.class).getBody();
    }

    @RequestMapping(value = "/template/products/{id}",method = RequestMethod.PUT)
    public String updateProduct(@PathVariable("id") String id, @RequestBody Product product) {
        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        HttpEntity<Product> entity = new HttpEntity<>(product, headers);
        return restTemplate.exchange("http://localhost:8080/products/" + id, HttpMethod.PUT, entity, String.class).getBody();
    }

    @RequestMapping(value = "/template/products/{id}",method = RequestMethod.DELETE)
    public String deleteProduct(@PathVariable("id") String id) {
        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        HttpEntity<Product> entity = new HttpEntity<Product>(headers);
        return restTemplate.exchange("http://localhost:8080/products/" + id, HttpMethod.DELETE, entity,String.class).getBody();
    }
}