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RestTemplate使用

一、依赖注入

	@Bean
	// 开启负载均衡
	@LoadBalanced
	RestTemplate restTemplate() {
		return new RestTemplate();
	}

二、调用服务

String url ="http://provider/getHi";
String respStr = restTemplate.getForObject(url, String.class);

三、get 请求

1、getForEntity

getForEntityMethod的Return值是一个ResponseEntity，ResponseEntity是Spring对HTTP请求响应的封装，包括了几个重要的元素，如响应码、contentType、contentLength、响应Message体等。

<200,Hi,[Content-Type:"text/plain;charset=UTF-8", Content-Length:"8", Date:"Fri, 10 Apr 2020 09:58:44 GMT", Keep-Alive:"timeout=60", Connection:"keep-alive"]>

2、返回Map

调用方

		String url ="http://provider/getMap";
		ResponseEntity<Map> entity = restTemplate.getForEntity(url, Map.class);
		System.out.println("respStr: "  + entity.getBody() );

生产方

	@GetMapping("/getMap")
	public Map<String, String> getMap() {
		HashMap<String, String> map = new HashMap<>();
		map.put("name", "500");
		return map; 
	}

3、返回对象(getForEntity)

调用方

		ResponseEntity<Person> entity = restTemplate.getForEntity(url, Person.class);
		System.out.println("respStr: "  + ToStringBuilder.reflectionToString(entity.getBody() ));

生产方

	@GetMapping("/getObj")
	public Person getObj() {
		Person person = new Person();
		person.setId(100);
		person.setName("xiaoming");
		return person; 
	}

Person类

	private int id;
	private String name;

4、传参调用

4.1、Usage占位符

	String url ="http://provider/getObjParam?name={1}";
	ResponseEntity<Person> entity = restTemplate.getForEntity(url, Person.class,"hehehe...");

4.2、Usagemap

		String url ="http://provider/getObjParam?name={name}";
		Map<String, String> map = Collections.singletonMap("name", " memeda");
		ResponseEntity<Person> entity = restTemplate.getForEntity(url, Person.class,map);

5、返回对象（getForObject）

Person person = restTemplate.getForObject(url, Person.class,map);

四、post 请求

1、postForEntity

调用方

		String url ="http://provider/postParam";
		Map<String, String> map = Collections.singletonMap("name", " memeda");
		ResponseEntity<Person> entity = restTemplate.postForEntity(url, map, Person.class);

生产方

	@PostMapping("/postParam")
	public Person postParam(@RequestBody String name) {

		System.out.println("name:" + name);

		Person person = new Person();
		person.setId(100);
		person.setName("xiaoming" + name);
		return person; 
	}

2、postForLocation

调用方

		String url ="http://provider/postParam";
		   
		Map<String, String> map = Collections.singletonMap("name", " memeda");
		URI location = restTemplate.postForLocation(url, map, Person.class);
		
		System.out.println(location);

生产方

需要Settings头信息，不然Return的是null

	public URI postParam(@RequestBody Person person,HttpServletResponse response) throws Exception {

	URI uri = new URI("https://www.baidu.com/s?wd="+person.getName());
	response.addHeader("Location", uri.toString());

五、exchange

可以自定义http请求的头信息，同时保护get和postMethod

第一步：自定义拦截器

需要ImplementationClientHttpRequestInterceptorInterface

public class LoggingClientHttpRequestInterceptor implements ClientHttpRequestInterceptor {

	@Override
	public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution)
			throws IOException {

		System.out.println("拦截啦！！！");
		System.out.println(request.getURI());

		ClientHttpResponse response = execution.execute(request, body);

		System.out.println(response.getHeaders());
		return response;
	}

第二步：添加到RestTemplate中

	@Bean
	@LoadBalanced
	RestTemplate restTemplate() {
		RestTemplate restTemplate = new RestTemplate();
		restTemplate.getInterceptors().add(new LoggingClientHttpRequestInterceptor());
		return restTemplate;
	}