Spring Boot：RestTemplate-蒲公英云

概述

TestRestTemplate 是用于 Restful 请求的模版,并支持异步调用，默认情况下 RestTemplate 依靠 JDK 工具来建立 HTTP 链接，你也可以通过 setRequestFactory 方法来切换不同的 HTTP 库，如 Apache 的 HttpComponents 或 Netty 和 OkHttp
通常在入口类或配置类将其注入到IOC容器，它有两个构造方法

默认初始化

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

构造方法中可以传入ClientHttpRequestFactory参数,ClientHttpRequestFactory接口的实现类中存在timeout属性等等

@Bean
RestTemplate restTemplate(){
    SimpleClientHttpRequestFactory requestFactory = new          SimpleClientHttpRequestFactory();
    requestFactory.setConnectTimeout(1000);
    requestFactory.setReadTimeout(1000);
    RestTemplate restTemplate = new RestTemplate(requestFactory);
    return restTemplate;
}

它主要提供了了以下方法，对应不同的 HTTP 请求

HTTP Method	RestTemplate Methods
DELETE	delete
GET	getForObject、getForEntity
HEAD	headForHeaders
OPTIONS	optionsForAllow
POST	postForLocation、postForObject
PUT	put
any	exchange、execute

GET请求测试

@Test
    public void get() throws Exception {
        Map<String,String> multiValueMap = new HashMap<>();
        multiValueMap.put("username","lake");//传值，但要在url上配置相应的参数
        ActResult result = testRestTemplate.getForObject("/test/get?username={username}",ActResult.class,multiValueMap);
        Assert.assertEquals(result.getCode(),0);
    }

POST请求测试

@Test
    public void post() throws Exception {
        MultiValueMap multiValueMap = new LinkedMultiValueMap();
        multiValueMap.add("username","lake");
        ActResult result = testRestTemplate.postForObject("/test/post",multiValueMap,ActResult.class);
        Assert.assertEquals(result.getCode(),0);
    }

文件上传测试

@Test
    public void upload() throws Exception {
        Resource resource = new FileSystemResource("/home/lake/github/wopi/build.gradle");
        MultiValueMap multiValueMap = new LinkedMultiValueMap();
        multiValueMap.add("username","lake");
        multiValueMap.add("files",resource);
        ActResult result = testRestTemplate.postForObject("/test/upload",multiValueMap,ActResult.class);
        Assert.assertEquals(result.getCode(),0);
    }

文件下载测试

@Test
    public void download() throws Exception {
        HttpHeaders headers = new HttpHeaders();
        headers.set("token","xxxxxx");
        HttpEntity formEntity = new HttpEntity(headers);
        String[] urlVariables = new String[]{"admin"};
        ResponseEntity<byte[]> response = testRestTemplate.exchange("/test/download?username={1}",HttpMethod.GET,formEntity,byte[].class,urlVariables);
        if (response.getStatusCode() == HttpStatus.OK) {
            Files.write(response.getBody(),new File("/home/lake/github/file/test.gradle"));
        }
    }

请求头信息测试

@Test
    public void getHeader() throws Exception {
        HttpHeaders headers = new HttpHeaders();
        headers.set("token","xxxxxx");
        HttpEntity formEntity = new HttpEntity(headers);
        String[] urlVariables = new String[]{"admin"};
        ResponseEntity<ActResult> result = testRestTemplate.exchange("/test/getHeader?username={username}", HttpMethod.GET,formEntity,ActResult.class,urlVariables);
        Assert.assertEquals(result.getBody().getCode(),0);
    }

PUT请求测试

@Test
    public void putHeader() throws Exception {
        HttpHeaders headers = new HttpHeaders();
        headers.set("token","xxxxxx");
        MultiValueMap multiValueMap = new LinkedMultiValueMap();
        multiValueMap.add("username","lake");
        HttpEntity formEntity = new HttpEntity(multiValueMap,headers);
        ResponseEntity<ActResult> result = testRestTemplate.exchange("/test/putHeader", HttpMethod.PUT,formEntity,ActResult.class);
        Assert.assertEquals(result.getBody().getCode(),0);
    }

DELETE请求测试

@Test

public void delete() throws Exception {
    HttpHeaders headers = new HttpHeaders();
    headers.set("token","xxxxx");
    MultiValueMap multiValueMap = new LinkedMultiValueMap();
    multiValueMap.add("username","lake");
    HttpEntity formEntity = new HttpEntity(multiValueMap,headers);
    String[] urlVariables = new String[]{"admin"};
    ResponseEntity<ActResult> result = testRestTemplate.exchange("/test/delete?username={username}", HttpMethod.DELETE,formEntity,ActResult.class,urlVariables);
    Assert.assertEquals(result.getBody().getCode(),0);
}

异步请求

- 异步调用要使用AsyncRestTemplate。 它是RestTemplate的扩展，提供了异步http请求处理的一种机制，通过返回ListenableFuture对象生成回调机制，以达到异步非阻塞发送http请求
public String asyncReq(){  
        String url = "http://localhost:8080/jsonAsync";  
        ListenableFuture<ResponseEntity<JSONObject>> future = asyncRestTemplate.getForEntity(url, JSONObject.class);  
        future.addCallback(new SuccessCallback<ResponseEntity<JSONObject>>() {  
            public void onSuccess(ResponseEntity<JSONObject> result) {  
                System.out.println(result.getBody().toJSONString());  
            }  
        }, new FailureCallback() {  
            public void onFailure(Throwable ex) {  
                System.out.println("onFailure:"+ex);  
            }  
        });  
        return "this is async sample";  
}