Java實現HTTP請求__Java

一、利用RestTemplate來實現

RestTemplate是spring-web封裝的一個請求類，基本可以滿足一般業務需求。

private static RestTemplate restTemplate = new RestTemplate();public static final HttpHeaders jsonAndXml;    static {        jsonAndXml = new HttpHeaders();        jsonAndXml.setContentType(MediaType.APPLICATION_JSON_UTF8);        List<MediaType> mediaTypeList = new ArrayList<MediaType>();        mediaTypeList.add(MediaType.APPLICATION_XML);        jsonAndXml.setAccept(mediaTypeList);    }>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>String response = restTemplate.exchange(url, HttpMethod.GET, new HttpEntity<>(jsonAndXml), String.class).getBody();

除了exchange外，RestTemplate有許多可供開發人員調用的介面，如傳路徑變數，參數等。

二、利用apache httpcomponents組件實現

1.導包

<dependency>    <groupId>org.apache.httpcomponents</groupId>    <artifactId>httpclient</artifactId>    <version>4.5.1</version></dependency>

2.實現

HttpEntity body = new StringEntity(new Gson().toJson(root), ContentType.create("application/json", Consts.UTF_8));DefaultBHttpClientConnection conn = null;        try {            HttpProcessor httpProcessor = HttpProcessorBuilder.create().add(new RequestContent()).add(new RequestTargetHost()).add(new RequestConnControl())                                                              .add(new RequestUserAgent("Test/1.1")).add(new RequestExpectContinue(true)).build();            HttpRequestExecutor httpRequestExecutor = new HttpRequestExecutor();            HttpCoreContext coreContext = new HttpCoreContext();            HttpHost host = new HttpHost(HOST, PORT);            coreContext.setTargetHost(host);            conn = new DefaultBHttpClientConnection(8 * 1024);            ConnectionReuseStrategy connectionReuseStrategy = DefaultConnectionReuseStrategy.INSTANCE;                if (!conn.isOpen()) {                    Socket socket = new Socket(host.getHostName(), host.getPort());                    conn.bind(socket);                }                BasicHttpEntityEnclosingRequest request = new BasicHttpEntityEnclosingRequest("POST", url);                request.setEntity(body);                System.out.println("URL:" + request.getRequestLine().getUri());                httpRequestExecutor.preProcess(request, httpProcessor, coreContext);                HttpResponse response = httpRequestExecutor.execute(request, conn, coreContext);                httpRequestExecutor.postProcess(response, httpProcessor, coreContext);                System.out.println("響應：" + response.getStatusLine());                System.out.println("響應的body" + EntityUtils.toString(response.getEntity()));                System.out.println("====結束====");                if (!connectionReuseStrategy.keepAlive(response, coreContext)) conn.close();                else System.out.println("保持連結");        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                conn.close();            } catch (IOException e) {                e.printStackTrace();            }        }