HttpClient 4.2 Fluent API学习：流畅的HTTP客户端调用

               相比于HttpClient 之前的版本，HttpClient 4.2 提供了一组基于流接口(fluent interface)概念的更易使用的API，即Fluent API.

               为了方便使用，Fluent API只暴露了一些最基本的HttpClient功能。这样，Fluent API就将开发者从连接管理、资源释放等繁杂的操作中解放出来，从而更易进行一些HttpClient的简单操作。

(原文地址:http://blog.csdn.net/vector_yi/article/details/24298629转载请注明出处)

               还是利用具体例子来说明吧。

以下是几个使用Fluent API的代码样例：

一、最基本的http请求功能

执行Get、Post请求，不对返回的响应作处理

package com.vectoryi.fluent; import java.io.File; import org.apache.http.HttpHost;import org.apache.http.HttpVersion;import org.apache.http.client.fluent.Form;import org.apache.http.client.fluent.Request;import org.apache.http.entity.ContentType;  public class FluentRequests {     public static void main(String[] args)throws Exception {    	//执行一个GET请求,同时设置Timeout参数并将响应内容作为String返回        Request.Get("http://blog.csdn.net/vector_yi")                .connectTimeout(1000)                .socketTimeout(1000)                .execute().returnContent().asString();         //以Http/1.1版本协议执行一个POST请求，同时配置Expect-continue handshake达到性能调优,        //请求中包含String类型的请求体并将响应内容作为byte[]返回        Request.Post("http://blog.csdn.net/vector_yi")                .useExpectContinue()                .version(HttpVersion.HTTP_1_1)                .bodyString("Important stuff", ContentType.DEFAULT_TEXT)                .execute().returnContent().asBytes();          //通过代理执行一个POST请求并添加一个自定义的头部属性,请求包含一个HTML表单类型的请求体        //将返回的响应内容存入文件        Request.Post("http://blog.csdn.net/vector_yi")                .addHeader("X-Custom-header", "stuff")                .viaProxy(new HttpHost("myproxy", 8080))                .bodyForm(Form.form().add("username", "vip").add("password", "secret").build())                .execute().saveContent(new File("result.dump"));    } }
二、在后台线程中异步执行多个请求

package com.vectoryi.fluent; import java.util.LinkedList;import java.util.Queue;import java.util.concurrent.ExecutionException;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future; import org.apache.http.client.fluent.Async;import org.apache.http.client.fluent.Content;import org.apache.http.client.fluent.Request;import org.apache.http.concurrent.FutureCallback;  public class FluentAsync {     public static void main(String[] args)throws Exception {        // 利用线程池        ExecutorService threadpool = Executors.newFixedThreadPool(2);        Async async = Async.newInstance().use(threadpool);         Request[] requests = new Request[] {                Request.Get("http://www.google.com/"),                Request.Get("http://www.yahoo.com/"),                Request.Get("http://www.apache.com/"),                Request.Get("http://www.apple.com/")        };          Queue<Future<Content>> queue = new LinkedList<Future<Content>>();        // 异步执行GET请求        for (final Request request: requests) {            Future<Content> future = async.execute(request, new FutureCallback<Content>() {                 public void failed(final Exception ex) {                    System.out.println(ex.getMessage() + ": " + request);                }                 public void completed(final Content content) {                    System.out.println("Request completed: " + request);                }                 public void cancelled() {                }             });            queue.add(future);        }         while(!queue.isEmpty()) {            Future<Content> future = queue.remove();            try {                future.get();            } catch (ExecutionException ex) {            }        }        System.out.println("Done");        threadpool.shutdown();    } }
三、更快速地启动请求

package com.vectoryi.fluent; import org.apache.http.client.fluent.Form;import org.apache.http.client.fluent.Request; public class FluentQuickStart {     public static void main(String[] args) throws Exception {         Request.Get("http://targethost/homepage")            .execute().returnContent();        Request.Post("http://targethost/login")            .bodyForm(Form.form().add("username",  "vip").add("password",  "secret").build())            .execute().returnContent();    }}
四、处理Response

在本例中是利用xmlparsers来解析返回的ContentType.APPLICATION_XML类型的内容。

package com.vectoryi.fluent; import java.io.IOException;import java.nio.charset.Charset; import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException; import org.apache.http.Consts;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.StatusLine;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpResponseException;import org.apache.http.client.ResponseHandler;import org.apache.http.client.fluent.Request;import org.apache.http.entity.ContentType;import org.w3c.dom.Document;import org.xml.sax.SAXException;  public class FluentResponseHandling {     public static void main(String[] args)throws Exception {        Document result = Request.Get("http://www.baidu.com")                .execute().handleResponse(new ResponseHandler<Document>() {             public Document handleResponse(final HttpResponse response) throws IOException {                StatusLine statusLine = response.getStatusLine();                HttpEntity entity = response.getEntity();                if (statusLine.getStatusCode() >= 300) {                    throw new HttpResponseException(                            statusLine.getStatusCode(),                            statusLine.getReasonPhrase());                }                if (entity == null) {                    throw new ClientProtocolException("Response contains no content");                }                DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();                try {                    DocumentBuilder docBuilder = dbfac.newDocumentBuilder();                    ContentType contentType = ContentType.getOrDefault(entity);                    if (!contentType.equals(ContentType.APPLICATION_XML)) {                        throw new ClientProtocolException("Unexpected content type:" + contentType);                    }                    Charset charset = contentType.getCharset();                    if (charset == null) {                        charset = Consts.ISO_8859_1;                    }                    return docBuilder.parse(entity.getContent(), charset.name());                } catch (ParserConfigurationException ex) {                    throw new IllegalStateException(ex);                } catch (SAXException ex) {                    throw new ClientProtocolException("Malformed XML document", ex);                }            }             });        // 处理得到的result        System.out.println(result);    } }

转载于:https://my.oschina. net /u/858166/blog/697310

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