HttpClient4.2 Fluent API学习

时间：2023-03-08 21:13:15

相比于HttpClient 之前的版本号，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仅仅暴露了一些最主要的HttpClient功能。

这样，Fluent API就将开发人员从连接管理、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.****.net/vector_yi/article/details/24298629转载请注明出处)

还是利用详细样例来说明吧。

下面是几个使用Fluent API的代码例子：

一、最主要的http请求功能

运行Get、Post请求，不正确返回的响应作处理

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 {

    	//运行一个GET请求,同一时候设置Timeout參数并将响应内容作为String返回

        Request.Get("http://blog.****.net/vector_yi")

                .connectTimeout(1000)

                .socketTimeout(1000)

                .execute().returnContent().asString();

        //以Http/1.1版本号协议运行一个POST请求，同一时候配置Expect-continue handshake达到性能调优,

        //请求中包括String类型的请求体并将响应内容作为byte[]返回

        Request.Post("http://blog.****.net/vector_yi")

                .useExpectContinue()

                .version(HttpVersion.HTTP_1_1)

                .bodyString("Important stuff", ContentType.DEFAULT_TEXT)

                .execute().returnContent().asBytes();

        //通过代理运行一个POST请求并加入一个自己定义的头部属性,请求包括一个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.****.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、在后台线程中异步运行多个请求

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>>();

        // 异步运行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、更高速地启动请求

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);

    }

}

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