HttpClient4.1 使用示例

一、HttpClient简介

HttpClient 是 Apache Jakarta Common 下的子项目，用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。HttpClient 已经应用在很多的项目中，比如 Apache Jakarta 上很著名的另外两个开源项目 Cactus 和 HTMLUnit 都使用了 HttpClient。现在HttpClient最新版本为 HttpClient 4.3.

二、HttpClient特性

1. 基于标准,纯净的java语言.实现了Http1.0和Http1.1
2. 以可扩展的面向对象的结构实现了Http全部的方法 (GET, POST, PUT, DELETE, HEAD, OPTIONS, and TRACE).
3. 支持HTTPS协议.
4. 通过Http代理建立透明的连接.
5. 利用CONNECT 方法通过Http代理建立隧道的https连接.
6. Basic, Digest, NTLMv1, NTLMv2, NTLM2 Session, SNPNEGO/Kerberos 认证方案.
7. 插件式的自定义认证方案.
8. 便携可靠的套接字工厂使它更容易的使用第三方解决方案.
9. 连接管理器支持多线程应用.支持设置最大连接数,同时支持设置每个主机的最大连接数.发现并关闭过期的连接.
10. Automatic Cookie handling for reading Set-Cookie: headers from the server and sending them back out in a Cookie: header when appropriate.
11. 插件式的自定义Cookie策略.
12. Request output streams to avoid buffering any content body by streaming directly to the socket to the server.
13. Response input streams to efficiently read the response body by streaming directly from the socket to the server.
14. 在http1.0和http1.1中利用KeepAlive保持持久连接.
15. 直接获取服务器发送的response code和 headers.
16. 设置连接超时的能力.
17. 实验性的支持http1.1 response caching.
18. 源代码基于Apache License 可免费获取.

下载地址: http://hc.apache.org/downloads.cgi

三、详细讲解

这里为了更好的理解，新建了一个java se的工程，如下图所示

HttpClientTest类

package com.yulore.httpproxy;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.UnsupportedEncodingException;import java.security.KeyManagementException;import java.security.KeyStore;import java.security.KeyStoreException;import java.security.NoSuchAlgorithmException;import java.security.UnrecoverableKeyException;import java.security.cert.CertificateException;import java.util.ArrayList;import java.util.List;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;import org.apache.http.ParseException;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.conn.scheme.Scheme;import org.apache.http.conn.ssl.SSLSocketFactory;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;import org.apache.http.util.EntityUtils;import org.junit.Test;public class HttpClientTest {@Testpublic void jUnitTest(){get();}/** * HttpClient连接SSL */private void ssl() {DefaultHttpClient httpclient = new DefaultHttpClient();try {KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());FileInputStream instream = new FileInputStream(new File("d:\\tomcat.keystore"));try {// 加载keyStore d:\\tomcat.keystoretrustStore.load(instream, "123456".toCharArray());} catch (CertificateException e) {e.printStackTrace();} finally {try {instream.close();} catch (Exception ignore) {}}// 穿件Socket工厂,将trustStore注入SSLSocketFactory socketFactory = new SSLSocketFactory(trustStore);// 创建SchemeScheme sch = new Scheme("https", 8443, socketFactory);// 注册Schemehttpclient.getConnectionManager().getSchemeRegistry().register(sch);// 创建http请求(get方式)HttpGet httpget = new HttpGet("https://localhost:8443/myDemo/Ajax/serivceJ.action");System.out.println("executing request" + httpget.getRequestLine());HttpResponse response = httpclient.execute(httpget);HttpEntity entity = response.getEntity();System.out.println("----------------------------------------");System.out.println(response.getStatusLine());if (entity != null) {System.out.println("Response content length: "+ entity.getContentLength());String ss = EntityUtils.toString(entity);System.out.println(ss);EntityUtils.consume(entity);}} catch (ParseException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} catch (KeyManagementException e) {e.printStackTrace();} catch (UnrecoverableKeyException e) {e.printStackTrace();} catch (NoSuchAlgorithmException e) {e.printStackTrace();} catch (KeyStoreException e) {e.printStackTrace();} finally {httpclient.getConnectionManager().shutdown();}}/** * post方式提交表单（模拟用户登录请求） */private void postForm() {// 创建默认的httpClient实例.HttpClient httpclient = new DefaultHttpClient();// 创建httppostHttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceJ.action");// 创建参数队列List<NameValuePair> formparams = new ArrayList<NameValuePair>();formparams.add(new BasicNameValuePair("username", "admin"));formparams.add(new BasicNameValuePair("password", "123456"));UrlEncodedFormEntity uefEntity;try {uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8");httppost.setEntity(uefEntity);System.out.println("executing request " + httppost.getURI());HttpResponse response;response = httpclient.execute(httppost);HttpEntity entity = response.getEntity();if (entity != null) {System.out.println("--------------------------------------");System.out.println("Response content: "+ EntityUtils.toString(entity, "UTF-8"));System.out.println("--------------------------------------");}} catch (ClientProtocolException e) {e.printStackTrace();} catch (UnsupportedEncodingException e1) {e1.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {// 关闭连接,释放资源httpclient.getConnectionManager().shutdown();}}/** * 发送 post请求访问本地应用并根据传递参数不同返回不同结果 */private void post() {// 创建默认的httpClient实例.HttpClient httpclient = new DefaultHttpClient();// 创建httppostHttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceJ.action");// 创建参数队列List<NameValuePair> formparams = new ArrayList<NameValuePair>();formparams.add(new BasicNameValuePair("type", "house"));UrlEncodedFormEntity uefEntity;try {uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8");httppost.setEntity(uefEntity);System.out.println("executing request " + httppost.getURI());HttpResponse response;response = httpclient.execute(httppost);HttpEntity entity = response.getEntity();if (entity != null) {System.out.println("--------------------------------------");System.out.println("Response content: "+ EntityUtils.toString(entity, "UTF-8"));System.out.println("--------------------------------------");}} catch (ClientProtocolException e) {e.printStackTrace();} catch (UnsupportedEncodingException e1) {e1.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {// 关闭连接,释放资源httpclient.getConnectionManager().shutdown();}}/** * 发送 get请求 */private void get() {HttpClient httpclient = new DefaultHttpClient();try {// 创建httpget.HttpGet httpget = new HttpGet("http://www.baidu.com/");System.out.println("executing request " + httpget.getURI());// 执行get请求.HttpResponse response = httpclient.execute(httpget);// 获取响应实体HttpEntity entity = response.getEntity();System.out.println("--------------------------------------");// 打印响应状态System.out.println(response.getStatusLine());if (entity != null) {// 打印响应内容长度System.out.println("Response content length: "+ entity.getContentLength());// 打印响应内容System.out.println("Response content: "+ EntityUtils.toString(entity));}System.out.println("------------------------------------");} catch (ClientProtocolException e) {e.printStackTrace();} catch (ParseException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {// 关闭连接,释放资源httpclient.getConnectionManager().shutdown();}}}

详细信息请看程序中的注释

注意事项

JUnit运行测试时报错，错误日志信息如下：

java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
at org.apache.http.impl.client.AbstractHttpClient.<init>(AbstractHttpClient.java:182)
at org.apache.http.impl.client.DefaultHttpClient.<init>(DefaultHttpClient.java:150)
at com.yulore.httpproxy.HttpClientTest.get(HttpClientTest.java:180)
at com.yulore.httpproxy.HttpClientTest.jUnitTest(HttpClientTest.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
... 27 more

缺少commons-logging jar包，导入commons-logging.jar即可

commons-logging.jar 下载地址