HttpClient使用具体解释
Http协议的重要性相信不用我多说了,HttpClient相比传统JDK自带的URLConnection,添加�了易用性和灵活性(详细差别,日后我们再讨论),它不仅是client发送Http请求变得easy,并且也方便了开发者測试接口(基于Http协议的),即提高了开发的效率,也方便提高代码的健壮性。因此熟练掌握HttpClient是非常重要的必修内容,掌握HttpClient后,相信对于Http协议的了解会更加深入。
一、简单介绍
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client编程工具包,而且它支持HTTP协议最新的版本号和建议。HttpClient已经应用在非常多的项目中,比方Apache Jakarta上非常著名的另外两个开源项目Cactus和HTMLUnit都使用了HttpClient。
下载地址: http://hc.apache.org/downloads.cgi
二、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所有的方法(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. 插件式的自己定义认证方案。
8. 便携可靠的套接字工厂使它更easy的使用第三方解决方式。
9. 连接管理器支持多线程应用。支持设置最大连接数,同一时候支持设置每一个主机的最大连接数,发现并关闭过期的连接。
10. 自己主动处理Set-Cookie中的Cookie。
11. 插件式的自己定义Cookie策略。
12. Request的输出流能够避免流中内容直接缓冲到socketserver。
13. Response的输入流能够有效的从socketserver直接读取对应内容。
14. 在http1.0和http1.1中利用KeepAlive保持持久连接。
15. 直接获取server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. 源码基于Apache License 可免费获取。
三、用法
使用HttpClient发送请求、接收响应非常easy,一般须要例如以下几步就可以。
1. 创建HttpClient对象。
2. 创建请求方法的实例,并指定请求URL。假设须要发送GET请求,创建HttpGet对象;假设须要发送POST请求,创建HttpPost对象。
3. 假设须要发送请求參数,可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来加入�请求參数;对于HttpPost对象而言,也可调用setEntity(HttpEntity entity)方法来设置请求參数。
4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求,该方法返回一个HttpResponse。
5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取server的响应头;调用HttpResponse的getEntity()方法可获取HttpEntity对象,该对象包装了server的响应内容。程序可通过该对象获取server的响应内容。
6. 释放连接。不管运行方法是否成功,都必须释放连接
四、实例
package com.test; 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.cert.CertificateException; import java.util.ArrayList; import java.util.List; import javax.net.ssl.SSLContext; import org.apache.http.HttpEntity; import org.apache.http.NameValuePair; import org.apache.http.ParseException; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.conn.ssl.SSLConnectionSocketFactory; import org.apache.http.conn.ssl.SSLContexts; import org.apache.http.conn.ssl.TrustSelfSignedStrategy; import org.apache.http.entity.ContentType; import org.apache.http.entity.mime.MultipartEntityBuilder; import org.apache.http.entity.mime.content.FileBody; import org.apache.http.entity.mime.content.StringBody; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.message.BasicNameValuePair; import org.apache.http.util.EntityUtils; import org.junit.Test; public class HttpClientTest { @Test public void jUnitTest() { get(); } /** * HttpClient连接SSL */ public void ssl() { CloseableHttpClient httpclient = null; try { KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType()); FileInputStream instream = new FileInputStream(new File("d:\\tomcat.keystore")); try { // 载入keyStore d:\\tomcat.keystore trustStore.load(instream, "123456".toCharArray()); } catch (CertificateException e) { e.printStackTrace(); } finally { try { instream.close(); } catch (Exception ignore) { } } // 相信自己的CA和全部自签名的证书 SSLContext sslcontext = SSLContexts.custom().loadTrustMaterial(trustStore, new TrustSelfSignedStrategy()).build(); // 仅仅同意使用TLSv1协议 SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslcontext, new String[] { "TLSv1" }, null, SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER); httpclient = HttpClients.custom().setSSLSocketFactory(sslsf).build(); // 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()); CloseableHttpResponse response = httpclient.execute(httpget); try { HttpEntity entity = response.getEntity(); System.out.println("----------------------------------------"); System.out.println(response.getStatusLine()); if (entity != null) { System.out.println("Response content length: " + entity.getContentLength()); System.out.println(EntityUtils.toString(entity)); EntityUtils.consume(entity); } } finally { response.close(); } } catch (ParseException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (KeyManagementException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (KeyStoreException e) { e.printStackTrace(); } finally { if (httpclient != null) { try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } } } /** * post方式提交表单(模拟用户登录请求) */ public void postForm() { // 创建默认的httpClient实例. CloseableHttpClient httpclient = HttpClients.createDefault(); // 创建httppost HttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceJ.action"); // 创建參数队列 Listformparams = new ArrayList (); 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()); CloseableHttpResponse response = httpclient.execute(httppost); try { HttpEntity entity = response.getEntity(); if (entity != null) { System.out.println("--------------------------------------"); System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8")); System.out.println("--------------------------------------"); } } finally { response.close(); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e1) { e1.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { // 关闭连接,释放资源 try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } } /** * 发送 post请求訪问本地应用并依据传递參数不同返回不同结果 */ public void post() { // 创建默认的httpClient实例. CloseableHttpClient httpclient = HttpClients.createDefault(); // 创建httppost HttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceJ.action"); // 创建參数队列 List formparams = new ArrayList (); 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()); CloseableHttpResponse response = httpclient.execute(httppost); try { HttpEntity entity = response.getEntity(); if (entity != null) { System.out.println("--------------------------------------"); System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8")); System.out.println("--------------------------------------"); } } finally { response.close(); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e1) { e1.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { // 关闭连接,释放资源 try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } } /** * 发送 get请求 */ public void get() { CloseableHttpClient httpclient = HttpClients.createDefault(); try { // 创建httpget. HttpGet httpget = new HttpGet("http://www.baidu.com/"); System.out.println("executing request " + httpget.getURI()); // 运行get请求. CloseableHttpResponse response = httpclient.execute(httpget); try { // 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("------------------------------------"); } finally { response.close(); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (ParseException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { // 关闭连接,释放资源 try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } } /** * 上传文件 */ public void upload() { CloseableHttpClient httpclient = HttpClients.createDefault(); try { HttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceFile.action"); FileBody bin = new FileBody(new File("F:\\image\\sendpix0.jpg")); StringBody comment = new StringBody("A binary file of some kind", ContentType.TEXT_PLAIN); HttpEntity reqEntity = MultipartEntityBuilder.create().addPart("bin", bin).addPart("comment", comment).build(); httppost.setEntity(reqEntity); System.out.println("executing request " + httppost.getRequestLine()); CloseableHttpResponse response = httpclient.execute(httppost); try { System.out.println("----------------------------------------"); System.out.println(response.getStatusLine()); HttpEntity resEntity = response.getEntity(); if (resEntity != null) { System.out.println("Response content length: " + resEntity.getContentLength()); } EntityUtils.consume(resEntity); } finally { response.close(); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } } }
本实例是採用HttpClient4.3最新版本号。该版本号与之前的代码写法风格相差较大,大家多留意下。