HttpClient

1：概述  

HttpClient是HttpComponents（简称为hc)项目其中的一部份,访问地址：http://hc.apache.org/ 

HttpClient是一个代码级的Http客户端工具,可以使用它模拟浏览器向Http服务器发送请求。使用HttpClient还需要HttpCore.后者包括Http请求与Http响应的代码封装。 

 

2：HttpGet 

 public final static void main(String[] args) throws Exception {
     HttpClient httpclient = new DefaultHttpClient();
     try {
         HttpGet httpget = new HttpGet("http://www.apache.org/");
         System.out.println("executing request " + httpget.getURI());
         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());
         }
         System.out.println("----------------------------------------");

         InputStream inSm = entity.getContent();
         Scanner inScn = new Scanner(inSm);
         while (inScn.hasNextLine()) {
             System.out.println(inScn.nextLine());
         }
         // Do not feel like reading the response body
         // Call abort on the request object
         httpget.abort();
     } finally {
         // When HttpClient instance is no longer needed,
         // shut down the connection manager to ensure
         // immediate deallocation of all system resources
         httpclient.getConnectionManager().shutdown();
     }
 }

httpcore：EntityUtils.toString(httpEntity)  

读取response响应内容部分，也可以借助于 httpcore-4.1.2.jar 里面的 

 String content = EntityUtils.toString(httpEntity);

具体： 

 /**
  * User: liuwentao
  * Time: 12-1-25 下午1:23
  */
 public class Demo1 {

     /**
      * 用 get 方法访问 www.apache.org 并返回内容
      *
      * @param args
      */
     public static void main(String[] args) {
         //创建默认的 HttpClient 实例
         HttpClient httpClient = new DefaultHttpClient();
         try {
             //创建 httpUriRequest 实例
             HttpGet httpGet = new HttpGet("http://www.apache.org/");
             System.out.println("uri=" + httpGet.getURI());

             //执行 get 请求
             HttpResponse httpResponse = httpClient.execute(httpGet);

             //获取响应实体
             HttpEntity httpEntity = httpResponse.getEntity();
             //打印响应状态
             System.out.println(httpResponse.getStatusLine());
             if (httpEntity != null) {
                 //响应内容的长度
                 long length = httpEntity.getContentLength();
                 //响应内容
                 String content = EntityUtils.toString(httpEntity);

                 System.out.println("Response content length:" + length);
                 System.out.println("Response content:" + content);
             }

             //有些教程里没有下面这行
             httpGet.abort();
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
             //关闭连接，释放资源
             httpClient.getConnectionManager().shutdown();
         }
     }
 }

执行结果： 



httpget.setHeader  

1:分析请求包中这六个头信息 

 

2:代码 

 /**
  * @param args
  * @throws IOException
  */
 public static void main(String[] args) {
     HttpClient httpClient = new DefaultHttpClient();
     try {
         HttpGet httpget = new HttpGet("http://www.iteye.com");

         httpget.setHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
         httpget.setHeader("Accept-Language", "zh-cn,zh;q=0.5");
         httpget.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 5.1; rv:7.0.1) Gecko/20100101 Firefox/7.0.1)");
         httpget.setHeader("Accept-Encoding", "gzip, deflate");
         httpget.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7");
         httpget.setHeader("Host", "www.iteye.com");
         httpget.setHeader("Connection", "Keep-Alive");

         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());
         }
         System.out.println("----------------------------------------");

         InputStream inSm = entity.getContent();
         Scanner inScn = new Scanner(inSm);
         while (inScn.hasNextLine()) {
             System.out.println(inScn.nextLine());
         }
         // Do not feel like reading the response body
         // Call abort on the request object
         httpget.abort();
     } catch (Exception e) {
         e.printStackTrace();
     } finally {
         // When HttpClient instance is no longer needed,
         // shut down the connection manager to ensure
         // immediate deallocation of all system resources
         httpClient.getConnectionManager().shutdown();
     }
 }

3：效果 



以上乱码是由于 

 httpget.setHeader("Accept-Encoding", "gzip, deflate");

注释掉这行，具体： 

 /**
  * User: liuwentao
  * Time: 12-1-25 下午1:23
  */
 public class Demo3 {

     /**
      * 用 get 方法访问 www.baidu.com 并返回内容
      *
      * @param args
      */
     public static void main(String[] args) {
         //创建默认的 HttpClient 实例
         HttpClient httpClient = new DefaultHttpClient();

         try {
             //创建 httpUriRequest 实例
             HttpGet httpGet = new HttpGet("http://www.iteye.com");

             httpGet.setHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
             httpGet.setHeader("Accept-Language", "zh-cn,zh;q=0.5");
             httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 5.1; rv:7.0.1) Gecko/20100101 Firefox/7.0.1)");
 //            httpGet.setHeader("Accept-Encoding", "gzip, deflate");
             httpGet.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7");
             httpGet.setHeader("Host", "www.iteye.com");
             httpGet.setHeader("Connection", "Keep-Alive");
             System.out.println("uri=" + httpGet.getURI());

             //执行 get 请求
             HttpResponse httpResponse = httpClient.execute(httpGet);

             //获取响应实体
             HttpEntity httpEntity = httpResponse.getEntity();
             //打印响应状态
             System.out.println(httpResponse.getStatusLine());
             if (httpEntity != null) {
                 //响应内容的长度
                 long length = httpEntity.getContentLength();
                 //响应内容
                 String content = EntityUtils.toString(httpEntity);

                 System.out.println("Response content length:" + length);
                 System.out.println("Response content:" + content);
             }

             //有些教程里没有下面这行
             httpGet.abort();
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
             //关闭连接，释放资源
             httpClient.getConnectionManager().shutdown();
         }
     }
 }

效果： 


用post方法访问本地应用根据传递参数不同，返回不同结果  

web.xml 

 <servlet>
     <servlet-name>Test1Servlet</servlet-name>
     <servlet-class>demo.servlet.Test1Servlet</servlet-class>
 </servlet>
 <servlet-mapping>
     <servlet-name>Test1Servlet</servlet-name>
     <url-pattern>/test1Servlet</url-pattern>
 </servlet-mapping>

Test1Servlet.java 

 /**
  * User: liuwentao
  * Time: 11-12-25 下午1:08
  */
 public class Test1Servlet extends HttpServlet {
     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         //接收地址栏参数
         String param1 = request.getParameter("param1");
         //输出
         response.setContentType("text/html;charset=UTF-8");
         PrintWriter out = response.getWriter();
         out.write("你传递来的参数param1=" + param1);
         out.close();
     }
 }

Demo2.java 

 /**
  * User: liuwentao
  * Time: 12-1-25 下午1:23
  */
 public class Demo2 {

     /**
      * 用post方法访问本地应用根据传递参数不同，返回不同结果
      *
      * @param args
      */
     public static void main(String[] args) {
         //创建默认的 HttpClient 实例
         HttpClient httpClient = new DefaultHttpClient();

         HttpPost httpPost = new HttpPost("http://localhost:86/test1Servlet");

         List<NameValuePair> formParams = new ArrayList<NameValuePair>();
         formParams.add(new BasicNameValuePair("param1", "刘文涛"));
         UrlEncodedFormEntity urlEncodedFormEntity;

         try {
             urlEncodedFormEntity = new UrlEncodedFormEntity(formParams, "UTF-8");
             httpPost.setEntity(urlEncodedFormEntity);
             System.out.println("execurting request:" + httpPost.getURI());
             HttpResponse httpResponse = null;
             httpResponse = httpClient.execute(httpPost);
             HttpEntity httpEntity = httpResponse.getEntity();
             if (httpEntity != null) {
                 String content = EntityUtils.toString(httpEntity, "UTF-8");
                 System.out.println("Response content:" + content);
             }
         } catch (ClientProtocolException e) {
             e.printStackTrace();
         } catch (UnsupportedEncodingException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } finally {
             //关闭连接，释放资源
             httpClient.getConnectionManager().shutdown();
         }
     }
 }

结果：