HttpClient 实例（1）

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  关闭
            httpget.abort();  
        } finally {  
            // When HttpClient instance is no longer needed,  
            // shut down the connection manager to ensure  
            // immediate deallocation of all system resources  关闭
            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：

   
    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

   
    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");
   注释掉这行就行

用post方法访问本地应用根据传递参数不同，返回不同结果
  1：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>  

  2：Test1Servlet.java
  

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();  
    }  
} 

   3：Demo2.java

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：