HttpClient基本操作

HttpClient请求

HttpClient支持HTTP/1.1这个版本定义的所有Http方法：GET,HEAD,POST,PUT,DELETE,TRACE和OPTIONS。对于每一种http方法，HttpClient都定义了一个相应的类：HttpGet,HttpHead,HttpPost,HttpPut,HttpDelete,HttpTrace和HttpOpquertions。

Httpclient还可以自定义uri，方法如下：

//http://www.baidu.com/ur/chengjiu?from=super

      URI uri = new URIBuilder()

      .setScheme("http")

      .setHost("www.baidu.com")

      .setPath("/ur/chengjiu")

      .setParameter("from", "super")

      .build();

       HttpGet httpget = new HttpGet(uri);

       System.out.println(httpget.getURI());

 

输出：http://www.baidu.com/ur/chengjiu?from=super

 

下面模仿一个简单的请求例子：

HttpClient httpclient =HttpClients.createDefault();

HttpResponse response = httpclient.execute(httpget);

 

消息回应

消息头

Response中包含了回应的消息，我们可以轻易的得到回应的消息，方法如下

//得到回应状态码

System.out.println(response.getProtocolVersion());

System.out.println(response.getStatusLine().getStatusCode());

System.out.println(response.getStatusLine().getReasonPhrase());

System.out.println(response.getStatusLine().toString());

     

//得到回应消息头，HeaderIterator是参数迭代器

HeaderIterator it =response.headerIterator();

while (it.hasNext()) {

   System.out.println(it.next());

}

消息实体

得到实体内容

HttpEntity entity =response.getEntity();

   if (entity !=null) {            

   try {

   InputStream content=entity.getContent();

   String charset=EntityUtils.getContentCharSet(entity);

   BufferedReader reader=new BufferedReader(new InputStreamReader(content,charset));

   String line=null;

   while((line = reader.readLine()) !=null){

       System.out.println(line);

   }

   reader.close();

   } catch (Exception e) {

   }

}

 

模拟表单登陆

很多应用程序需要模拟提交Html表单的过程，举个例子，登陆一个网站或者将输入内容提交给服务器。HttpClient提供了UrlEncodedFormEntity这个类来帮助实现这一过程。

List<NameValuePair>formparams = new ArrayList<NameValuePair>();

formparams.add(new BasicNameValuePair("email","value1"));

formparams.add(new BasicNameValuePair("password","value2"));

HttpPost httppost = new HttpPost("http://www.renren.com/PLogin.do");

UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formparams, Consts.UTF_8);

httppost.setEntity(entity);

httpclient.execute(httppost);