HttpClient

介绍下一篇上好的文章，对HttpClient有很全很详细的见解https://www.ibm.com/developerworks/cn/opensource/os-cn-crawler/。

这个是里面的部分内容

/* 1 生成 HttpClinet 对象并设置参数*/
  HttpClient httpClient=new HttpClient();
  //设置 Http 连接超时为5秒
httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000);

  /*2 生成 GetMethod 对象并设置参数*/
  GetMethod getMethod=new GetMethod(url);
  //设置 get 请求超时为 5 秒
getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT,5000);
  //设置请求重试处理，用的是默认的重试处理：请求三次
getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
          new DefaultHttpMethodRetryHandler());

  /*3 执行 HTTP GET 请求*/
  try{
      int statusCode = httpClient.executeMethod(getMethod);
      /*4 判断访问的状态码*/
      if (statusCode != HttpStatus.SC_OK)
      {
System.err.println("Method failed: "+ getMethod.getStatusLine());
      }

      /*5 处理 HTTP 响应内容*/
      //HTTP响应头部信息，这里简单打印
  Header[] headers=getMethod.getResponseHeaders();
      for(Header  h:  headers)
            System.out.println(h.getName()+" "+h.getValue());*/
      //读取 HTTP 响应内容，这里简单打印网页内容
      byte[] responseBody = getMethod.getResponseBody();//读取为字节数组
System.out.println(new String(responseBody));
      //读取为 InputStream，在网页内容数据量大时候推荐使用
      InputStream response = getMethod.getResponseBodyAsStream();//
      …
}
catch (HttpException e)
{
      // 发生致命的异常，可能是协议不对或者返回的内容有问题
          System.out.println("Please check your provided http address!");
e.printStackTrace();
     }
catch (IOException e)
  {
            // 发生网络异常
        e.printStackTrace();
     } finally {
                 /*6 .释放连接*/
            getMethod.releaseConnection();
            }

其实我只是想利用它来模 拟输入用户名和口令进行登录然后访问另一个页面

但是关键问题还是怎么得到NameValuePair name = new NameValuePair("name", "ld"); 里的key和value，还是不明白

/*
 * Created on 2003-12-7 by Liudong
 */
package http.demo;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.cookie.*;
import org.apache.commons.httpclient.methods.*;
/**
 * 用来演示登录表单的示例
 * @author Liudong
 */
public class FormLoginDemo {
    static final String LOGON_SITE = "localhost";
    static final int    LOGON_PORT = 8080;

    public static void main(String[] args) throws Exception{
       HttpClient client = new HttpClient();
       client.getHostConfiguration().setHost(LOGON_SITE, LOGON_PORT);

       //模拟登录页面login.jsp->main.jsp
       PostMethod post = new PostMethod("/main.jsp");
       NameValuePair name = new NameValuePair("name", "ld");
       NameValuePair pass = new NameValuePair("password", "ld");
       post.setRequestBody(new NameValuePair[]{name,pass});
       int status = client.executeMethod(post);
       System.out.println(post.getResponseBodyAsString());
       post.releaseConnection();

       //查看cookie信息
       CookieSpec cookiespec = CookiePolicy.getDefaultSpec();
       Cookie[] cookies = cookiespec.match(LOGON_SITE, LOGON_PORT, "/", false, client.getState().getCookies());
       if (cookies.length == 0) {
           System.out.println("None");
       } else {
           for (int i = 0; i < cookies.length; i++) {
              System.out.println(cookies[i].toString());
           }
       }
       //访问所需的页面main2.jsp
       GetMethod get = new GetMethod("/main2.jsp");
       client.executeMethod(get);
       System.out.println(get.getResponseBodyAsString());
       get.releaseConnection();
    }
}