HttpClient 4.x 执行网站登录并抓取网页的代码

HttpClient 4.x 的 API 变化还是很大，这段代码可用来执行登录过程，并抓取网页。 
HttpClient API 文档(4.0.x)， HttpCore API 文档(4.1)

package spider;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.*;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

/**
 * 以 dict.cn 网站为例的爬虫
 * @author Winter Lau
 */
public class DictSpider {

    private final static HttpClient client = new DefaultHttpClient();

    public static void main(String[] args) throws IOException {
        login("<用户名>","<密码>", false);
        get("http://www16.dict.cn/bdc/141");
    }

    /**
     * 抓取网页
     * @param url
     * @throws IOException
     */
    static void get(String url) throws IOException {
        HttpGet get = new HttpGet(url);
        HttpResponse response = client.execute(get);
        System.out.println(response.getStatusLine());
        HttpEntity entity = response.getEntity();
        dump(entity);
    }

    /**
     * 执行登录过程
     * @param user
     * @param pwd
     * @param debug
     * @throws IOException
     */
    static void login(String user, String pwd, boolean debug) throws IOException {
        HttpPost post = new HttpPost("http://dict.cn/login.php");
        post.setHeader("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/534.3 (KHTML, like Gecko) Chrome/6.0.472.63 Safari/534.3");

        //登录表单的信息
        List<NameValuePair> qparams = new ArrayList<NameValuePair>();
        qparams.add(new BasicNameValuePair("username", user));
        qparams.add(new BasicNameValuePair("password", pwd));
        qparams.add(new BasicNameValuePair("url", "http://www16.dict.cn/bdc/141"));
        qparams.add(new BasicNameValuePair("loginforever", "1"));

        UrlEncodedFormEntity params = new UrlEncodedFormEntity(qparams, "UTF-8");
        post.setEntity(params);

        // Execute the request
        HttpResponse response = client.execute(post);

        if(debug){
            // Examine the response status
            System.out.println(response.getStatusLine());

            // Get hold of the response entity
            HttpEntity entity = response.getEntity();

            dump(entity);
        }
    }

    /**
     * 打印页面
     * @param entity
     * @throws IOException
     */
    private static void dump(HttpEntity entity) throws IOException {
        BufferedReader br = new BufferedReader(
                new InputStreamReader(entity.getContent(), "GBK"));

        System.out.println(IOUtils.toString(br));
    }

}

　　网址：http://www.oschina.net/code/snippet_12_2209