根据URL抓取网页内容

1. 准备工作

    需要下载jar包：commons-httpclient   

   下载地址：http://hc.apache.org/downloads.cgi 4.1.2 

   2.   获取网页内容

 

package cn.edu.xmu.utils;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

public class WebPageGetter {
	public static String getWebPage(String url) throws Exception {

		// 初始化，与3.1中不同
		HttpClient httpclient = new DefaultHttpClient();

		// HttpHost targetHost = new HttpHost("http://www.kinkbomb.com/p/9699");
		// HttpGet httpget = new HttpGet("http://www.apache.org/");
		HttpGet httpget = new HttpGet(url);

		// 查看默认request头部信息
		System.out.println("Accept-Charset:"
				+ httpget.getFirstHeader("Accept-Charset"));
		// 以下这条如果不加会发现无论你设置Accept-Charset为gbk还是utf-8，他都会默认返回gb2312（本例针对google.cn来说）
		httpget.setHeader("User-Agent",
				"Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.2)");
		// 用逗号分隔显示可以同时接受多种编码
		httpget.setHeader("Accept-Language", "zh-cn,zh;q=0.5");
		httpget.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7");
		// 验证头部信息设置生效
		System.out.println("Accept-Charset:"
				+ httpget.getFirstHeader("Accept-Charset").getValue());

		// Execute HTTP request
		System.out.println("executing request " + httpget.getURI());
		// HttpResponse response = httpclient.execute(targetHost, httpget);
		HttpResponse response = httpclient.execute(httpget);

		// HttpResponse response = httpclient.execute(httpget);

		System.out.println("----------------------------------------");
		System.out.println("Location: " + response.getLastHeader("Location"));
		System.out.println(response.getStatusLine().getStatusCode());
		System.out.println(response.getLastHeader("Content-Type"));
		System.out.println(response.getLastHeader("Content-Length"));

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

		// 判断页面返回状态判断是否进行转向抓取新链接
		int statusCode = response.getStatusLine().getStatusCode();
		if ((statusCode == HttpStatus.SC_MOVED_PERMANENTLY)
				|| (statusCode == HttpStatus.SC_MOVED_TEMPORARILY)
				|| (statusCode == HttpStatus.SC_SEE_OTHER)
				|| (statusCode == HttpStatus.SC_TEMPORARY_REDIRECT)) {
			// 此处重定向处理 此处还未验证
			String newUri = response.getLastHeader("Location").getValue();
			httpclient = new DefaultHttpClient();
			httpget = new HttpGet(newUri);
			response = httpclient.execute(httpget);
		}

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

		// 查看所有返回头部信息
		Header headers[] = response.getAllHeaders();
		int ii = 0;
		while (ii < headers.length) {
			System.out.println(headers[ii].getName() + ": "
					+ headers[ii].getValue());
			++ii;
		}

		// If the response does not enclose an entity, there is no need
		// to bother about connection release

		byte[] bytes = null;
		if (entity != null) {
			// 将源码流保存在一个byte数组当中，因为可能需要两次用到该流，
			bytes = EntityUtils.toByteArray(entity);
			String charSet = "";

			// 如果头部Content-Type中包含了编码信息，那么我们可以直接在此处获取
			charSet = EntityUtils.getContentCharSet(entity);

			System.out.println("In header: " + charSet);
			// 如果头部中没有，那么我们需要 查看页面源码，这个方法虽然不能说完全正确，因为有些粗糙的网页编码者没有在页面中写头部编码信息
			if (charSet == "") {
				String regEx = "(?=<meta).*?(?<=charset=[\\'|\\\"]?)([[a-z]|[A-Z]|[0-9]|-]*)";
				Pattern p = Pattern.compile(regEx, Pattern.CASE_INSENSITIVE);
				Matcher m = p.matcher(new String(bytes)); // 默认编码转成字符串，因为我们的匹配中无中文，所以串中可能的乱码对我们没有影响
				Boolean result = m.find();
				if (m.groupCount() == 1) {
					charSet = m.group(1);
				} else {
					charSet = "";
				}
			}
			System.out.println("Last get: " + charSet);
			// 至此，我们可以将原byte数组按照正常编码专成字符串输出（如果找到了编码的话）
			// System.out.println("Encoding string is: " + new String(bytes,
			// charSet));
		}

		httpclient.getConnectionManager().shutdown();

		return new String(bytes);
	}
}