import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * java采集网页
 * 
 */
public class HttpWebCollecter {

	/**
	 * 网页抓取方法
	 * 
	 * @param urlString
	 *            要抓取的url地址
	 * @param charset
	 *            网页编码方式
	 * @param timeout
	 *            超时时间
	 * @return 抓取的网页内容
	 * @throws IOException
	 *             抓取异常
	 */
	public static String GetWebContent(String urlString, final String charset,
			int timeout) throws IOException {
		if (urlString == null || urlString.length() == 0) {
			return "";
		}
		urlString = (urlString.startsWith("http://") || urlString
				.startsWith("https://")) ? urlString : ("http://" + urlString)
				.intern();
		URL url = new URL(urlString);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		conn.setDoOutput(true);
		conn.setRequestProperty("Pragma", "no-cache");
		conn.setRequestProperty("Cache-Control", "no-cache");

		int temp = Integer.parseInt(Math.round(Math.random()
				* (UserAgent.length - 1))
				+ "");
		conn.setRequestProperty("User-Agent", UserAgent[temp]); // 模拟手机系统
		conn.setRequestProperty("Accept",
				"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");// 只接受text/html类型，当然也可以接受图片,pdf,*/*任意，就是tomcat/conf/web里面定义那些
		conn.setConnectTimeout(timeout);
		try {
			if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
				return "";
			}
		} catch (Exception e) {
			try {
				System.out.println(e.getMessage());
			} catch (Exception e2) {
				e2.printStackTrace();
			}
			return "";
		}
		InputStream input = conn.getInputStream();
		BufferedReader reader = new BufferedReader(new InputStreamReader(input,
				charset));
		String line = null;
		StringBuffer sb = new StringBuffer("");
		while ((line = reader.readLine()) != null) {
			sb.append(line).append("\r\n");
		}
		if (reader != null) {
			reader.close();
		}
		if (conn != null) {
			conn.disconnect();
		}
		return sb.toString();
	}

	public static String[] UserAgent = {
			"Mozilla/5.0 (Linux; U; Android 2.2; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.2",
			"Mozilla/5.0 (iPad; U; CPU OS 3_2_2 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Version/4.0.4 Mobile/7B500 Safari/531.21.11",
			"Mozilla/5.0 (SymbianOS/9.4; Series60/5.0 NokiaN97-1/20.0.019; Profile/MIDP-2.1 Configuration/CLDC-1.1) AppleWebKit/525 (KHTML, like Gecko) BrowserNG/7.1.18121",
			"Nokia5700AP23.01/SymbianOS/9.1 Series60/3.0",
			"UCWEB7.0.2.37/28/998", "NOKIA5700/UCWEB7.0.2.37/28/977",
			"Openwave/UCWEB7.0.2.37/28/978",
			"Mozilla/4.0 (compatible; MSIE 6.0; ) Opera/UCWEB7.0.2.37/28/989" };

}