SimpleWgetService.java

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;

import org.apache.commons.codec.binary.Base64;

/**
 * 一个封装好的Wget服务
 * <p>
 * 不要再自己写new URL了
 * </p>
 * 
 * @author Arbow
 */
public class SimpleWgetService {

	private static final int DEFAULT_CONNECT_TIMEOUT_MS = 2000;
	private static final int DEFAULT_READ_TIMEOUT_MS = 20000;
	private static final String DEFAULT_CHARSET = "UTF-8";

	/**
	 * 直接取URL的页面内容，使用默认的超时和编码
	 */
	public static String fetchContent(String url) throws Exception {
		return fetchContent(url, DEFAULT_READ_TIMEOUT_MS, DEFAULT_CHARSET);
	}

	/**
	 * 直接取URL的页面内容，使用给定的超时和编码
	 */
	public static String fetchContent(String url, int readTimeoutMs, String charset) throws Exception {
		URL u = new URL(url);
		HttpURLConnection urlConn = (HttpURLConnection) u.openConnection();
		try {
			urlConn.setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MS);
			urlConn.setReadTimeout(readTimeoutMs);
			urlConn.connect();

			return readContentFromURLConnection(urlConn, charset);
		} finally {
			urlConn.disconnect();
		}
	}

	private static String readContentFromURLConnection(HttpURLConnection urlConn, String charset) throws IOException {
		String encoding = urlConn.getContentEncoding();
		if (encoding == null)
			encoding = charset;
		InputStream in = urlConn.getInputStream();
		byte[] buffer = new byte[8192];
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		int len = -1;
		while ((len = in.read(buffer)) != -1)
			baos.write(buffer, 0, len);
		in.close();

		try {
			return baos.toString(encoding);
		} catch (UnsupportedEncodingException e) {
			return baos.toString();
		}
	}

	/**
	 * 直接取需要HTTP BASIC认证的URL的页面内容，使用给定的超时和编码
	 */
	public static String fetchAuthContent(String url, String username, String password) throws Exception {
		return fetchAuthContent(url, username, password, DEFAULT_READ_TIMEOUT_MS, DEFAULT_CHARSET);
	}

	/**
	 * 直接取需要HTTP BASIC认证的URL的页面内容，使用给定的超时和编码
	 */
	public static String fetchAuthContent(String url, String username, String password, int readTimeoutMs,
			String charset) throws Exception {
		URL u = new URL(url);
		HttpURLConnection urlConn = (HttpURLConnection) u.openConnection();
		try {
			urlConn.setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MS);
			urlConn.setReadTimeout(readTimeoutMs);

			byte[] encoded = Base64.encodeBase64((username + ':' + password).getBytes());
			String authString = "Basic " + new String(encoded);
			urlConn.setRequestProperty("Authorization", authString);
			urlConn.connect();

			return readContentFromURLConnection(urlConn, charset);
		} finally {
			urlConn.disconnect();
		}
	}

	/**
	 * 直接取URL页面的输入流，使用默认的超时。使用完毕后务必关闭输入流
	 */
	public static InputStream fetchStream(String url) throws Exception {
		return fetchStream(url, DEFAULT_READ_TIMEOUT_MS);
	}

	/**
	 * 直接取URL页面的输入流，使用指定的超时。使用完毕后务必关闭输入流
	 */
	public static InputStream fetchStream(String url, int readTimeoutMs) throws Exception {
		URL u = new URL(url);
		HttpURLConnection urlConn = (HttpURLConnection) u.openConnection();
		urlConn.setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MS);
		urlConn.setReadTimeout(readTimeoutMs);
		urlConn.connect();
		return new WrapperInputStream(urlConn.getInputStream(), urlConn);
	}

	private static class WrapperInputStream extends InputStream {

		private InputStream delegateIn;
		private HttpURLConnection conn;

		public WrapperInputStream(InputStream delegateInputStream, HttpURLConnection connection) {
			this.delegateIn = delegateInputStream;
			this.conn = connection;
		}

		@Override
		public int read() throws IOException {
			return delegateIn.read();
		}

		@Override
		public int available() throws IOException {
			return delegateIn.available();
		}

		@Override
		public void close() throws IOException {
			try {
				delegateIn.close();
			} finally {
				conn.disconnect();
			}
		}

		@Override
		public synchronized void mark(int readlimit) {
			delegateIn.mark(readlimit);
		}

		@Override
		public synchronized void reset() throws IOException {
			delegateIn.reset();
		}

		@Override
		public boolean markSupported() {
			return delegateIn.markSupported();
		}

	}
}