filemanager.java

使用http协议从指定服务器下载文件的主要代码

package com.hssj.gimts.client.advertisement;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.Properties;

/**
 * Description:用http从服务器下载文件
 * Date 2007-11-12
 * @version  1.0
*/
public abstract class FileManager {
	/**
	 * Description: 下载文件的长度
	 */
	private int fileLength;

	/**
	 * Description: 缓冲字节数
	 */
	private final static int READFILESIZE = 8192;

	/**
	 * Description:获取服务器的http输入流
	 * @param fileurl：服务器文件的url地址
	 * @return 返回服务器的http输入流
	 */
	public InputStream createInputStream(String fileurl) {
		InputStream input = null;
		URLConnection conn;
		int httpStatusCode;
		try {
			URL url = new URL(fileurl);
			conn = url.openConnection();
			conn.connect();
			HttpURLConnection httpconn = (HttpURLConnection) conn;
			httpStatusCode = httpconn.getResponseCode();
			if (httpStatusCode != HttpURLConnection.HTTP_OK) {// HttpURLConnection
				System.out.println("Connect   to   " + fileurl
						+ "   failed,return   code:" + httpStatusCode);
				return null;
			}
			fileLength = conn.getContentLength();
			input = conn.getInputStream();
		} catch (Exception e) {
			return null;
			//e.printStackTrace();
		}
		return input;
	};

	/**
	 * Description:获取服务器文件长度
	 * @param fileurl：服务器文件的url地址
	 * @return 返回服务器文件长度
	 */
	public int connectionFileLength(String fileurl) {
		URLConnection conn;
		int httpStatusCode;
		try {
			URL url = new URL(fileurl);
			conn = url.openConnection();
			conn.connect();
			HttpURLConnection httpconn = (HttpURLConnection) conn;
			httpStatusCode = httpconn.getResponseCode();
			if (httpStatusCode != HttpURLConnection.HTTP_OK) {// HttpURLConnection
				System.out.println("Connect   to   " + fileurl
						+ "   failed,return   code:" + httpStatusCode);
				return -1;
			} else
				return conn.getContentLength();
		} catch (Exception e) {
			e.printStackTrace();
			return -1;
		}
	}

	/**
	 * Description:从服务器下载文件到本地
	 * @param fileurl：服务文件url
	 * @param saveFile：本地文件
	 * @return 如果下载成功返回true，下载失败返回false
	 */
	public boolean WriteToSaveFile(String fileurl, String saveFile) {
		InputStream in = createInputStream(fileurl);
		if (in != null) {
			File savefile = new File(saveFile);
			try {
				if (!savefile.exists())
					savefile.createNewFile();
				FileOutputStream fos = new FileOutputStream(saveFile);
				return WriteToSaveFile(in, fos);
			} catch (Exception e) {
				e.printStackTrace();
				return false;
			}
		} else
			return false;

	};

	/**
	 * Description:从输入流读取数据写入输出流
	 * @param input:数据源(输入流)
	 * @param out：输出流
	 * @return 写完成返回true,有异常返回false
	 * @throws IOException
	 */
	public boolean WriteToSaveFile(InputStream input, OutputStream out)
			throws IOException {
		int blockSize = READFILESIZE;
		int readBytes = 0;
		byte[] tmpbuf = new byte[READFILESIZE];
		int totalRead = 0;
		while ((readBytes = input.read(tmpbuf, 0, blockSize)) != -1) {
			totalRead += readBytes;
			out.write(tmpbuf, 0, readBytes);
		}
		out.flush();
		input.close();
		out.close();
		if (totalRead < getFileLength())// 未下载完成
			return false;
		else
			return true;

	}

	/**
	 * Description:从属性文件中读取数字写入输出流
	 * @param input：属性文件流
	 * @param out：输出流
	 */
	public void WriteToSaveFile(Properties input, OutputStream out) {
		try {
			input.store(out, " ");
			out.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * Description:获取文件长度
	 * @return 返回文件长度
	 */
	public synchronized int getFileLength() {
		return this.fileLength;
	}
}