【转】java文件下载

public HttpServletResponse download(String path, HttpServletResponse response) {
        try {
            // path是指欲下载的文件的路径。
            File file = new File(path);
            // 取得文件名。
            String filename = file.getName();
            // 取得文件的后缀名。
            String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();

            // 以流的形式下载文件。
            InputStream fis = new BufferedInputStream(new FileInputStream(path));
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();
            // 清空response
            response.reset();
            // 设置response的Header
            response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));
            response.addHeader("Content-Length", "" + file.length());
            OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
            response.setContentType("application/octet-stream");
            toClient.write(buffer);
            toClient.flush();
            toClient.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        return response;
    }

下载到本地

public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {
        // 下载本地文件
        String fileName = "Operator.doc".toString(); // 文件的默认保存名
        // 读到流中
        InputStream inStream = new FileInputStream("c:/Operator.doc");// 文件的存放路径
        // 设置输出的格式
        response.reset();
        response.setContentType("bin");
        response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
        // 循环取出流中的数据
        byte[] b = new byte[100];
        int len;
        try {
            while ((len = inStream.read(b)) > 0)
                response.getOutputStream().write(b, 0, len);
            inStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

下载网络文件

public void downloadNet(HttpServletResponse response) throws MalformedURLException {
        // 下载网络文件
        int bytesum = 0;
        int byteread = 0;

        URL url = new URL("windine.blogdriver.com/logo.gif");

        try {
            URLConnection conn = url.openConnection();
            InputStream inStream = conn.getInputStream();
            FileOutputStream fs = new FileOutputStream("c:/abc.gif");

            byte[] buffer = new byte[1204];
            int length;
            while ((byteread = inStream.read(buffer)) != -1) {
                bytesum += byteread;
                System.out.println(bytesum);
                fs.write(buffer, 0, byteread);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

在线打开文件的一种方式

public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {
        File f = new File(filePath);
        if (!f.exists()) {
            response.sendError(404, "File not found!");
            return;
        }
        BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));
        byte[] buf = new byte[1024];
        int len = 0;

        response.reset(); // 非常重要
        if (isOnLine) { // 在线打开方式
            URL u = new URL("file:///" + filePath);
            response.setContentType(u.openConnection().getContentType());
            response.setHeader("Content-Disposition", "inline; filename=" + f.getName());
            // 文件名应该编码成UTF-8
        } else { // 纯下载方式
            response.setContentType("application/x-msdownload");
            response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());
        }
        OutputStream out = response.getOutputStream();
        while ((len = br.read(buf)) > 0)
            out.write(buf, 0, len);
        br.close();
        out.close();
    }

参考了上面写的：

package com.talkweb.qmessage.service.servlet;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.Properties;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.PropertyUtils;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

import com.talkweb.qmessage.service.QmessageManager;
 

public class QmessageServlet extends HttpServlet{
	public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 		
		String message = new String(request.getParameter("content").getBytes("ISO8859-1"));
		ServletContext application;   
        WebApplicationContext wac;   
        application = getServletContext();   
        wac = WebApplicationContextUtils.getWebApplicationContext(application);//获取spring的context   
        QmessageManager qmessageManager = (QmessageManager) wac.getBean("QmessageManager");   //获取spring的bean
        
        String StringXML = qmessageManager.getGifXML(message);
        String StringURL = qmessageManager.getGifURL(StringXML);
        if(StringURL!=""){
        	//更新数据库，并返回唯一标识（主键）
        	String resultId = qmessageManager.updateDB(message,StringXML);        
	        //清空response   
	        response.reset();   
	        //加入属性
	        InputStream in =PropertyUtils.class.getClassLoader().getResourceAsStream("static_config.properties");
			Properties properties = new Properties();
			properties.load(in);
			String service_no = properties.getProperty("SERVICE-NO");
			response.addHeader("service_no", service_no);
			response.addHeader("auth_code", resultId);
	        //写入文件流   
        	int bytesum = 0;   
            int byteread = 0;  
	        URL url = new URL(StringURL);   
	        URLConnection conn = url.openConnection();   
	        InputStream inStream = conn.getInputStream();   
	        OutputStream toClient = new BufferedOutputStream(response.getOutputStream());  
	        //得到文件长度
	        byte[] buffer = new byte[2048];     
            while ((byteread = inStream.read(buffer)) != -1) {   
                bytesum += byteread;   
                toClient.write(buffer, 0, byteread);   
            }     
            inStream.close();
	        response.addHeader("Content-Length", "" + bytesum);  
	        response.setContentType("image/gif"); 
	        toClient.flush();   
	        toClient.close();   
        }
	}
}