Java下载多个网络文件并打成压缩包

需求：浏览器访问后台的http地址后，后台将多个网络文件打成压缩包返回给浏览器，用户可以通过浏览器直接下载压缩包。

实现：

根据文件链接把文件下载下来并且转成字节码  ，代码：

package com.zwy.blog.servelt;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class UrlFilesToZip {
//    private static final Logger logger = LoggerFactory.getLogger(UrlFilesToZip.class);
    //根据文件链接把文件下载下来并且转成字节码
    public byte[] getImageFromURL(String urlPath) {
        byte[] data = null;
        InputStream is = null;
        HttpURLConnection conn = null;
        try {
            URL url = new URL(urlPath);
            conn = (HttpURLConnection) url.openConnection();
            conn.setDoInput(true);
            // conn.setDoOutput(true);
            conn.setRequestMethod("GET");
            conn.setConnectTimeout(6000);
            is = conn.getInputStream();
            if (conn.getResponseCode() == 200) {
                data = readInputStream(is);
            } else {
                data = null;
            }
        } catch (MalformedURLException e) {
//            logger.error("MalformedURLException", e);
        } catch (IOException e) {
//            logger.error("IOException", e);
        } finally {
            try {
                if (is != null) {
                    is.close();
                }
            } catch (IOException e) {
//                logger.error("IOException", e);
            }
            conn.disconnect();
        }
        return data;
    }  

    public byte[] readInputStream(InputStream is) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int length = -1;
        try {
            while ((length = is.read(buffer)) != -1) {
                baos.write(buffer, 0, length);
            }
            baos.flush();
        } catch (IOException e) {
//            logger.error("IOException", e);
        }
        byte[] data = baos.toByteArray();
        try {
            is.close();
            baos.close();
        } catch (IOException e) {
//            logger.error("IOException", e);
        }
        return data;
    }
}

新建DownFileServlet，调用上面的工具类，代码如下：

package com.zwy.blog.servelt;

import java.io.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

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

public class DownFileServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    public DownFileServlet() {
        super();
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        try {
            //String filename = new String("xx.zip".getBytes("UTF-8"), "ISO8859-1");//控制文件名编码
            String fileName = URLEncoder.encode("证据材料.zip","UTF-8");
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            ZipOutputStream zos = new ZipOutputStream(bos);
            UrlFilesToZip s = new UrlFilesToZip();
            String urls[]={"https://hr-minio.cas-air.cn/pdf-temp/001d535005784d3d8220e89d5ce4b3ab.pdf","https://hr-minio.cas-air.cn/pdf-temp/001ee146be864a848a04bef6abfb1a89.pdf"};
            for (String oneFile : urls) {
                String filename=oneFile.substring(oneFile.lastIndexOf("/")+1);
                zos.putNextEntry(new ZipEntry(filename));
                byte[] bytes = s.getImageFromURL(oneFile);
                zos.write(bytes, 0, bytes.length);
                zos.closeEntry();
            }
            zos.close();
            response.setContentType("application/force-download");// 设置强制下载不打开
            response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);// 设置文件名
            OutputStream os = response.getOutputStream();
            os.write(bos.toByteArray());
            os.close();
        } catch (FileNotFoundException ex) {
//            logger.error("FileNotFoundException", ex);
        } catch (Exception ex) {
//            logger.error("Exception", ex);
        }
    }  

}

浏览器直接访问DownFileServlet的地址，即可直接下载压缩包。