Java下載多個網路檔案並打成壓縮包
阿新 • • 發佈:2021-11-29
需求:瀏覽器訪問後臺的http地址後,後臺將多個網路檔案打成壓縮包返回給瀏覽器,使用者可以通過瀏覽器直接下載壓縮包。
實現:
根據檔案連結把檔案下載下來並且轉成位元組碼 ,程式碼:
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); //根據檔案連結把檔案下載下來並且轉成位元組碼 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,呼叫上面的工具類,程式碼如下:
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");//控制檔名編碼 String fileName = URLEncoder.encode("證據材料.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");// 設定強制下載不開啟 response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);// 設定檔名 OutputStream os = response.getOutputStream(); os.write(bos.toByteArray()); os.close(); } catch (FileNotFoundException ex) { // logger.error("FileNotFoundException", ex); } catch (Exception ex) { // logger.error("Exception", ex); } } }
瀏覽器直接訪問DownFileServlet的地址,即可直接下載壓縮包。
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