java下載文件工具類

java下載文件工具類

package com.skjd.util; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.URL; import javax.servlet.http.HttpServletResponse; public class DownloadUtils { /** * 根據網絡url下載文件 * 下載到指定文件 * @throws MalformedURLException */
    public static void DownloadByUrlToFile(String urlPath,String filename2) throws Exception{ URL url = new URL(urlPath); /* //文件後綴名 String str = url.getFile().substring( url.getFile().lastIndexOf(".")+1); //文件名 String filename = url.getFile().substring(url.getFile().lastIndexOf("/")+1,url.getFile().lastIndexOf("."));*/ HttpURLConnection conn = (HttpURLConnection)url.openConnection(); int code = conn.getResponseCode(); if (code != HttpURLConnection.HTTP_OK) { throw new Exception("文件讀取失敗"); } InputStream fis = new BufferedInputStream(conn.getInputStream()); File file = new File(filename2); OutputStream toClient = new BufferedOutputStream(new FileOutputStream(file)); // 以流的形式下載文件。
        byte[] buffer = new byte[1024*8]; int read=0; //若是沒有數據了會返回-1；若是還有會返回數據的長度
        while ((read = fis.read(buffer))!=-1) { //讀取多少輸出多少
            toClient.write(buffer,0,read); } toClient.flush(); toClient.close(); fis.close(); } /** * 根據網絡url下載文件 * 直接返回給瀏覽器 * @throws MalformedURLException */
    public static void DownloadByUrl(String urlPath,HttpServletResponse response) throws Exception{ URL url = new URL(urlPath); //文件後綴名
         String str = url.getFile().substring( url.getFile().lastIndexOf(".")+1); //文件名
         String filename = url.getFile().substring(url.getFile().lastIndexOf("/")+1,url.getFile().lastIndexOf(".")); HttpURLConnection conn = (HttpURLConnection)url.openConnection(); int code = conn.getResponseCode(); if (code != HttpURLConnection.HTTP_OK) { throw new Exception("文件讀取失敗"); } InputStream fis = new BufferedInputStream(conn.getInputStream()); OutputStream toClient = new BufferedOutputStream(response.getOutputStream()); // 設置response的Header
        response.addHeader("Content-Disposition", "attachment;filename=" +filename+"."+str); response.setContentType("application/octet-stream"); // 以流的形式下載文件。
        byte[] buffer = new byte[1024*8]; int read=0; //若是沒有數據了會返回-1；若是還有會返回數據的長度
        while ((read = fis.read(buffer))!=-1) { //讀取多少輸出多少
            toClient.write(buffer,0,read); } toClient.flush(); toClient.close(); fis.close(); } }

使用案例代碼

/** * 導出購票碼 */ @RequestMapping(value="/getAllCode") public void getAllCode(HttpServletResponse response){ PageData pd = new PageData(); pd = this.getPageData(); try { List<PageData> list = driverService.listAll(pd); //獲取當前項目的絕對路徑
            String realPath = this.getRequest().getSession().getServletContext().getRealPath("/"); File file = new File(realPath+"/codes/"); //判斷是否存在這個文件夾，若是不存在則從新建立一個文件
            if(!file.exists()){ file.mkdirs(); } String url2=""; List<PageData> list3 = dictionariesService.getIMGUrl(null); for(int i=0;i<list3.size();i++){ if(String.valueOf(list3.get(i).get("remarks")).length()>6){ url2=String.valueOf(list3.get(i).get("remarks")); } } for(int i=0;i<list.size();i++){ if(list.get(i).get("code_url")!=null&&!"".equals(String.valueOf(list.get(i).get("code_url")))){ DownloadUtils.DownloadByUrlToFile(url2+String.valueOf(list.get(i).get("code_url")),realPath+"/codes/"+String.valueOf(list.get(i).get("idcode"))+".png"); } } FileZip.zip(realPath+"/codes/", realPath+"/codes.zip"); InputStream fis = new BufferedInputStream(new FileInputStream(new File(realPath+"/codes.zip"))); OutputStream toClient = new BufferedOutputStream(response.getOutputStream()); Cookie cookie = new Cookie("abcd", "123"); cookie.setPath("/"); response.addCookie(cookie); // 設置response的Header
            response.setContentType("application/zip");// 指明response的返回對象是文件流
            response.setHeader("content-Disposition", "attachment;filename=codes.zip");// 設置在下載框默認顯示的文件名 // 以流的形式下載文件。
            byte[] buffer = new byte[1024*8]; int read=0; //若是沒有數據了會返回-1；若是還有會返回數據的長度
            while ((read = fis.read(buffer))!=-1) { //讀取多少輸出多少
                toClient.write(buffer,0,read); } toClient.flush(); toClient.close(); fis.close(); } catch (Exception e) { // TODO Auto-generated catch block
 e.printStackTrace(); } }