根据网络url 实现web下载图片 java_url图片下载-优快云博客

本文介绍了一个基于Java的图片下载API实现方法，通过HTTP请求下载指定路径的图片，并将其返回给客户端。文章详细展示了如何处理文件读取、内容类型设置、响应头配置等关键步骤。

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/*
       *
       * 图片下载*/

   @RequestMapping(value = "download")
       @ResponseBody
       public void download(FileSaveModel fileSaveModel,HttpServletResponse response) throws IOException {
BufferedInputStream dis = null;
BufferedOutputStream fos = null;
try {
   String fileId = fileSaveModel.getFileId();
// path是指欲下载的文件的路径。绝对路径
File file = new File(fileId);
// 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();

// fileId = "http://30.20.110.185:22/home/pic/ad/87632cc4-2c86-44be-b3c6-f5d17abb867a.jpg";
// 步骤1：创建 URL
URL url = new URL (fileId);
// 步骤2：为specificURL 获得用户名称和密码将它们放入String并用冒号":"分开
String userPassword = USERNAME + ":" + PASSWORD;
// 步骤4：对字符串进行编码
String encoding = new sun.misc.BASE64Encoder().encode (userPassword.getBytes());
// 步骤5：通过 URL 创建 URLConnection
URLConnection uc = url.openConnection();
//步骤6：为URLConnection 设置“授权”要求属性
uc.setRequestProperty ("Authorization", "Basic " + encoding);
URL url2 = uc.getURL();

response.setContentType("image/jpeg");
// response.setHeader("Content-disposition", "attachment; filename=" + java.net.URLEncoder.encode("aaa.jsp", "UTF-8"));
response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));


response.setHeader("Content-Length", String.valueOf(uc.getContentLength()));

dis = new BufferedInputStream(url2.openStream());
fos = new BufferedOutputStream(response.getOutputStream());
byte [] buff = new byte[2048];
int bytesRead;
while(-1!= (bytesRead = dis.read(buff,0,buff.length))){
   fos.write(buff, 0, bytesRead);
}

} catch (IOException e) {
   logger.error("异常:", e);
   throw new BusinessException(CodeConstant.REQUEST_PROGRAM_ERROR_CODE, e+"系统异常", false);
}finally {
           if(fos != null){
               fos.close();
           }
           if(dis != null){
               dis.close();
           }
       }
}