Spring MVC实现大文件下载功能
话不多说,先填上代码再来一步步分析:
package com.zbb.controller;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("/uploadFile")
public class UploadFileController {
@RequestMapping("/download")
public void downloadNet(HttpServletResponse response) throws Exception {
try {
String path = "E:\\BaiduYunDownload\\黑马程序员视频.z03";
File file = new File(path);
if (file.exists()) {
String filename = file.getName();
InputStream fis = new BufferedInputStream(new FileInputStream(file));
response.reset();
response.setContentType("application/x-download");
response.addHeader("Content-Disposition",
"attachment;filename=" + new String(filename.getBytes(), "UTF-8"));
response.addHeader("Content-Length", "" + file.length());
OutputStream out = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/octet-stream");
byte[] buffer = new byte[1024 * 1024 * 10];
int i = -1;
while ((i = fis.read(buffer)) != -1) {
out.write(buffer, 0, i);
}
fis.close();
out.flush();
out.close();
try {
response.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
PrintWriter out = response.getWriter();
out.print("<script>");
out.print("alert(\"not find the file\")");
out.print("</script>");
}
} catch (IOException ex) {
PrintWriter out = response.getWriter();
out.print("<script>");
out.print("alert(\"not find the file\")");
out.print("</script>");
}
}
}
实现文件下载主要主要步骤如下
- 创建文件对象:File file = new File(path);
- 利用BufferedInputStream从文件流读取数据:这里选用BufferedInputStream而不是InputStream,是因为在读取大文件时,BufferedInputStream的速度快上很多;
- 设置reponsed对象,响应客户端的请求,即下载文件。
- 这里需要注意的是,由于一般的视频文件都是G级别的,若一次性从文件流读取数据如:
byte[] buffer = new byte[fis. available()]
会导致内存溢出,所以不能一次性读取,应每次读取一部分,如每次读取10M:
byte[] buffer = new byte[1024 * 1024 * 10];
- 接下去就是响应客户端的请求了,这里就不用多说了吧。
在jsp页面只需设置一个链接指向该action即可
<a href="/download" >下载</a>
页面点击链接即可下载该视频: