Servlet的response实现 文件下载

文件下载

public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         //获取文件路径
        String realPath = "D:\\javaweb-02-maven\\servlet-01\\src\\main\\resource\\img.png";
        //D:\javaweb-02-maven\servlet-01\src\main\resource\img.png
        System.out.println("下载路径"+realPath);
        //下载的文件名
        String filename = realPath.substring(realPath.lastIndexOf("\\") + 1);
       //让浏览器能支持所下载的的东西
        resp.setHeader("Content-disposition","attachment;filename"+filename);
       //获得下载文件的输入流
        FileInputStream fileInputStream = new FileInputStream(realPath);
        //创建缓冲区
        int len=0;
        byte[] buffer=new byte[1024];
        //获得OutputStream流
        ServletOutputStream outputStream = resp.getOutputStream();
        //将FileInputStream写到缓冲区
        while((len=fileInputStream.read(buffer))>0){
            outputStream.write(buffer,0,len);
        }
        //关闭流保证安全
           fileInputStream.close();;
           outputStream.close();
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}
```
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