使用Response下载文件示例

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // 1.获取文件路径
    String realPath = "D:\\project\\servlet-main\\response\\src\\main\\resources\\头像.jpg";
    // 2.获取文件名
    String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
    // 3.设置请求头（支持文件下载的头部Content-Disposition）
    resp.setHeader("Content-Disposition","attachment;filename=" + URLEncoder.encode(fileName,"UTF-8"));
    // 4.获取下载文件的输入流：FileInputStream
    FileInputStream inputStream = new FileInputStream(realPath);
    // 5.创建缓冲区
    int length = 0;
    byte[] buffer = new byte[1024];
    // 6.获取输入流对象：OutputStream
    ServletOutputStream outputStream = resp.getOutputStream();
    // 7.将流写入缓冲区，使用OutputStream将缓冲区中的数据输出到客户端
    while ((length = inputStream.read(buffer)) > 0) {
        outputStream.write(buffer, 0, length);
    }
    inputStream.close();
    outputStream.close();
}