java web 如何实现文件的下载 前台和后台

//这是html中的一部分 下载按钮

<button type="button" id="btn" class="layui-btn">下载
					</button>

//以下是js代码  点击按钮的时候调用

  $("#btn").on('click',function () {

        postDownLoadFile({
            url : base_url + "/file/download", //这里写后台请求的url
            data :{
                params1:params1, //这里可以选择自己要传递的参数
				params2:params2
           
			},
            method : 'post'
        });
    });
//后台返回成功后回填的数据
    var postDownLoadFile = function(options) {
        var config = $.extend(true, {
            method : 'post'
        }, options);
        var $iframe = $('<iframe id="down-file-iframe" />');
        var $form = $('<form target="down-file-iframe" method="' + config.method + '" />');
        $form.attr('action', config.url);
        for ( var key in config.data) {
            $form
                .append('<input type="hidden" name="' + key + '" value="' + config.data[key] + '" />');
        }
        $iframe.append($form);
        $(document.body).append($iframe);
        $form[0].submit();
        $iframe.remove();
    }

以下是后台代码

@RestController
@RequestMapping("/file")
public class DownloadController1 {

    //业务上需要的参数可以如param1 传递
    @RequestMapping(value = "/download")
    public Map<String, Object> download(HttpServletRequest request, HttpServletResponse response,String param1,String param2 ) throws Exception {

        String realName = "第一节（2）.zip"; //文件在浏览器的显示位置
        String downLoadPath = ""; //这个参数表示文件在服务器的存储路径
        String contentType = "application/octet-stream";
        try {

            response.setContentType("text/html;charset=UTF-8");
            request.setCharacterEncoding("UTF-8");
            BufferedInputStream bis = null;
            BufferedOutputStream bos = null;

            long fileLength = new File(downLoadPath).length();

            response.setContentType(contentType);
            response.setHeader("Content-disposition",
                    "attachment; filename=" + new String(realName.getBytes("utf-8"), "ISO8859-1"));
            response.setHeader("Content-Length", String.valueOf(fileLength));

            bis = new BufferedInputStream(new FileInputStream(downLoadPath));
            bos = new BufferedOutputStream(response.getOutputStream());
            byte[] buff = new byte[2048];
            int bytesRead;
            while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
                bos.write(buff, 0, bytesRead);
            }
            bis.close();
            bos.close();
            return ResultUtil.put(ConstantUtil.REQUEST_SUCCESS, "", "");
        } catch (Exception e) {
            return ResultUtil.put(ConstantUtil.REQUEST_FAIL, "", "");
        }


    }


}

 

 

后台成功返回后，浏览器如下图显示，点击下载就可以了

 

前端部分参考的这位大兄弟，在此感谢。

https://blog.youkuaiyun.com/xuxie13/article/details/82145099