APK下载后台代码

最新推荐文章于 2021-02-04 08:06:07 发布

原创最新推荐文章于 2021-02-04 08:06:07 发布 · 997 阅读

1 ·

CC 4.0 BY-SA版权

Java 专栏收录该内容

1 篇文章

订阅专栏

项目中遇到后台APK下载时解析失败和下载进度显示不准确的问题。问题根源在于Content-Length值不正确，需后台提供正确的apk大小信息。通过调整Controller代码和前端Retrofit或OkHttp的请求方式，可以解决这些问题。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

1.我做的这个项目，后台下载总是报解析失败错误，或者下载百分比问题。
百分比问题是由于Content-Length不正确导致的，必须要求后台传正确的apk大小。
Controll 代码

	@RequestMapping(value = "/downloadApp", method = RequestMethod.GET)
	@ApiOperation(httpMethod = "GET", value = "下载文件", produces = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
	@ResponseBody
	public Object download(@ApiParam(value = "应用App主键ID", name = "appId")String appId,HttpServletResponse response) throws Exception {
		try {	
				// 清空response
				response.reset();
				// 设置response的Header
				response.setContentType("application/vnd.android.package-archive;");
				response.setHeader("Content-disposition", "attachment; filename=" + new String(apkInfoVO.getFileName().getBytes("utf-8"), "ISO8859-1"));
				response.setHeader("Content-Length", String.valueOf(getFileLength(apkInfo.getFilePath())));
				OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
				Utils.setOutputStream(apkInfo.getFilePath(), outputStream);
				outputStream.flush();
				outputStream.close();
		} catch (Exception e) {
			response.reset();
			throw new Exception(e);
		}
		return WebDTO.success();
	}

//获取文件长度
private int getFileLength(String filePath) {
		HttpURLConnection connection = null;
		URL conurl = null;
		try {
			String url =Constant.getName("HTTP")+filePath;
			conurl = new URL(url);
			connection = (HttpURLConnection) conurl.openConnection();
			int fileLength = connection.getContentLength();
			return fileLength;
		}catch (Exception e) {
			// TODO: handle exception
		}
		return 0;
	}

上面的这种写法，要求前端传的是单独的参数，retrofit如下传参

    @FormUrlEncoded
    @POST("###")
    Observable<NewsResponse> newsListQuery(@Field("currentPage") int currentPage,@Field("size") int size);

2.如果后台用这种方式，传的是json字符串

	@RequestMapping(value = "/downloadApp", method = RequestMethod.POST)
	@ApiOperation(httpMethod = "POST", value = "下载文件", produces = MediaType.APPLICATION_JSON_VALUE)
	public Object download(@RequestBody  @ApiParam(value="用户Id",name="appId" ,required = true) String paramStr,HttpServletResponse response) throws Exception {
	try {
			JSONObject object = JSONObject.parseObject(paramStr);
			String appId = object.getString("appId");
			...
}

前端应如下写，这次用的okhtttp请求，使用requestBody

JSONObject jsonObject = new JSONObject();
        try {
            jsonObject.put("appId", appCenter.getAppId());
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return jsonObject.toString();

 RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), jsonString);
 this.okHttpClient.newCall(new Request.Builder()).url(url).post(requestBody).build()).enqueue(new Callback() {}