java - 下载图像并将其保存到 SD 卡中

Question

我正在尝试下载图像并将其保存到 SD 卡中，有时可以，有时则不行。我需要帮助试图理解为什么，我尝试用谷歌搜索，但找不到答案。

所以这是我的代码，用于检索杂志问题，然后循环遍历 json 数组中的每个项目，然后下载并将它们存储到 SD 卡中。但是有些图像没有下载，而是跳过(查看 logcat)

    /**
     * Background Async Task to Load all product by making HTTP Request
     * */
    class downloadMagazine extends AsyncTask<String, String, String> {

         @Override
            protected void onPreExecute() {
                super.onPreExecute();
                progressDialog = new ProgressDialog(Store.this);
                progressDialog.setMessage("Loading.." + "\n" + "加载中..");
                progressDialog.setIndeterminate(false);
                progressDialog.setCancelable(false);
                progressDialog.show();
            } 
        /**
         * getting preview url and then load them
         * */
        protected String doInBackground(String... args) {
            URL myFileUrl = null;

            // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                // getting JSON string from URL
                JSONObject json = jParser.makeHttpRequest(url_magazine, "GET", params);

                // Check your log cat for JSON reponse
                //Log.d("All Products: ", json.toString());

                try {
                    // Checking for SUCCESS TAG
                    int success = json.getInt(TAG_SUCCESS);

                    if (success == 1) {
                        // products found
                        // Getting Array of Products
                        mag = json.getJSONArray(TAG_MAGAZINE);

                        for (int i = 0; i < mag.length(); i++) {
                            JSONObject c = mag.getJSONObject(i);

                            // Storing each json item in variable
                            String magazineUrl = c.getString(TAG_MAGAZINE_URL);
                            String issueName = c.getString(TAG_MAGAZINE_NAME);

                            urlList.add(magazineUrl);
                            issueNameList.add(issueName);
                            //System.out.println(urlList);
                        }                   
                    } 
                } catch (JSONException e) {
                    e.printStackTrace();
                }           

                // Building Parameters
                List<NameValuePair> param = new ArrayList<NameValuePair>();
                // getting JSON string from URL
                JSONObject json1 = jParser.makeHttpRequest(urlList.get(pos), "GET", param);

                // CHECKING OF JSON RESPONSE
                Log.d("All guide: ", json.toString());

                try {
                    issues = json1.getJSONArray(TAG_ISSUE);

                    for (int i = 0; i < issues.length(); i++) {
                        JSONObject c = issues.getJSONObject(i);

                        String image = c.getString(TAG_IMAGE);

                        imageList.add(image);
                        //System.out.println(imageList);
                    }   


                    // STOP THE LOOP
                    //break;

                } catch (JSONException e) {
                    e.printStackTrace();
                }

                for (int i = 0; i < imageList.size(); i ++)
                {
                imageUrl = imageList.get(i).toString();
                Log.d("thumbnail", imageUrl);
                number = i;
                try {
                    myFileUrl = new URL(imageUrl);    // RETRIEVE IMAGE URL
                    }
                 catch (MalformedURLException e) {
                    e.printStackTrace();
                }
                try {
                    HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();
                    conn.setDoInput(true);
                    conn.connect();
                    InputStream in = conn.getInputStream();
                    Log.i("I'm connected", "Download");
                    bmImg = BitmapFactory.decodeStream(in);

                    File filename;
                    // GET EXTERNAL STORAGE, SAVE FILE THERE
                    File storagePath = new File(Environment.getExternalStorageDirectory(),folderName+"issue"+issueNumber+"/");
                    storagePath.mkdirs();

                    filename = new File(storagePath + "/page"+number+".jpg");
                    FileOutputStream out = new FileOutputStream(filename);
                    bmImg.compress(Bitmap.CompressFormat.JPEG, 90, out);

                        out.flush();
                        out.close();

                        MediaStore.Images.Media.insertImage(getContentResolver(),filename.getAbsolutePath(), filename.getName(),
                                filename.getName());          
                        in.close();

                         // displayImage();
                } catch (IOException e) {
                    e.printStackTrace();
                }   
                }

                return null;

}

这是我的 logcat 每当跳过下载页面时的输出(我知道它与我发布的问题之一类似，但我确实需要帮助解决问题)。我不知道发生了什么，我用谷歌搜索发现许多使用 android 4.0 及以上版本的人都遇到了这个问题

01-23 17:09:29.120: W/System.err(24339): java.io.EOFException
01-23 17:09:29.120: W/System.err(24339):    at libcore.io.Streams.readAsciiLine(Streams.java:203)
01-23 17:09:29.120: W/System.err(24339):    at libcore.net.http.HttpEngine.readResponseHeaders(HttpEngine.java:544)
01-23 17:09:29.120: W/System.err(24339):    at libcore.net.http.HttpEngine.readResponse(HttpEngine.java:784)
01-23 17:09:29.120: W/System.err(24339):    at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:274)
01-23 17:09:29.120: W/System.err(24339):    at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
01-23 17:09:29.130: W/System.err(24339):    at libcore.net.http.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:270)
01-23 17:09:29.130: W/System.err(24339):    at com.sfcca.coverflow.Store$downloadMagazine.doInBackground(Store.java:881)
01-23 17:09:29.130: W/System.err(24339):    at com.sfcca.coverflow.Store$downloadMagazine.doInBackground(Store.java:1)
01-23 17:09:29.130: W/System.err(24339):    at android.os.AsyncTask$2.call(AsyncTask.java:264)
01-23 17:09:29.130: W/System.err(24339):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
01-23 17:09:29.130: W/System.err(24339):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
01-23 17:09:29.130: W/System.err(24339):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
01-23 17:09:29.130: W/System.err(24339):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
01-23 17:09:29.130: W/System.err(24339):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
01-23 17:09:29.130: W/System.err(24339):    at java.lang.Thread.run(Thread.java:856)

Answer 1

检查您是否已向 list 授予适当的权限

 <uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />