Question

好吧，这让我疯了，我正在向你们寻求帮助，因为我喜欢自己解决问题，这是一场噩梦。我正在制作一个应用程序，用于学习目的，解析reddit首页的儿子数据，并将信息填充到列表视图中。我有几节课：

下载程序类

public class DataDownloader extends AsyncTask<String, Void, String> {

private String downloadedData;

@Override
protected String doInBackground(String... params) {
    downloadedData = downloadData(params[0]);
    if(downloadedData == null){
        Log.d("DataDownloader", "There was an error downloading the file");
    }
    return downloadedData;
}

@Override
protected void onPostExecute(String downloadedFile) {
    super.onPostExecute(downloadedFile);
}

private String downloadData(String urlPath){

    StringBuilder buffer = new StringBuilder();

    try{
        URL urlAddress = new URL(urlPath);
        HttpURLConnection connect = (HttpURLConnection) urlAddress.openConnection();
        int serverResponse = connect.getResponseCode();
        Log.d("DataDownloader", "Server responded with response code: " + serverResponse);
        InputStream stream = connect.getInputStream();
        InputStreamReader streamReader = new InputStreamReader(stream);
        int charRead;
        char[] inputBuffer = new char[500];
        while(true){
            charRead = streamReader.read(inputBuffer);
            if(charRead <= 0){
                break;
            }
            buffer.append(String.copyValueOf(inputBuffer, 0, charRead));
        }
        return buffer.toString();
    } catch (MalformedURLException e) {
        Log.d("DataDownloader", "MalformedURLException");
    } catch (IOException e) {
        Log.d("DataDownloader", "IOException");
    }

    return null;
}

}

JSON解析器类

public class JSONParser {

private String jsonData;
private ArrayList<Submission> submissions;

public JSONParser(String jsonData) {
    this.jsonData = jsonData;
    submissions = new ArrayList<Submission>();
}

public ArrayList<Submission> getSubmissions() {
    return submissions;
}

public void parseJSON() {
    Submission submissionContents = null;

    if (jsonData != null) {
        Log.d("JSONParser.parseJSON", "Looks like JSON data to me");
        try {
            JSONObject redditJSONObject = new JSONObject(jsonData);
            JSONObject data = redditJSONObject.getJSONObject("data");
            JSONArray children = data.getJSONArray("children");

            for(int i = 0; i < children.length(); i++){
                submissionContents = new Submission();
                JSONObject submissionDetails = children.getJSONObject(i);
                JSONObject submissionInfo = submissionDetails.getJSONObject("data");
                submissionContents.setTitle(submissionInfo.getString("title"));
                submissionContents.setAuthor(submissionInfo.getString("author"));
                submissionContents.setSubReddit(submissionInfo.getString("subreddit"));
                submissionContents.setThumbnailLink(submissionInfo.getString("thumbnail"));
                submissionContents.setUrlLink(submissionInfo.getString("url"));
                submissionContents.setNumComments(submissionInfo.getInt("num_comments"));
                submissionContents.setScore(submissionInfo.getInt("score"));
                submissions.add(submissionContents);
            }


        } catch (JSONException j) {
            Log.d("JSON.parseJSON", "Error creating JSON object");
        }

    } else {
        Log.d("JSONParser", "The file was empty!");
    }

}

}

我必须通过缩略图网址下载每个链接的位图。

public class ImageDownloader extends AsyncTask<String, Void, Bitmap> {

@Override
protected Bitmap doInBackground(String... params) {
    String imageUrl = params[0];
    Bitmap image = null;
    try{
        URL url = new URL(imageUrl);
        InputStream imageStream = url.openStream();
        image = BitmapFactory.decodeStream(imageStream);
    } catch (Exception e){
        Log.d("ImageDownloader", "Error establishing connection to url: " + imageUrl);
    }
    return image;
}

}

}

我可以轻松地实现一个常规的ArrayAdapter来填充列表，但这只会用文本填充它，我正在寻找一种用图像填充它的方法。我知道我必须创建一个自定义适配器，但老实说我无法搞清楚。我知道你需要创建一个xml，它代表每一行，我已经做到了。此xml包含图像和2个文本视图。我有我的“提交”数组，其中包含每个提交内容（标题，日期等）作为Submission对象，但我还必须在那里的某处下载图像。任何人都能指出我在正确的方向吗？

Answer 1

如果您正在从网络网址填充图片，则此问题已在Android上解决。

我强烈建议您从Square搜索Picasso或从Google搜索Glide。两者都有非常简单的语法，可以很好地解决您的问题。他们还将处理缓存，并在加载图像和进一步回收问题之前处理视图滚动屏幕的问题。

你们最终会得到类似的东西：

Picasso.with(context).load(imageUrl).into(imageView);

当你正在学习Android时，尝试用更现代的RecyclerView替换你的ListView，它会为你处理循环模式，让你更酷地启动。

定制阵列适配器帮助

1 个答案: