我有多个 Activity ，每个 Activity 都从不同的 URL 和不同的 HTTP 方法(如 POST、GET、PUT、DELETE等 有些请求有头数据，有些有正文，有些可能两者都有。 我正在使用具有多个构造函数的单个 AsyncTask 类来传递来自 Activity 的数据，以便我可以将它们添加到 HttpUrlConnection 实例。

我试过这个教程:http://cyriltata.blogspot.in/2013/10/android-re-using-asynctask-class-across.html .

但是上面的教程使用了HttpClient和NameValuePair。我将 NameValuePair 替换为 Pair。但我发现很难使用 HttpUrlConnection 实现相同的逻辑，因为我需要向我的请求添加多个 POST 数据和 header 。

但是返回的字符串是空的。我该如何正确实现这种情况？

完整代码:

public class APIAccessTask extends AsyncTask<String,Void,String> {
URL requestUrl;
Context context;
HttpURLConnection urlConnection;
List<Pair<String,String>> postData, headerData;
String method;
int responseCode = HttpURLConnection.HTTP_NOT_FOUND;


APIAccessTask(Context context, String requestUrl, String method){
    this.context = context;
    this.method = method;
    try {
        this.requestUrl = new URL(requestUrl);
    }
    catch(Exception ex){
        ex.printStackTrace();
    }
 }


APIAccessTask(Context context, String requestUrl, String method,    List<Pair<String,String>> postData,){
    this(context, requestUrl, method);
    this.postData = postData;
}

APIAccessTask(Context context, String requestUrl, String method, List<Pair<String,String>> postData,
              List<Pair<String,String>> headerData){
    this(context, requestUrl,method,postData);
    this.headerData = headerData;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
}

@Override
protected String doInBackground(String... params) {

    setupConnection();

    if(method.equals("POST"))
    {
        return httpPost();
    }

    if(method.equals("GET"))
    {
        return httpGet();
    }

    if(method.equals("PUT"))
    {
        return httpPut();
    }

    if(method.equals("DELETE"))
    {
        return httpDelete();
    }
    if(method.equals("PATCH"))
    {
        return httpPatch();
    }

    return null;
}

@Override
protected void onPostExecute(String result) {
    Toast.makeText(context,result,Toast.LENGTH_LONG).show();
    super.onPostExecute(result);
}

void setupConnection(){
    try {
        urlConnection = (HttpURLConnection) requestUrl.openConnection();
        urlConnection.setDoOutput(true);
        urlConnection.setDoInput(true);
        urlConnection.setChunkedStreamingMode(0);
        if(headerData != null){
            for (Pair pair: headerData)
            {
                urlConnection.setRequestProperty(pair.first.toString(), Base64.encodeToString(pair.second.toString().getBytes(),Base64.DEFAULT));
            }
        }
    }
    catch(Exception ex) {
        ex.printStackTrace();
    }

}

private String httpPost(){
    try{
        urlConnection.setRequestMethod("POST");
    }
    catch (Exception ex){
        ex.printStackTrace();

    return stringifyResponse();
}

String httpGet(){

    try{
        urlConnection.setRequestMethod("GET");
    }
    catch (Exception ex){
        ex.printStackTrace();
    }
    return stringifyResponse();
}

String httpPut(){

    try{
        urlConnection.setRequestMethod("PUT");
    }
    catch (Exception ex){
        ex.printStackTrace();
    }
    return stringifyResponse();
}

String httpDelete(){
    try{
        urlConnection.setRequestMethod("DELETE");
    }
    catch (Exception ex){
        ex.printStackTrace();
    }
    return stringifyResponse();

}

String httpPatch(){
    try{
        urlConnection.setRequestMethod("PATCH");
    }
    catch (Exception ex){
        ex.printStackTrace();
    }
    return stringifyResponse();

}

String stringifyResponse() {

    StringBuilder sb = new StringBuilder();
    try {
        OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out, "UTF-8"));
        writer.write(getQuery(postData));
        writer.flush();
        writer.close();
        out.close();

        urlConnection.connect();
        responseCode = urlConnection.getResponseCode();
        if (responseCode == 200) {
            InputStream in = new BufferedInputStream(urlConnection.getInputStream());
            BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));
            String line = null;

            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
        }

    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return sb.toString();
}


private String getQuery(List<Pair<String,String>> params) throws UnsupportedEncodingException{
    Uri.Builder builder = null;
    for (Pair pair : params)
    {
         builder = new Uri.Builder()
                .appendQueryParameter(pair.first.toString(), pair.second.toString());
                }
    return builder.build().getEncodedQuery();
}
}

最佳答案

IMO，你可以引用我下面的示例代码:

   /**         
     * HTTP request using HttpURLConnection
     *
     * @param method
     * @param address
     * @param header
     * @param mimeType
     * @param requestBody
     * @return
     * @throws Exception
     */
    public static URLConnection makeURLConnection(String method, String address, String header, String mimeType, String requestBody) throws Exception {
        URL url = new URL(address);

        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

        urlConnection.setDoInput(true);
        urlConnection.setDoOutput(!method.equals(HTTP_METHOD_GET));
        urlConnection.setRequestMethod(method);

        if (isValid(header)) {   // let's assume only one header here             
            urlConnection.setRequestProperty(KEYWORD_HEADER_1, header);
        }

        if (isValid(requestBody) && isValid(mimeType) && !method.equals(HTTP_METHOD_GET)) {
            urlConnection.setRequestProperty(KEYWORD_CONTENT_TYPE, mimeType);
            OutputStream outputStream = new BufferedOutputStream(urlConnection.getOutputStream());
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "utf-8");
            writer.write(requestBody);
            writer.flush();
            writer.close();
            outputStream.close();
        }

        urlConnection.connect();

        return urlConnection;
    }

requestBody 是使用以下方法生成的:

    public static String buildRequestBody(Object content) {
        String output = null;
        if ((content instanceof String) ||
                (content instanceof JSONObject) ||
                (content instanceof JSONArray)) {
            output = content.toString();
        } else if (content instanceof Map) {
            Uri.Builder builder = new Uri.Builder();
            HashMap hashMap = (HashMap) content;
            if (isValid(hashMap)) {
                Iterator entries = hashMap.entrySet().iterator();
                while (entries.hasNext()) {
                    Map.Entry entry = (Map.Entry) entries.next();
                    builder.appendQueryParameter(entry.getKey().toString(), entry.getValue().toString());
                    entries.remove(); // avoids a ConcurrentModificationException
                }
                output = builder.build().getEncodedQuery();
            }
        } else if (content instanceof byte[]) {
            try {
                output = new String((byte[]) content, "UTF-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }

        return output;
    }
}

然后，在您的 AsyncTask 类中，您可以调用:

       String url = "http://.......";
       HttpURLConnection urlConnection;
       Map<String, String> stringMap = new HashMap<>();           
       stringMap.put(KEYWORD_USERNAME, "bnk");
       stringMap.put(KEYWORD_PASSWORD, "bnk123");
       String requestBody = buildRequestBody(stringMap);
       try {
           urlConnection = (HttpURLConnection) Utils.makeURLConnection(HTTP_METHOD_POST, url, null, MIME_FORM_URLENCODED, requestBody);               
           if (urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
               // do something...
           } else {
               // do something...
           }
           ...
       } catch (Exception e) {
           e.printStackTrace();
       }

或

       String url = "http://.......";
       HttpURLConnection urlConnection;
       JSONObject jsonBody;                      
       String requestBody;
       try {
           jsonBody = new JSONObject();
           jsonBody.put("Title", "Android Demo");
           jsonBody.put("Author", "BNK");
           requestBody = Utils.buildRequestBody(jsonBody);
           urlConnection = (HttpURLConnection) Utils.makeURLConnection(HTTP_METHOD_POST, url, null, MIME_JSON, requestBody);               
           if (urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
               // do something...
           } else {
               // do something...
           }
           ...
       } catch (Exception e) {
           e.printStackTrace();
       }

关于java - 如何将 HttpUrlConnection 的逻辑拆分为多个方法？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34408126/