我在我的应用程序中使用网络服务。基本上我的应用程序显示了 wordpress 网站的帖子。用户还可以为帖子添加书签。我正在使用帖子 url 将所有书签帖子保存在 sqlite 中。现在的问题是我有很多不同的网址。我想在一个 ListView 中显示这些 url 的内容。

所有这些 url 的 json 结构也是相同的。

我已经查看了与此问题相关的其他问题，但这些问题并没有太大帮助。

让我告诉你到目前为止我做了多少尝试。

这是代码 这是 BookmarkActivity

ArrayList<HashMap<String,String>> allData;
String[] urlarray;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bookmark);
    SqliteController controller= new SqliteController(this);

    allData = controller.getAllData();
    for (int i=0; i<allData.size(); i++){
        String url=allData.get(i).get("link");
        urlarray= new String[]{url};
    }
    for(int i=0; i <urlarray.length; i++){
        MyAsyncTask task = new MyAsyncTask(i);
        task.execute();
    }
}
private class MyAsyncTask extends AsyncTask<Object,Void,String>{
    int urlNumber;
    HttpURLConnection connection=null;
    BufferedReader reader=null;
    public MyAsyncTask (int number){
        this.urlNumber=number;
    }
    @Override
    protected String doInBackground(Object... params) {
        try {
            URL url = new URL(urlarray[urlNumber]);
            connection= (HttpURLConnection) url.openConnection();
            connection.connect();
            StringBuffer buffer = new StringBuffer();
            String line = "";
            while ((line = reader.readLine()) != null) {
                buffer.append(line);
            }
            String json = buffer.toString();
            return json;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        //Log.d("TAG",s);
    }
}

这里是json。 (它不是完全相同的 json，但我确信每个 url 都将具有相同的 json 结构)

{
  "status": "ok",
  "count": 1,
  "count_total": 1,
  "pages": 1,
  "posts": [
    {
      "id": 1,
      "type": "post",
      "slug": "hello-world",
      "url": "http:\/\/localhost\/wordpress\/?p=1",
      "title": "Hello world!",
      "title_plain": "Hello world!",
      "content": "<p>Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!<\/p>\n",
      "excerpt": "Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!\n",
      "date": "2009-11-11 12:50:19",
      "modified": "2009-11-11 12:50:19",
      "categories": [],
      "tags": [],
      "author": {
        "id": 1,
        "slug": "admin",
        "name": "admin",
        "first_name": "",
        "last_name": "",
        "nickname": "",
        "url": "",
        "description": ""
      },
      "comments": [
        {
          "id": 1,
          "name": "Mr WordPress",
          "url": "http:\/\/wordpress.org\/",
          "date": "2009-11-11 12:50:19",
          "content": "<p>Hi, this is a comment.<br \/>To delete a comment, just log in and view the post's comments. There you will have the option to edit or delete them.<\/p>\n",
          "parent": 0
        }
      ],
      "comment_count": 1,
      "comment_status": "open"
    }
  ]
}

有人可以帮我解决这个问题吗？我应该如何解决这种情况？

最佳答案

试试这个...实际上，在这段代码中，我正在使用 Volley 库进行网络操作。 首先在您的应用程序中创建应用程序类，以避免为网络操作创建新的 Volley 库实例。

public class ApplicationController extends Application {

public static final String TAG = ApplicationController.class
        .getSimpleName();

private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;

private static ApplicationController mInstance;

@Override
public void onCreate() {
    super.onCreate();
    mInstance = this;
}

public static synchronized ApplicationController getInstance() {
    return mInstance;
}

public RequestQueue getRequestQueue() {
    if (mRequestQueue == null) {
        mRequestQueue = Volley.newRequestQueue(getApplicationContext());
    }

    return mRequestQueue;
}

 //This function  request the volley library to process with tag
  //where <T> a generic method with an unbound type variable T.You can pass any datatype to functions.for more info About generic method.go through this link:http://docs.oracle.com/javase/tutorial/extra/generics/methods.html
public <T> void addToRequestQueue(Request<T> req, String tag) {
    // set the default tag if tag is empty
    req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
    getRequestQueue().add(req);
}
 //This function  request the volley library to process with tag
public <T> void addToRequestQueue(Request<T> req) {
    req.setTag(TAG);
    getRequestQueue().add(req);
}
//This function cancel the requested Url those are all in pending
public void cancelPendingRequests(Object tag) {
    if (mRequestQueue != null) {
        mRequestQueue.cancelAll(tag);
    }
}
}

在 app build.gradle 中的 dependencies 下添加这一行

 compile 'com.mcxiaoke.volley:library-aar:1.0.0'

在 list 文件中添加访问网络的权限

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

在Application标签中提到应用类名

  <application
    android:name=".ApplicationController" 
     android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
     //your activity....
     </application>

在 Activity onCreate 添加这一行...

    progressDialog=new ProgressDialog(MainClass.this);
    progressDialog.setMessage("Loading...");
    progressDialog.show();
   //place your code to form urlarray
    urlarray = new String[5];
   //where datas represents the arraylist to store received content from json response.if you want to show more datas add your custom object to arraylist
    datas=new ArrayList<String>();

     adapter= new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, android.R.id.text1);
    try {
        for (int i = 0; i < urlarray.length; i++) {
            final int j = i;
            String url=urlarray[i];
            JsonObjectRequest objectRequest = new JsonObjectRequest(Request.Method.GET, url, (JSONObject) null, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.e("Response is for  " + Integer.toString(j), response.toString());
        //Here i assumed received json response is same as of sample json Provided by you.
                    try{
                    JSONArray jsonArray=response.getJSONArray("posts");
                    if(jsonArray.length()>0){
                        JSONObject obj=jsonArray.getJSONObject(0);
                        String content=obj.getString("content");
                        datas.add(content);
                    }
                    if(j==urlarray.length-1) {
                        progressDialog.dismiss();
                        adapter= new ArrayAdapter<String>(MainClass.this,
                                android.R.layout.simple_list_item_1, android.R.id.text1,datas);
                        listView.setAdapter(adapter);
                    }
                    }catch(Exception e){
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.e("error",error.toString());
                    if(j==urlarray.length-1) {
                        progressDialog.dismiss();
                    }
                    }
            }){
                @Override
                public Map<String, String> getHeaders() throws AuthFailureError {
                    HashMap<String, String> headers = new HashMap<String, String>();
                    headers.put("Content-Type", "application/json");
                    headers.put( "charset", "utf-8");
                    return headers;
                }
            };
            objectRequest.setRetryPolicy(new DefaultRetryPolicy(5000,
                    DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                    DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
        ApplicationController.getInstance().addToRequestQueue(objectRequest, "JSON");
        }

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

关于android - 超过 1 个不同的网址，只有一个 ListView ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34813614/