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Android 通过侦听器将HTTP-JSON数据从asyncTask返回到Activity

android json

Android 通过侦听器将HTTP-JSON数据从asyncTask返回到Activity,android,json,Android,Json,我正在尝试将JSON数据从AsyncTask扩展类返回到活动。 我的活动代码如下： public class MainActivity extends Activity implements JSONListener{ private JSONObject jsonData = null; @Override public void JSONFeedBack(JSONObject jsonData) { // TOD

我正在尝试将JSON数据从AsyncTask扩展类返回到活动。 我的活动代码如下：

  public class MainActivity extends Activity implements JSONListener{

        private JSONObject jsonData = null;

        @Override
        public void JSONFeedBack(JSONObject jsonData) {
            // TODO Auto-generated method stub
            this.jsonData = jsonData;
            Log.e("JSON check in JSONFeedBack(): ", jsonData.toString()  );
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            new JsonObj(this).execute("http://xml/url");

        }
    }

import org.json.JSONObject;

public interface JSONListener {
    void JSONFeedBack(JSONObject jsonObj);
}

public class JsonObj extends AsyncTask<String, Void, JSONObject>{
    MainActivity activity;
    JSONListener jsonListener;
    int tid;
    String term;

    public JsonObj(JSONListener jsonListener){
        this.jsonListener = jsonListener;
    }

    @Override
    protected JSONObject doInBackground(String... url) {

        // TODO Auto-generated method stub
        DefaultHttpClient   httpclient = new DefaultHttpClient(new BasicHttpParams());
        HttpPost httppost = new HttpPost(url[0]);
        JSONObject jsonObject = null;
        // Depends on your web service
        httppost.setHeader("Content-type", "application/json");

        InputStream inputStream = null;
        String result = null;
        try {
            HttpResponse response = httpclient.execute(httppost);           
            HttpEntity entity = response.getEntity();

            inputStream = entity.getContent();
            // json is UTF-8 by default
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
            StringBuilder sb = new StringBuilder();

            String line = null;
            while ((line = reader.readLine()) != null){
                sb.append(line + "\n");
            }
            result = sb.toString();
            Log.e("JSON-Test [RESULT]: ", result);
            jsonObject = new JSONObject(result);


        } catch (Exception e) { 
            Log.e("JSON-Test [exception]: ", e.toString());
        }
        finally {
            try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
        }

        return jsonObject;
    }

    @Override
    protected void onPostExecute(JSONObject result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        this.jsonListener.JSONFeedBack(result);
        Log.e("OnPostExecute TEST: ", result.toString());

    }
}

[
{
"data": {
"term": "All Nations Praise",
"tid": "10"
}
},
{
"data": {
"term": "Classified Advertisements",
"tid": "16"
}
},
{
"data": {
"term": "Kid&#039;s",
"tid": "11"
}
},
{
"data": {
"term": "KT Creative",
"tid": "9"
}
},
{
"data": {
"term": "KT Diary",
"tid": "8"
}
},
{
"data": {
"term": "Live at the Coronet",
"tid": "14"
}
},
{
"data": {
"term": "Situations Vacant",
"tid": "15"
}
},
{
"data": {
"term": "X:Change",
"tid": "13"
}
},
{
"data": {
"term": "Youth",
"tid": "12"
}
}
]

 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }
我的JSONListener如下所示：

  public class MainActivity extends Activity implements JSONListener{

        private JSONObject jsonData = null;

        @Override
        public void JSONFeedBack(JSONObject jsonData) {
            // TODO Auto-generated method stub
            this.jsonData = jsonData;
            Log.e("JSON check in JSONFeedBack(): ", jsonData.toString()  );
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            new JsonObj(this).execute("http://xml/url");

        }
    }

import org.json.JSONObject;

public interface JSONListener {
    void JSONFeedBack(JSONObject jsonObj);
}

public class JsonObj extends AsyncTask<String, Void, JSONObject>{
    MainActivity activity;
    JSONListener jsonListener;
    int tid;
    String term;

    public JsonObj(JSONListener jsonListener){
        this.jsonListener = jsonListener;
    }

    @Override
    protected JSONObject doInBackground(String... url) {

        // TODO Auto-generated method stub
        DefaultHttpClient   httpclient = new DefaultHttpClient(new BasicHttpParams());
        HttpPost httppost = new HttpPost(url[0]);
        JSONObject jsonObject = null;
        // Depends on your web service
        httppost.setHeader("Content-type", "application/json");

        InputStream inputStream = null;
        String result = null;
        try {
            HttpResponse response = httpclient.execute(httppost);           
            HttpEntity entity = response.getEntity();

            inputStream = entity.getContent();
            // json is UTF-8 by default
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
            StringBuilder sb = new StringBuilder();

            String line = null;
            while ((line = reader.readLine()) != null){
                sb.append(line + "\n");
            }
            result = sb.toString();
            Log.e("JSON-Test [RESULT]: ", result);
            jsonObject = new JSONObject(result);


        } catch (Exception e) { 
            Log.e("JSON-Test [exception]: ", e.toString());
        }
        finally {
            try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
        }

        return jsonObject;
    }

    @Override
    protected void onPostExecute(JSONObject result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        this.jsonListener.JSONFeedBack(result);
        Log.e("OnPostExecute TEST: ", result.toString());

    }
}

[
{
"data": {
"term": "All Nations Praise",
"tid": "10"
}
},
{
"data": {
"term": "Classified Advertisements",
"tid": "16"
}
},
{
"data": {
"term": "Kid&#039;s",
"tid": "11"
}
},
{
"data": {
"term": "KT Creative",
"tid": "9"
}
},
{
"data": {
"term": "KT Diary",
"tid": "8"
}
},
{
"data": {
"term": "Live at the Coronet",
"tid": "14"
}
},
{
"data": {
"term": "Situations Vacant",
"tid": "15"
}
},
{
"data": {
"term": "X:Change",
"tid": "13"
}
},
{
"data": {
"term": "Youth",
"tid": "12"
}
}
]

 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }
我的asyncTask类如下所示：

  public class MainActivity extends Activity implements JSONListener{

        private JSONObject jsonData = null;

        @Override
        public void JSONFeedBack(JSONObject jsonData) {
            // TODO Auto-generated method stub
            this.jsonData = jsonData;
            Log.e("JSON check in JSONFeedBack(): ", jsonData.toString()  );
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            new JsonObj(this).execute("http://xml/url");

        }
    }

import org.json.JSONObject;

public interface JSONListener {
    void JSONFeedBack(JSONObject jsonObj);
}

public class JsonObj extends AsyncTask<String, Void, JSONObject>{
    MainActivity activity;
    JSONListener jsonListener;
    int tid;
    String term;

    public JsonObj(JSONListener jsonListener){
        this.jsonListener = jsonListener;
    }

    @Override
    protected JSONObject doInBackground(String... url) {

        // TODO Auto-generated method stub
        DefaultHttpClient   httpclient = new DefaultHttpClient(new BasicHttpParams());
        HttpPost httppost = new HttpPost(url[0]);
        JSONObject jsonObject = null;
        // Depends on your web service
        httppost.setHeader("Content-type", "application/json");

        InputStream inputStream = null;
        String result = null;
        try {
            HttpResponse response = httpclient.execute(httppost);           
            HttpEntity entity = response.getEntity();

            inputStream = entity.getContent();
            // json is UTF-8 by default
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
            StringBuilder sb = new StringBuilder();

            String line = null;
            while ((line = reader.readLine()) != null){
                sb.append(line + "\n");
            }
            result = sb.toString();
            Log.e("JSON-Test [RESULT]: ", result);
            jsonObject = new JSONObject(result);


        } catch (Exception e) { 
            Log.e("JSON-Test [exception]: ", e.toString());
        }
        finally {
            try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
        }

        return jsonObject;
    }

    @Override
    protected void onPostExecute(JSONObject result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        this.jsonListener.JSONFeedBack(result);
        Log.e("OnPostExecute TEST: ", result.toString());

    }
}

[
{
"data": {
"term": "All Nations Praise",
"tid": "10"
}
},
{
"data": {
"term": "Classified Advertisements",
"tid": "16"
}
},
{
"data": {
"term": "Kid&#039;s",
"tid": "11"
}
},
{
"data": {
"term": "KT Creative",
"tid": "9"
}
},
{
"data": {
"term": "KT Diary",
"tid": "8"
}
},
{
"data": {
"term": "Live at the Coronet",
"tid": "14"
}
},
{
"data": {
"term": "Situations Vacant",
"tid": "15"
}
},
{
"data": {
"term": "X:Change",
"tid": "13"
}
},
{
"data": {
"term": "Youth",
"tid": "12"
}
}
]

 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }
因此，在调用
Log.e（“JSON检入JSONFeedBack（）：”，jsonData.toString（））时，我得到一个空指针异常在我的
JSONFeedBack
在我的活动类中


 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }



我已确认JSON数据是在AsynchClass中获取的，但我尝试将其发送到activity时，却一直导致空指针异常。
我刚刚运行了您的代码，使用我的一项服务更改url，效果很好。。。我认为在创建
JSONObject


jsonObject = new JSONObject(result);



 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }


是否确实不记录此行：


Log.e("JSON-Test [exception]: ", e.toString());



 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }


i、 e.如果我使用这个url，我会得到一个异常，创建
JSONObject
，然后创建您得到的NPE


 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }



我很确定AsynchTask和Activity之间的通信是有效的，问题在于您的响应或如何解析它。
不要在Json字符串中添加新行字符


 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }



编辑：您应该在
Log.e（“JSON测试[exception]：”，e.toString（））中看到一个异常，因为这一点
您是否尝试将
Log.e（“OnPostExecute测试：，result.toString（））
before
this.jsonListener.JSONFeedBack（结果）
确保
结果
不为空？谢谢您的回答。我对你的代码感到非常困惑，这可能证实了我的json数据有问题的怀疑。让我知道你的想法。我粘贴了有问题的JSON输出

 String line = null;
     while ((line = reader.readLine()) != null){
     sb.append(line); // remove + "\n" here
 }