Question

您好我是android的新手，我跟着一些在线教程从android.But中的mysql获取数据当我试图获取数据时我得到json异常“没有价值：json数据”。

    public class MainActivity extends ActionBarActivity {

    String myJSON;

    private static final String TAG_RESULTS="result";
    private static final String TAG_NAME = "message_recd";
    private static final String TAG_ADD ="message_sent";

    JSONArray peoples = null;

    ArrayList<HashMap<String, String>> personList;

    ListView list;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        list = (ListView) findViewById(R.id.listView);
        personList = new ArrayList<HashMap<String,String>>();
        getData();
    }


    protected void showList(){
        try {
            JSONObject jsonObj = new JSONObject(myJSON);
            peoples = jsonObj.getJSONArray(TAG_RESULTS);
                for(int i=0;i<peoples.length();i++){
                JSONObject c = peoples.getJSONObject(i);
                String name=null, address=null;

                if(c.has("message_recd"))
                    name = c.getString("message_recd");
                else if(c.has("message_sent"))
                    address = c.getString("message_sent");

                HashMap<String,String> persons = new HashMap<String,String>();


                persons.put(TAG_NAME,name);
                persons.put(TAG_ADD,address);
                personList.add(persons);
            }

            ListAdapter adapter = new SimpleAdapter(
                    MainActivity.this, personList, R.layout.list_item,
                    new String[]{TAG_NAME,TAG_ADD},
                    new int[]{R.id.name, R.id.address}
            );

            list.setAdapter(adapter);

        } catch (JSONException e) {
            Log.i("tagconvertstr", "["+myJSON+"]");
        }
    }

    public void getData(){
        class GetDataJSON extends AsyncTask<String, Void, String>{

            @Override
            protected String doInBackground(String... params) {
                DefaultHttpClient httpclient = new DefaultHttpClient(new BasicHttpParams());
                HttpPost httppost = new HttpPost("http://10.0.2.2/progress_card/messages/get_messages1.php");

                // 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();
                } catch (Exception e) {
                    // Oops
                }
                finally {
                    try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
                }
                return result;
            }

            @Override
            protected void onPostExecute(String result){
                myJSON=result;
                showList();
            }
        }
        GetDataJSON g = new GetDataJSON();
        g.execute();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

logcat的：

    10-01 03:07:55.910: I/tagconvertstr(1953): [{"0":{"message_recd":"hello is it working really?"},"1":{"message_recd":"hello"},"2":{"message_recd":"checking"},"3":{"message_recd":"qwerty"},"4":{"message_recd":"qweqwdqdqd"},"5":{"message_recd":"ojhdsgwkjsbawdfvkjn"},"6":{"message_recd":"qwertyyt"},"7":{"message_recd":"qwertyytqwertyytqwertyytqwertyytqwertyytqwertyyt"},"8":{"message_sent":"hey whtas up"},"9":{"message_sent":"hey whtas up again"},"10":{"message_sent":"hey whtas up hey whtas up hey whtas up hey whtas up hey whtas up "}}
10-01 03:07:55.910: I/tagconvertstr(1953): ]

Json回复：

{"0":{"message_recd":"hello is it working really?"},"1":{"message_recd":"hello"},"2":{"message_recd":"checking"},"3":{"message_recd":"qwerty"},"4":{"message_recd":"qweqwdqdqd"},"5":{"message_recd":"ojhdsgwkjsbawdfvkjn"},"6":{"message_recd":"qwertyyt"},"7":{"message_sent":"hey whtas up"},"8":{"message_sent":"hey whtas up again"}}

Answer 1

看到这是你想要做的： - 在帖子执行中，您可以： - myJSON=result;

现在myJson的json结构是： - {"0":{"message_recd":"hello is it working really?"},"1":{"message_recd":"hello"},"2":{"message_recd":"checking"},"3":{"message_recd":"qwerty"},"4":{"message_recd":"qweqwdqdqd"},"5":{"message_recd":"ojhdsgwkjsbawdfvkjn"},"6":{"message_recd":"qwertyyt"},"7":{"message_sent":"hey whtas up"},"8":{"message_sent":"hey whtas up again"}}

在Json {}中表示Json对象，而[]表示其Json Array ..现在在方法showList（）中执行： -

JSONObject jsonObj = new JSONObject(myJSON);
peoples = jsonObj.getJSONArray(TAG_RESULTS);

其中TAG_RESULTS =“结果”

所以我问Json Object jsonObj给我一个Json数组，其键是“result”但是没有，请参阅Json结构。事实上，Json对象上没有数组，它有多个带有键0,1,2,3 ... 8的Json对象。

所以为了从jsonObj获取所有Json对象，我们将循环这样： -

for(int i=0;i < jsonObj.length;i++) {

JsonObject myJsonObject = jsonObj.getJsonObject(i);

//check if it has value for key and do something with value
if(myJsonObject.has("message_recd")) {

  String meesageRecieved = myJsonObject.getString("message_recd")

//Add it to the hash map
}

// do same if we have more keys like message_recd in json 
}

你从那个网址得到的Json结构不是你认为你得到的，它没有结果数组..快乐的android编码:)

Answer 2

你得到的回应不是json结构。

中的外观

Advance Rest Client

/^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+.[a-zA-Z]{2,6}$|^$/

但在android json应该看起来像：

{"0":{"message_recd":"hello is it working really?"},"1":{"message_recd":"hello"},"2":{"message_recd":"checking"},"3":{"message_recd":"qwerty"},"4":{"message_recd":"qweqwdqdqd"},"5":{"message_recd":"ojhdsgwkjsbawdfvkjn"},"6":{"message_recd":"qwertyyt"},"7":{"message_sent":"hey whtas up"},"8":{"message_sent":"hey whtas up again"}}

如何从android中的mysql中获取数据？

2 个答案:

Advance Rest Client