【发布时间】：2014-07-31 06:51:33
【问题描述】：
how to fetch data from local json file?
根据上面的链接。我试图从存储在内部存储器中的 json 文件中获取数据。但我收到系统错误，从内部存储（json 文件）中获取数据。请帮忙。
public class MainActivity extends Activity implements OnClickListener {
private static final String TAG = "MainActivity";
Button b1,b2;
TextView t1;
JSONArray jsonBranchArray;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (isNetworkAvailable()) {
new PrefetchData().execute();
} else {
Toast.makeText(MainActivity.this,
"No Internet Connection Available", Toast.LENGTH_LONG)
.show();
}
b1 = (Button) findViewById(R.id.button1);
b1.setOnClickListener(this);
}
@Override
public void onClick(
View v) {
if (v == b1) {
WriteToFile();
readResponse();
}
}
private boolean isNetworkAvailable() {
ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager
.getActiveNetworkInfo();
if (activeNetworkInfo != null && activeNetworkInfo.isConnected())
{
return true;
}
return false;
}
private class PrefetchData extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... arg0) {
AppUtils appUtils = new AppUtils();
String jsonResultStr = appUtils
.getDataFromUrl("URL for json");
Log.d(TAG, "JSON content ::: "
+ jsonResultStr);
if (jsonResultStr != null) {
try {
JSONObject jsObj = new JSONObject(jsonResultStr);
jsonBranchArray = jsObj
.getJSONArray("ImageData");
Log.d(TAG, "JSONArray content ::: "
+ jsonBranchArray);
for (int j = 0; j < jsonBranchArray.length(); j++) {
JSONObject objBranchJson = (JSONObject) jsonBranchArray
.get(j);
img_id = objBranchJson.getString("ImageId");
img_name = objBranchJson.getString("ImageName");
img_desc = objBranchJson.getString("ImageDesc");
img_url = objBranchJson.getString("ImageUrl");
}
}
catch (JSONException e) {
e.printStackTrace();
}
}
return null;
}
protected void onPostExecute(Void result) {
super.onPostExecute(result);
Toast.makeText(MainActivity.this,
"Json values saved", Toast.LENGTH_LONG)
.show();
}
}
@SuppressWarnings("deprecation")
public void WriteToFile() {
try {
final String TESTSTRING =jsonBranchArray.toString();
FileOutputStream fOut = openFileOutput("samplefile.json",
MODE_WORLD_READABLE);
OutputStreamWriter osw = new OutputStreamWriter(fOut);
// Write the string to the file
osw.write(TESTSTRING);
/* ensure that everything is
* really written out and close */
osw.flush();
osw.close();
//Reading the file back...
/* We have to use the openFileInput()-method
* the ActivityContext provides.
* Again for security reasons with
* openFileInput(...) */
FileInputStream fIn = openFileInput("samplefile.json");
InputStreamReader isr = new InputStreamReader(fIn);
/* Prepare a char-Array that will
* hold the chars we read back in. */
char[] inputBuffer = new char[TESTSTRING.length()];
// Fill the Buffer with data from the file
isr.read(inputBuffer);
// Transform the chars to a String
String readString = new String(inputBuffer);
// Check if we read back the same chars that we had written out
boolean isTheSame = TESTSTRING.equals(readString);
Log.i("File Reading stuff", "success = " + isTheSame);
} catch (IOException ioe)
{ioe.printStackTrace();}
}
public JSONObject readResponse() {
InputStream inputStream = null;
try {
inputStream = this.openFileInput("samplefile.json");
} catch (IOException e1) {
e1.printStackTrace();
}
JSONObject jsonObject = null;
if (inputStream != null) {
BufferedReader reader = new BufferedReader(new InputStreamReader(
inputStream));
StringBuffer buffer = new StringBuffer();
String statement;
try {
while ((statement = reader.readLine()) != null) {
if (statement.trim().length() > 0) {
buffer.append(statement);
if (img_id=="12"){
System.out.println("ID can able to fetch using this method");
Log.i("File Reading stuff", "success");
}
}
}
} catch (IOException e1) { // TODO Auto-generated catch block
e1.printStackTrace();
}
if (buffer.length() > 0) {
try {
jsonObject = new JSONObject(buffer.toString());
} catch (JSONException e) {
e.printStackTrace();
}
}
}
return (JSONObject) jsonObject;
}}
错误是..W/System.err(407): org.json.JSONException: Value [{"ImageDesc":"Img1 Img1Img1","ImageId":"12","ImageName":"Img1", "ImageUrl":"http://192.168.10.200/dinesh/images/pro1.jpg"},{"ImageDesc":"Img13 Img13 Img13Img13","ImageId":"13","ImageName":"Img13", "ImageUrl":"http://192.168.10.200/dinesh/images/pro2.jpg"},{"ImageDesc":"Img14 Img14 Img14 Img14 Img14","ImageId":"14","ImageName":"Img14 org.json.JSONArray 类型的 ","ImageUrl":"http://192.168.10.200/dinesh/images/pro3.jpg.jpg"},null] 无法转换为 JSONObject 07-31 11:57:11.804: W/System.err(407): 在 org.json.JSON.typeMismatch(JSON.java:107) 07-31 11:57:11.804: W/System.err(407): 在 org.json.JSONObject.(JSONObject.java:158) 07-31 11:57:11.804: W/System.err(407): 在 org.json.JSONObject.(JSONObject.java:171) 07-31 11:57:11.804: W/System.err(407): 在 com.example.MainActivity.readResponse(MainActivity.java:310) 07-31 11:57:11.814: W/System.err(407): 在 com.example.MainActivity.onClick(MainActivity.java:111) 07-31 11:57:11.814: W/System.err(407): 在 android.view.View.performClick(View.java:2485) 07-31 11:57:11.814: W/System.err(407): 在 android.view.View$PerformClick.run(View.java:9080) 07-31 11:57:11.814: W/System.err(407): 在 android.os.Handler.handleCallback(Handler.java:587) 07-31 11:57:11.824: W/System.err(407): 在 android.os.Handler.dispatchMessage(Handler.java:92) 07-31 11:57:11.824: W/System.err(407): 在 android.os.Looper.loop(Looper.java:123) 07-31 11:57:11.824: W/System.err(407): 在 android.app.ActivityThread.main(ActivityThread.java:3683) 07-31 11:57:11.824: W/System.err(407): 在 java.lang.reflect.Method.invokeNative(Native Method) 07-31 11:57:11.834: W/System.err(407): 在 java.lang.reflect.Method.invoke(Method.java:507) 07-31 11:57:11.834: W/System.err(407): 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 07-31 11:57:11.834: W/System.err(407): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 07-31 11:57:11.834: W/System.err(407): at dalvik.system.NativeStart.main(Native Method)
我需要从存储在内部存储中的 json 文件中获取数据并将其显示在列表视图中。请帮忙。
示例 JSON 文件是.. {"ImageData":[{"ImageId":"12","ImageName":"Img1","ImageDesc":"Img1 Img1Img1 ","ImageUrl":"img_url/pro1. jpg"},{"ImageId":"13","ImageName":"Img13","ImageDesc":"Img13 Img13 Img13Img13","ImageUrl":"img_url/pro2.jpg"},{"ImageId":" 14","ImageName":"Img14","ImageDesc":"Img14 Img14 Img14 Img14 Img14","ImageUrl":"img_url/pro3.jpg.jpg"},]}
【问题讨论】：
-
当您尝试将 jsonarray 转换为 jsonobject 时发生此错误，您的文件包含您尝试转换为 jsonobject 的 jsonarray
-
阅读错误信息。它清楚地说明了问题所在。
-
但我的 json 文件仅以对象开头。请检查示例。
-
@Pramod Yadav 请检查整个代码 json 示例和错误。
-
@Marius 请检查整个代码 json 示例和错误。
标签： android json android-activity offline-caching