how to fetch data from local json file?
根据以上链接。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）获取数据。请帮帮忙。
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：值[{＆＃34; ImageDesc＆＃34;：＆＃34; Img1 Img1Img1＆＃34;，＆＃34; ImageId＆ ＃34;：＆＃34; 12＆＃34;＆＃34; ImageName＆＃34;：＆＃34; IMG1＆＃34;＆＃34;的ImageUrl＆＃34;：＆＃34; HTTP：//192.168。 10.200 / dinesh / images / pro1.jpg＆＃34;}，{＆＃34; ImageDesc＆＃34;：＆＃34; Img13 Img13 Img13Img13＆＃34;，＆＃34; ImageId＆＃34;：＆＃34; 13＆ ＃34;＆＃34; ImageName＆＃34;：＆＃34; Img13＆＃34;＆＃34;的ImageUrl＆＃34;：＆＃34; HTTP：//192.168.10.200/dinesh/images/pro2.jpg& ＃34;}，{＆＃34; ImageDesc＆＃34;：＆＃34; Img14 Img14 Img14 Img14 Img14＆＃34;，＆＃34; ImageId＆＃34;：＆＃34; 14＆＃34;，＆＃34 ; ImageName＆＃34;：＆＃34;看好你哦！＆＃34;＆＃34;的ImageUrl＆＃34;：＆＃34; HTTP：//192.168.10.200/dinesh/images/pro3.jpg.jpg"}，类型为org.json.JSONArray的null]无法转换为JSONObject 07-31 11：57：11.804：W / System.err（407）：at org.json.JSON.typeMismatch（JSON.java:107） 07-31 11：57：11.804：W / System.err（407）：at org.json.JSONObject。（JSONObject.java:158） 07-31 11：57：11.804：W / System.err（407）：at org.json.JSONObject。（JSONObject.java:171） 07-31 11：57：11.804：W / System.err（407）：at com.example.MainActivity.readResponse（MainActivity.java:310） 07-31 11：57：11.814：W / System.err（407）：at 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）：at java.lang.reflect.Method.invokeNative（Native Method） 07-31 11：57：11.834：W / System.err（407）：at java.lang.reflect.Method.invoke（Method.java:507） 07-31 11：57：11.834：W / System.err（407）：at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:839） 07-31 11：57：11.834：W / System.err（407）：at 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json文件中获取数据，该文件存储在内部存储中并在列表视图中显示。请帮忙。
示例JSON文件是.. {＆＃34; ImageData＆＃34;：[{＆＃34; ImageId＆＃34;：＆＃34; 12＆＃34;，＆＃34; ImageName＆＃34;：＆＃ 34; Img1＆＃34;，＆＃34; ImageDesc＆＃34;：＆＃34; Img1 Img1Img1＆＃34;，＆＃34; ImageUrl＆＃34;：＆＃34; img_url / pro1.jpg＆＃34;}， {＆＃34;图像标识＆＃34;：＆＃34; 13＆＃34;＆＃34; ImageName＆＃34;：＆＃34; Img13＆＃34;＆＃34; ImageDesc＆＃34;：＆＃34; Img13 Img13 Img13Img13＆＃34;，＆＃34; ImageUrl＆＃34;：＆＃34; img_url / pro2.jpg＆＃34;}，{＆＃34; ImageId＆＃34;：＆＃34; 14＆＃34;， ＆＃34; ImageName＆＃34;：＆＃34; Img14＆＃34;，＆＃34; ImageDesc＆＃34;：＆＃34; Img14 Img14 Img14 Img14 Img14＆＃34;，＆＃34; ImageUrl＆＃34;： ＆＃34; img_url / pro3.jpg.jpg＆＃34;}，]}
答案 0 :(得分：0)
这段代码在提供的示例json上运行得非常好：
package com.so.test.java;
import org.json.JSONArray;
import org.json.JSONObject;
/**
* @author prashant
*
*/
public class JsonParser {
/**
* @param args
*/
public static void main(String[] args) {
String sampleJson = "{\"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\"}]}";
try {
JSONObject rootObj = new JSONObject(sampleJson);
JSONArray imageDataArr = rootObj.getJSONArray("ImageData");
System.out.println("JSONArray content ::: "+ rootObj.toString());
for (int j = 0; j < imageDataArr.length(); j++) {
JSONObject imageDataObj = (JSONObject) imageDataArr.get(j);
System.out.println(imageDataObj.getString("ImageId") + " " + imageDataObj.getString("ImageName"));
}
}catch(Exception e){
e.printStackTrace();
}
}
}
此代码生成输出
JSONArray content ::: {"ImageData":[{"ImageId":"12","ImageName":"Img1","ImageUrl":"img_url/pro1.jpg","ImageDesc":"Img1 Img1Img1 "},{"ImageId":"13","ImageName":"Img13","ImageUrl":"img_url/pro2.jpg","ImageDesc":"Img13 Img13 Img13Img13 "},{"ImageId":"14","ImageName":"Img14","ImageUrl":"img_url/pro3.jpg.jpg","ImageDesc":"Img14 Img14 Img14 Img14 Img14 "}]}
12 Img1
13 Img13
14 Img14
您正在使用的json库。我希望，这一个
答案 1 :(得分：0)
试试这个，你应该能够让它运转起来。
try {
JSONObject jsonObject = new JSONObject(jsonstring);
Iterator keys = jsonObject.keys();
while(keys.hasNext()) {
Object next = keys.next();
String strKey = (String) next;
Object obj = jsonObject.get(strKey);
if(obj instanceof String) {
JSONObject jsonObject = new JSONObject((String)obj);
//do your stuff..
} else if(obj instanceof JSONObject) {
//do your stuff..
if(jsonObject.has("<KEY>")) {
String value = jsonObject.getString("<KEY>"));
}
} else if(obj instanceof JSONArray) {
JSONArray jsonArray = (JSONArray) obj;
for(int j = 0; j < jsonArray.length(); j ++) {
JSONObject jsonObject1 = jsonArray.getJSONObject(j);
//do your stuff..
if(jsonObject1.has("<KEY>")) {
String value = jsonObject1.getString("<KEY>"));
} .... and so on
}
}
}
} catch (JSONException e) {
e.printStackTrace();
}