这是什么意思“由于异常而没有DRP密钥：java.lang.ClassNotFound
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我试图解析本地URL(
http://192.168.1.94/wamp/up.php)在我的应用程序android(JSON解析)中使用它.
mainActivity android： package itawfik.com.myapplication;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class MainActivity extends ActionBarActivity {
Button btnHit;
TextView txtJson;
ProgressDialog pd;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnHit = (Button) findViewById(R.id.btnHit);
txtJson = (TextView) findViewById(R.id.name);
btnHit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new JsonTask().execute("http://192.168.1.94/wamp/up.php");
}
});
}
private class JsonTask extends AsyncTask<String,String,String> {
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(MainActivity.this);
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
}
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line + "n");
Log.d("Response: ","> " + line); //here u ll get whole response...... :-)
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (pd.isShowing()) {
pd.dismiss();
}
txtJson.setText(result);
}
}
}
错误看起来像：
解决方法
我不确定它会解决您的问题,但在很多情况下,API 23或更高版本中存在权限请求问题.
我在项目中也面临同样的问题,我通过使用波纹管程序解决了这个问题. 避免由于异常导致的无DRP密钥：上面的API中的Splash屏幕中的java.lang.ClassNotFoundException请求权限23 例如： if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
permission = Settings.System.canWrite(this);
} else {
permission = ContextCompat.checkSelfPermission(this,Manifest.permission.WRITE_SETTINGS) == PackageManager.PERMISSION_GRANTED;
}
if (!permission) {
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
Intent intent = new Intent(Settings.ACTION_MANAGE_WRITE_SETTINGS);
intent.setData(Uri.parse("package:" + getPackageName()));
startActivityForResult(intent,CODE_WRITE_SETTINGS_PERMISSION);
}
}
检查上述权限后,逐个检查onActivityResult中的剩余权限. 例如, if (ActivityCompat.checkSelfPermission(this,Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
Log.v("Permission",Manifest.permission.WRITE_EXTERNAL_STORAGE+" Permission is revoked");
ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},CODE_WRITE_SETTINGS_PERMISSION);
return;
}
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