这是什么意思：“由于异常情况，没有DRP密钥：java.lang.ClassNotFoundException：com.android.webview.chromium.Drp”？

Question

我想解析本地URL（http://192.168.1.94/wamp/up.php），以便在我的Android应用程序中使用（JSON解析）。

Android的mainActivity：

    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：

08-14 17:21:23.599 4201-4201/itawfik.com.myapplication E/SysUtils: ApplicationContext 在 ApplicationStatus 中为空 08-14 17:21:23.607 4201-4201/itawfik.com.myapplication E/libEGL: validate_display:255 错误 3008 (EGL_BAD_DISPLAY) 08-14 17:21:23.607 4201-4201/itawfik.com.myapplication E/libEGL: validate_display:255 错误 3008 (EGL_BAD_DISPLAY) [ 08-14 17:21:23.608 4201: 4201 D/ ] HostConnection::get() 新主机连接已建立 0xb07743d0，tid 4201 08-14 17:21:23.799 4201-4201/itawfik.com.myapplication E/DataReductionProxySettingListener: 由于异常没有 DRP 键：java.lang.ClassNotFoundException: com.android.webview.chromium.Drp 08-14 17:21:23.820 4201-4201/itawfik.com.myapplication E/AndroidRuntime: 致命异常: 主要进程 进程: itawfik.com.myapplication, PID: 4201 java.lang.RuntimeException: 无法启动活动 ComponentInfo{itawfik.com.myapplication/itawfik.com.myapplication.MainActivity}: java.lang.NullPointerException: 尝试在空对象引用上调用虚拟方法“void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)” at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: 尝试在空对象引用上调用虚拟方法“void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)” at itawfik.com.myapplication.MainActivity.onCreate(MainActivity.java:36) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

- Towfik Alrazihi

---

你在模拟器上还是设备上遇到了以上错误？ - ViramP

Answer 1

我不确定这能解决你的问题，但在API 23或以上版本中，许可请求问题在很多情况下都存在。

我的项目也遇到了同样的问题，我通过以下过程解决了它。

为了避免在API 23及以上版本中出现“No DRP key due to exception:java.lang.ClassNotFoundException”错误，请在启动屏幕中请求权限。

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);

    }
}

在检查了上述权限之后，在onActivityResult中逐一检查剩余的权限。

e.g,

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;
}

- Sathish kumar