Android DexClassLoader error, 'optimized data directory .. not owned by current user'

问题

I am trying to produce a simple android application that can load a DEX file from the SD card at run-time.

The application has two activites. The first activity is a simple screen that has a button. When the button is pressed, the second activity is launched which causes the loadDex() method to be invoked. The loadDex() method attempts to locate a jar file on the SD card and load it into the current application.

Here is my code for the first activity:

package poc.example.del.customclass;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;


public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


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

    public void launchLoadClass(View view) {
        Intent intent = new Intent(MainActivity.this, LoadClass.class);
        startActivity(intent);
    }
}

Here is the code for my second activity (the one that loads the DEX file):

package poc.example.del.customclass;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import dalvik.system.DexClassLoader;


public class LoadClass extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_load_class);
        loadDex();
    }


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

    public void loadDex() {
        String dexFile = "/sdcard/output.jar";
        File jarFile = new File(dexFile);
        if (jarFile.exists()) {
            // Toast.makeText(getApplicationContext(), "It Worked!", Toast.LENGTH_LONG).show();
            DexClassLoader cl = new DexClassLoader (jarFile.toString (), "/data/test", null, ClassLoader.getSystemClassLoader());

        }
    }
}

The issue arise when the DexClassLoader constructor is called. The following error can be found in the log:

03-25 10:15:48.441    1934-1934/poc.example.del.customclass E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{poc.example.del.customclass/poc.example.del.customclass.LoadClass}: java.lang.IllegalArgumentException: Optimized data directory /data/test is not owned by the current user. Shared storage cannot protect your application from code injection attacks.
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5039)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.IllegalArgumentException: Optimized data directory /data/test is not owned by the current user. Shared storage cannot protect your application from code injection attacks.
            at dalvik.system.DexFile.<init>(DexFile.java:100)
            at dalvik.system.DexFile.loadDex(DexFile.java:149)
            at dalvik.system.DexPathList.loadDexFile(DexPathList.java:261)
            at dalvik.system.DexPathList.makeDexElements(DexPathList.java:229)
            at dalvik.system.DexPathList.<init>(DexPathList.java:96)
            at dalvik.system.BaseDexClassLoader.<init>(BaseDexClassLoader.java:56)
            at dalvik.system.DexClassLoader.<init>(DexClassLoader.java:57)
            at poc.example.del.customclass.LoadClass.loadDex(LoadClass.java:54)
            at poc.example.del.customclass.LoadClass.onCreate(LoadClass.java:23)
            at android.app.Activity.performCreate(Activity.java:5104)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5039)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
            at dalvik.system.NativeStart.main(Native Method)

Here is the line in the log that I believe represents the issue:

java.lang.IllegalArgumentException: Optimized data directory /data/test is not owned by the current user. Shared storage cannot protect your application from code injection attacks.

Any help would be appreciate as I have found very little information on the web regarding the issue. I am developing the application for Android 4.2, Api 17.

Thanks in advance.

回答1:

I found an answer after a few days of following various tutorials. I thought id post the solution here in case anyone else has a similar problem.

For security reasons, Android does not allow the application to load files to any random folder. Instead it should be loaded to the applications environment. Here is the modified code that has allowed me to continue with the project. The code shown is for the 'loadDex()' method:

public void loadDex() {
    // Toast the show the method has been invoked correctly
    // Toast.makeText(getApplicationContext(), "loadDex() Method invoked", Toast.LENGTH_LONG).show();

    // name of the DEX file
    String dexFile = "/output.jar";

    // Get the path to the SD card
    File f = new File(Environment.getExternalStorageDirectory().toString() + dexFile);

    // optimized directory, the applciation and package directory
    final File optimizedDexOutputPath = getDir("outdex", 0);

    // DexClassLoader to get the file and write it to the optimised directory
    DexClassLoader classLoader = new DexClassLoader(f.getAbsolutePath(),
    optimizedDexOutputPath.getAbsolutePath(),null, getClassLoader());

    // The classpath is created for the new class
    String completeClassName = "poc.example.del.mylibrary.name";
    String methodToInvoke = "display";

    try {
        Class<?> myClass = classLoader.loadClass(completeClassName);
        Object obj = (Object)myClass.newInstance();
        Method m = myClass.getMethod(methodToInvoke);
        String s = ""+m.invoke(obj);
        makeToast(s);
    }
    catch (Exception e) {
        e.printStackTrace();
        makeToast("Something went wrong!");
    }


}

The specific line(s) of code that resolved the problem is:

// DexClassLoader to get the file and write it to the optimized directory
DexClassLoader classLoader = new DexClassLoader(f.getAbsolutePath(),
optimizedDexOutputPath.getAbsolutePath(),null, getClassLoader());

As you can see, the optimizedDexOutputPath,getAbsolutePath() method returns the directory that can be used to write files to by the application.

Hope this helps anyone else with a similar issue!

来源：https://stackoverflow.com/questions/29253434/android-dexclassloader-error-optimized-data-directory-not-owned-by-current