我正在尝试生成一个简单的Android应用程序，可以在运行时从SD卡加载DEX文件。
该应用程序有两个活动。第一个活动是一个带按钮的简单屏幕。按下该按钮时，将启动第二个活动，这将导致调用loadDex（）方法。 loadDex（）方法尝试在SD卡上找到一个jar文件并将其加载到当前应用程序中。
以下是第一项活动的代码：
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);
}
}
以下是我的第二个活动的代码（加载DEX文件的代码）：
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());
}
}
}
调用DexClassLoader构造函数时会出现问题。可以在日志中找到以下错误：
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)
以下是我认为代表问题的日志行：
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.
任何帮助都会受到赞赏，因为我在网上发现的关于这个问题的信息非常少。我正在开发Android 4.2，Api 17的应用程序。
提前致谢。
答案 0 :(得分：3)
经过几天的各种教程后，我找到了答案。我认为id会在这里发布解决方案，以防其他人遇到类似的问题。
出于安全原因，Android不允许应用程序将文件加载到任何随机文件夹。相反，它应该加载到应用程序环境。以下是修改后的代码，它允许我继续项目。显示的代码适用于＆＃39; loadDex（）＆＃39;方法：
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!");
}
}
解决问题的特定代码行是：
// DexClassLoader to get the file and write it to the optimized directory
DexClassLoader classLoader = new DexClassLoader(f.getAbsolutePath(),
optimizedDexOutputPath.getAbsolutePath(),null, getClassLoader());
如您所见，optimizedDexOutputPath，getAbsolutePath（）方法返回可用于由应用程序写入文件的目录。
希望这可以帮助其他有类似问题的人！