FDex2报错: 这台设备不支持此软件

FDex2大多配合VirtualXposed一起使用,大概的原理:

1. 通过反射调用Dex.java的getBytes()方法
   
2. 然后通过io把bytes写出到目录下

FDex2源码

public class MainHook implements IXposedHookLoadPackage {

    XSharedPreferences xsp;
    Class Dex;
    Method Dex_getBytes;
    Method getDex;
    String packagename;


    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam lpparam) throws Throwable {
        xsp = new XSharedPreferences("com.ppma.appinfo", "User");
        xsp.makeWorldReadable();
        xsp.reload();
        initRefect();
        packagename = xsp.getString("packagename", null);
        XposedBridge.log("设定包名："+packagename);
        if ((!lpparam.packageName.equals(packagename))||packagename==null) {
            XposedBridge.log("当前程序包名与设定不一致或者包名为空");
            return;
        }
        XposedBridge.log("目标包名："+lpparam.packageName);
        String str = "java.lang.ClassLoader";
        String str2 = "loadClass";

        XposedHelpers.findAndHookMethod(str, lpparam.classLoader, str2, String.class, Boolean.TYPE, new XC_MethodHook() {
            protected void afterHookedMethod(MethodHookParam param) throws Throwable {
                super.afterHookedMethod(param);
                Class cls = (Class) param.getResult();
                if (cls == null) {
                    //XposedBridge.log("cls == null");
                    return;
                }
                String name = cls.getName();
                XposedBridge.log("当前类名：" + name);
                byte[] bArr = (byte[]) Dex_getBytes.invoke(getDex.invoke(cls, new Object[0]), new Object[0]);
                if (bArr == null) {
                    XposedBridge.log("数据为空：返回");
                    return;
                }
                XposedBridge.log("开始写数据");
                String dex_path = "/data/data/" + packagename + "/" + packagename + "_" + bArr.length + ".dex";
                XposedBridge.log(dex_path);
                File file = new File(dex_path);
                if (file.exists()) return;
                writeByte(bArr, file.getAbsolutePath());
            }
            } );
    }

    public void initRefect() {
        try {
            Dex = Class.forName("com.android.dex.Dex");
            Dex_getBytes = Dex.getDeclaredMethod("getBytes", new Class[0]);
            getDex = Class.forName("java.lang.Class").getDeclaredMethod("getDex", new Class[0]);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }

    }

    public  void writeByte(byte[] bArr, String str) {
        try {
            OutputStream outputStream = new FileOutputStream(str);
            outputStream.write(bArr);
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
            XposedBridge.log("文件写出失败");
        }
    }
}

但是在8.0的真机上会出现这台设备不支持此软件,反编译Fdex源码,发现在反射调用
Class.forName("com.android.dex.Dex")的时候抛出了该异常.但是在7.0及以下的真机上都没有问题

    private void checkSupport() {
        Object obj = 1;
        try {
            Class cls = Class.forName("com.android.dex.Dex");
        } catch (ClassNotFoundException e) {
            ClassNotFoundException classNotFoundException = e;
            obj = null;
        }
      
            AlertDialog show = builder.setMessage("这台设备不支持本软件").setPositiveButton("退出", anonymousClass100000000).show();
        }
    }

猜测是目录的问题,使用 androidxref查看下不同版本的源码

Android O

Android O

Android N

Android N

可以看到, Dex.class文件在Android O以上就被迁移到了dalivk目录下,我们反射的时候只能调用libcore内的代码