在 API 1.6 上部署验证错误 [英] VerifyError deploying on API 1.6

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问题描述

在 android 1.6 上部署我的应用程序时,我遇到了向后兼容性问题.我在这段代码上收到了一个验证错误:

I've come across a backwards compatibility issue when deploying my application on android 1.6. Im getting a VerifyError on this piece of code:

if(android.os.Build.VERSION.SDK_INT >= 11) {
    getActionBar().setBackgroundDrawable(getResources().getDrawable(R.drawable.actionbar_bg));
}

这并不意外,因为 getActionBar() 在 API 11 之前不存在,但是 1.6 之后(API 5 及更高版本?)根据我在部署时收到的 logcat 消息,所有构建都半优雅地解决了这个问题,例如API 级别 8 设备;

This is not unexpected since getActionBar() doesn't exist pre API 11, however post-1.6 (API 5 and higher?) builds all semi-gracefully go around this according to the logcat message im getting when deploying for example on a API level 8 device;

06-27 16:47:04.333: INFO/dalvikvm(11529): Could not find method com.me.app.MyActivity.getActionBar, referenced from method com.me.app.MyActivity.init
06-27 16:47:04.333: WARN/dalvikvm(11529): VFY: unable to resolve virtual method 1090: Lcom.me.app.MyActivity;.getActionBar ()Landroid/app/ActionBar;
06-27 16:47:04.333: DEBUG/dalvikvm(11529): VFY: replacing opcode 0x6e at 0x004f
06-27 16:47:04.333: DEBUG/dalvikvm(11529): VFY: dead code 0x0052-005f in Lcom.me.app.MyActivity;.init (Z)V

1.6 及更早版本不会这样做,而是抛出一个验证错误:

1.6 and earlier wont do this but instead throw a VerifyError:

06-27 16:23:45.561: ERROR/dalvikvm(427): Could not find method com.me.app.MyActivity.getActionBar, referenced from method com.me.app.MyActivity.init
06-27 16:23:45.561: WARN/dalvikvm(427): VFY: unable to resolve virtual method 1090: Lcom/me/app/MyActivity;.getActionBar ()Landroid/app/ActionBar;
06-27 16:23:45.561: WARN/dalvikvm(427): VFY:  rejecting opcode 0x6e at 0x004f
06-27 16:23:45.561: WARN/dalvikvm(427): VFY:  rejected Lcom/me/app/MyActivity;.init (Z)V
06-27 16:23:45.561: WARN/dalvikvm(427): Verifier rejected class Lcom/me/app/MyActivity;
06-27 16:23:45.561: WARN/dalvikvm(427): Class init failed in newInstance call (Lcom/me/app/MyActivity;)
06-27 16:26:44.841: ERROR/AndroidRuntime(427): Uncaught handler: thread main exiting due to uncaught exception
06-27 16:26:44.941: ERROR/AndroidRuntime(427): java.lang.VerifyError: com.me.app.MyActivity
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at java.lang.Class.newInstanceImpl(Native Method)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at java.lang.Class.newInstance(Class.java:1472)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.app.Instrumentation.newActivity(Instrumentation.java:1097)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2316)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.app.ActivityThread.access$2100(ActivityThread.java:116)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.os.Looper.loop(Looper.java:123)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at android.app.ActivityThread.main(ActivityThread.java:4203)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at java.lang.reflect.Method.invokeNative(Native Method)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at java.lang.reflect.Method.invoke(Method.java:521)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
06-27 16:26:44.941: ERROR/AndroidRuntime(427):     at dalvik.system.NativeStart.main(Native Method)

有没有办法优雅地解决这个问题并向后兼容 1.6?

Is there a way to fix this elegantly and have backwards compatibility to 1.6?

所以我最终用静态方法创建了一个 HoneycombHelper 类:

So I ended up creating a HoneycombHelper class with static methods:

public class HoneycombHelper {
    public static void setActionBarBackgroundDrawable(Activity a, Drawable d) {
        a.getActionBar().setBackgroundDrawable(d);
    }
    ...
}

不确定这是否是最优雅的方式,但它似乎确实有效.

Not sure if this is the most elegant way, but it does seem to work.

推荐答案

当 Dalvik 将您的类/函数从字节码编译成本机机器代码时,它会编译所有语句,甚至那些在 if 条件内的语句.在Android 1.6虚拟机上尝试解析(验证)getActionBar函数,由于没有这个函数,Dalvik抛出VerifyError.

When Dalvik compiles your class/function from bytecode into native machine code, it compiles all statements, even those that are inside if conditions. On Android 1.6 virtual machine tries to resolve (verify) getActionBar function, and since there is no such function, Dalvik throws VerifyError.

你可以做下一个技巧:

class ActionBarHelper{
   void setBackground(){
      getActionBar().setBackgroundDrawable(...);
   }
}

...

if(android.os.Build.VERSION.SDK_INT >= 11) {
   new ActionBarHelper().setBackground();    
}

这种方式 ActioBarHelper 类只会在您在 SDK 11+ 上运行时编译/验证.这将反过来允许在不使用反射的情况下调用 getActionBar 函数(反射是另一个可能的解决方案).

This way ActioBarHelper class will only be compiled/verified when you're running on SDK 11+. This will in turn allow calling getActionBar function without using reflection (reflection is another possible solution to this problem).

这篇关于在 API 1.6 上部署验证错误的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

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