Question

我关注了动态壁纸的教程，并且已经看到了其他开发人员的代码，并且大多数都比我使用相同的代码稍微修改得更远。我只想显示带有一系列图像的动态壁纸，但它在启动时崩溃。这是我的代码，包含堆栈跟踪和清单。我需要为此设置xml布局吗？

package com.warzone.livewallpaper;

import android.os.Handler;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.view.SurfaceHolder;
import android.service.wallpaper.WallpaperService;

public class LiveActivity extends WallpaperService {

public void onCreate() {
    super.onCreate();
}

public void onDestroy() {
    super.onDestroy();
}

public Engine onCreateEngine() {
    return new WarEngine();
}

class WarEngine extends Engine {

    private final Handler handler = new Handler();
    private final Runnable drawRunner = new Runnable() {
        @Override
        public void run() {
            draw();
        }
    };
    private boolean visible = true;
    public Bitmap image1, image2, image3;

    WarEngine() {
        image1 = BitmapFactory.decodeResource(getResources(),
                R.drawable.wz0351);
        image2 = BitmapFactory.decodeResource(getResources(),
                R.drawable.wz0375);
        image3 = BitmapFactory.decodeResource(getResources(),
                R.drawable.wz0391);
    }


    public void onCreate(SurfaceHolder surfaceHolder) {
        super.onCreate(surfaceHolder);
    }

    @Override
    public void onVisibilityChanged(boolean visible) {
        this.visible = visible;
        if (visible) {
            handler.post(drawRunner);
        } else {
            handler.removeCallbacks(drawRunner);
        }
    }

    @Override
    public void onSurfaceDestroyed(SurfaceHolder holder) {
        super.onSurfaceDestroyed(holder);
        this.visible = false;
        handler.removeCallbacks(drawRunner);
    }

    public void onOffsetsChanged(float xOffset, float yOffset, float xStep,
            float yStep, int xPixels, int yPixels) {
        draw();
    }

    void draw() {
        final SurfaceHolder holder = getSurfaceHolder();

        Canvas c = null;
        try {
            c = holder.lockCanvas();
            if (c != null) {
                c.drawBitmap(image1, 0, 0, null);
                c.drawBitmap(image2, 0, 0, null);
                c.drawBitmap(image3, 0, 0, null);
            }
        } finally {
            if (c != null)
                holder.unlockCanvasAndPost(c);
        }

        handler.removeCallbacks(drawRunner);
        if (visible) 
        {
           handler.postDelayed(drawRunner, 1000); // delay 1 sec
        }

    }
}

}

*07-14 02:10:50.524: E/AndroidRuntime(622): FATAL EXCEPTION: main
*07-14 02:10:50.524: E/AndroidRuntime(622): java.lang.RuntimeException: Unable to                                                                                                     instantiate activity ComponentInfo{com.warzone.livewallpaper/com.warzone.livewallpaper.LiveActivity}:java.lang.ClassCastException: com.warzone.livewallpaper.LiveActivity cannot be cast to android.app.Activity
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.app.ActivityThread.access$600(ActivityThread.java:130)
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.os.Handler.dispatchMessage(Handler.java:99)
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.os.Looper.loop(Looper.java:137)
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.app.ActivityThread.main(ActivityThread.java:4745)
*07-14 02:10:50.524: E/AndroidRuntime(622): at java.lang.reflect.Method.invokeNative(Native Method)
*07-14 02:10:50.524: E/AndroidRuntime(622): at java.lang.reflect.Method.invoke(Method.java:511)
*07-14 02:10:50.524: E/AndroidRuntime(622): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
*07-14 02:10:50.524: E/AndroidRuntime(622): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
*07-14 02:10:50.524: E/AndroidRuntime(622): at dalvik.system.NativeStart.main(NativeMethod)
*07-14 02:10:50.524: E/AndroidRuntime(622): Caused by: java.lang.ClassCastException: com.warzone.livewallpaper.LiveActivity cannot be cast to android.app.Activity
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
*07-14 02:10:50.524: E/AndroidRuntime(622): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
*07-14 02:10:50.524: E/AndroidRuntime(622):     ... 11 more

我的清单文件

    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.warzone.livewallpaper"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="7"
        android:targetSdkVersion="15" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".LiveActivity"
            android:label="@string/title_activity_live" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

这是布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:padding="@dimen/padding_medium"
    android:text="@string/hello_world"
    tools:context=".LiveActivity" />

我注意到ClassCastException，但我不知道如何解决它。有什么想法吗？

Answer 1

这里的问题是您的LiveActivity类无法作为Android应用程序启动，因为它来自WallpaperService而非活动。
您可以在Android开发者网站上获得有关服务和活动的更多信息 http://developer.android.com/

我自己一直在线学习教程，以下教程对我有用：
http://learnandroideasily.blogspot.kr/2013/07/android-livewallpaer-tutorial.html

启动时动态壁纸崩溃

1 个答案: