StrictMode:非UI的Context来访问UI相关的AP

2023-07-02  本文已影响0人  WilsonMing

在Android11以上版本,项目开启了严格模式StrictMode下,经常会看到以下报错:

StrictMode policy violation: 
android.os.strictmode.IncorrectContextUseViolation: 
WindowManager should be accessed from Activity or other visual Context. Use an Activity or a Context created with Context#createWindowContext(int, Bundle), 
which are adjusted to the configuration and visual bounds of an area on screen.

这个问题的原因是在StrictMode下,使用了非UI的Context来访问UI相关的API,如ViewConfiguration。这样会导致配置不正确,无法获取到正确的显示参数或窗口参数。

例如,如果您在Adapter中使用了inflater来加载布局,那么您应该使用Activity的Context而不是Application的Context来创建inflater。

public class ImageAdapter extends BaseAdapter {
    private LayoutInflater inflater;

    public ImageAdapter(Context context) {
        inflater = LayoutInflater.from(context); //使用Activity的Context
    }

    public View getView (int pos, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = inflater.inflate (R.layout.thumbitem, parent, false); //不会报错
            ...
        }
        ...
        return convertView;
    }
}

解决方案是使用UI的Context来访问UI相关的API,有三种解决方案:

  1. Application的context替换使用Activity的context
  2. 通过Application.createWindowContext(Display, int, Bundle)获取UI的context
  3. createConfigurationContext(Configuration)创建的Context

一、Application的context替换使用Activity的context

二、通过Application.createWindowContext(Display, int, Bundle)获取UI的context

官网提供提供了示例解决方案,见地址:

[Context | Android Developers](https://developer.android.com/reference/android/content/Context#createWindowContext(int,)

...
//重点代码,start
//anyContext为Application
 final DisplayManager dm = anyContext.getSystemService(DisplayManager.class);
 final Display primaryDisplay = dm.getDisplay(DEFAULT_DISPLAY);
 final Context windowContext = anyContext.createDisplayContext(primaryDisplay)
         .createWindowContext(TYPE_APPLICATION_OVERLAY, null);
//重点代码,end
 final View overlayView = Inflater.from(windowContext).inflate(someLayoutXml, null);

 // WindowManager.LayoutParams initialization
 ...
 // The types used in addView and createWindowContext must match.
 mParams.type = TYPE_APPLICATION_OVERLAY;
 ...

 windowContext.getSystemService(WindowManager.class).addView(overlayView, mParams);

基于方案进行封装,可直接使用Java/Kotlin方法使用:

/**
     *  兼容Android11以后。无UI Context(Application context)不能获取UI(Activity context)相关资源问题
     * @param context {@link android.app.Application}
     * @return
     */
    private static Context getWindowContext(Context context) {
        if (context instanceof Activity){
            return context;
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            final DisplayManager dm = context.getSystemService(DisplayManager.class);
            final Display primaryDisplay = dm.getDisplay(Display.DEFAULT_DISPLAY);
            return context.createDisplayContext(primaryDisplay)
                        .createWindowContext(WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY, null);
        }else {
            return context;
        }
    }
//测试方法
        private void Test(Context context){
    Context windowContext = getWindowContext(context);
 //需要使用Activity的Context
    LayoutInflater inflater = LayoutInflater.from(windowContext);
    //....以下其他逻辑

}

/**
 * 兼容Android11以后。无UI Context(Application context)不能获取UI(Activity context)相关资源问题
 * @param context {@link android.app.Application}
 * @return
 */
fun Context.getWindowContext(context: Context): Context? {
    if (context is Activity) {
        return context
    }
    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
        val dm = context.getSystemService(DisplayManager::class.java)
        val primaryDisplay = dm.getDisplay(Display.DEFAULT_DISPLAY)
        context.createDisplayContext(primaryDisplay)
            .createWindowContext(WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY, null)
    } else {
        context
    }
}

使用该方法后Android11的设备在严格模式下就不会报android.os.strictmode.IncorrectContextUseViolation: 错误了

三、createConfigurationContext(Configuration)创建的Context

目前该方法没有找到官网实现链接,后续补充

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