前几天接到一个需求，在自主开发的SDK中接入其他的项目，而其他的项目是打成了aar包，需要把Context传入到aar中，让该aar包中调用该SDK的Context，原本双方写一个接口传递就可以了，但是该项目不愿意动任何代码，这个时候就另开一种途径，通过反射获取aar包中的Context值，并赋值当前的Context.
 
 
不说了上代码：
 
public class ContextUtil {

/**
     * 通过反射把context赋值给支付的MyApplication
     * 首先进行attach，然后再调用onCreate方法初始化
     * @return Context
     */

public static void setContext(Context context) {
        Context appContext = new ContextThemeWrapper(context,android.R.style.Theme);
        //aar包中的application
		MyApplication myApplication = new MyApplication();
        try {
            Method sAttachBaseContextMethod = Application.class.getDeclaredMethod("attach",Context.class);
			sAttachBaseContextMethod.setAccessible(true);
			sAttachBaseContextMethod.invoke(myApplication,appContext); //先attach
			myApplication.onCreate();//在调用onCreate
		}catch (Throwable e){
        	Log.e("errorMessage",e.toString());
	}
   }
 }
 
通过上面的注释就可以看懂了，最后就是在初始化的地方，把Context传进去就可以了！！！

无需上下文context获取当前Application
 
Android使用反射获取当前Application
 没有Activity，没有Application，快速获取当前应用的Application。当个工具类用，再也不烦恼，目前在Android Q上并且是targetSdk为29也能获取到，已验证可用。
 
 /**
     * 获取当前应用的Application
     * 先使用ActivityThread里获取Application的方法，如果没有获取到，
     * 再使用AppGlobals里面的获取Application的方法
     * @return
     */
    public static Application getCurApplication(){
        Application application = null;
        try{
            Class atClass = Class.forName("android.app.ActivityThread");
            Method currentApplicationMethod = atClass.getDeclaredMethod("currentApplication");
            currentApplicationMethod.setAccessible(true);
            application = (Application) currentApplicationMethod.invoke(null);
            Log.d("fw_create","curApp class1:"+application);
        }catch (Exception e){
            Log.d("fw_create","e:"+e.toString());
        }

        if(application != null)
            return application;

        try{
            Class atClass = Class.forName("android.app.AppGlobals");
            Method currentApplicationMethod = atClass.getDeclaredMethod("getInitialApplication");
            currentApplicationMethod.setAccessible(true);
            application = (Application) currentApplicationMethod.invoke(null);
            Log.d("fw_create","curApp class2:"+application);
        }catch (Exception e){
            Log.d("fw_create","e:"+e.toString());
        }

        return application;
    }
 
无需上下文context获取当前Resources
 
没有Activity，没有Application，快速获取当前应用的Resources 。当个工具类用，再也不烦恼，目前在Android Q上并且是targetSdk为29也能获取到，已验证可用。
 
 public static Resources getResources(){
        Resources resources = Resources.getSystem();
        return resources;
    }

package sc.tools;

import java.lang.reflect.Field;
import java.lang.reflect.Method;

import android.app.Application;
import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
//import android.widget.Toast;


/** 通过反射获取当前应用的Application、Context */
public class AppliactionTool
{
	private static Application application;
	private static Context context;
	
	/** 反射获取Application */
	public static Application getApplication()
	{
		if (application != null) { return application; }
		try
		{
			Class localClass1 = Class.forName("com.android.internal.os.RuntimeInit");
			Field localField1 = localClass1.getDeclaredField("mApplicationObject");
			localField1.setAccessible(true);
			Object localObject1 = localField1.get(localClass1);
			
			Class localClass2 = Class.forName("android.app.ActivityThread$ApplicationThread");
			Field localField2 = localClass2.getDeclaredField("this$0");
			localField2.setAccessible(true);
			Object localObject2 = localField2.get(localObject1);
			
			Class localClass3 = Class.forName("android.app.ActivityThread");
			Method localMethod = localClass3.getMethod("getApplication", new Class[0]);
			localMethod.setAccessible(true);
			Application localApplication = (Application) localMethod.invoke(localObject2, new Object[0]);
			if (localApplication != null) application = localApplication;
		}
		catch (Exception localException)
		{
			localException.printStackTrace();
		}
		
		//		Toast.makeText(application, "AppliactionTool -> getApplication()", Toast.LENGTH_SHORT).show();
		return application;
	}
	
	/** 获取Context */
	public static Context getContext()
	{
		if (context != null) return context;
		return getApplication();
	}
	
	/** 获取targetSdkVersion */
	public static int getTargetSdkVersion()
	{
		PackageManager localPackageManager = getContext().getPackageManager();
		ApplicationInfo localApplicationInfo;
		try
		{
			localApplicationInfo = localPackageManager.getApplicationInfo(getContext().getPackageName(), 0);
		}
		catch (PackageManager.NameNotFoundException localNameNotFoundException)
		{
			localNameNotFoundException.printStackTrace();
			return 0;
		}
		if (localApplicationInfo != null) { return localApplicationInfo.targetSdkVersion; }
		return 0;
	}
}
 
 

             Toast.makeText(getApplicationContext(), "发送广播成功", Toast.LENGTH_SHORT).show();  
 

 
 
 

 
 
 

 
 
 

 用 getApplicationContext()