1)比如普通的startActivity
InstrumentationProxy.java

      
public class InstrumentationProxy extends Instrumentation {
    Instrumentation instrumentation;
    Method execStartActivityMethod = null;
    ActivityResult result = null;

    //持有真正启动Activity的Instrumentation引用
    public InstrumentationProxy(Instrumentation instrumentation) {
        this.instrumentation = instrumentation;
    }
    public ActivityResult execStartActivity(
            Context who, IBinder contextThread, IBinder token, Activity target,
            Intent intent, int requestCode, Bundle options) {
        try {
            // 查找当前方法
            execStartActivityMethod = Instrumentation.class.getDeclaredMethod("execStartActivity",
                    Context.class, IBinder.class, IBinder.class, Activity.class, Intent.class, int.class, Bundle.class);
            execStartActivityMethod.setAccessible(true);
            //可在此修改判断是否登录 然后intent.setClassName(who,"study.hank.com.androidhookdemo2.LoginActivity");
//            intent.setClassName(who, "study.hank.com.androidhookdemo2.LoginActivity");
            // 执行activity启动
            result = (ActivityResult) execStartActivityMethod.invoke(instrumentation, who,
                    contextThread, token, target, intent, requestCode, options);
            return result;
        } catch (Throwable t) {
            t.printStackTrace();
        }
        return null;
    }


    public static void replace(Activity activity) {
        //通过反射获取Activity的class对象
        Class<? extends Activity> aClass = Activity.class;
        try {
            //获取Activity的mInstrumentation属性
            Field field = aClass.getDeclaredField("mInstrumentation");
            //取消权限检查
            field.setAccessible(true);
            //获取传入的activity的mInstrumentation字段
            Instrumentation mInstrumentation = (Instrumentation) field.get(activity);
            //构造InstrumentationProxy，并将获取到的Activity字段传入
            InstrumentationProxy instrumentationProxy = new InstrumentationProxy(mInstrumentation);
            //用构造InstrumentationProxy替换掉当前Activity的mInstrumentation。
            field.set(activity, instrumentationProxy);

        } catch (Exception e) {
        }

    }
}

测试类

    static class MainActivity  {
         InstrumentationProxy.replace(this);
        startActivity(new Intent(MainActivity.this, TestActivity.class));
    }