Android判断当前App应用处于前台(可见)或后台(不可见)

心已赠人 2023-10-17 22:02 5阅读 0赞

**Android判断当前App应用处于前台(可见)或后台(不可见)**

也即判断当前App应用是否被用户按home键切换至后台（不可见）/前台（可见）。

package zhangphil.test;
    
    import android.app.ActivityManager;;
    import android.content.Context;
    import android.os.Bundle;
    import android.support.annotation.Nullable;
    import android.support.v7.app.AppCompatActivity;
    
    import java.util.List;
    import java.util.concurrent.TimeUnit;
    
    public class JavaActivity extends AppCompatActivity {
        private ActivityManager activityManager;
        private String packageName;
        private boolean stop = false;
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            //setContentView(R.layout.drawable_activity);
            activityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
            packageName = this.getPackageName();
    
            new Thread(new AppStatus()).start();
        }
    
        private class AppStatus implements Runnable {
            @Override
            public void run() {
                stop = false;
    
                while (!stop) {
                    try {
                        if (appOnForeground()) {
                            System.out.println("当前App处于前台");
                        } else {
                            System.out.println("当前App处于后台");
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
    
                    try {
                        TimeUnit.SECONDS.sleep(1);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    
        private boolean appOnForeground() {
            List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
    
            if (appProcesses == null)
                return false;
    
            for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
                if (appProcess.processName.equals(packageName) && appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                    return true;
                }
            }
    
            return false;
        }
    }

以上这个方案是全局性的判断当前App是否处于前台可见，抑或后台不可见。

**需要明白的一点儿是，在大型Android项目中，存在很多Activity时候，仅靠让全部Activity继承自一个类似Base的Activity，然后在Base的Activity生命周期中做相应逻辑处理，进而判断当前App是否处于前台后台的方法是不可取行不通的。**