Android 返回键返回到指定的Activity

落日映苍穹つ 2023-10-10 12:58 43阅读 0赞

按后退键的时候，让程序退出。  
  
实现起来的思路：  
  
1.捕获后退键被按了这个事件。

Java代码

1.  @Override
2.  public boolean onKeyDown(int keyCode, KeyEvent event) \{
3.  
4.  if(keyCode == KeyEvent.KEYCODE\_BACK )\{
5.  //DO SOMETHING 
6.  return true;
7.  \}
8.  return false;
9.  \}

@Override
        public boolean onKeyDown(int keyCode, KeyEvent event) {
    
        	if(keyCode == KeyEvent.KEYCODE_BACK ){
        		//DO SOMETHING  
        		return true;
        	}
        	return false;
        }

2-1.通过intent返回都主屏幕中

Java代码

1.  @Override
2.  public boolean onKeyDown(int keyCode, KeyEvent event) \{
3.  if (keyCode == KeyEvent.KEYCODE\_BACK && event.getRepeatCount() == 0) \{ // 按下的如果是BACK，同时没有重复 
4.  Intent home = new Intent(Intent.ACTION\_MAIN);
5.  home.setFlags(Intent.FLAG\_ACTIVITY\_CLEAR\_TOP);
6.  home.addCategory(Intent.CATEGORY\_HOME);
7.  startActivity(home);
8.  \}
9.  return super.onKeyDown(keyCode, event);
10. \}

@Override  
      public boolean onKeyDown(int keyCode, KeyEvent event) {  
       if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { // 按下的如果是BACK，同时没有重复  
        Intent home = new Intent(Intent.ACTION_MAIN);  
        home.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);  
        home.addCategory(Intent.CATEGORY_HOME);  
        startActivity(home);  
       }  
       return super.onKeyDown(keyCode, event);  
      }

2-2.记录所有打开的activity，关闭的时候将所有的activity关闭

使用单例模式创建一个Activity管理对象，该对象中有一个Activity容器专门负责存储新开启的每一个Activity  
  
MyApplication类（储存每一个Activity，并实现关闭所有Activity的操作

Java代码

1.  public class MyApplication extends Application \{
2.  
3.  
4.  private List<Activity> activityList = new LinkedList<Activity>();
5.  private static MyApplication instance;
6.  
7.  private MyApplication()
8.  \{
9.  \}
10. //单例模式中获取唯一的MyApplication实例 
11. public static MyApplication getInstance()
12. \{
13. if(null == instance)
14. \{
15. instance = new MyApplication();
16. \}
17. return instance;
18. 
19. \}
20. //添加Activity到容器中 
21. public void addActivity(Activity activity)
22. \{
23. activityList.add(activity);
24. \}
25. //遍历所有Activity并finish 
26. 
27. public void exit()
28. \{
29. 
30. for(Activity activity:activityList)
31. \{
32. activity.finish();
33. \}
34. 
35. System.exit(0);
36. 
37. \}
38. \}

public class MyApplication extends Application {
    
    
     private List<Activity> activityList = new LinkedList<Activity>(); 
     private static MyApplication instance;
     
                private MyApplication()
                {
                }
                 //单例模式中获取唯一的MyApplication实例 
                 public static MyApplication getInstance()
                 {
                                if(null == instance)
                              {
                                 instance = new MyApplication();
                              }
                     return instance;             
    
                 }
                 //添加Activity到容器中
                 public void addActivity(Activity activity)
                 {
                                activityList.add(activity);
                 }
                 //遍历所有Activity并finish
    
                 public void exit()
                 {
    
                              for(Activity activity:activityList)
                             {
                               activity.finish();
                             }
    
                               System.exit(0);
    
                }
    }

在每一个Activity中的onCreate方法里添加该Activity到MyApplication对象实例容器中

Java代码

1.  MyApplication.getInstance().addActivity(this);

MyApplication.getInstance().addActivity(this);

在需要结束所有Activity的时候调用exit方法

Java代码

1.  MyApplication.getInstance().exit();