简叙 Activity 生命周期及android 返回按钮扑捉

来源：互联网发布：央视网络直播室编辑：程序博客网时间：2024/04/30 01:53

  @Override    protected void onPostCreate(Bundle savedInstanceState) {        super.onPostCreate(savedInstanceState);    //To change body of overridden methods use File | Settings | File Templates.    }    @Override    protected void onStart() {        System.out.println("---------------onStart---------------");        super.onStart();    //To change body of overridden methods use File | Settings | File Templates.    }    @Override    protected void onRestart() {        System.out.println("---------------onRestart---------------");        super.onRestart();    //To change body of overridden methods use File | Settings | File Templates.    }    @Override    protected void onResume() {        System.out.println("---------------onResume---------------");        super.onResume();    //To change body of overridden methods use File | Settings | File Templates.    }    @Override    protected void onPostResume() {        System.out.println("---------------onPostResume---------------");        super.onPostResume();    //To change body of overridden methods use File | Settings | File Templates.    }    @Override    protected void onPause() {        System.out.println("---------------onPause---------------");        super.onPause();    //To change body of overridden methods use File | Settings | File Templates.    }    @Override    protected void onStop() {        System.out.println("---------------onStop---------------");        super.onStop();    //To change body of overridden methods use File | Settings | File Templates.    }    @Override      protected void onDestroy() {          System.out.println("---------------onDestroy---------------");          super.onDestroy();    //To change body of overridden methods use File | Settings | File Templates.      }    public boolean onKeyDown(int keyCode, KeyEvent event) {        if(keyCode== KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0){           Toast.makeText(_context,"点击了返回【onKeyDown】",Toast.LENGTH_LONG).show();            System.out.println("---------------onKeyDown---------------");            this.onBackPressed();             return true; //确认返回了        }        return false;  //不允许返回    }    @Override    public void onBackPressed() {        Toast.makeText(_context,"点击了返回【onBackPressed】",Toast.LENGTH_LONG).show();        System.out.println("---------------onBackPressed---------------");        super.onBackPressed();       }

简单的说，

当activity 启动的时候会启动以下方法，按先后顺序

onCreate->onStart->onResume->onPostResume

当按返回的时候，也就是结束这个Activity的时候，先后顺序是：

onPase->onStop->onDestroy

手机键盘“返回”键判断：

如果在你方法中没有onKeyDown（）这个方法，而只有如下构造方法

 public void onBackPressed() {        Toast.makeText(_context,"点击了返回【onBackPressed】",Toast.LENGTH_LONG).show();        System.out.println("---------------onBackPressed---------------");        super.onBackPressed();    //To change body of overridden methods use File | Settings | File Templates.    }

那么，你键盘点击返回的时候，会调用onBackPressed（）方法！

如果onKeyDown以及onBackPressed两个方法同时存在会优先运行onKeyDown（）方法

 public boolean onKeyDown(int keyCode, KeyEvent event) {        // keyCode 判断用户是否触发键盘“返回按钮”        if(keyCode== KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0){           Toast.makeText(_context,"点击了返回【onKeyDown】",Toast.LENGTH_LONG).show();            System.out.println("---------------onKeyDown---------------");            this.onBackPressed();             return true; //确认返回了        }        return false;  //不允许返回    }    @Override    public void onBackPressed() {        Toast.makeText(_context,"点击了返回【onBackPressed】",Toast.LENGTH_LONG).show();        System.out.println("---------------onBackPressed---------------");        super.onBackPressed();    //To change body of overridden methods use File | Settings | File Templates.    }