使用onBackPressed（）向后兼容

Question

我想使用onBackPressed（）方法，并且仍然希望在2.0之前为Android SDK提供支持。 onBackPressed（）在Android SDK 2.0中引入。但怎么办？

Answer 1

使用onKeyDown;

public boolean onKeyDown(int keyCode, KeyEvent event) { 
    if (keyCode == KeyEvent.KEYCODE_BACK) { 

      // Your Code Here 

     return true; 
    } 
    return super.onKeyDown(keyCode, event); 
} 

Answer 2

你可以捕捉的关键事件，并检查是否有返回键。在您的活动上：

@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
    if(keyCode == KeyEvent.KEYCODE_BACK){ 
     goBack(); 
     return true; 
    } 
    return super.onKeyDown(keyCode, event); 
} 

并写入goBack方法去你需要的地方。

更多在：Android - onBackPressed() not working

Answer 3

答案---> http://apachejava.blogspot.com/2011/01/backward-compatibility-using.html

@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
    if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.ECLAIR 
      && keyCode == KeyEvent.KEYCODE_BACK 
      && event.getRepeatCount() == 0) { 
     // Take care of calling this method on earlier versions of 
     // the platform where it doesn't exist. 
     onBackPressed(); 
    } 

    return super.onKeyDown(keyCode, event); 
} 

@Override 
public void onBackPressed() { 
    // This will be called either automatically for you on 2.0 
    // or later, or by the code above on earlier versions of the 
    // platform. 
    return; 
}