Android onKeyDown 方法的代码在什么地方？

Android onKeyDown 方法的代码在什么地方？怎么找都找不到，具体在哪个目录里面？

http://www.cnblogs.com/mybkn/archive/2012/07/14/2591716.html

你要找源码 还是使用？
如果要是使用的话，就参考如下代码:

 @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        Log.i("info","onKeyDown");
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            //          drawerLayout.dispatchKeyEvent(event);
            Log.i("info","KEYCODE_BACK");
            // 创建退出对话框
            AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this)
            .setTitle("退出").setIcon(R.drawable.icon_app)
            .setMessage("确认退出本程序？");
            builder.setPositiveButton("确定",
                    new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // finish();
                    ExitApplication.getInstance().exit();
                }
            });
            builder.setNegativeButton("取消",
                    new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                }
            });
            builder.create().show();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

 public boolean onKeyDown(int keyCode, KeyEvent event)  {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            if (getApplicationInfo().targetSdkVersion
                    >= Build.VERSION_CODES.ECLAIR) {
                event.startTracking();
            } else {
                onBackPressed();
            }
            return true;
        }

        if (mDefaultKeyMode == DEFAULT_KEYS_DISABLE) {
            return false;
        } else if (mDefaultKeyMode == DEFAULT_KEYS_SHORTCUT) {
            if (getWindow().performPanelShortcut(Window.FEATURE_OPTIONS_PANEL, 
                    keyCode, event, Menu.FLAG_ALWAYS_PERFORM_CLOSE)) {
                return true;
            }
            return false;
        } else {
            // Common code for DEFAULT_KEYS_DIALER & DEFAULT_KEYS_SEARCH_*
            boolean clearSpannable = false;
            boolean handled;
            if ((event.getRepeatCount() != 0) || event.isSystem()) {
                clearSpannable = true;
                handled = false;
            } else {
                handled = TextKeyListener.getInstance().onKeyDown(
                        null, mDefaultKeySsb, keyCode, event);
                if (handled && mDefaultKeySsb.length() > 0) {
                    // something useable has been typed - dispatch it now.

                    final String str = mDefaultKeySsb.toString();
                    clearSpannable = true;

                    switch (mDefaultKeyMode) {
                    case DEFAULT_KEYS_DIALER:
                        Intent intent = new Intent(Intent.ACTION_DIAL,  Uri.parse("tel:" + str));
                        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                        startActivity(intent);    
                        break;
                    case DEFAULT_KEYS_SEARCH_LOCAL:
                        startSearch(str, false, null, false);
                        break;
                    case DEFAULT_KEYS_SEARCH_GLOBAL:
                        startSearch(str, false, null, true);
                        break;
                    }
                }
            }
            if (clearSpannable) {
                mDefaultKeySsb.clear();
                mDefaultKeySsb.clearSpans();
                Selection.setSelection(mDefaultKeySsb,0);
            }
            return handled;
        }
    }

楼上2015.04.20 17:32这个回答就是源码！