1. frameworks/base/packages/SettingsProvider/res/values/defaults.xml

        增加<stringname="time_12_24">12</string>   //24小时制的话改为24即可

 

2. frameworks/base/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java文件下，

        在loadSystemSettings()方法中增加

        loadStringSetting(stmt,Settings.System.TIME_12_24,R.string.time_12_24);

 

3. 【设置-》日期和时间-》使用24小时格式，修改默认为打开】

    frameworks\base\core\java\android\text\format\DateFormat.java

    改为

    public static booleanis24HourFormat(Context context) {

        String value = Settings.System.getString(context.getContentResolver(),

                Settings.System.TIME_12_24);

 

         if (value ==null) {

           

                Settings.System.putString(context.getContentResolver(),

                                  Settings.System.TIME_12_24,"24");

          value = "24";

        }

 

        returnvalue.equals("24");

    }