android中DatePickerDialog只显示年月

今天项目中碰到一个需求，就是在填信用卡的时候，需要填信用卡的有效期（包括年月，没有日），但是正常的日期选择器都是有日的。。。。另外项目中希望弹出个dialog来显示日期选择器，所以这里采用DatePickerDialog。

实现的效果是：无论在什么语言的系统下，都只显示年月，并且月在前，年在后（在英文的系统中，是mmddyy的顺序，但是在中文系统中是yymmdd的顺序）

看下代码：

        final Calendar calendar = Calendar.getInstance();        int yy = calendar.get(Calendar.YEAR);        int mm = calendar.get(Calendar.MONTH);        int dd = calendar.get(Calendar.DAY_OF_MONTH);        DatePickerDialog dlg = new DatePickerDialog(new ContextThemeWrapper(getActivity(),                android.R.style.Theme_Holo_Light_Dialog_NoActionBar), null, yy, mm, dd) {            @Override            protected void onCreate(Bundle savedInstanceState) {                super.onCreate(savedInstanceState);                LinearLayout mSpinners = (LinearLayout) findViewById(getContext().getResources().getIdentifier("android:id/pickers", null, null));                if (mSpinners != null) {                    NumberPicker mMonthSpinner = (NumberPicker) findViewById(getContext().getResources().getIdentifier("android:id/month", null, null));                    NumberPicker mYearSpinner = (NumberPicker) findViewById(getContext().getResources().getIdentifier("android:id/year", null, null));                    mSpinners.removeAllViews();                    if (mMonthSpinner != null) {                        mSpinners.addView(mMonthSpinner);                    }                    if (mYearSpinner != null) {                        mSpinners.addView(mYearSpinner);                    }                }                View dayPickerView = findViewById(getContext().getResources().getIdentifier("android:id/day", null, null));                if(dayPickerView != null){                    dayPickerView.setVisibility(View.GONE);                }            }            @Override            public void onDateChanged(DatePicker view, int year, int month, int day) {                super.onDateChanged(view, year, month, day);                setTitle("请选择信用卡有效期");            }        };        dlg.setTitle("请选择信用卡有效期");

运行上述代码的效果是这样的：

怎么样，是不是好看了很多？效果的变化来源于在声明DatePickerDialog的时候，传了一个主题theme给它：

new ContextThemeWrapper(getActivity(),android.R.style.Theme_Holo_Light_Dialog_NoActionBar)

如果没有传入style的话，长这个样子：

现在再来看看，是如何做到隐藏日的选择器，只显示年和月的，并且让月显示在年前面的。

在DatePickerDialog中，也是有一个DatePicker的，现在来看下DatePicker的代码，我找到了他引用的layout资源：

打开该资源文件：

<?xml version="1.0" encoding="utf-8"?><!--**** Copyright 2007, The Android Open Source Project**** Licensed under the Apache License, Version 2.0 (the "License");** you may not use this file except in compliance with the License.** You may obtain a copy of the License at****     http://www.apache.org/licenses/LICENSE-2.0**** Unless required by applicable law or agreed to in writing, software** distributed under the License is distributed on an "AS IS" BASIS,** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.** See the License for the specific language governing permissions and** limitations under the License.*/--><!-- Layout of date picker--><!-- Warning: everything within the "pickers" layout is removed and re-ordered     depending on the date format selected by the user.--><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:layout_gravity="center_horizontal"    android:orientation="horizontal"    android:gravity="center">    <LinearLayout android:id="@+id/pickers"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:orientation="horizontal"        android:gravity="center">        <!-- Month -->        <NumberPicker            android:id="@+id/month"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginStart="1dip"            android:layout_marginEnd="1dip"            android:focusable="true"            android:focusableInTouchMode="true"            />        <!-- Day -->        <NumberPicker            android:id="@+id/day"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginStart="1dip"            android:layout_marginEnd="1dip"            android:focusable="true"            android:focusableInTouchMode="true"            />        <!-- Year -->        <NumberPicker            android:id="@+id/year"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginStart="1dip"            android:layout_marginEnd="1dip"            android:focusable="true"            android:focusableInTouchMode="true"            />    </LinearLayout>    <!-- calendar view -->    <CalendarView        android:id="@+id/calendar_view"        android:layout_width="245dip"        android:layout_height="280dip"        android:layout_marginStart="44dip"        android:layout_weight="1"        android:focusable="true"        android:focusableInTouchMode="true"        android:visibility="gone"        /></LinearLayout>

preview的效果是：

看到了吧，其实内部是三个NumberPicker，外部的布局是LinearLayout，横向排列。那我在想隐藏日的选择器很简单，直接获取该view，然后设置为gone就好了。（看上面的代码你就懂了，这里不说明了）

但是再一看代码，发现该layout原来的顺序就是month-day-year，那为什么中文系统中会修改顺序呢？继续找代码！

往下翻找，找到了一个reorderSpinner的方法，原来就是这段代码，根据当前系统的语言，来重排序了！

/**         * Reorders the spinners according to the date format that is         * explicitly set by the user and if no such is set fall back         * to the current locale's default format.         */        private void reorderSpinners() {            mSpinners.removeAllViews();            // We use numeric spinners for year and day, but textual months. Ask icu4c what            // order the user's locale uses for that combination. http://b/7207103.            String pattern = DateFormat.getBestDateTimePattern(Locale.getDefault(), "yyyyMMMdd");            char[] order = ICU.getDateFormatOrder(pattern);            final int spinnerCount = order.length;            for (int i = 0; i < spinnerCount; i++) {                switch (order[i]) {                    case 'd':                        mSpinners.addView(mDaySpinner);                        setImeOptions(mDaySpinner, spinnerCount, i);                        break;                    case 'M':                        mSpinners.addView(mMonthSpinner);                        setImeOptions(mMonthSpinner, spinnerCount, i);                        break;                    case 'y':                        mSpinners.addView(mYearSpinner);                        setImeOptions(mYearSpinner, spinnerCount, i);                        break;                    default:                        throw new IllegalArgumentException(Arrays.toString(order));                }            }        }

看完这段代码，我就大概知道怎么重排年和月了，看最上面我提供的实现代码，你就应该知道了，不再赘述了。