android系统为开发者提供了AlertDialog,用于快捷创建dialog。

用Builder模式创建，可以轻松设置title,message,取消，确定按钮点击事件等。但是本人实际项目用的比较少，因为跟UI设计的样式不太一样，按钮文字颜色不太好修改。经过一番查找，找到了修改按钮文字颜色的方法。

AlertDialog最底层的构造方法：

/**
     * Construct an AlertDialog that uses an explicit theme.  The actual style
     * that an AlertDialog uses is a private implementation, however you can
     * here supply either the name of an attribute in the theme from which
     * to get the dialog's style (such as {@link R.attr#alertDialogTheme}.
     */
    protected AlertDialog(@NonNull Context context, @StyleRes int themeResId) {
        super(context, resolveDialogTheme(context, themeResId));
        mAlert = new AlertController(getContext(), this, getWindow());
    }

AlertController控制的布局。

public AlertController(Context context, AppCompatDialog di, Window window) {
        mContext = context;
        mDialog = di;
        mWindow = window;
        mHandler = new ButtonHandler(di);

        final TypedArray a = context.obtainStyledAttributes(null, R.styleable.AlertDialog,
                R.attr.alertDialogStyle, 0);

        mAlertDialogLayout = a.getResourceId(R.styleable.AlertDialog_android_layout, 0);
        mButtonPanelSideLayout = a.getResourceId(R.styleable.AlertDialog_buttonPanelSideLayout, 0);

        mListLayout = a.getResourceId(R.styleable.AlertDialog_listLayout, 0);
        mMultiChoiceItemLayout = a.getResourceId(R.styleable.AlertDialog_multiChoiceItemLayout, 0);
        mSingleChoiceItemLayout = a
                .getResourceId(R.styleable.AlertDialog_singleChoiceItemLayout, 0);
        mListItemLayout = a.getResourceId(R.styleable.AlertDialog_listItemLayout, 0);
        mShowTitle = a.getBoolean(R.styleable.AlertDialog_showTitle, true);

        a.recycle();

        /* We use a custom title so never request a window title */
        di.supportRequestWindowFeature(Window.FEATURE_NO_TITLE);
    }

可以看到各种自定义属性，是用R.styleable.AlertDialog获取的。打开android系统values搜索AlertDialog:

可以看到有一个style的属性，与AlertDialog的R.styleable.AlertDialog自定义属性是对应的，说明可以控制UI样式。

		<item name="android:layout">@layout/abc_alert_dialog_material</item>
        <item name="listLayout">@layout/abc_select_dialog_material</item>
        <item name="listItemLayout">@layout/select_dialog_item_material</item>
        <item name="multiChoiceItemLayout">@layout/select_dialog_multichoice_material</item>
        <item name="singleChoiceItemLayout">@layout/select_dialog_singlechoice_material</item>

打开@layout/abc_alert_dialog_material：

<?xml version="1.0" encoding="utf-8"?>
<!--
     Copyright (C) 2015 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.
-->

<android.support.v7.widget.AlertDialogLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/parentPanel"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="start|left|top"
    android:orientation="vertical">

    <include layout="@layout/abc_alert_dialog_title_material"/>

    <FrameLayout
        android:id="@+id/contentPanel"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minHeight="48dp">

        <View android:id="@+id/scrollIndicatorUp"
              android:layout_width="match_parent"
              android:layout_height="1dp"
              android:layout_gravity="top"
              android:background="?attr/colorControlHighlight"
              android:visibility="gone"/>

        <android.support.v4.widget.NestedScrollView
            android:id="@+id/scrollView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:clipToPadding="false">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical">

                <android.support.v4.widget.Space
                    android:id="@+id/textSpacerNoTitle"
                    android:layout_width="match_parent"
                    android:layout_height="@dimen/abc_dialog_padding_top_material"
                    android:visibility="gone"/>

                <TextView
                    android:id="@android:id/message"
                    style="@style/TextAppearance.AppCompat.Subhead"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:paddingLeft="?attr/dialogPreferredPadding"
                    android:paddingRight="?attr/dialogPreferredPadding"/>

                <android.support.v4.widget.Space
                    android:id="@+id/textSpacerNoButtons"
                    android:layout_width="match_parent"
                    android:layout_height="@dimen/abc_dialog_padding_top_material"
                    android:visibility="gone"/>
            </LinearLayout>
        </android.support.v4.widget.NestedScrollView>

        <View android:id="@+id/scrollIndicatorDown"
              android:layout_width="match_parent"
              android:layout_height="1dp"
              android:layout_gravity="bottom"
              android:background="?attr/colorControlHighlight"
              android:visibility="gone"/>

    </FrameLayout>

    <FrameLayout
        android:id="@+id/customPanel"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minHeight="48dp">

        <FrameLayout
            android:id="@+id/custom"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </FrameLayout>

    <include layout="@layout/abc_alert_dialog_button_bar_material"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"/>

</android.support.v7.widget.AlertDialogLayout>

最下面include了一个layout点进去：

<?xml version="1.0" encoding="utf-8"?>
<!--
     Copyright (C) 2014 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.
-->

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/buttonPanel"
            style="?attr/buttonBarStyle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fillViewport="true"
            android:scrollIndicators="top|bottom">

    <android.support.v7.widget.ButtonBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="bottom"
        android:layoutDirection="locale"
        android:orientation="horizontal"
        android:paddingBottom="4dp"
        android:paddingLeft="12dp"
        android:paddingRight="12dp"
        android:paddingTop="4dp">

        <Button
            android:id="@android:id/button3"
            style="?attr/buttonBarNeutralButtonStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <android.support.v4.widget.Space
            android:id="@+id/spacer"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:visibility="invisible"/>

        <Button
            android:id="@android:id/button2"
            style="?attr/buttonBarNegativeButtonStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <Button
            android:id="@android:id/button1"
            style="?attr/buttonBarPositiveButtonStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

    </android.support.v7.widget.ButtonBarLayout>

</ScrollView>

button2和button1就是AlertDialog的取消和确定按钮。样式分别用了buttonBarNegativeButtonStyle和buttonBarPositiveButtonStyle两个style。搜索这两个style发现：

<item name="buttonBarStyle">@style/Widget.AppCompat.ButtonBar</item>
	<item name="buttonBarButtonStyle">@style/Widget.AppCompat.Button.ButtonBar.AlertDialog</item>
        <item name="buttonBarPositiveButtonStyle">?attr/buttonBarButtonStyle</item>
        <item name="buttonBarNegativeButtonStyle">?attr/buttonBarButtonStyle</item>
        <item name="buttonBarNeutralButtonStyle">?attr/buttonBarButtonStyle</item>

那么我们只需要在自己的主题重新定buttonBarNegativeButtonStyle和buttonBarPositiveButtonStyle两个style就可以修改按钮样式了。
看下效果：

我修改的样式：

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>

        <item name="buttonBarPositiveButtonStyle">@style/positiveBtnStyle</item>
        <item name="buttonBarNegativeButtonStyle">@style/negativeBtnstyle</item>

    </style>

    <!--确定按钮样式-->
    <style name="positiveBtnStyle" parent="Widget.AppCompat.Button.ButtonBar.AlertDialog">
        <item name="android:textColor">#0000ff</item>
    </style>

    <!--取消按钮样式-->
    <style name="negativeBtnstyle" parent="Widget.AppCompat.Button.ButtonBar.AlertDialog">
        <item name="android:textColor">#999999</item>
    </style>


</resources>


AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("你确定要把这5块钱捐给红十字会吗？")
                .setTitle("标题")
                .setNegativeButton("取消",null)
                .setPositiveButton("确定",null)
                .show();