WPF语言切换，国际化

winform语言切换在每个窗口下面有一个.resx结尾的资源文件，在上面添加新字符串就好了；

WPF语言切换跟winform不一样的地方在于需要自己添加资源文件，并且这个资源文件可以写一个，也可以写多个。

// 英文资源文件：enus.xaml
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:sys="clr-namespace:System;assembly=mscorlib">
    <sys:String x:Key ="label_text_1">Click the button to change language.</sys:String>
    <sys:String x:Key="button_text_1">Change</sys:String>
    
    <sys:String x:Key ="label_text_2">Click the button to change language.2222</sys:String>
    <sys:String x:Key="button_text_2">Change2222</sys:String>
</ResourceDictionary>

// 中文资源文件：zhcn.xaml
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:sys="clr-namespace:System;assembly=mscorlib">
    <sys:String x:Key="label_text_1">点击按钮更换语言</sys:String>
    <sys:String x:Key="button_text_1">更换</sys:String>

    <sys:String x:Key ="label_text_2">点击按钮更换语言.2222</sys:String>
    <sys:String x:Key="button_text_2">更换2222</sys:String>
</ResourceDictionary>

// 项目默认资源添加：App.xaml
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <!--绝对地址，不容易报错-->
                <!--<ResourceDictionary Source="pack://application:,,,/{工程名字};component{资源文件地址}"/>-->
                <ResourceDictionary Source="pack://application:,,,/ChangeLanguages;component/Languages/zhcn.xaml"/>
                <!--普通引用，跨工程容易找不到-->
                <!--<ResourceDictionary Source="Languages/enus.xaml"/>-->
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>

// 前台绑定使用
        <Label Height="28" Content="{DynamicResource label_text_1}" VerticalAlignment="Top" x:Name="lable"/>
        <Button Name="btnChange" Content="{DynamicResource button_text_1}" Height="23" Width="75" Click="btnChange_Click" />
        <Button Name="btn_1" Click="btn_1_Click" Height="23" Width="75" Content="{Binding ElementName=root,Path=ContentTypeProperty}"/>

// 后台绑定方法1,添加到当前页的资源字典，适合资源文件分开的情况同winform

string windowCurrentLanguageFile = "Languages\\enus.xaml";
        private void setLanguage()
        {
            windowCurrentLanguageFile = windowCurrentLanguageFile == "Languages\\enus.xaml"
                ? "Languages\\zhcn.xaml"
                : "Languages\\enus.xaml";
            var rd = new ResourceDictionary() { Source = new Uri(windowCurrentLanguageFile, UriKind.RelativeOrAbsolute) };

            if (this.Resources.MergedDictionaries.Count == 0)
                this.Resources.MergedDictionaries.Add(rd);
            else
                this.Resources.MergedDictionaries[0] = rd;
        }
//  后台绑定方法2，添加到App.xaml中指定的资源，demo中就是0，App.xaml中字典中默认的条数是多少，从0开始
string windowCurrentLanguageFile = "Languages\\enus.xaml";
        private void setLanguage()
        {
            windowCurrentLanguageFile = windowCurrentLanguageFile == "Languages\\enus.xaml"
                  ? "Languages\\zhcn.xaml"
                  : "Languages\\enus.xaml";
            Application.Current.Resources.MergedDictionaries[0] = new ResourceDictionary() { Source = new Uri(windowCurrentLanguageFile, UriKind.RelativeOrAbsolute) };

              //windowCurrentLanguageFile = windowCurrentLanguageFile == "enus.xaml"
              // ? "zhcn.xaml"
              // : "enus.xaml";
              //Application.Current.Resources.MergedDictionaries[0] = new ResourceDictionary() { Source = new Uri(string.Format("pack://application:,,,/ChangeLanguages;component/Languages/{0}", windowCurrentLanguageFile), UriKind.Absolute) };

        }
// 后台绑定方法3，添加到App.xaml中指定的资源，通过查找来进行替换，防止报索引的错，该查找方法只支持绝对地址，2,3方法方便全局设置，即设置一次全局改变
string windowCurrentLanguageFile = "enus.xaml";
        private void setLanguage()
        {
            windowCurrentLanguageFile = windowCurrentLanguageFile == "enus.xaml"
                  ? "zhcn.xaml"
                  : "enus.xaml";
            Application.Current.Resources.MergedDictionaries.FirstOrDefault(s => s.Source.AbsoluteUri.Contains("Languages")).Source = new Uri(string.Format("pack://application:,,,/ChangeLanguages;component/Languages/{0}", windowCurrentLanguageFile), UriKind.Absolute);
        }

示例代码