c#:界面多语言动态切换简单实现

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终于有空整理下多语言实现思路。查阅已有方案，有用不同resx文件的，有每个控件动态设置的，有用反射去整的，颇为繁琐。

结合项目中实现方法，并做简化，实现通用的多语言切换方案，以做备忘。

它支持语言自定义添加与扩充，灵活易用，更易于维护。它以xml格式存储语言信息，支持自定义语言、ToolTip等字串，支持即时切换。

一、语言格式：

每种语言对应一个xml格式文件，比如中文为Chinese.lng，英文为English.lng，置于程序运行目录之Languages文件夹下，其存放位置可自定义。

本欲以反射获取已有程序集之字串，却未有成功，因为字串值初始化在InitializeComponent()中动态设置，反射不出来这些属性值，所以手动提取，以NotePad++做批量处理，亦是方便。

文件分为自定义字串区(strings节点)、窗体语言文件区(forms节点)，结构如下图示：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<language Id="CHS" Name="Chinese" LocaleName="中文(简体)" LangID="0x0409" CodePage="1252">
  <strings>
    <INF_AppName>记事本</INF_AppName>
    <INF_NoTitle>无标题</INF_NoTitle>
    <INF_Information>提示</INF_Information>
    <INF_CannotFound>找不到 "{0}"</INF_CannotFound>
    <INF_ContentChanged>文件内容已被改变，要保存吗？</INF_ContentChanged>
  </strings>
  <forms>
    <MainForm Text="记事本">
      <miFile Text="文件(&amp;F)" />
      <miNew Text="新建(&amp;N)" />
      <miOpen Text="打开(&amp;0)..." />
      <miSave Text="保存(&amp;S)" />
      <miSaveAs Text="另存为(&amp;A)..." />
      <miPageSet Text="页面设置(&amp;U)..." />
      <miPrint Text="打印(&amp;P)..." />
      <miExit Text="退出(&amp;X)" />
      ...
      <miHelp Text="帮助(&amp;H)" />
      <miHelpTopic Text="帮助主题(&amp;H)" />
      <miLanguage Text="语言" />
      <miAbout Text="关于记事本(&amp;A)" />
    </MainForm>
    <GotoLineForm Text="跳转到指定行">
      <lblLine Text="行数(&amp;L)：" />
      <txtLine ToolTip="请输入您想要跳转到的行号：" />
      <btnOk Text="确定" />
      <btnCancel Text="取消" />
    </GotoLineForm>
    <SearchForm Text="查找">
      <btnCancel Text="取消" />
      <btnSearch Text="查找下一个(&amp;F)" />
      <lblContent Text="查找内容(&amp;N)：" />
      <cbCaseSensitive Text="区分大小写" />
      <gbDirection Text="方向" />
      <rbDown Text="向下" />
      <rbUp Text="向上" />
    </SearchForm>
  </forms>
</language>

二、解析与加载类

仍然对每个窗体做遍历，加载对应字串，提取语言文件语种信息。

此文件是个完整的语言管理器类，且可根据需要自行扩充，列码如下：

//多语言管理类
using System;
using System.Collections.Generic;
using System.IO;
using System.Windows.Forms;
using System.Xml;

namespace Notepad
{
    //单个语言项
    public class LanguageItem
    {
        private const string RootNodeName = "language";
        private const string StringsNodeName = "strings";
        private const string FormsNodeName = "forms";

        private XmlNode stringsNode;
        private XmlNode formsNode;

        private string id;
        private string name;
        private string localeName;

        public LanguageItem(string fileName)
        {
            var xmlDoc = new XmlDocument();
            xmlDoc.Load(fileName);
            var root = xmlDoc.DocumentElement;
            if (root != null)
            {
                this.id = GetAttributeValue(root, "Id");
                this.name = GetAttributeValue(root, "Name");
                this.localeName = GetAttributeValue(root, "LocaleName");

                this.stringsNode = root.SelectSingleNode(StringsNodeName);
                this.formsNode = root.SelectSingleNode(FormsNodeName);
            }
        }

        public string Id
        {
            get { return this.id; }
        }

        public string Name
        {
            get { return this.name; }
        }

        public string LocaleName
        {
            get { return this.localeName; }
        }

        private void ApplyLanguage(Control control, XmlNode formNode, ToolTip toolTip = null)
        {
            if (string.IsNullOrEmpty(control.Name))
                return;

            var ctrlNode = formNode.SelectSingleNode(control.Name);
            if (ctrlNode != null)
            {
                control.Text = GetAttributeValue(ctrlNode, "Text");
                string tips = GetAttributeValue(ctrlNode, "ToolTip");
                if (!string.IsNullOrEmpty(tips) && toolTip != null)
                    toolTip.SetToolTip(control, tips);
            }
            //弹出菜单
            if (control.ContextMenuStrip != null)
                ApplyMenuLanguage(control.ContextMenuStrip, formNode);
            foreach (Control ctrl in control.Controls)
                ApplyLanguage(ctrl, formNode, toolTip);
            //菜单项，特别遍历
            if (control is ToolStrip)
            {
                foreach (ToolStripItem toolItem in (control as ToolStrip).Items)
                    ApplyMenuLanguage(toolItem, formNode);
            }
        }

        private void ApplyMenuLanguage(ToolStrip menu, XmlNode formNode)
        {
            foreach (ToolStripItem toolItem in menu.Items)
                ApplyMenuLanguage(toolItem, formNode);
        }

        private void ApplyMenuLanguage(ToolStripItem menuItem, XmlNode formNode)
        {
            if (string.IsNullOrEmpty(menuItem.Name))
                return;

            var itemNode = formNode.SelectSingleNode(menuItem.Name);
            if (itemNode != null)
            {
                menuItem.Text = GetAttributeValue(itemNode, "Text");
                menuItem.ToolTipText = GetAttributeValue(itemNode, "ToolTip");
            }
            if (menuItem is ToolStripDropDownItem)
            {
                foreach (ToolStripItem item in (menuItem as ToolStripDropDownItem).DropDownItems)
                    ApplyMenuLanguage(item, formNode);
            }
        }

        public bool LoadLanguageRes(ContainerControl cc)
        {
            if (cc == null || formsNode == null || !formsNode.HasChildNodes || formsNode.SelectSingleNode(cc.Name) == null)
                return false;

            //创建ToolTip控件， 以支持ToolTip显示
            var toolTip = new ToolTip();
            var formNode = formsNode.SelectSingleNode(cc.Name);
            cc.Text = GetAttributeValue(formNode, "Text");
            foreach (Control ctrl in cc.Controls)
                ApplyLanguage(ctrl, formNode, toolTip);
            return true;
        }

        public bool LoadLanguageRes(ContainerControl cc, ToolStrip menu)
        {
            if (cc == null || formsNode == null || !formsNode.HasChildNodes || formsNode.SelectSingleNode(cc.Name) == null)
                return false;

            var formNode = formsNode.SelectSingleNode(cc.Name);
            ApplyLanguage(menu, formNode);
            return true;
        }

        private string GetAttributeValue(XmlNode xmlNode, string attrName)
        {
            if (xmlNode.Attributes != null && xmlNode.Attributes[attrName] != null)
                return xmlNode.Attributes[attrName].Value;
            return string.Empty;
        }

        public string GetText(string textID, string defaultText = "")
        {
            if (stringsNode == null || !stringsNode.HasChildNodes)
                return defaultText;

            foreach (XmlNode node in stringsNode.ChildNodes)
                if (node.Name.Equals(textID))
                    return node.InnerText;

            return defaultText;
        }
    }

    public class LanguageList : List<LanguageItem>
    {
    }

    /// <summary>
    /// 多语言管理器
    /// </summary>
    public static class ML
    {
        private static LanguageItem activeLanguage;
        private static LanguageList languages;

        //最初调用
        public static int LoadLanguages(string searchPattern, string defaultLanguageId = "")
        {
            string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Languages");
            return LoadLanguages(path, searchPattern, defaultLanguageId);
        }

        public static int LoadLanguages(string path, string searchPattern, string defaultLanguageId = "")
        {
            languages = new LanguageList();
            if (!Directory.Exists(path))
                return 0;

            var files = Directory.GetFiles(path, searchPattern);
            foreach (string file in files)
                languages.Add(new LanguageItem(file));
            if (!string.IsNullOrEmpty(defaultLanguageId))
                LoadLanguageById(defaultLanguageId);

            return languages.Count;
        }

        public static string ActiveLanguageId
        {
            get { return (activeLanguage != null) ? activeLanguage.Id : string.Empty; }
        }

        public static string[] LanguageLocalNames
        {
            get
            {
                if (languages == null || languages.Count == 0)
                    return new string[0];
                var names = new string[languages.Count];
                for (int i = 0; i <= languages.Count - 1; i++)
                    names[i] = languages[i].LocaleName;
                return names;
            }
        }

        public static LanguageItem ActiveLanguage
        {
            get { return activeLanguage; }
        }

        public static LanguageList Languages
        {
            get { return languages; }
        }

        public static bool LoadLanguageRes(ContainerControl cc)
        {
            return (ActiveLanguage != null) ? ActiveLanguage.LoadLanguageRes(cc) : false;
        }

        //为动态弹出菜单设计
        public static bool LoadLanguageRes(ContainerControl cc, ToolStrip menu)
        {
            return (ActiveLanguage != null) ? ActiveLanguage.LoadLanguageRes(cc, menu) : false;
        }

        public static string Text(string textId, string defaultText = "")
        {
            return GetText(textId, defaultText);
        }

        public static string GetText(string textId, string defaultText = "")
        {
            return (ActiveLanguage != null) ? ActiveLanguage.GetText(textId, defaultText) : defaultText;
        }

        public static bool LoadLanguageById(string id)
        {
            if (languages == null)
                return false;

            foreach (var language in languages)
            {
                if (language.Id.Equals(id))
                {
                    activeLanguage = language;
                    return true;
                }
            }

            return false;
        }

        public static bool LoadLanguageByIndex(int index)
        {
            if (index < 0 || index > languages.Count - 1)
                return false;

            activeLanguage = languages[index];
            return true;
        }
    }
}

OK，一行加载完成。

窗体创建事件中，加入加载语言代码：

        //改写构造函数
        public MainForm(string[] args)
        {
            InitializeComponent();

            appName = ML.GetText("INF_AppName", APP_NAME);
            ML.LoadFormLanguage(this);
//若有未与控件关联的弹出菜单，可加如下代码实现：
            //ML.LoadLanguageRes(this, pmMain);
            BuildLanguageMenuItems();
            this.args = args;
        }

这样就完成了语言加载。

这里有个多语言项生成菜单，其动态生成语言菜单项并加入事件触发，函数片段如下：

        private void BuildLanguageMenuItems()
        {
            if (ML.LanguageLocalNames.Length == 0)
            {
                miLanguage.Visible = false;
                return;
            }

            for (int i = 0; i <= ML.LanguageLocalNames.Length - 1; i++)
            {
                string ln = ML.LanguageLocalNames[i];
                var menuItem = new ToolStripMenuItem(ln);
                //menuItem.CheckOnClick = true;
                menuItem.Tag = i;
                if (i == 0)
                    menuItem.Checked = true;
                menuItem.Click += new EventHandler((sender, e) =>
                {
                    foreach (ToolStripMenuItem item in miLanguage.DropDownItems)
                        item.Checked = (item == sender);
                    ML.LoadLanguageByIndex((int)(sender as ToolStripItem).Tag);
                    ML.LoadFormLanguage(this);
                });
                miLanguage.DropDownItems.Add(menuItem);
            }
        }

功能完美实现。

四、自定义语言用法

语言串中，自定义语言定义在了strings节点，程序中如此调用：

MessageBox.Show(this.searchForm, string.Format(ML.GetText("INF_CannotFound", "找不到 \"{0}\""), this.searchText), ML.GetText("INF_Information", "提示"), MessageBoxButtons.OK, MessageBoxIcon.Warning);

switch (MessageBox.Show(ML.GetText("INF_ContentChanged", "文件内容已被改变，要保存吗？"), ML.GetText("INF_Information", "提示"), MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question))
{
    case DialogResult.Yes:
        return Save();
    case DialogResult.No:
        return true;
    case DialogResult.Cancel:
        return false;
    default:
        return true;
}