近期開發項目中用到的編碼小技巧匯總說明，開發項目小技巧

近期開發項目中用到的編碼小技巧匯總說明，開發項目小技巧

1.默認EF生成的連接字符串比較的長和怪異，若想使用普通的連接字符串來連接EF，則可以通過創建分部類，並重寫一個構造函數，在構造函數中通過動態拼接EntityConnectionString得到EF所需的連接字符串，具代實現代碼如下：

    public partial class DataEntities
    {
        private static ConcurrentDictionary<string, string> entityConnStrings = new ConcurrentDictionary<string, string>();

        public DataEntities(string connName)
            : base(BuildEntityConnectionString(connName))
        {

        }

        private static string BuildEntityConnectionString(string connName)
        {

            if (!entityConnStrings.ContainsKey(connName))
            {
                var connStrSetting = System.Configuration.ConfigurationManager.ConnectionStrings[connName];

                EntityConnectionStringBuilder entityConnStrBuilder = new EntityConnectionStringBuilder();
                entityConnStrBuilder.Provider = connStrSetting.ProviderName;
                entityConnStrBuilder.ProviderConnectionString = EncryptUtility.DesDecrypt("XXXXX", connStrSetting.ConnectionString);
                entityConnStrBuilder.Metadata = "res://*/Data.csdl|res://*/Data.ssdl|res://*/Data.msl";
                string entityConnString = entityConnStrBuilder.ToString();
                entityConnStrings.AddOrUpdate(connName, entityConnString, (key, value) => entityConnString);
            }
            return entityConnStrings[connName];
        }
    }

注意上面的類是一個分部類：partial，同時BuildEntityConnectionString方法是一個靜態方法，在BuildEntityConnectionString方法中ProviderConnectionString = EncryptUtility.DesDecrypt("XXXXX", connStrSetting.ConnectionString);是關鍵，我這裡是對config中的連接字符串 也都進行了加密，故此處我需要解密，若無這個需求可以直接：ProviderConnectionString =connStrSetting.ConnectionString即可。後續實例化EF上下文對象時，請使用：DataEntities(string connName)這個構造涵數即可，DataEntities是具體的EF上下文對象，大家的EF上下文類名均可能不相同。

2.支持一個通用對象的XML序列化（即：一個類中有可變類型屬性成員，需要不同的序列結果及生成不同的序列元素名稱），具體實現代碼如下：

一個需要被序列化成XML的類：其中要求生成的XML元素detail必需有子元素，且子元素名稱及子元素內部屬性根據類型的不同而不同（即：detail元素下的子元素是可變的）

    [XmlRootAttribute("master")]
    public class DemoMaster<T> where T : class
    {
        [XmlElement("attr")]
        public string DemoAttr { get; set; }

        [XmlElement("detail")]
        public DemoDetail<T> DemoDetail { get; set; } //關鍵點在這裡，該屬性元素為：detail，但其子元素根據T不同而不同

    }
    public class DemoDetail<T> : IXmlSerializable where T : class
    {
        public T body { get; set; }

        public System.Xml.Schema.XmlSchema GetSchema()
        {
            return null;
        }

        public void ReadXml(System.Xml.XmlReader reader)
        {
            string bodyStr = reader.ReadInnerXml();
            this.body = XmlHelper.XmlDeserialize<T>(bodyStr, Encoding.UTF8);
        }

        public void WriteXml(System.Xml.XmlWriter writer)
        {
            writer.WriteRaw(XmlHelper.XmlSerialize(this.body, Encoding.UTF8, true));
        }
    }

    [XmlTypeAttribute("list-a", AnonymousType = false)]
    public class DemoDetailA
    {
        public string Apro1 { get; set; }

        public string Apro2 { get; set; }

        public string Apro3 { get; set; }
    }

    [XmlTypeAttribute("list-b", AnonymousType = false)]
    public class DemoDetailB
    {
        public string Bpro1 { get; set; }

        public string Bpro2 { get; set; }

        public string Bpro3 { get; set; }
    }

    [XmlTypeAttribute("list-c", AnonymousType = false)]
    public class DemoDetailC
    {
        public string Cpro1 { get; set; }

        public string Cpro2 { get; set; }

        public string Cpro3 { get; set; }
    }

注意上面代碼中，需要關注：DemoDetail屬性及DemoDetail<T>類，DemoDetail屬性僅是為了生成detail元素節點，而子節點則由DemoDetail<T>類來進行生成，DemoDetail<T>是實現了IXmlSerializable接口，在XML序列化時，DemoDetail<T>類僅將body屬性對應的T類型實例內容進行序列化（WriteRaw），而反序列化時，則先反序列化body屬性對應的T類型實例，然後賦值給body屬性，這也是巧妙之處，DemoDetail<T>類本身並沒有真正參與到序列化中，故序列化的字符串也看不到DemoDetail<T>類相關的元素，DemoDetail<T>類僅僅是一個XML序列化格式生成的中介。序列化的XML結果如下：

序列化代碼：

            var demo1 = new DemoMaster<DemoDetailA>()
            {
                DemoAttr = "demo1",
                DemoDetail = new DemoDetail<DemoDetailA>() { body = new DemoDetailA() { Apro1 = "demoA1", Apro2 = "demoA2", Apro3 = "demoA3" } }
            };

            var demo2 = new DemoMaster<DemoDetailB>()
            {
                DemoAttr = "demo2",
                DemoDetail = new DemoDetail<DemoDetailB>() { body = new DemoDetailB() { Bpro1 = "demoB1", Bpro2 = "demoB2", Bpro3 = "demoB3" } }
            };

            var demo3 = new DemoMaster<DemoDetailC>()
            {
                DemoAttr = "demo3",
                DemoDetail = new DemoDetail<DemoDetailC>() { body = new DemoDetailC() { Cpro1 = "demoC1", Cpro2 = "demoC2", Cpro3 = "demoC3" } }
            };

            textBox1.Text = XmlHelper.XmlSerialize(demo1, Encoding.UTF8);

            textBox1.Text += "\r\n" + XmlHelper.XmlSerialize(demo2, Encoding.UTF8);

            textBox1.Text += "\r\n" + XmlHelper.XmlSerialize(demo3, Encoding.UTF8);

序列化的XML:

<?xml version="1.0" encoding="utf-8"?>
<master>
    <attr>demo1</attr>
    <detail><list-a>
    <Apro1>demoA1</Apro1>
    <Apro2>demoA2</Apro2>
    <Apro3>demoA3</Apro3>
</list-a></detail>
</master>

<?xml version="1.0" encoding="utf-8"?>
<master>
    <attr>demo2</attr>
    <detail><list-b>
    <Bpro1>demoB1</Bpro1>
    <Bpro2>demoB2</Bpro2>
    <Bpro3>demoB3</Bpro3>
</list-b></detail>
</master>

<?xml version="1.0" encoding="utf-8"?>
<master>
    <attr>demo3</attr>
    <detail><list-c>
    <Cpro1>demoC1</Cpro1>
    <Cpro2>demoC2</Cpro2>
    <Cpro3>demoC3</Cpro3>
</list-c></detail>
</master>

3.winform DataGridView 實現指定列采取密碼框模式顯示與編輯，以及列綁定到復合屬性（即：綁定到多層次屬性），具體實現代碼如下：

            dataGridView1.CellFormatting += new DataGridViewCellFormattingEventHandler(dataGridView1_CellFormatting);
            dataGridView1.EditingControlShowing += new DataGridViewEditingControlShowingEventHandler(dataGridView1_EditingControlShowing);


        public string EvaluateValue(object obj, string property)
        {
            string retValue = string.Empty;
            string[] names = property.Split('.');

            for (int i = 0; i < names.Count(); i++)
            {
                try
                {
                    var prop = obj.GetType().GetProperty(names[i]);
                    var result = prop.GetValue(obj, null);
                    if (result != null)
                    {
                        obj = result;
                        retValue = result.ToString();
                    }
                    else
                    {
                        break;
                    }
                }
                catch (Exception)
                {
                    throw;
                }
            }

            return retValue;
        }


        private void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
        {

            if (dataGridView1.Columns[e.ColumnIndex].DataPropertyName.Contains("."))
            {
                e.Value = EvaluateValue(dataGridView1.Rows[e.RowIndex].DataBoundItem, dataGridView1.Columns[e.ColumnIndex].DataPropertyName);
            }


            if (dataGridView1.Columns[e.ColumnIndex].Name == "KeyCode")
            {
                if (e.Value != null && e.Value.ToString().Length > 0)
                {
                    e.Value = new string('*', e.Value.ToString().Length);
                }
            }
        }

        private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
        {
            int i = this.dataGridView1.CurrentCell.ColumnIndex;
            bool usePassword = false;
            if (dataGridView1.Columns[i].Name == "KeyCode")
            {
                usePassword = true;
            }
            TextBox txt = e.Control as TextBox;
            if (txt != null)
            {
                txt.UseSystemPasswordChar = usePassword;
            }
        }

//示例：綁定的源數據類定義
    public class DemoBindClass
    {
        public string Attr { get; set; }

        public string KeyCode { get; set; }

        public DemoDetailA Detail { get; set; }
    }


    public class DemoDetailA
    {
        public string Apro1 { get; set; }

        public string Apro2 { get; set; }

        public string Apro3 { get; set; }

        public DemoDetailB DetailChild { get; set; }
    }


    public class DemoDetailB
    {
        public string Bpro1 { get; set; }

        public string Bpro2 { get; set; }

        public string Bpro3 { get; set; }
    }

綁定到數據源：

            var demo = new[] {
                new DemoBindClass()
                    {
                        Attr = "demo",
                        KeyCode="a123456789b",
                        Detail = new DemoDetailA()
                        {
                            Apro1 = "demoA1",
                            Apro2 = "demoA2",
                            Apro3 = "demoA3",
                            DetailChild = new DemoDetailB()
                            {
                                Bpro1 = "demoB1",
                                Bpro2 = "demoB2",
                                Bpro3 = "demoB3"
                            }
                        }
                    }
            };


            dataGridView1.AutoGenerateColumns = false;
            dataGridView1.DataSource = demo;

實現指定列采取密碼框模式顯示與編輯，以及列綁定到復合屬性均需要訂閱DataGridView的CellFormatting及EditingControlShowing事件，並在其中寫轉換當前Cell的Value，實現列綁定到復合屬性，關鍵點在：EvaluateValue方法，該方法邏輯很簡單，就是根據綁定的屬性層級（.分隔）層層遍歷獲取屬性的值，直到遍歷完或為空時停止，最後得到的結果即是綁定的屬性的值。最終實現的效果如下圖示：