把功能強大的Spring EL表達式應用在.net平台

Spring EL 表達式是什么？

Spring3中引入了Spring表達式語言—SpringEL,SpEL是一種強大,簡潔的裝配Bean的方式,他可以通過運行期間執行的表達式將值裝配到我們的屬性或構造函數當中,更可以調用C#中提供的靜態常量,獲取外部json xml文件中的的配置值

為什么要使用SpringEL?

可以方便的注入 外部配置文件到 類的構造方法，屬性或者 字段，支持注入容器里面的對象的某個屬性值，還可以調用對象的方法，功能非常的強大，請看官方文檔的例子或者下面我的單元測試例子

SpringEL與Autofac容器相結合框架

el表達式靈活使用能極大提高代碼的活性

SpringEL 如何使用

NUGET地址： Install-Package Spring.EL

該項目是從spring.core項目抽取出來的，因為我只想用 EL 功能，其他的功能我都去掉了。

外部暴露的對象有下面幾個重要對象

- ExpressionEvaluator 提供了很關鍵的幾個靜態方法

public static object GetValue(object root, string expression);

public static object GetValue(object root, string expression, IDictionary variables)

public static void SetValue(object root, string expression, object newValue)

public static void SetValue(object root, string expression, IDictionary variables, object newValue)

 

Spring官方文檔

對象的某個屬性獲取和重新賦值

 

 

 

 

 

 

 

 

文字表達式

        [TestMethod]
        public void TestMethod_02()
        {
            string tonyPizza = (string)ExpressionEvaluator.GetValue(null, "'Tony''s Pizza'"); // evals to "Tony's Pizza"

            string helloWorld = (string)ExpressionEvaluator.GetValue(null, "'Hello World'"); // evals to "Hello World"

            double avogadrosNumber = (double)ExpressionEvaluator.GetValue(null, "6.0221415E+23");

            int maxValue = (int)ExpressionEvaluator.GetValue(null, "0x7FFFFFFF");  // evals to 2147483647

            DateTime birthday = (DateTime)ExpressionEvaluator.GetValue(null, "date('1974/08/24')");

            DateTime exactBirthday = (DateTime)ExpressionEvaluator.GetValue(null, " date('19740824T131030', 'yyyyMMddTHHmmss')");

            bool trueValue = (bool)ExpressionEvaluator.GetValue(null, "true");

            object nullValue = ExpressionEvaluator.GetValue(null, "null");
        }

 

Properties, Arrays, Lists, Dictionaries, Indexers

  [TestMethod]
        public void TestMethod_03()
        {
            Inventor tesla = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");

            tesla.PlaceOfBirth.City = "Smiljan";
            string invention = (string)ExpressionEvaluator.GetValue(tesla, "Inventions[2]"); // "Induction motor"

            string name = (string)ExpressionEvaluator.GetValue(tesla, "Members[0].Name"); // "Nikola Tesla"


            string invention1 = (string)ExpressionEvaluator.GetValue(tesla, "Members[0].Inventions[2]"); // "Wireless communication"
            
            
            Bar bar = new Bar();

            int val = (int)ExpressionEvaluator.GetValue(bar, "[1]"); // evaluated to 2

            ExpressionEvaluator.SetValue(bar, "[1]", 3);  // set value to 3
            
        }

 

Defining Arrays, Lists and Dictionaries Inline

        [TestMethod]
        public void TestMethod_05()
        {

            var val = ExpressionEvaluator.GetValue(null, "{1, 2, 3, 4, 5}");
            var val2 = ExpressionEvaluator.GetValue(null, "{'abc', 'xyz'}");
            var val21 = ExpressionEvaluator.GetValue(null, "new int[] {1, 2, 3, 4, 5}");
            var val22 = ExpressionEvaluator.GetValue(null, "#{'key1' : 'Value 1', 'today' : DateTime.Today}");
            var val221 = ExpressionEvaluator.GetValue(null, "#{1 : 'January', 2 : 'February', 3 : 'March'}");

        }

 

Methods

        [TestMethod]
        public void TestMethod_06()
        {
            Inventor tesla = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            //string literal
            char[] chars = (char[])ExpressionEvaluator.GetValue(null, "'test'.ToCharArray(1, 2)");  // 't','e'

            //date literal
            int year = (int)ExpressionEvaluator.GetValue(null, "date('1974/08/24').AddYears(31).Year"); // 2005

            // object usage, calculate age of tesla navigating from the IEEE society.

            int age = (int)ExpressionEvaluator.GetValue(tesla, "Members[0].GetAge(date('2005-01-01'))"); // 149 (eww..a big anniversary is coming up ;)

        }

 

Relational operators

        [TestMethod]
        public void TestMethod_07()
        {
            var a1 = ExpressionEvaluator.GetValue(null, "2 == 2");  // true

            var a12 = ExpressionEvaluator.GetValue(null, "date('1974-08-24') != DateTime.Today");  // true

            var a13 = ExpressionEvaluator.GetValue(null, "2 < -5.0"); // false

            var a14 = ExpressionEvaluator.GetValue(null, "DateTime.Today <= date('1974-08-24')"); // false

            var a15 = ExpressionEvaluator.GetValue(null, "'Test' >= 'test'"); // true


            a1 = ExpressionEvaluator.GetValue(null, "3 in {1, 2, 3, 4, 5}");  // true

            a1 = ExpressionEvaluator.GetValue(null, "'Abc' like '[A-Z]b*'");  // true

            a1 = ExpressionEvaluator.GetValue(null, "'Abc' like '?'");  // false

            a1 = ExpressionEvaluator.GetValue(null, "1 between {1, 5}");  // true

            a1 = ExpressionEvaluator.GetValue(null, "'efg' between {'abc', 'xyz'}");  // true

            a1 = ExpressionEvaluator.GetValue(null, "'xyz' is int");  // false

            a1 = ExpressionEvaluator.GetValue(null, "{1, 2, 3, 4, 5} is ArrayList");  // true

            a1 = ExpressionEvaluator.GetValue(null, "'5.0067' matches '^-?\\d+(\\.\\d{2})?$'");  // false
            a1 = ExpressionEvaluator.GetValue(null, @"'5.00' matches '^-?\d+(\.\d{2})?$'"); // true
        }
        

 

Logical operators

        [TestMethod]
        public void TestMethod_10()
        {
            Inventor ieee = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            // AND
            bool falseValue = (bool)ExpressionEvaluator.GetValue(null, "true and false"); //false

            string expression = @"IsMember('Nikola Tesla') and IsMember('Mihajlo Pupin')";
            bool trueValue = (bool)ExpressionEvaluator.GetValue(ieee, expression);  //true

            // OR
            trueValue = (bool)ExpressionEvaluator.GetValue(null, "true or false");  //true

            expression = @"IsMember('Nikola Tesla') or IsMember('Albert Einstien')";
            trueValue = (bool)ExpressionEvaluator.GetValue(ieee, expression); // true

            // NOT
            falseValue = (bool)ExpressionEvaluator.GetValue(null, "!true");

            // AND and NOT
            expression = @"IsMember('Nikola Tesla') and !IsMember('Mihajlo Pupin')";
            falseValue = (bool)ExpressionEvaluator.GetValue(ieee, expression);

        }

 

Bitwise operators

        [TestMethod]
        public void TestMethod_11()
        {
            // AND
            int result = (int)ExpressionEvaluator.GetValue(null, "1 and 3"); // 1 & 3

            // OR
            result = (int)ExpressionEvaluator.GetValue(null, "1 or 3");  // 1 | 3

            // XOR
            result = (int)ExpressionEvaluator.GetValue(null, "1 xor 3");  // 1 ^ 3

            // NOT
            result = (int)ExpressionEvaluator.GetValue(null, "!1"); // ~1

        }

 

Mathematical operators

        [TestMethod]
        public void TestMethod_12()
        {
            // Addition
            int two = (int)ExpressionEvaluator.GetValue(null, "1 + 1"); // 2

            String testString = (String)ExpressionEvaluator.GetValue(null, "'test' + ' ' + 'string'"); //'test string'

            DateTime dt = (DateTime)ExpressionEvaluator.GetValue(null, "date('1974-08-24') + 5"); // 8/29/1974

            // Subtraction

            int four = (int)ExpressionEvaluator.GetValue(null, "1 - -3"); //4

            Decimal dec = (Decimal)ExpressionEvaluator.GetValue(null, "1000.00m - 1e4"); // 9000.00

            TimeSpan ts = (TimeSpan)ExpressionEvaluator.GetValue(null, "date('2004-08-14') - date('1974-08-24')"); //10948.00:00:00

            // Multiplication

            int six = (int)ExpressionEvaluator.GetValue(null, "-2 * -3"); // 6

            double twentyFour = (double)ExpressionEvaluator.GetValue(null, "2.0 * 3e0 * 4"); // 24

            // Division

            int minusTwo = (int)ExpressionEvaluator.GetValue(null, "6 / -3"); // -2

            var one = ExpressionEvaluator.GetValue(null, "8.0 / 4e0 / 2"); // 1

            // Modulus

            int three = (int)ExpressionEvaluator.GetValue(null, "7 % 4"); // 3

            one = ExpressionEvaluator.GetValue(null, "8.0 % 5e0 % 2"); // 1

            // Exponent

            var sixteen = ExpressionEvaluator.GetValue(null, "-2 ^ 4"); // 16

            // Operator precedence

            var minusFortyFive = ExpressionEvaluator.GetValue(null, "1+2-3*8^2/2/2"); // -45

        }

 

Assignment

        [TestMethod]
        public void TestMethod_13()
        {
            Inventor inventor = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");

            String aleks = (String)ExpressionEvaluator.GetValue(inventor, "Name = 'Aleksandar Seovic'");

            DateTime dt = (DateTime)ExpressionEvaluator.GetValue(inventor, "DOB = date('1974-08-24')");
        }

 

Expression lists

        [TestMethod]
        public void TestMethod_14()
        {
            Inventor ieee = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");

            String pupin = (String)ExpressionEvaluator.GetValue(ieee.Members, "([1].Place.City = 'Beograd'; [1].Place.Name = 'Serbia'; [1].Name)");
        }

 

Types

        [TestMethod]
        public void TestMethod_15()
        {
            var a1 = ExpressionEvaluator.GetValue(null, "1 is int");

            var a2 = ExpressionEvaluator.GetValue(null, "DateTime.Today");
            var a3 = ExpressionEvaluator.GetValue(null, "new string[] {'abc', 'efg'}");

            Inventor tesla = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            Type dateType = (Type)ExpressionEvaluator.GetValue(null, "T(System.DateTime)");

            Type evalType =
                (Type)ExpressionEvaluator.GetValue(null, "T(Spring.Expressions.ExpressionEvaluator, Spring.EL)");

            bool trueValue = (bool)ExpressionEvaluator.GetValue(tesla, "T(System.DateTime) == DOB.GetType()");

        }

 

Type Registration & Constructors

        [TestMethod]
        public void TestMethod_17()
        {
            Inventor2 tesla = new Inventor2("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            DateTime dt = (DateTime)ExpressionEvaluator.GetValue(null, "new DateTime(1974, 8, 24)");

            // Register Inventor type then create new inventor instance within Add method inside an expression list.
            // Then return the new count of the Members collection.

            TypeRegistry.RegisterType(typeof(PlaceOfBirth));
            int three = (int)ExpressionEvaluator.GetValue(tesla.Members, "( Add(new PlaceOfBirth('Aleksandar Seovic')); Count)");

            TypeRegistry.RegisterType(typeof(Inventor));
            Inventor aleks = (Inventor)ExpressionEvaluator.GetValue(null, "new Inventor('Aleksandar Seovic', date('1974-08-24'), 'Serbian', Inventions = new string[]{'SPELL'})");
        }

 

Variables

        [TestMethod]
        public void TestMethod_19()
        {
            Inventor tesla = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            Dictionary<string, object> vars = new Dictionary<string, object>();
            vars["newName"] = "Mike Tesla2";
            var a = ExpressionEvaluator.GetValue(tesla, "Name = #newName", vars);


            ExpressionEvaluator.GetValue(tesla, "( #oldName = Name; Name = 'Nikola Tesla' )", vars);
            String oldName = (String)vars["oldName"]; // Mike Tesla


            vars["prez"] = "president";
            Inventor2 pupin = (Inventor2)ExpressionEvaluator.GetValue(tesla, "Officers[#prez]", vars);

        }

 

The '#this' and '#root' variables

        [TestMethod]
        public void TestMethod_20()
        {
            Inventor ieee = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            // sets the name of the president and returns its instance
            var a1 = ExpressionEvaluator.GetValue(ieee, "Officers['president'].( #this.Name = 'Nikola Tesla'; #this )");


            var a2 = ExpressionEvaluator.GetValue(ieee, "Officers['president'].( #root.Officers.Remove('president'); #this )");
        }

 

Ternary Operator (If-Then-Else)

        [TestMethod]
        public void TestMethod_21()
        {
            String aTrueString = (String)ExpressionEvaluator.GetValue(null, "false ? 'trueExp' : 'falseExp'"); // trueExp
        }
        
        [TestMethod]
        public void TestMethod_22()
        {
            Inventor ieee = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            ExpressionEvaluator.SetValue(ieee, "Name", "IEEE");
            Dictionary<string, object> vars = new Dictionary<string, object>();
            vars["queryName"] = "Nikola Tesla";

            string expression = @"IsMember(#queryName)
                      ? #queryName + ' is a member of the ' + Name + ' Society'
                      : #queryName + ' is not a member of the ' + Name + ' Society'";

            String queryResultString = (String)ExpressionEvaluator.GetValue(ieee, expression, vars);
        }

 

List Projection and Selection

        [TestMethod]
        public void TestMethod_23()
        {
            Inventor ieee = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), "Serbian");
            IList placesOfBirth = (IList)ExpressionEvaluator.GetValue(ieee, "Members.!{Name}"); // { 'Smiljan', 'Idvor' }


            IList serbianInventors = (IList)ExpressionEvaluator.GetValue(ieee, "Members.?{Name == '1'}"); // { tesla, pupin }


            IList sonarInventors = (IList)ExpressionEvaluator.GetValue(ieee, "Members.?{'1' in Inventions}"); // { pupin }


            IList sonarInventorsNames = (IList)ExpressionEvaluator.GetValue(ieee, "Members.?{'1' in Inventions}.!{Name}"); // { 'Mihajlo Pupin' }


            var a1 = ExpressionEvaluator.GetValue(ieee, "Members.^{Name == '1'}.Name");  // 'Nikola Tesla'
            var a3 = ExpressionEvaluator.GetValue(ieee, "Members.${Name == '3'}.Name"); // 'Mihajlo Pupin'

        }

 

Collection Processors and Aggregators

        [TestMethod]
        public void TestMethod_24()
        {
            var a1 = ExpressionEvaluator.GetValue(null, "{1, 5, -3}.count()");  // 3
            var a2 = ExpressionEvaluator.GetValue(null, "count()"); // 0
            a2 = ExpressionEvaluator.GetValue(null, "{1, 5, -3, 10}.sum()");  // 13 (int)
            a2 = ExpressionEvaluator.GetValue(null, "{5, 5.8, 12.2, 1}.sum()"); // 24.0 (double)
            a2 = ExpressionEvaluator.GetValue(null, "{1, 5, -4, 10}.average()");  // 3
            a2 = ExpressionEvaluator.GetValue(null, "{1, 5, -2, 10}.average()"); // 3.5
            a2 = ExpressionEvaluator.GetValue(null, "{1, 5, -3, 10}.min()");  // -3
            a2 = ExpressionEvaluator.GetValue(null, "{'abc', 'efg', 'xyz'}.min()"); // 'abc'

            a2 = ExpressionEvaluator.GetValue(null, "{1, 5, -3, 10}.max()");  // 10
            a2 = ExpressionEvaluator.GetValue(null, "{'abc', 'efg', 'xyz'}.max()"); // 'xyz'


            a2 = ExpressionEvaluator.GetValue(null, "{ 'abc', 'xyz', null, 'abc', 'def', null}.nonNull()");  // { 'abc', 'xyz', 'abc', 'def' }
            a2 = ExpressionEvaluator.GetValue(null,
                "{ 'abc', 'xyz', null, 'abc', 'def', null}.nonNull().distinct().sort()"); // { 'abc', 'def', 'xyz' }

            a2 = ExpressionEvaluator.GetValue(null, "{ 'abc', 'xyz', 'abc', 'def', null, 'def' }.distinct(true).sort()"); // { null, 'abc', 'def', 'xyz' }
            a2 = ExpressionEvaluator.GetValue(null,
                "{ 'abc', 'xyz', 'abc', 'def', null, 'def' }.distinct(false).sort()"); // { 'abc', 'def', 'xyz' }
        }

 

DI Object References(方便和DI容器結合使用)

        [TestMethod]
        public void TestMethod_26()
        {
            Dictionary<string, object> vars = new Dictionary<string, object>();
            vars["_sprint_context_resove_"] = new SprintContextResove((name) =>
            {
                if (name == "Inventor") return new Inventor("a", DateTime.Now, "d");
                return new Inventor2("a", DateTime.Now, "d");
            });

            var IsMember = ExpressionEvaluator.GetValue(null, "@(Inventor).IsMember('Nikola Tesla1')", vars);

        }

SpringEL與Autofac容器相結合框架項目的目的

基於參考 Java的 Spring注解方式開發思想，

所有autofac容器的注冊 和 裝配 都是依賴標簽來完成。

這樣一來 一方面很容易分清楚 哪些是DI 哪些非DI， 哪些是攔截器，哪些需要攔截器 代碼也好看，編程效率能夠大大提升。

支持的標簽一覽

標簽名稱	使用位置	使用說明
AutoConfiguration	打在class上面	自動裝配class里面帶有Bean標簽的方法
Bean	打在方法上面	配合AutoConfiguration標簽使用
Component	打在class上面	自動注冊
Autowired	打在構造方法的Parameter，類的Property，類的Field	自動裝配
PropertySource	打在class上面	配合Value標簽使用，設置Value的數據源，支持json,xml,支持資源內嵌
Value	打在構造方法的Parameter，類的Property，類的Field	靜態數據裝配(支持SPEL表達式)
Aspect	打在class上面	開啟攔截器，默認注冊為類攔截器，可以指定接口型攔截器

歡迎追求代碼極客精神的你來試用和反饋。