乾貨分享:ASP.NET CORE(C#)與Spring Boot MVC(JAVA)異曲同工的程式設計方式總結

夢在旅途發表於2019-07-13

我(夢在旅途,http://zuowj.cnblogs.com; http://www.zuowenjun.cn)最近發表的一篇文章《.NET CORE與Spring Boot編寫控制檯程式應有的優雅姿勢》看到都上48小時閱讀排行榜(當然之前發表的文章也有哦!),說明關注.NET CORE及Spring Boot的人很多,也是目前的主流方向,於是我便決定系統性的總結一下C# 與JAVA 、ASP.NET CORE 與 Spring Boot MVC,讓更多的人瞭解它們,消除之前可能存在的對.NET或JAVA的誤解。

本文目的是通過全面簡述C# 與JAVA 在基礎語法以及ASP.NET CORE 與 Spring Boot MVC的在框架規範、部署、執行的異曲同工的實現方式,讓大家更多的瞭解C#與JAVA,本文不會刻意說哪門語言好,我認為這是沒有意義的,更多的是瞭解每種語言的特點、優點以及不同語言的共性,掌握程式設計內功(如:物件導向、DI、AOP、設計模式、演算法),這樣才能讓自己更能適應社會及未來的變化。

本文主要以示例程式碼為主,輔以簡單文字說明,不會細講每個語法點,只會體現不同的實現方式而矣,全文無廢話,全是乾貨,慢慢欣賞吧。

(注:本文內容是使用Markdown編輯器進行編輯完成!)

C# VS JAVA 基礎語法類比篇:

一、匿名類

C#(直接new{},在{}中直接定義只讀公開屬性或委託方法,無需預先定義任何介面或類)
            #region 1.匿名類
            var helloWord = new
            {
                CodeBy = "C#匿名類",
                Output = new Action<string, string>((name, codeBy) =>
                {
                    System.Console.WriteLine($"Welcome:{name},Hello Word!  by {codeBy}");
                })
            };

            helloWord.Output("夢在旅途", helloWord.CodeBy);
            #endregion
JAVA(需要先定義介面或類,然後 new 介面或類的建構函式{},{}內實現介面方法或重寫父類介面)
        //1.匿名類
        IHelloWord helloWord=new IHelloWord() {
            @Override
            public void output(String name) {
                System.out.printf("Welcome:%s,Hello Word!  by %s\n",name,getCodeBy());
            }

            @Override
            public String getCodeBy() {
                return "JAVA匿名類";
            }
        };

        helloWord.output("夢在旅途");


public interface IHelloWord {
    void output(String name);
    String getCodeBy();
}

二、型別初始化

C#(IList型別(Dictionary、List)直接在new 型別{},在{}內直接使用{key,value}或{value}方式新增集合元素,其實是隱式呼叫了add方法)
            #region 2.型別初始化

            Dictionary<string, string> map = new Dictionary<string, string>
            {
              { "key1","value1" },//(隱式自動呼叫add方法)
              { "key2", "value2" },
              { "key3", "value3" }
            };

            foreach (var item in map)
            {
                System.Console.WriteLine($"key:{item.Key},value:{item.Value}");
            }

            List<string> list = new List<string>
            {
                "list-item1",//(隱式自動呼叫add方法)
                "list-item2",
                "list-item3"
            };

            foreach (string item in list)
            {
                System.Console.WriteLine(item);
            }

            String[] strArr = { "arr1", "arr2", "arr3" };
            foreach (string item in strArr)
            {
                System.Console.WriteLine(item);
            }


            Person person = new Person
            {
                Name = "夢在旅途",
                Age = 23,
                Sex = "男"
            };


            string json = JsonConvert.SerializeObject(person);
            System.Console.WriteLine("Person json:" + json);

            #endregion
JAVA(new集合型別{},並在{}內再次使用{},即{{賦值 }},在雙大括號內進行賦值操作,省略類名,這個特點有點類似VB及VB.NET的with語句,大家有興趣可以瞭解一下,陣列的初始化與C#相同,都可以直接在定義陣列的時候在{}中給定元素)
        //2.型別初始化
        Map<String,String> map=new HashMap(){
            {
                put("key1","value1");
                put("key2","value2");
                put("key3","value3");
            }
        };

        for (Map.Entry<String, String> item:map.entrySet()) {
            System.out.printf("key:%1$s,value:%2$s\n",item.getKey(),item.getValue());
        }

        List<String> list=new ArrayList(){
            {
                add("list-item1");
                add("list-item2");
                add("list-item3");
            }
        };

        for (String item :list) {
            System.out.printf("%s\n",item);
        }



        String[] strArr={"arr1","arr2","arr3"};

        for (String item :strArr) {
            System.out.printf("%s\n",item);
        }


        Person person=new Person(){
            {
                setName("zwj");
                setAge(32);
                setSex("男");
            }
        };

        ObjectMapper jsonMapper=new ObjectMapper();
        String json= jsonMapper.writeValueAsString(person);
        System.out.println("Person json:" + json);

三、委託(方法引用)

C#(委託定義使用delegate關鍵字,後面就跟方法答名定義【不含方法體】,可委託普通方法,靜態方法,有很多的現成的預定義委託型別,如:Action<T0...T16>,Func<T0...T16,TOut>各有16個過載)
            #region 3.委託
            delegate void HelloDelegate(string name);//定義委託型別(重點是方法簽名)

            //常規普通自定義委託型別及委託相應的方法
            HelloWord helloWordObj = new HelloWord();

            HelloDelegate helloDelegate = helloWordObj.Output; //委託例項方法
            helloDelegate.Invoke("夢在旅途");// OR helloDelegate("夢在旅途");

            HelloDelegate helloDelegate2 = HelloWord.OutputForStatic; //委託類的靜態方法
            helloDelegate2.Invoke("zuowenjun"); // OR helloDelegate2("zuowenjun");

            //使用通用的已封裝好的委託型別(如:Func、Action)並例項化
            Func<int, int, int> multiplyFunc = new Func<int, int, int>(delegate (int a, int b)
            {
                return a * b;
            });

            int x = 12, y = 25;
            int multiplyResult = multiplyFunc.Invoke(x, y); //OR multiplyFunc(x,y);
            System.Console.WriteLine($"{x}乘以{y}等於:{multiplyResult}");

            Action<string> helloAction = new Action<string>(delegate (string name)
            {
                System.Console.WriteLine($"hello,{name},how are you!");
                System.Console.WriteLine("learning keep moving!");
            });
            helloAction.Invoke("www.zuowenjun.cn");

            #endregion
JAVA(定義委託需要先定義委託型別【即:函式式介面,規則:介面+@FunctionalInterface+一個方法定義】,然後就可以普通方法,靜態方法,有很多的現成的預定義委託型別【即:函式式介面】,如:BiFunction,Consumer等)
        //3.委託

        HelloWord helloWordObj = new HelloWord();

        HelloWordDelegate helloWordDelegate = helloWordObj::output;
        helloWordDelegate.invoke("夢在旅途");

        HelloWordDelegate helloWordDelegate2 = HelloWord::outputForStatic;
        helloWordDelegate2.invoke("zuowenjun");


        //使用已封裝好的委託方法(JAVA這邊稱:函式式介面,有很多詳見:https://www.runoob.com/java/java8-functional-interfaces.html)
        BiFunction<Integer, Integer, Integer> multiplyFunc = new BiFunction<Integer, Integer, Integer>() {
            @Override
            public Integer apply(Integer i, Integer i2) {
                return i * i2;
            }
        };

        int x = 12, y = 25;
        int multiplyResult = multiplyFunc.apply(x, y);
        System.out.printf("%d乘以%d等於:%d%n", x, y, multiplyResult);


        Consumer<String> helloAction=new Consumer<String>() {
            @Override
            public void accept(String s) {
                System.out.printf("hello,%s,how are you!%n",s);
                System.out.printf("learning keep moving!%n");
            }
        };
        helloAction.accept("www.zuowenjun.cn");


@FunctionalInterface
public interface HelloWordDelegate {
    void  invoke(String name);
}

public class HelloWord implements IHelloWord {

    @Override
    public void output(String name) {
        System.out.printf("Welcome:%s,Hello Word!  by %s\n",name,getCodeBy());
    }

    public  static void outputForStatic(String name){
        System.out.printf("Welcome:%s,Hello Word!  by JAVA static\n",name);
    }

    @Override
    public String getCodeBy() {
        return "JAVA";
    }
}

四、Lambda表示式

C#(使用(入參)=>{方法處理體},與要傳入或要例項化的委託方法簽名相同即可)
            #region 4.Lambda

            Func<int, int, int> multiplyFunc2 = new Func<int, int, int>((a, b) => a * b);

            int x2 = 12, y2 = 25;
            int multiplyResult2 = multiplyFunc2.Invoke(x2, y2); //OR multiplyFunc(x,y);
            System.Console.WriteLine($"{x2}乘以{y2}等於:{multiplyResult2}");

            Action<string> helloAction2 = new Action<string>(name =>
            {
                System.Console.WriteLine($"hello,{name},how are you!");
                System.Console.WriteLine("learning keep moving!");
            });

            helloAction2.Invoke("www.zuowenjun.cn");

            int[] intArr = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            intArr = intArr.Where(i => i >= 5).ToArray();
            foreach (int i in intArr)
            {
                System.Console.WriteLine($"int-{i}");
            }

            string msg = "測試外部變數被Lambda引用";
            Action testMsgAction = () =>
            {
                msg += "--改變內容";
                System.Console.WriteLine("Lambda方法體中的值:" + msg);
            };
            testMsgAction();
            System.Console.WriteLine("原始值:" + msg);

            #endregion
JAVA(使用(入參)->{方法處理體},與要傳入或要例項化的方法簽名相同,且傳入或例項化的型別必需是函式式介面【可以理解為自定義的委託型別】,注意與C#不同,Lambda方法體內不能引用外部非final的變數,與C# Lambda有本質不同
        //4.Lambda

        BiFunction<Integer, Integer, Integer> multiplyFunc = (i1, i2) -> i1 * i2;

        int x = 12, y = 25;
        int multiplyResult = multiplyFunc.apply(x, y);
        System.out.printf("%d乘以%d等於:%d%n", x, y, multiplyResult);


        Consumer<String> helloAction= s -> {
            System.out.printf("hello,%s,how are you!%n",s);
            System.out.printf("learning keep moving!%n");
        };
        helloAction.accept("www.zuowenjun.cn");

        int[] intArr = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
        intArr= Arrays.stream(intArr).filter(value -> value>=5).toArray();
        for (int n : intArr) {
            System.out.printf("int-%d%n",n);
        }

五、泛型

C#(真泛型,不同的泛型型別引數視為不同的型別,有泛型介面,泛型類,泛型方法,泛型委託,泛型約束:in表示逆變【泛型引數父型別轉子型別,屬於消費者,一般用於入參】,out 表示協變【泛型引數子型別轉父型別】,只有委託、介面才支援可變性)
            #region 5.泛型

            //常用泛型集合型別
            List<int> intList = new List<int> { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

            List<long> longList = new List<long> { 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L };

            Dictionary<string, string> dic = new Dictionary<string, string> {
                { "k1","v1"},{ "k2","v2"},{ "k3","v3"}
            };

            //泛型方法
            var demo = new DemoGenericClass();
            //demo.DisplayResult("學習永無止境"); 錯誤,因為約束是值型別
            demo.DisplayResult(ConsoleColor.DarkGreen);

            List<YellowPerson> yellowPersonList = new List<YellowPerson> {
                new YellowPerson(){ Name="zzz",Age=11,Sex="G"},
                new YellowPerson(){ Name="xxx",Age=22,Sex="B"}
            };

            //協變(泛型引數子類轉父類)
            //public interface IEnumerable<out T>
            IEnumerable<YellowPerson> yellowPersons = yellowPersonList;
            IEnumerable<Person> persons = yellowPersons;//協變(子類到父類的轉變) ,泛型引數 out標記,一般用於出參,這個正確的

            // List<Person> personList = yellowPersonList; 因為List是類,而且泛型引數並沒有標記out,不適用協變,故這樣轉換是錯誤的

            foreach (var p in persons)
            {
                System.Console.WriteLine($"item :【Name={p.Name},Age={p.Age},Sex={p.Sex},Color={p.Color}】");
            }

            //逆變(泛型引數父類轉子類)
            Action<object, object> showPlusResultAction = (d1, d2) => Console.WriteLine($"{d1}+{d2}={d1.ToString() + d2.ToString()}");

            Action<string, string> showStrPlusResultAction = showPlusResultAction;//逆變(父類到子類的轉變),泛型引數 in標記,一般用於入參

            showPlusResultAction(55, 66);
            showStrPlusResultAction("你好", "中國");

            ShowMsg<Person> showMsg = new ShowMsg<Person>((p) =>
            {
                System.Console.WriteLine($"ShowMsg :【Name={p.Name},Age={p.Age},Sex={p.Sex},Color={p.Color}】");
            });
            //ShowMsg<HelloWord> showMsg2 = new ShowMsg<HelloWord>(...); 這樣是不行的,因為泛型約束為需繼承自Person

            showMsg.Invoke(new Person() { Name = "zuowenjun", Age = 33, Sex = "B" });
            showMsg.Invoke(new YellowPerson() { Name = "zuowenjun2", Age = 33, Sex = "B" });

            //綜合演示:入參逆變,出參協變
            Func<Person, Person, string> getDataFunc = (x, y) => x.Name + y.Name;
            Func<YellowPerson, YellowPerson, object> getDataFunc2 = getDataFunc;
            object dataResult = getDataFunc2(new YellowPerson() { Name = "張三", Age = 33, Sex = "G" }, new YellowPerson() { Name = "趙六", Age = 33, Sex = "B" });
            System.Console.WriteLine($"getDataFunc2:{dataResult}");

            List<int> a = new List<int>();
            List<String> b = new List<string>();
            bool isEqual = (a.GetType() == b.GetType());
            System.Console.WriteLine($"List<int> 與 List<String> {(isEqual ? "is" : "not")} Equal ");//結果是不相等


            #endregion
   
   //以上示例需要用到的類
   
   public class BaseClass
    {
        /// <summary>
        /// 必需是用virtual標記的方法(即:虛方法)或abstract標記的方法(即:抽象方法)子類才能使用override進行重寫
        /// </summary>
        /// <param name="name"></param>
        public virtual void SayHello(string name)
        {
            System.Console.WriteLine($"{nameof(BaseClass)} Say:{name},hello!");
        }
        
    }
   
            
    public class DemoGenericClass : BaseClass, IDisposable
    {
        public void DisplayResult<T>(T arg) where T : struct
        {
            System.Console.WriteLine($"DemoGenericClass.DisplayResult:{arg}");
        }

        public void Dispose()
        {
            System.Console.WriteLine("DemoGenericClass Disposed");
        }

        public override void SayHello(string name)
        {
            base.SayHello(name);
            System.Console.WriteLine($"{nameof(DemoGenericClass)} Say:{name},hello again!");
        }
    }
    

    public class Person
    {
        public virtual Color Color { get; }
        public string Name { get; set; }

        public int Age { get; set; }

        public string Sex { get; set; }

    }

    public class BlackPerson : Person
    {
        public override Color Color => Color.Black;
    }

    public class YellowPerson : Person
    {
        public override Color Color => Color.Yellow;
    }

    public class WhitePerson : Person
    {
        public override Color Color => Color.White;
    }
JAVA(偽泛型,編譯後型別引數擦除,同一個泛型型別不同的泛型引數型別相同,有泛型介面,泛型類,泛型方法,泛型約束:super限定下邊界,逆變,用於入參,屬於消費者,extends限定上邊界,協變,用於出參,屬於生產者,還有?通匹符)
      //常用泛型集合
        List<Integer> intList = new ArrayList(){
            {
                add(1);
                add(2);
                add(3);
                add(4);
                add(5);
            }
        };

        Map<String,String> map=new HashMap(){
            {
                put("k1","v1");
                put("k2","v2");
                put("k3","v3");
            }
        };

        //泛型方法
        DemoGenericClass demo=new DemoGenericClass();
        demo.displayResult(new YellowPerson(){{
            setName("zwj");setSex("B");setAge(33);
        }});

        List<Integer> a=new ArrayList<>();
        List<String> b=new ArrayList<>();
        boolean isEqual =(a.getClass()==b.getClass());
        System.out.printf("List<Integer>與List<String> %s Equal %n",isEqual?"is":"not"); //結果是相等,都是同一個List型別,不能使用instanceof判斷泛型型別例項

        //協變、逆變(詳見說明:https://www.jianshu.com/p/2bf15c5265c5 ,意義與C#相同)
        List<? super Person> persons=new ArrayList<>(); //super:限定下邊界,逆變,用於入參
        persons.add(new Person(){
            {
                setName("張三");
                setAge(25);
                setSex("B");
            }
        });

        persons.add(new YellowPerson(){
            {
                setName("趙六");
                setAge(18);
                setSex("G");
            }
        });

       List<? extends Person> result= (List<? extends Person>) persons;//extends:限定上邊界,協變,用於出參
       for (Person p:result){
           System.out.printf("Person list item:%s %n",p.toString());
       }

//以上示例需要用到的類
    public class DemoGenericClass implements AutoCloseable
    {
        @Override
        public void close() throws Exception {
            System.out.println("DemoGenericClass closed");
        }

        public <T extends Person> void displayResult(T arg) //泛型約束(泛型引數上邊界,協變)
        {
           System.out.printf("DemoGenericClass.DisplayResult:%s %n",arg.toString());
        }
    }
    

public class Person {
    private String name;
    private int age;
    private String sex;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return String.format("Person=[Name:%s,Age:%d,Sex:%s] %n", name, age, sex);
    }
}

class YellowPerson extends Person {

    @Override
    public String toString() {
        return "YellowPerson#toString-"+ super.toString();
    }
}

六、自動釋放

C#(採用using包裹,要實現自動釋放必需實現AutoCloseable介面)
            using (var demo2 = new DemoGenericClass()) //DemoGenericClass實現IDisposable介面
            {
                demo2.DisplayResult(123456);
            }
JAVA(採用try包裹,要實現自動釋放必需實現IDisposable介面)
        try(DemoGenericClass demo=new DemoGenericClass()) {
            demo.displayResult(new YellowPerson(){
                {
                    setName("zuowenjun");
                    setAge(33);
                    setSex("B");
                }
            });
        }

七、重寫(override)

C#(必需是用virtual標記的方法(即:虛方法)或abstract標記的方法(即:抽象方法)子類才能使用override進行重寫,重寫後父類的方法將被子類取代,若需在子類中執行父類被重寫的方法,應使用base關鍵字,若父類方法非虛方法或抽象方法但又想“重寫”怎麼辦?則只能使用new覆蓋方法,覆蓋方法與重寫方法的不同之處在於,在父類中仍可以正常執行父類的方法而不會執行子類的覆蓋方法,覆蓋方法的方法簽名、訪問修飾符均沒有嚴格限制,即使不相同仍不會報錯,但IDE會有提示,如需真正覆蓋父類方法,則應按照重寫的規範來,只是使用new來修飾覆蓋方法,但覆蓋方法與重寫方法有本質不同,一般情況下更建議使用重寫方法)

C#所有類的普通方法預設是密封方法(類似JAVA的final方法),是不允許被重寫,可以理解為預設是不開放的,需要開放重寫的方法必需使用virtual標記為虛方法(虛方法至少是protected及以上的訪問許可權),若重寫後不想被後續的子類再次重寫,則可以標記為sealed,即:密封方法

    public class BaseClass
    {
        /// <summary>
        /// 必需是用virtual標記的方法(即:虛方法)或abstract標記的方法(即:抽象方法)子類才能使用override進行重寫
        /// </summary>
        /// <param name="name"></param>
        public virtual void SayHello(string name)
        {
            System.Console.WriteLine($"{nameof(BaseClass)} Say:{name},hello!");
        }
        
    }

    public class DemoGenericClass : BaseClass
    {
        public override void SayHello(string name)
        {
            base.SayHello(name);
            System.Console.WriteLine($"{nameof(DemoGenericClass)} Say:{name},hello again!");
        }
    }
JAVA(非private 且非 final 修飾的普通方法預設均可在子類中進行重寫,重寫要求基本與C#相同,只是無需強制Override關鍵字,但建議仍使用@Override註解,以便IDE進行重寫規範檢查,重寫後父類的方法將被子類取代,若需在子類中執行父類被重寫的方法,應使用super關鍵字)

JAVA所有類的普通方法預設是虛方法,都是可以被重寫,可以理解為預設是開放重寫的,若不想被重寫則應標記為final ,即:最終方法(C#中稱密封方法)

    public  class BaseClass{
        public  void  testOutput(String msg){
            System.out.println("output Msg:" + msg);
        }
    }

    public class DemoGenericClass extends BaseClass
    {
        @Override
        public  void  testOutput(String msg){
            super.testOutput(msg);
            System.out.println("output again Msg:" + msg);
        }
    }

ASP.NET CORE VS Spring Boot 框架部署類比篇:

一、引用依賴(包)

C#(編輯csproj檔案,可以通過PackageReference引用包、ProjectReference引用同一個解決方案下的其它專案,Reference引用本地DLL元件,csproj除了引用包以外,還可以通過在PropertyGroup元素下配置相關的屬性,比如TargetFramework指定SDK框架版本等)

.NET專案的包是NuGet包,可以從nuget.org上查詢瀏覽所需的包,專案中引用依賴包,除了在csproj檔案中使用PackageReference新增編輯外(具體用法參見:專案檔案中的包引用 (PackageReference))還可以使用package manager控制檯使用包管理命令,如:Install-Package ExcelEasyUtil -Version 1.0.0,或者直接使用.NET CLI命令列工具,如:dotnet add package ExcelEasyUtil --version 1.0.0

.NET有包、元包、框架 之分,詳細瞭解:包、元包和框架

  <!--包引用-->
  <ItemGroup>
    <PackageReference Include="Autofac.Extras.DynamicProxy" Version="4.5.0" />
    <PackageReference Include="Autofac" Version="4.9.2" />
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.1.1" />
    <PackageReference Include="Autofac.Extensions.DependencyInjection" Version="4.4.0" />
  </ItemGroup>

  <!--同一解方案下的專案引用-->
  <ItemGroup>
    <ProjectReference Include="..\StandardClassLib2019\StandardClassLib2019.csproj"  />
  </ItemGroup>

  <!--本地元件直接引用-->
  <ItemGroup>
    <Reference Include="KYExpress.Common">
      <HintPath>xxxx\xxxx.dll</HintPath>
      <Private>true</Private>
    </Reference>
  </ItemGroup>
JAVA(編輯POM 檔案,通過dependencies.dependency來宣告引入多個依賴,根據scope可以指定依賴的有效作用範圍)
    <dependencies>
        <!--maven包依賴-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <!--本地JAR包依賴(scope=system,systemPath=jar包存放目錄)-->
        <dependency>
            <groupId>cn.zuowenjun.boot.mybatis.plugin</groupId>
            <artifactId>cn.zuowenjun.boot.mybatis.plugin</artifactId>
            <version>1.0</version>
            <scope>system</scope>
            <systemPath>${basedir}/src/main/libs/xxxxx.jar</systemPath>
        </dependency>

        <!--同一父專案Module之間依賴,注意這個必需先建立基於POM的父專案,然後各子Moudle 的POM 的parent指向父專案-->
        <dependency>
            <groupId>cn.zuowenjun.springboot</groupId>
            <artifactId>springboot-demo1</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

JAVA POM 依賴繼承兩種方式

通過parent繼承,如下所示:(如下是非常典型的spring boot的parent繼承),專案將繼承spring-boot-starter-parent POM中的所有設定及依賴(如:properties、dependencies等)

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>

通過dependencyManagement繼承,如下所示:(這是依賴管理,dependencyManagement裡只是宣告依賴,並不實現引入,因此子專案可按需顯式的宣告所需的依賴項。如果不在子專案中宣告依賴,則不會從父專案中繼承依賴,只有在子專案中宣告瞭依賴項,且沒有指定具體版本,才會從父專案中繼承依賴項,(寫了版本號相當於覆蓋),version和scope都讀取自父pom)

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

二、依賴注入 DI (IOC容器)

C#(一般在Startup檔案中ConfigureServices方法中按需註冊依賴,註冊依賴可以指定生命週期如:AddTransient【瞬時,即:每次都建立新例項】、AddScoped【作用域範圍內】、AddSingleton【單例,僅例項化一次】,具體效果可以參見:在 ASP.NET Core 依賴注入
//1.使用ASP.NET CORE預設的DI框架,在Startup檔案中ConfigureServices方法中按需註冊依賴
        public void ConfigureServices(IServiceCollection services)
        {
            //採用ASP.NET CORE預設的IOC容器註冊
            services.AddTransient<IOperationTransient, Operation>();
            services.AddScoped<IOperationScoped, Operation>();
            services.AddSingleton<IOperationSingleton, Operation>();
            services.AddSingleton<IOperationSingletonInstance>(new Operation(Guid.Empty));
        }

//2.在Controller中就可以直接採用建構函式注入或指明從IOC容器中獲得例項[FromServices]
    [ApiController]
    [Route("api/[controller]")]
    public class DemoController : Controller
    {
        private readonly OperationService operationService;

        public DemoController(OperationService operationService)
        {
            this.operationService = operationService;
        }

        [Route("optid")]
        public object Operation([FromServices]OperationService optSrv){
            //TODO:方法體中直接使用operationService 或 入參optSrv均可
        }
      }

//如上所需介面及類定義

    public interface IOperation
    {
        Guid OperationId { get; }
    }


    public interface IOperationTransient : IOperation
    {
    }

    public interface IOperationScoped : IOperation
    {
    }

    public interface IOperationSingleton : IOperation
    {
    }

    public interface IOperationSingletonInstance : IOperation
    {
    }
    

    public class Operation : IOperationTransient,
        IOperationScoped,
        IOperationSingleton,
        IOperationSingletonInstance
    {
        public Operation() : this(Guid.NewGuid())
        {
        }

        public Operation(Guid id)
        {
            OperationId = id;
        }

        public Guid OperationId { get; private set; }
    }
    
    public class OperationService
    {
        public OperationService(
            IOperationTransient transientOperation,
            IOperationScoped scopedOperation,
            IOperationSingleton singletonOperation,
            IOperationSingletonInstance instanceOperation)
        {
            TransientOperation = transientOperation;
            ScopedOperation = scopedOperation;
            SingletonOperation = singletonOperation;
            SingletonInstanceOperation = instanceOperation;
        }

        public IOperationTransient TransientOperation { get; }
        public IOperationScoped ScopedOperation { get; }
        public IOperationSingleton SingletonOperation { get; }
        public IOperationSingletonInstance SingletonInstanceOperation { get; }

    }

C#使用第三方IOC容器,如:autofac,由第三方IOC容器接管並實現DI,示例如下:(autofac支援更多、更靈活的依賴注入場景)

        public IServiceProvider ConfigureServices(IServiceCollection services)
        {
            //採用ASP.NET CORE預設的IOC容器註冊
            services.AddTransient<IOperationTransient, Operation>();
            services.AddScoped<IOperationScoped, Operation>();
            services.AddSingleton<IOperationSingleton, Operation>();
            services.AddSingleton<IOperationSingletonInstance>(new Operation(Guid.Empty));

            services.AddTransient<OperationService, OperationService>();

            var containerBuilder = new ContainerBuilder();
            containerBuilder.Populate(services); //交由autofac IOC容器管理

            var container = containerBuilder.Build();
            return new AutofacServiceProvider(container);//使用utofac IOC容器
        }
JAVA(可以使用xml來進行Bean的依賴註冊,也可使用註解方式來進行依賴註冊,目前在DI方面更多的是流行註解註冊及注入,故這裡也以註解依賴註冊及注入為簡要說明,更多有關注解依賴註冊及注入以及XML的依賴註冊及注入詳細說明,可查閱我之前的文章:JAVA WEB快速入門之通過一個簡單的Spring專案瞭解Spring的核心(AOP、IOC)

註解依賴註冊一般可以通過自定義一個spring統一註冊配置類,如程式碼中所示BeansConfig,這種一般對於集中註冊Bean或Bean之間有先後依賴,先後順序時比較有效果;另一種是直接在Bean上使用@Component註解(或其它專用含義的註解,如:@Repository、@Service,這些註解本身也標記了@Component註解)

//1. 在自定義的spring統一註冊配置類中註冊相關Bean
@Configuration
public class BeansConfig {

    @Bean
    @Scope("prototype") //singleton,request,session
    @Order(1) //註冊順序
    public DemoBean demoBean(){
        return new DemoBean();
    }

    @Bean("demo") //定義名稱
    @Order(2)
    public  DemoInterface demoInterface(){
        return  new DemoImplBean(demoBean()); //建構函式注入
    }
}

//2.在Controller中就可以直接通過屬性注入或建構函式注入獲得例項,並在ACTION中使用這些例項物件
@RestController
public class DemoController {

    @Autowired
    private  DemoBean demoBean;

    @Autowired
    @Qualifier("demo")//指定從IOC中解析的bean註冊名
    private  DemoInterface demoInterface;

    @Autowired
    private  DemoBean2 demoBean2;

    @RequestMapping(path = "/demo/msg",method = RequestMethod.GET,produces = "application/json;charset=utf-8")
    public Object testMsg(@RequestParam(value = "m",required = false) String m){
        //TODO:可直接使用:demoBean、demoInterface、demoBean2這些私有欄位,它們通過屬性注入
        return "test msg:" + m;
    }

}

//以下是如上所需的類及介面定義

public class DemoBean {

}

public interface DemoInterface {
    void showMsg(String msg);
}

public class DemoImplBean implements  DemoInterface {

    private  DemoBean demoBean;

    public  DemoImplBean(DemoBean demoBean){
        this.demoBean=demoBean;
    }

    @Override
    public void showMsg(String msg) {
        System.out.println("show msg:" + msg);
    }
}

//通過標記Component,交由spring IOC自動掃描註冊
@Component
public class DemoBean2 {

}

三、過濾器、攔截器 AOP

C#(在ASP.NET CORE中實現AOP常見有三種方式:第一種:新增ACTION過濾器(僅適用於MVC);第二種:使用第三方的AOP切面攔截器(如下文的AopInterceptor,可攔截指定的任意位置的虛方法),第三種:在請求管道中新增中介軟體(僅適用MVC))
        public IServiceProvider ConfigureServices(IServiceCollection services)
        {
            services.AddMvc(opt => opt.Filters.Add<AopFilter>() //第一種:新增過濾器,實現ACTION執行前後記錄耗時
                ).SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
            
            var containerBuilder = new ContainerBuilder();
            containerBuilder.Populate(services);

            containerBuilder.RegisterType<AopInterceptor>();
            containerBuilder.RegisterType<OperationService>().InterceptedBy(typeof(AopInterceptor)).EnableClassInterceptors(); //第二種:啟用autofac的AOP攔截
            
            var container = containerBuilder.Build();
            return new AutofacServiceProvider(container);
            
        }


        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            //第三種:使用一個自定義的中介軟體,實現AOP的效果
            app.Use(async (ctx, next) =>
            {
                //如果為示例邏輯
                if (!ctx.Request.Query.TryGetValue("token", out var tokenVal) || tokenVal != "zuowenjun")
                {
                    await ctx.Response.WriteAsync("驗證token失敗,禁止訪問!");
                    return;
                }

                ctx.Request.EnableBuffering();//啟動用buffer,以便可以重置Position
                var requestReader = new StreamReader(ctx.Request.Body);

                var requestContent = requestReader.ReadToEnd();
                ctx.Request.Body.Position = 0; //需要重置為流開頭,否則將導致後續的Model Binding失效等各種問題

                var originalResponseStream = ctx.Response.Body;//記錄原始請求
                using (var ms = new MemoryStream())
                {
                    ctx.Response.Body = ms;//因原始請求為只寫流,故此處用自定義的記憶體流來接收響應流資料

                    var watch = Stopwatch.StartNew();
                    await next.Invoke();
                    watch.Stop();

                    ms.Position = 0;
                    var responseReader = new StreamReader(ms);
                    var responseContent = responseReader.ReadToEnd();

                    string logMsg = $"execedTime:{ watch.ElapsedMilliseconds.ToString() }ms,Request,{requestContent},Response: { responseContent}";
                    Logger.LogInformation(logMsg);

                    ms.Position = 0;//恢復流位置為開頭

                    await ms.CopyToAsync(originalResponseStream); //將當前的流合併到原始流中
                    ctx.Response.Body = originalResponseStream; //恢復原始響應流
                };
            });

            app.UseMvc();

        }



    /// <summary>
    /// Filter僅針對接入層(MVC)有效,底層服務若需使用AOP,則必需使用特定的AOP框架
    /// </summary>
    public class AopFilter : IActionFilter
    {
        private readonly Stopwatch stopWatch = new Stopwatch();

        public void OnActionExecuting(ActionExecutingContext context)
        {
            //執行前邏輯
            stopWatch.Start();
        }

        public void OnActionExecuted(ActionExecutedContext context)
        {
            //執行後邏輯
            stopWatch.Stop();
            var returnResult = context.Result;
            if (returnResult is ObjectResult)
            {
                var objResult = (returnResult as ObjectResult);
                objResult.Value = new { Original = objResult.Value, ElapsedTime = stopWatch.ElapsedMilliseconds.ToString() + "ms" };
            }
            else if (returnResult is JsonResult)
            {
                var jsonResult = (returnResult as JsonResult);
                jsonResult.Value = new { Original = jsonResult.Value, ElapsedTime = stopWatch.ElapsedMilliseconds.ToString() + "ms" };
            }
        }


    }
JAVA(可以通過自定義Filter、HandlerInterceptor、MethodInterceptor 、around AOP增強等方式實現AOP攔截處理)

//最先執行,由servlet攔截請求(適用WEB)
@WebFilter(filterName = "demoFilter",urlPatterns = "/*")
class  DemoFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        //初始化
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //過濾處理
    }

    @Override
    public void destroy() {
        //銷燬之前執行
    }
}

//其次執行,由spring MVC攔截請求(適用Spring MVC)
@Component
public class DemoHandlerInterceptor implements HandlerInterceptor  {
//也可繼承自HandlerInterceptorAdapter

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //執行前

        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        //執行後,生成檢視之前執行
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        //在DispatcherServlet完全處理完請求之後被呼叫,可用於清理資源
    }
}

//最後執行,攔截方法
@Component
class DemoMethodInterceptor implements MethodInterceptor{

    @Override
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        return null;
    }
}

//方法攔截的另一種形式
@Component
@Aspect
class AutoAspectJInterceptor {

    @Around("execution (*..controller.*.*(..))")
    public Object around(ProceedingJoinPoint point) throws Throwable{
        //執行前
        Object object = point.proceed();
        //執行後
        return object;
    }

}

特別說明:ASP.NET CORE中的Fitler 與Spring MVC中的MethodInterceptor類似,都是控制方法,而ASP.NET CORE中的請求管道中介軟體與Spring MVC中的Filter、HandlerInterceptor類似,都是控制請求過程。這點要搞清楚。

四、配置讀取

C#(支援多種配置資料提供程式,支援多種獲取配置資訊的方式,詳見:ASP.NET Core 中的配置
            //Configuration為IConfiguration例項物件
            Configuration.GetValue("key");//適用單個key-value
            Configuration.Get<TConfig>();//適用整個config檔案對映為一個TConfig型別的物件
            Configuration.GetSection("key").GetChildren();//獲取子項集合
JAVA(支援多種配置資料來源格式(yml,Properties),可通過@value、@ConfigurationProperties、Environment等常見方法來獲取配置資訊)
    //1.通過@value方式獲取配置資訊
    @Value("${zuowenjun.site}")
    public String zwjSite;

    //2.通過建立一個對映配置資訊的Bean(ConfigProperties) 方式獲取配置資訊
    @Component
    @ConfigurationProperties()//如果有字首,則可以設定prefix=XXX
        public static class Zuowenjun {

        private String site;
        private String skills;
        private String motto;


        public String getSite() {
            return site;
        }

        public void setSite(String site) {
            this.site = site;
        }

        public String getSkills() {
            return skills;
        }

        public void setSkills(String skills) {
            this.skills = skills;
        }

        public String getMotto() {
            return motto;
        }

        public void setMotto(String motto) {
            this.motto = motto;
        }

    }

//3.通過Environment來直接獲取配置資訊
environment.getProperty("zuowenjun.site");

五、釋出、部署、執行

C#(ASP.NET CORE:除了如下使用.NET CLI命今進行釋出打包,也可以使用VS或VS CODE視覺化操作進行釋出操作)

dotnet publish --configuration Release

JAVA(Spring MVC:除了如下使用MAVEN命令進行清理打包,還可以使用IDEA來進行打包,具體方法可參見:Springboot專案打包成jar執行2種方式

mvn clean package;

C#(ASP.NET CORE)、JAVA(Spring MVC)都可以:

  1. 都支援WINDOWS伺服器、Linux伺服器等多種平臺伺服器 部署執行

  2. 都支援使用命令列啟動執行ASP.NET CORE 或Spring MVC應用,例如:

    dotnet aspnetcoreApp.dll --urls="http://*:5001"

    java -jar springmvcApp.jar --server.port=5001

  3. 都支援Jenkins CI&CD ,Docker、k8s虛擬化部署

  4. 都支援在Linux伺服器中以守護程式方式執行,例如:

    nohup dotnet aspnetcoreApp.dll > aspnetcoreApp.out 2>&1 &

    nohup java -jar springmvcApp.jar > springmvcApp.out 2>&1 &

    //或者都使用Supervisor來構建守護程式,還提供管理UI,具體請參見網上相關資源

好了,總結到此結束,願能幫助到那些處於.NET 轉JAVA 或JAVA 轉.NET或者想多瞭解一門程式語言的朋友們,祝大家事業有成。今後將分享更多關於分散式、演算法等方面的知識,不侷限.NET或JAVA語言,敬請期待,謝謝!

碼字不易,若需轉載及轉載我之前的文章請註明出處,謝謝。

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