【Groovy】MOP 元对象协议与元编程 ( 方法注入 | 同时注入普通方法、静态方法、构造方法 )

public static MetaClass metaClass(Class self, Closure closure) {
        MetaClassRegistry metaClassRegistry = GroovySystem.getMetaClassRegistry();
        MetaClass mc = metaClassRegistry.getMetaClass(self);
        if (mc instanceof ExpandoMetaClass) {
            ((ExpandoMetaClass)mc).define(closure);
            return mc;
        } else if (mc instanceof DelegatingMetaClass && ((DelegatingMetaClass)mc).getAdaptee() instanceof ExpandoMetaClass) {
            ((ExpandoMetaClass)((DelegatingMetaClass)mc).getAdaptee()).define(closure);
            return mc;
        } else if (mc instanceof DelegatingMetaClass && ((DelegatingMetaClass)mc).getAdaptee().getClass() == MetaClassImpl.class) {
            ExpandoMetaClass emc = new ExpandoMetaClass(self, false, true);
            emc.initialize();
            emc.define(closure);
            ((DelegatingMetaClass)mc).setAdaptee(emc);
            return mc;
        } else if (mc.getClass() == MetaClassImpl.class) {
            MetaClass mc = new ExpandoMetaClass(self, false, true);
            mc.initialize();
            ((ExpandoMetaClass)mc).define(closure);
            metaClassRegistry.setMetaClass(self, mc);
            return mc;
        } else {
            throw new GroovyRuntimeException("Can't add methods to custom meta class " + mc);
        }
    }

类名.mateClass {
  // 注入普通方法
  普通方法名 = {闭包}
  // 注入静态方法
  'static' {
  静态方法名 = {闭包}
  }
    // 注入构造方法
    constructor = {
        构造方法参数列表 ->
          构造方法内容
            要返回的实例对象
    }
}

class Student {
    def name;
}

// 注入多个类型的方法
Student.metaClass {
    // 注入普通方法
    hello = {
        println "Hello ${delegate.name}"
    }
    // 注入普通方法
    say = {
        println "My name is ${delegate.name}"
    }
    // 注入静态方法
    'static' {
        fun = {
            println "Class Type : ${delegate}"
        }
    }
    // 注入构造方法
    constructor = {
        String str ->
            new Student(name: str)
    }
}

class Student {
    def name;
}
// 注入多个类型的方法
Student.metaClass {
    // 注入普通方法
    hello = {
        println "Hello ${delegate.name}"
    }
    // 注入普通方法
    say = {
        println "My name is ${delegate.name}"
    }
    // 注入静态方法
    'static' {
        fun = {
            println "Class Type : ${delegate}"
        }
    }
    // 注入构造方法
    constructor = {
        String str ->
            new Student(name: str)
    }
}
// 调用注入的静态方法
Student.fun()
// 使用注入的构造方法初始化 Student 类
def student = new Student("Tom")
// 调用注入的普通方法
student.hello()
student.say()

Class Type : class Student
Hello Tom
My name is Tom