Groovy DSL与Java [英] Groovy DSL with Java

问题描述

从我开始使用Groovy已经过去了几天。但是随着所有的阅读和冲浪，我还没有完全弄清楚如何实现我的想法。所以，请原谅我作为初学者。感谢您的帮助，一如既往。

我想实现的是：我有一个Java类，比如<$ （code> getMethod（）， postMethod（）的c $ c> ServiceClass 等等）做出一些REST GET / POST请求（在它自己的情况下，它工作正常）。现在，我想公开一个DSL，以便最终用户可以这样说： callService ServiceClass方法getMethod 并且执行 ServiceClass .getMethod（）

我一直在尝试的是：我得到了一个 userCommand 文件放在某处，现在只读： callService ServiceClass

我有一个<$ c $

  class示例{
 def  sample.groovy  srvc 
 def callService（srvc）{
 this.srvc = srvc 
调用$ srvc
} 
} 
  

我得到了一个 integrator.groovy 文件：

  //必要的输入
 class Integrator {
 def sample = new Sample（）
 def binding = new Binding（[
 sample：sample，
 ServiceClass：new ServiceClass（），
 callService：sample。& callService]）
 def sh ell = new GroovyShell（binding）
 
 def runIt（）{
 shell.evaluate（userCommand）
} 
} 
  
 
然后从我的Java应用程序运行它，我这样做： 
 
 
 public static void main（String [] args）{
 Integator i = new Integrator（）
 i.runIt（）; 
} 
  
但这不起作用。使用上面的语法说：
 
 
 
 
线程main中的异常java.lang.NullPointerException：无法在null对象上调用方法setVariable（） .... 
 
任何人都可以告诉我如何传递参数并创建对象实例？
解决方案
 更新：考虑以下 userCommand 文件：
 
 $ b 
文件 userCommand ：
  callService ServiceClass getMethod 
  
 groovy将解析为 callService（ServiceClass） .getGetMethod（）。因此，您需要一个 getProperty 方法，将调用重定向到正确的方法： 
 
 
文件 Dsl.groovy ：
  class Dsl {
 static void main（args）{
新的Integrator（）。runIt（）
} 
} 
 
 class DslDelegate {
 def service 
 def callService（service）{
 this.service = service 
 this 
} 
 $ b $ def getProperty（String prop）{
 if（prop ==getMethod）{service.getMethod（ ）} 
 else {throw new RuntimeException（Unrecognized property'$ prop'）} 
} 
} 
 
 class ServiceClass {
 def getMethod（ ）{serviceClass getMethod} 
} 
 $ b $ class Integrator {
 def dslDelegate = new DslDelegate（）
 def binding = new Binding（[
 ServiceClass ：new ServiceClass（），
 callService：dslDelegate。& callService]）
 def shell = new GroovyShell（binding）
 
 def run It（）{
 assert shell.evaluate（new File（userCommand））== 
serviceClass getMethod
} 
} 
  Sample 类，所以它变成了一个委托给<$ c $>的类。 
 C>服务类。现在它分离了DSL /服务的职责。
 
 
 
您也可以执行 callService ServiceClass方法getMethod ，但它需要更多的代码。
 
It has been a couple of days since I started with Groovy. But with all the reading and surfing, I haven't quite been able to figure out how to accomplish what I have in mind. So, please excuse me as a beginner. Would be much grateful for your help, as always.

What I want to achieve is this: I have a Java class, say ServiceClass that has some methods (getMethod(), postMethod() etc) to make some REST GET/POST requests (on its own, it works fine). Now, I want to expose a DSL so that the end-user may just say something like: callService ServiceClass method getMethod and I have the execution of ServiceClass.getMethod()

What I have been trying so far is this: I got a userCommand file placed somewhere, that for now just reads: callService ServiceClass

I have a sample.groovy that just does this now:
class Sample {
    def srvc
    def callService(srvc) {
        this.srvc = srvc
        "Calling $srvc"
    }
}
I got an integrator.groovy file that has:
//necessary imports
class Integrator{
    def sample = new Sample()
    def binding = new Binding([
        sample:sample, 
        ServiceClass: new ServiceClass(), 
        callService:sample.&callService ])
    def shell = new GroovyShell(binding)

    def runIt() {
        shell.evaluate("userCommand")
    }
}
And then to run it from my Java application, I am doing:
public static void main(String[] args) {
    Integator i = new Integrator()
    i.runIt();
}
But this is just not working. With the above syntax it says: 

  
Exception in thread "main" java.lang.NullPointerException: Cannot invoke method setVariable() on null object....
Could anyone please tell me how do I pass around parameters and create object instances?
解决方案
Update: Consider the following userCommand file:

File userCommand:
callService ServiceClass getMethod
Which will be parsed by groovy as callService(ServiceClass).getGetMethod(). So you need a getProperty method which reroute the call to the correct method:

File Dsl.groovy: 
class Dsl {
  static void main(args) {
      new Integrator().runIt()
  }
}

class DslDelegate {
    def service
    def callService(service) {
        this.service = service
        this
    }

    def getProperty(String prop) {
      if (prop == "getMethod") { service.getMethod() }
      else { throw new RuntimeException("Unrecognized property '$prop'") }
    }
}

class ServiceClass {
  def getMethod() { "serviceClass getMethod" }
}

class Integrator{
    def dslDelegate = new DslDelegate()
    def binding = new Binding([
        ServiceClass: new ServiceClass(), 
        callService:dslDelegate.&callService ])
    def shell = new GroovyShell(binding)

    def runIt() {
        assert shell.evaluate(new File("userCommand")) == 
            "serviceClass getMethod"
    }
}
Note I renamed the Sample class, so it becomes a delegator to ServiceClass. Now it separates DSL/Service responsibilities.

You can do callService ServiceClass method getMethod too, but it requires more code.

                        
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