动态调用方法 [英] Dynamically invoke methods

问题描述

我在这里需要一点帮助，如果您知道如何解决我的问题，请告诉我.

I need a little bit of help here, tell me if you have any idea how to solve my problem.

假设我有这门课:

public testClass{

    public int example1(){
    return 2;
    }
    public int example2(){
    return 0;
    }
    public int example3(){
    return 456;
    }
}

我想要一个方法和这个方法做同样的事情，但是以动态的方式

I want a method which will do the same thing that this method, but in a dynamic way

public int methodeSwitch(int a){
   if (a==1){return method1;}
   if (a==2){return method2;}
   if (a==3){return method3;}
   return null;
}

我的问题是我有一个包含 50 多个字段的大型类 (dto)，所以我想根据我目前使用的字段来使用 getter 和 setter(所以是的，动态的).我知道如何访问字段(使用 java.lang.Field，wouuu)，但我不知道如何按名称强制转换方法(将动态创建).

My problem is that I have a huge class (dto) with 50+ fields, so i'd like to use getters and setters depending on the fields that i use at the moment (so yeah, dynamically). I know how to access fields (with java.lang.Field, wouuu), but i have no clue on how I could cast a method by its name (which will be created dynamically).

只要给我一个提示就太棒了！

Just giving me a hint would be amazing!

谢谢法比安

澄清一下，我必须编写一个方法，它基本上使用我班上的每个 setter，所以如果我可以使用类似

to clarify, I have to write a method who basically use every setters of my class, so if I could use something like

useMethod("set"+fields[i]+"();");

这会很有帮助，并且可以防止我编写数十行代码.

That would be helpful and prevent me from writing dozens of lines of code.

再次感谢帮助的人！;)

Thanks again for the ones helping! ;)

推荐答案

您需要使用反射从您的类中获取声明的方法.我假设这些方法存在于您想要调用 getter/setter 的类中，并且 fields 是字段名称的 String[].

You need to use reflection to get the declared method from you class. I have assumed that these methods live in the class on which you want to invoke the getter/setter and that fields is a String[] of field names.

private Object callGet(final String fieldName) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
    final Method method = getClass().getDeclaredMethod("get" + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1));
    return method.invoke(this, (Object[]) null);
}

private void callSet(final String fieldName, final Object valueToSet) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
    final Method method = getClass().getDeclaredMethod("set" + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1), new Class[]{valueToSet.getClass()});
    method.invoke(this, new Object[]{valueToSet});
}

你也可以看看 Commons BeansUtil 这是一个设计的库正是为了做到这一点...

You could also have a look at Commons BeansUtil which is a library designed for doing exactly this...

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