Java Reflection教程(5):Methods类方法

2014-11-24 08:07:28 · 作者: · 浏览: 0

过Class 的getMethods 可以取的类方法的定义

[java]
Class aClass = ...//obtain class object
Method[] methods = aClass.getMethods();
Class aClass = ...//obtain class object
Method[] methods = aClass.getMethods();

如果知道类方法的参数类型,则可以使用getMethod 取的对应的方法定义,如:

[java]
Class aClass = ...//obtain class object
Method method =
aClass.getMethod("doSomething", new Class[]{String.class});
Class aClass = ...//obtain class object
Method method =
aClass.getMethod("doSomething", new Class[]{String.class});

上例取的方法名为doSomething 带一个String为参数的方法定义。如果找不到对应的方法,Java Reflection 抛出NoSuchMethodException 异常。

如果需要方法的方法不带参数,则使用null 做为getMethod的第二个参数,如下:

[java]
Class aClass = ...//obtain class object
Method method =
aClass.getMethod("doSomething", null);
Class aClass = ...//obtain class object
Method method =
aClass.getMethod("doSomething", null);

1. 获取方法的参数和返回值定义

获取参数定义

[java]
Method method = ... // obtain method - see above
Class[] parameterTypes = method.getParameterTypes();
Method method = ... // obtain method - see above
Class[] parameterTypes = method.getParameterTypes();

获取返回值定义

[java]
Method method = ... // obtain method - see above
Class returnType = method.getReturnType();
Method method = ... // obtain method - see above
Class returnType = method.getReturnType();
2. 使用Method对象调用该方法

[java]
//get method that takes a String as argument
Method method = MyObject.class.getMethod("doSomething", String.class);

Object returnValue = method.invoke(null, "parameter-value1");
//get method that takes a String as argument
Method method = MyObject.class.getMethod("doSomething", String.class);

Object returnValue = method.invoke(null, "parameter-value1");
method.invoke 的调用个参数为该方法对应的类对象,如果方法为static 类型,则使用null,后面的参数为该方法的参数值。

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