使用JAVA反射类执行函数

Question

当我调用myClass时，我有以下课程。doprocess（），我应该得到字符串“hai”，如何实现它

public class myClass{
    public int doprocess(){
        dataClass objSt = new dataClass();
        Class newCls = objSt.getClass();
        Method[] methods = newCls.getMethods();
        for (Method method : methods) {
            if(method.getName() == "getList"){
                return method;
            }

        }
    }
 }

class dataClass{
   public String getList(){
        return "hai,";
    }
}

如果我执行上述代码，我会得到如下响应

public java.lang.String com.myproject.controller.dataClass.getList()

但我需要响应是getList函数的返回值

Answer 1

无法编译当前代码，因为doprocess方法声明为返回int，但方法体返回Method对象

要使用反射调用该方法，请使用invoke

试试这个：

class myClass {
    public Method doprocess() {
        dataClass objSt = new dataClass();
        Class newCls = objSt.getClass();
        Method[] methods = newCls.getMethods();
        for (Method method : methods) {
            System.out.println(method.getName());
            if (method.getName() == "getList") {
                return method;
            }

        }
        return null;
    }

    public static void main(String[] args) {
        try {
            Method m = new myClass().doprocess();
            if(m != null) System.out.println(m.invoke(new dataClass()));
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

class dataClass {
    public String getList() {
        return "hai,";
    }
}

Answer 2

您可以使用getDeclaredMethod获取具有给定名称和参数集的方法，然后可以使用Method.invoke(instance, params...)调用该方法

class myClass {
    public String doprocess() throws SecurityException, NoSuchMethodException,
            IllegalArgumentException, IllegalAccessException,
            InvocationTargetException {
        dataClass objSt = new dataClass();
        Method m = dataClass.class
                .getDeclaredMethod("getList", (Class<?>) null);
        return (String) m.invoke(objSt, (Object) null);
    }
}

class dataClass {
    public String getList() {
        return "hai,";
    }
}

试验

public class Test {

    public static void main(String[] args) throws SecurityException,
            IllegalArgumentException, NoSuchMethodException,
            IllegalAccessException, InvocationTargetException {
        myClass m = new myClass();
        System.out.println(m.doprocess());
    }

}