Object obj;

Method method = obj.getClass().getMethod("methodName", null);

method.invoke(obj, null);

为了完成我同事的回答，你可能需要密切关注以下问题:

static or instance calls (in one case, you do not need an instance of the class, in the other, you might need to rely on an existing default constructor that may or may not be there) public or non-public method call (for the latter,you need to call setAccessible on the method within an doPrivileged block, other findbugs won't be happy) encapsulating into one more manageable applicative exception if you want to throw back the numerous java system exceptions (hence the CCException in the code below)

下面是一个旧的java1.4代码，它考虑了这些要点:

/**
 * Allow for instance call, avoiding certain class circular dependencies. <br />
 * Calls even private method if java Security allows it.
 * @param aninstance instance on which method is invoked (if null, static call)
 * @param classname name of the class containing the method 
 * (can be null - ignored, actually - if instance if provided, must be provided if static call)
 * @param amethodname name of the method to invoke
 * @param parameterTypes array of Classes
 * @param parameters array of Object
 * @return resulting Object
 * @throws CCException if any problem
 */
public static Object reflectionCall(final Object aninstance, final String classname, final String amethodname, final Class[] parameterTypes, final Object[] parameters) throws CCException
{
    Object res;// = null;
    try {
        Class aclass;// = null;
        if(aninstance == null)
        {
            aclass = Class.forName(classname);
        }
        else
        {
            aclass = aninstance.getClass();
        }
        //Class[] parameterTypes = new Class[]{String[].class};
    final Method amethod = aclass.getDeclaredMethod(amethodname, parameterTypes);
        AccessController.doPrivileged(new PrivilegedAction() {
    public Object run() {
                amethod.setAccessible(true);
                return null; // nothing to return
            }
        });
        res = amethod.invoke(aninstance, parameters);
    } catch (final ClassNotFoundException e) {
        throw new CCException.Error(PROBLEM_TO_ACCESS+classname+CLASS, e);
    } catch (final SecurityException e) {
        throw new CCException.Error(PROBLEM_TO_ACCESS+classname+GenericConstants.HASH_DIESE+ amethodname + METHOD_SECURITY_ISSUE, e);
    } catch (final NoSuchMethodException e) {
        throw new CCException.Error(PROBLEM_TO_ACCESS+classname+GenericConstants.HASH_DIESE+ amethodname + METHOD_NOT_FOUND, e);
    } catch (final IllegalArgumentException e) {
        throw new CCException.Error(PROBLEM_TO_ACCESS+classname+GenericConstants.HASH_DIESE+ amethodname + METHOD_ILLEGAL_ARGUMENTS+String.valueOf(parameters)+GenericConstants.CLOSING_ROUND_BRACKET, e);
    } catch (final IllegalAccessException e) {
        throw new CCException.Error(PROBLEM_TO_ACCESS+classname+GenericConstants.HASH_DIESE+ amethodname + METHOD_ACCESS_RESTRICTION, e);
    } catch (final InvocationTargetException e) {
    throw new CCException.Error(PROBLEM_TO_ACCESS+classname+GenericConstants.HASH_DIESE+ amethodname + METHOD_INVOCATION_ISSUE, e);
    } 
    return res;
}

从通俗的角度来说，它应该是这样的:

java.lang.reflect.Method method;
try {
  method = obj.getClass().getMethod(methodName, param1.class, param2.class, ..);
} catch (SecurityException e) { ... }
  catch (NoSuchMethodException e) { ... }

参数确定你需要的非常具体的方法(如果有几个重载可用，如果方法没有参数，只给出methodName)。

然后通过调用调用该方法

try {
  method.invoke(obj, arg1, arg2,...);
} catch (IllegalArgumentException e) { ... }
  catch (IllegalAccessException e) { ... }
  catch (InvocationTargetException e) { ... }

同样，如果没有.invoke中的参数，请省略。但是是的。阅读Java反射

从反射使用方法调用:

Class<?> c = Class.forName("class name");
Method method = c.getDeclaredMethod("method name", parameterTypes);
method.invoke(objectToInvokeOn, params);

地点:

“class name”是类的名称 objectToInvokeOn类型为Object，是您希望在其上调用方法的对象 "method name"是你想要调用的方法的名称 parameterTypes的类型是Class[]，声明方法所接受的参数 params类型为Object[]，声明要传递给方法的参数

对于那些想要Java 7中简单的代码示例的人:

狗类:

package com.mypackage.bean;

public class Dog {
    private String name;
    private int age;

    public Dog() {
        // empty constructor
    }

    public Dog(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void printDog(String name, int age) {
        System.out.println(name + " is " + age + " year(s) old.");
    }
}

ReflectionDemo类:

package com.mypackage.demo;

import java.lang.reflect.*;

public class ReflectionDemo {

    public static void main(String[] args) throws Exception {
        String dogClassName = "com.mypackage.bean.Dog";
        Class<?> dogClass = Class.forName(dogClassName); // convert string classname to class
        Object dog = dogClass.newInstance(); // invoke empty constructor

        String methodName = "";

        // with single parameter, return void
        methodName = "setName";
        Method setNameMethod = dog.getClass().getMethod(methodName, String.class);
        setNameMethod.invoke(dog, "Mishka"); // pass arg

        // without parameters, return string
        methodName = "getName";
        Method getNameMethod = dog.getClass().getMethod(methodName);
        String name = (String) getNameMethod.invoke(dog); // explicit cast

        // with multiple parameters
        methodName = "printDog";
        Class<?>[] paramTypes = {String.class, int.class};
        Method printDogMethod = dog.getClass().getMethod(methodName, paramTypes);
        printDogMethod.invoke(dog, name, 3); // pass args
    }
}

输出: 米什卡3岁了。

你可以用这种方法调用带形参的构造函数:

Constructor<?> dogConstructor = dogClass.getConstructor(String.class, int.class);
Object dog = dogConstructor.newInstance("Hachiko", 10);

或者，您可以删除

String dogClassName = "com.mypackage.bean.Dog";
Class<?> dogClass = Class.forName(dogClassName);
Object dog = dogClass.newInstance();

,做

Dog dog = new Dog();

Method method = Dog.class.getMethod(methodName, ...);
method.invoke(dog, ...);

推荐阅读:创建新类实例

Object obj;

Method method = obj.getClass().getMethod("methodName", null);

method.invoke(obj, null);