Java:反射调用类的函数

1.若调用的函数所属的类为自定义类，则将函数和类写进map中

Map methods = new HashMap();

methods.put("__plus","Param.tool");

2.通过将函数名称获取相应的class，再获取函数对象

Class c = Class.forName((String)methods.get(name.toString())); //通过函数名称获取对应的类名，通过类名获取类

Object obj = c.newInstance();

Method methods = c.getMethod(name.replace("__", ""), args.getClass()); //通过类对象获取方法对象

3.调用函数

methods.invoke(obj, (Object)args);

注意：若传递的对象为数组时，传递被认为是多个参数，导致wrong number of arguments异常

此处强制转为一个Object对象即可

package Param;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.HashMap;

import java.util.Map;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import org.apache.jmeter.functions.BeanShell;

public class CallMethod {

private static Map methods = new HashMap();

public CallMethod() {

    methods.put("__plus","Param.tool");

}

public static Object getMethod(String method) throws ClassNotFoundException, NoSuchMethodException,

    SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {

    Matcher m = Pattern.compile("(__[a-z]{1,})\\((.*?)\\)").matcher(method.toLowerCase());

    String name = "";

    String[] args = new String[] {};

    while(m.find()) {

        System.out.println(m.group());

        name = m.group(1);

        args = m.group(2).split(",");

    }

    Class c = Class.forName((String)methods.get(name.toString()));

    Object obj = c.newInstance();

    Method methods =  c.getMethod(name.replace("__", ""), args.getClass());

    System.out.println(methods.toString());

    return methods.invoke(obj, (Object)args);

public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {

CallMethod md = new CallMethod();

Object m = md.getMethod("__plus(1,2,3,4,5)");

System.out.println(m.toString());

}

}

相应的加函数

package Param;

public class tool {

    public static String plus(String[] args) {

        int sum =0;

        for(int i=0;i<args.length;i++) {

            sum += new Integer(args[i]);

        }

        return "" + sum;

}