java反射使用及性能比较

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环境准备

package com.lilei.pack09;public class Logger { public void show(){
System.out.println("hello world");
} public int cal(int a,int b){
return a + b;
} public String multi(String... args){ return args.length+";";
}}

使用反射

package com.lilei.pack09;import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;public class app1 { public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException { Class c = Class.forName("com.lilei.pack09.Logger"); Method[] ms = c.getMethods(); Method m_show = c.getMethod("show", null); m_show.invoke(new Logger(), null); Method m_cal = c.getMethod("cal", new Class[]{int.class,int.class}); Object result = m_cal.invoke(new Logger(), 233,2233); new Logger().multi("v","dd","ds"); System.out.println(result); Method m_multi = c.getMethod("multi", new Class[]{String[].class}); result = m_multi.invoke(new Logger(), new Object[]{new String[]{"v","dd","ds"}}); System.out.println(result);
}}

性能比较

常规创建对象调用方法和通过反射进行调用方法

package com.lilei.pack09;import java.util.Date;public class app2 { public static void main(String[] args) { Logger logger = new Logger(); int result = 0; System.out.println(new Date());
for (int i = 0; i < 2000000000; i++){
result += logger.cal(i,i);
} System.out.println(result);
System.out.println(new Date());
}}

消耗时间：

package com.lilei.pack09;import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Date;public class app3 { public static void main(String[] args) throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException { Logger logger = new Logger(); Method m = logger.getClass().getMethod("cal", new Class[]{int.class,int.class}); int result = 0; System.out.println(new Date());
for (int i = 0; i < 2000000000; i++){
Integer in = (Integer)m.invoke(logger, i,i);
result += in.intValue();
} System.out.println(result);
System.out.println(new Date());
}}

消耗时间：