java反射技术的简单应用

一.反射介绍

java反射技术的应用广泛，能够对类的方法和参数进行配置，完成对象的初始化工作，增加了java的灵活性，SpringIOC也使用了反射技术，下文主要讲解对象的构建和方法的反射调用。

二.通过反射调用对象

1.构建无参方法的类

public class ReflectService {
    public void hello(String name){
        System.out.println("hello"+name);
    }

    public  ReflectService getInsatance() {
        ReflectService reflectService=null;
        try{
//通过给类加载器一个类的全限定类名，再通过newInstance()方法初始化一个类对象
//也可以用对象.getClass();或者类.Class得到类对象

reflectService= (ReflectService) 
Class.forName("com.mc74120.project_learn.config.ReflectService").newInstance(); 
} catch 
(ClassNotFoundException|InstantiationException|IllegalAccessException exception){ 
ex.printStackTrace();
} 
return reflectService; 
} }

2.构建有参方法的类

public class ReflectService {
    private String name;
    public void hello(String name){
        System.out.println("hello"+name);
    }

    public ReflectService(String name) {
        this.name = name;
    }

    public  ReflectService getInsatance() {
        ReflectService reflectService=null;
        try{
            reflectService= (ReflectService) Class.forName("com.mc74120.project_learn.config.ReflectService").getConstructor(String.class).newInstance("010");
        }
        catch (ClassNotFoundException | InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException exception){

        }
        return  reflectService;
    }
}

先通过forName得到类加载器，getConstructor()方法设定参数的类型，再通过newInstance()生成对象。

3.反射方法

 public void reflectMethod() {
        Object returnObj = null;
        ReflectService target = null;
        try {
            target = ReflectService.class.newInstance();
            Method method = ReflectService.class.getMethod("hello", String.class);
            returnObj = method.invoke(target, "010");
        } catch (NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }
}
//Method method = ReflectService.class.getMethod("hello", String.class);
//returnObj = method.invoke(target, "010"); target 哪个对象调用此方法，010为参数，