Java反射机制-简单案例实现（代码篇）

package cn.gzx.baike;import java.io.Serializable;import java.lang.reflect.Array;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import java.lang.reflect.Proxy;import java.util.ArrayList;public class TestReflect implements Serializable{    private static final long serialVersionUI = -2862585049955236662L;//L代表长整型    private String proprety = null;    public static void main(String[] args) throws Exception{        /* 通过一个对象获得完整的包名 和 类名*/        TestReflect testReflect = new TestReflect();        System.out.println(testReflect.getClass().getName());        // 实例化Class对象        Class<?> class1 = null;        Class<?> class2 = null;        Class<?> class3 = null;        //一般采用这种形式        class1 = Class.forName("cn.gzx.baike.TestReflect");        class2 = new TestReflect().getClass();        class3 = TestReflect.class;        System.out.println(class1.getName());        System.out.println(class2.getName());        System.out.println(class3.getName());        /* 获取一个对象的父类与实现的接口*/        Class<?> clazz = Class.forName("cn.gzx.baike.TestReflect");        //取得父类        Class<?> parentClass = clazz.getSuperclass();        System.out.println("clazz的父类为:" + parentClass.getName());        //clazz的父类为：java.lang.Object        //获取所有的接口        Class<?> intes[] = clazz.getInterfaces();        System.out.println("clazz实现的接口有：");        for(int i = 0;i<intes.length;i++) {            System.out.println((i+1) + ": " + intes[i].getName());        }        /*通过反射机制实例化一个类的对象*/        class1 = Class.forName("cn.gzx.baike.User");        //第一种方法，实例化默认构造方法，调用set赋值        User user = (User)class1.newInstance();        user.setAge(20);        user.setName("Gzx");        System.out.println(user);        //第二种方法，取得全部的构造函数 使用构造函数赋值        Constructor<?> cons[] = class1.getConstructors();        //查看每个构造方法需要的参数        for(int i = 0; i < cons.length; i++) {            Class<?> clazzs[] = cons[i].getParameterTypes();            System.out.print("cons["+ i +"] (");            for(int j = 0; j < clazzs.length; j++) {                if(j == clazzs.length - 1) {                    System.out.print(clazzs[j].getName());                }else {                    System.out.print(clazzs[j].getName()+",");                }            }            System.out.println(")");        }        user = (User) cons[1].newInstance("Gzx");        System.out.println(user);        user = (User) cons[2].newInstance(20,"Gzx");        System.out.println(user);        //获取某个类的全部属性        System.out.println("==============本类属性==============");        //取得本类的全部属性        Field[] field = clazz.getDeclaredFields();        for(int i = 0; i < field.length; i++){            //权限修饰符            int mo = field[i].getModifiers();            String priv = Modifier.toString(mo);            //属性类型            Class<?> type = field[i].getType();            System.out.println(priv + " " + type.getName()+ " "+ field[i].getName() +";");        }        System.out.println("=========实现的接口或父类的属性=========");        //取得实现的接口或者父类的属性        Field[] field1 = clazz.getFields();        for(int j = 0; j<field.length; j++){            //权限修饰符            int mo = field[j].getModifiers();            String priv = Modifier.toString(mo);            //属性类型            Class<?> type = field[j].getType();            System.out.println(priv + " " + type.getName()+ " "+ field[j].getName() +";");        }        /*获取某个类的全部方法*/        Method method[] = clazz.getMethods();        for(int i = 0; i<method.length;i++){            Class<?> returnType = method[i].getReturnType();            Class<?> para[] = method[i].getParameterTypes();            int temp = method[i].getModifiers();            System.out.print(Modifier.toString(temp) + " ");            System.out.print(returnType.getName() + "  ");            System.out.print(method[i].getName() + " ");            System.out.print("(");            for (int j = 0; j < para.length; ++j) {                System.out.print(para[j].getName() + " " + "arg" + j);                if (j < para.length - 1) {                    System.out.print(",");                }            }            Class<?> exce[] = method[i].getExceptionTypes();            if (exce.length > 0) {                System.out.print(") throws ");                for (int k = 0; k < exce.length; ++k) {                    System.out.print(exce[k].getName() + " ");                    if (k < exce.length - 1) {                        System.out.print(",");                    }                }            } else {                System.out.print(")");            }            System.out.println();        }        /*通过反射机制调用某个类的方法*/        Method method1 = clazz.getMethod("reflect1");        method1.invoke(clazz.newInstance());        method1 = clazz.getMethod("reflect2", int.class, String.class);        method1.invoke(clazz.newInstance(), 20, "张三");        /*通过反射机制操作某个类的属性*/        Object obj = clazz.newInstance();        //可以直接对private         Field fie = clazz.getDeclaredField("proprety");        fie.setAccessible(true);        fie.set(obj, "Java_Reflect");        System.out.println(fie.get(obj));        /**反射机制的动态代理*/        MyInvocationHandler demo = new MyInvocationHandler();        Subject sub = (Subject)demo.bind(new RealSubject());        String info = sub.say("Gzx", 20);        System.out.println(info);        /*在泛型为Integer的ArrayList中存放一个String类型的对象*/        ArrayList<Integer> list = new ArrayList<Integer>();        Method method2 = list.getClass().getMethod("add", Object.class);        method2.invoke(list, "Java_Reflect");        System.out.println(list.get(0));        /*通过反射机制修改数组的大小*/        int[] temp = {1,2,3,4,5,6,7,8,9};        int[] newtemp = (int[])arrayInc(temp, 15);        print(newtemp);        String[] atr = {"a","b","c"};        String[] str1 = (String[]) arrayInc(atr, 8);        print(str1);    }    public void reflect1() {        System.out.println("调用了方法1.");    }    public void reflect2(int age, String name) {        System.out.println("调用了方法2.");        System.out.println("age : " + age + ", name : " + name);    }    public static Object arrayInc(Object obj,int len){        Class<?> arr = obj.getClass().getComponentType();        Object newArr = Array.newInstance(arr, len);        int co = Array.getLength(obj);        System.arraycopy(obj, 0, newArr, 0, co);        return newArr;    }    public static void print(Object obj){        Class<?> c = obj.getClass();        if(!c.isArray()){            return;        }        System.out.println("数组长度为： " + Array.getLength(obj));        for(int i = 0; i < Array.getLength(obj); i++){            System.out.println(Array.get(obj, i) + " ");        }        System.out.println("");        /*反射模式应用于工厂模式*/        fruit f = Factory.getInstance("cn.gzx.baike.Apple");        if(f != null){            f.eat();        }    }}class User{    private int age;    private String name;    public User(int age, String name) {        super();        this.age = age;        this.name = name;    }    public User(String name) {        super();        this.name = name;    }    public User() {        super();    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String toString() {        return "User [age=" + age + ", name=" + name + "]";    }}//定义项目接口interface Subject{    public String say(String name, int age);}//定义真实项目class RealSubject implements Subject{    public String say(String name,int age){        return name + " " + age;    }}class MyInvocationHandler implements InvocationHandler{    private Object obj = null;    public Object bind(Object obj){        this.obj = obj;        return Proxy.newProxyInstance(obj.getClass().getClassLoader(), obj.getClass().getInterfaces(), this);    }    @Override    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {        // TODO Auto-generated method stub        Object temp = method.invoke(this.obj, args);        return temp;    }}interface fruit{    public abstract void eat();}class Apple implements fruit{    @Override    public void eat() {        // TODO Auto-generated method stub        System.out.println("Apple");    }}class Orange implements fruit{    @Override    public void eat() {        // TODO Auto-generated method stub        System.out.println("Orange");    }}class Factory{    public static fruit getInstance(String ClassName){        fruit f = null;        try{            f = (fruit)Class.forName(ClassName).newInstance();        }catch(Exception e){            e.printStackTrace();        }        return f;    }}