反射机制总结归纳

<strong abp="697"><span abp="698" style="font-size:24px;BACKGROUND-COLOR: #ffffff">通过<span abp="699" style="font-size:32px;color:#000099;">反射机制取得</span>类中的公有或私有等的<span abp="700" style="font-size:32px;color:#000099;">构造方法</span>信息、访问公有或私有的<span abp="701" style="font-size:32px;color:#000099;">成员方法</span>以及访问公有或私有的<span abp="702" style="font-size:32px;color:#000099;">成员变量</span>。</span></strong>

<strong abp="704"><span abp="705" style="font-size:24px;"><strong abp="706"><span abp="707" style="font-size:24px;"></span></strong></span></strong> 

<span abp="709" style="BACKGROUND-COLOR: #ffffff"><strong abp="710"><span abp="711" style="font-size:24px;">主</span><span abp="713" style="font-size:24px;">要看第一段代码。</span></strong></span>

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package com.fs.po;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.Method;public class Test {private void m1() throws Exception {/** 得到Stu中的public类型的构造方法<得到公有构造方法> */// 通过Stu类的public构造方法创建Stu对象Class c = Class.forName("com.fs.po.Stu");// Class.forName("全类名") ===> 得到Class对象的方式二  <推荐使用>//Class c = Stu.class;// 类名.class ===> 得到Class对象的方式一//Class c = new Stu().getClass();// 对象.getClass() ===> 得到Class对象的方式三  <很少使用，不推荐，知道了解就好>// 取得Stu()无参构造方法信息         <体现强转>Constructor con1 = c.getConstructor();Stu stu1 = (Stu) con1.newInstance();// 调用Stu()创建Stu对象stu1.say2();System.out.println("==============");// 取得public Stu(String name, int age)构造方法信息        <体现泛型>Constructor<Stu> con2 = c.getConstructor(String.class,Integer.class);Stu stu2 = con2.newInstance("小米",20);// 调用Stu(String name, Integer age)创建对象stu2.say2();//System.out.println("========此种写法不建议，可读性差=======");//  取得public Stu(String s, String s2, int age)构造方法信息//Stu stu3 = (Stu) Class.forName("com.fs.po.Stu").getConstructor(String.class,String.class ,int.class).newInstance("民大","曉曉",4);//stu3.say2();}private void m2() throws Exception {/** 得到Stu中的private类型的构造方法<私有构造方法，理论上通过new对象是得不到的> *///通过Stu类的private构造方法创建Stu对象Class c = Class.forName("com.fs.po.Stu");// 封装了Stu的信息// 取得private Stu(String name)构造方法信息Constructor<Stu> con1 = c.getDeclaredConstructor(String.class);// getDeclaredConstructor()方法不管是公有还是私有的都能取出 con1.setAccessible(true);// 修改访问权限为可访问Stu stu1 = con1.newInstance("小糯米");// 调用Stu()创建Stu对象stu1.say2();// 通过Stu(String s, String s2, int age)创建Stu对象// 取得public Stu(String s, String s2, int age)构造方法信息Constructor<Stu> con2 = c.getDeclaredConstructor(String.class, String.class, int.class);Stu stu2 = con2.newInstance("ss", "ss", 100);stu2.say2();}private void m3() throws Exception {/** 访问成员变量 */Class c = Class.forName("com.fs.po.Stu");Constructor<Stu> con = c.getConstructor();// public Stu()Stu stu = con.newInstance();// 访问公有成员变量public int age信息//stu.age = 100;// 访问成员变量private String name信息Field field = c.getDeclaredField("name");field.setAccessible(true);// 设置可访问// 访问并修改private String name信息field.set(stu, "石头");// 取得stu对象中的name的值String name = (String) field.get(stu);System.out.println("Stu private String name" + name);}private void m4() throws Exception {/** 访问私有的成员方法 */Class c = Class.forName("com.fs.po.Stu");Constructor<Stu> con = c.getConstructor();// public Stu()Stu stu = con.newInstance();// 访问私有成员方法private void say(String name, int age, Teacher t)信息Method method1 = c.getDeclaredMethod("say",String.class,int.class,Teacher.class);method1.setAccessible(true);method1.invoke(stu, "小昭",20,new Teacher());// 访问私有成员方法private void say()信息Method method2 = c.getDeclaredMethod("say");//Method method2 = c.getDeclaredMethod("say", null);method2.setAccessible(true);method2.invoke(stu);//method2.invoke(stu, null);}public static void main(String[] args) throws Exception {Test t = new Test();t.m4();}}

package com.fs.po;public class Stu {private String name;private float hight;public int age;public Stu() {System.out.println("Stu()");}/*** * dfsdfdafasd * @param name * @param age */public Stu(String name, Integer age) {this.name = name;this.age = age;}public Stu(String s, String s2, int age) {System.out.println("Stu(String s, String s2, int age)");}private Stu(String name) {System.out.println("Stu(String name)...");}private void say(String name, int age, Teacher t) {System.out.println("上.....");}private void say() {System.out.println("下....");}public void say2() {System.out.println("stu say2...."+name);}}

package com.fs.po;public class Teacher {public void teacherSay() {System.out.println("good good study");}}