目录

一.什么是反射

       用实体类Student做示范

三.反射实例化

四.反射动态方法调用

五.反射读写属性

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一.什么是反射

反射java语言中的一种机制，通过这种机制可以动态的实例化对象，读写属性，调用方法

二.类类

1. Class.forName(完整类名)
2. 类名 .class
3. 对象 .getClass

       用实体类Student做示范

package com.zking.fanshe;public class Student {private String sid;private String sname;public Integer age;static{System.out.println("加载进jvm中！");}public Student() {super();System.out.println("调用无参构造方法创建了一个学生对象");}public Student(String sid) {super();this.sid = sid;System.out.println("调用带一个参数的构造方法创建了一个学生对象");}public Student(String sid, String sname) {super();this.sid = sid;this.sname = sname;System.out.println("调用带二个参数的构造方法创建了一个学生对象");}@SuppressWarnings("unused")private Student(Integer age) {System.out.println("调用Student类私有的构造方法创建一个学生对象");this.age = age;}public String getSid() {return sid;}public void setSid(String sid) {this.sid = sid;}public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public void hello() {System.out.println("你好！我是" + this.sname);}public void hello(String name) {System.out.println(name + "你好！我是" + this.sname);}@SuppressWarnings("unused")private Integer add(Integer a, Integer b) {return new Integer(a.intValue() + b.intValue());}@Overridepublic String toString() {return "Student [sid=" + sid + ", sname=" + sname + ", age=" + age + "]";}}

	//1.Class.forname()Class stuClass	=Class.forName("com.zking.fanshe.Student");//2.类Class Class = Student.class;//3.对象 .getClassStudent student = new Student();Class class2 = student.getClass();System.out.println(stuClass);System.out.println(class2);System.out.println(Class);

三.反射实例化

• getConstructor
• getDeclaredConstructor
• newInstance

  //实例化对象Constructor con = stuClass.getConstructor();Student stu = (Student) con.newInstance();stu.setSid("001");stu.setSname("宝宝");System.out.println(stu);//有参 参数构造Constructor con1 = stuClass.getConstructor(String.class,String.class);Student stu02 = (Student) con1.newInstance("004","瑶宝");System.out.println(stu02);//私有方法①Constructor<Student> con3 = stuClass.getDeclaredConstructor(Integer.class);con3.setAccessible(true);Student stu04 = con3.newInstance(18);System.out.println(stu04);

四.反射动态方法调用

• getMethod
• getDeclaredMethod

    //无参的公共方法Method method = stuClass.getMethod("hello");method.invoke(stu);//有参的公共方法Method method2 = stuClass.getMethod("hello", String.class);method2.invoke(stu, "辉辉");//②Method method3 = stuClass.getDeclaredMethod("add", Integer.class,Integer.class);method3.setAccessible(true);int n = (Integer) method3.invoke(stu, 1,2);System.out.println(n);

五.反射读写属性

• getField
• getDeclaredField

    //公有反射属性Field field = stuClass.getField("age");field.set(stu, 98);System.out.println(stu);//私有反射属性Field sname = stuClass.getDeclaredField("sname");sname.setAccessible(true);sname.set(stu, "小红花");System.out.println(stu);