反射

package cn.itcast_01; public class Person { private String name; int age; public String address; public Person() { } private Person(String name) { this.name = name; } Person(String name, int age) { this.name = name; this.age = age; } public Person(String name, int age, String address) { this.name = name; this.age = age; this.address = address; } public void show() { System.out.println("show"); } public void method(String s) { System.out.println("method:" + s); } public String getString(String name, int age) { return name + "----" + age; } private void function() { System.out.println("function"); } @Override public String toString() { return "Person [" + "name=" + name + ", " + "age=" + age + ", " + "address=" + address + "]"; } }

package cn.itcast_04; import java.lang.reflect.Constructor; import java.lang.reflect.Field; import java.lang.reflect.Method; /* * 需求:通过反射对Person进行操作使用 * * private String name; * int age; * public String address; * * public Person() * private Person(String name) * Person(String name, int age) * public Person(String name, int age, String address) * * public void show() * public void method(String s) * public String getString(String name, int age) * private void function() */ public class ReflectDemo2 { public static void main(String[] args) throws Exception { // 获取字节码文件对象 Class c = Class.forName("cn.itcast_01.Person"); // 获取无参构造方法对象 Constructor con = c.getConstructor(); // 通过无参构造方法对象创建对象 Object obj = con.newInstance(); System.out.println(obj); // 通过反射给所有成员变量赋值 System.out.println("****通过反射给所有成员变量赋值****"); // private String name; Field nameField = c.getDeclaredField("name"); nameField.setAccessible(true); nameField.set(obj, "风清杨"); System.out.println(obj); // int age; Field ageField = c.getDeclaredField("age"); ageField.setAccessible(true); ageField.set(obj, 27); System.out.println(obj); // public String address; Field addressField = c.getField("address"); addressField.set(obj, "上海"); System.out.println(obj); // 通过反射给所有构造方法赋值 System.out.println("****通过反射给所有构造方法赋值****"); // public Person() // private Person(String name) Constructor con2 = c.getDeclaredConstructor(String.class); con2.setAccessible(true); Object obj2 = con2.newInstance("王小明"); System.out.println(obj2); // Person(String name, int age) Constructor con3 = c.getDeclaredConstructor(String.class, int.class); con3.setAccessible(true); Object obj3 = con3.newInstance("林子聪", 35); System.out.println(obj3); // public Person(String name, int age, String address) Constructor con4 = c.getConstructor(String.class, int.class, String.class); Object obj4 = con4.newInstance("江小斐", 56, "山东"); System.out.println(obj4); // 通过反射调用所有成员方法 System.out.println("****通过反射调用所有成员方法****"); // public void show() Method m1 = c.getMethod("show"); m1.invoke(obj); // public void method(String s) Method m2 = c.getMethod("method", String.class); m2.invoke(obj, "hello"); // public String getString(String name, int age) Method m3 = c.getMethod("getString", String.class, int.class); Object objString = m3.invoke(obj, "world", 100); System.out.println(objString); // private void function() Method m4 = c.getDeclaredMethod("function"); m4.setAccessible(true); m4.invoke(obj); } }