package com.yemaozi.reflect; import java.lang.reflect.Constructor; import java.lang.reflect.Field; import java.lang.reflect.Method; public class ReflectTest { /** * 通过java的反射机制获取类的所有属性和方法 */ public void test1() { try { Class c = Class.forName("com.yemaozi.reflect.Customer"); System.out.println("属性："); Field f[] = c.getDeclaredFields(); for (int i = 0; i < f.length; i++) { System.out.println(f[i].getName()); } System.out.println("方法："); Method m[] = c.getDeclaredMethods(); for (int i = 0; i < m.length; i++) { System.out.println(m[i].toString()); } } catch (Throwable e) { System.err.println(e); } } /** * 通过java的反射机制动态修改对象的属性 * @param o */ public void test2(Customer o) { try { Class c = o.getClass(); //getMethod方法第一个参数指定一个需要调用的方法名称，第二个参数是需要调用方法的参数类型列表，如无参数可以指定null，该方法返回一个方法对象 Method sAge = c.getMethod("setAge", new Class[] { int.class }); Method gAge = c.getMethod("getAge", null); Method sName = c.getMethod("setName", new Class[] { String.class }); //动态修改Customer对象的age Object[] args1 = { new Integer(25) }; sAge.invoke(o, args1); //动态取得Customer对象的age Integer AGE = (Integer) gAge.invoke(o, null); System.out.println("the Customer age is: " + AGE.intValue()); //动态修改Customer对象的name Object[] args2 = { new String("李四") }; sName.invoke(o, args2); } catch (Throwable e) { System.err.println(e); } } /** * 通过java的反射机制做一个简单对象的克隆 * @param o * @return */ public Object test3(Customer o) { Object o2 = null; try { Class c = o.getClass(); //通过默认构造方法创建一个新的对象 o2 = c.getConstructor(new Class[] {}).newInstance( new Object[] {}); Field fields[] = c.getDeclaredFields(); for (int i = 0; i < fields.length; i++) { Field field = fields[i]; String fieldName = field.getName(); String firstLetter = fieldName.substring(0, 1).toUpperCase(); // 获得和属性对应的getXXX()方法的名字 String getMethodName = "get" + firstLetter + fieldName.substring(1); // 获得和属性对应的setXXX()方法的名字 String setMethodName = "set" + firstLetter + fieldName.substring(1); // 获得和属性对应的getXXX()方法 Method getMethod = c.getMethod(getMethodName, new Class[] {}); // 获得和属性对应的setXXX()方法 Method setMethod = c.getMethod(setMethodName, new Class[] { field.getType() }); // 调用原对象的getXXX()方法 Object value = getMethod.invoke(o, new Object[] {}); // 调用拷贝对象的setXXX()方法 setMethod.invoke(o2, new Object[] { value }); } } catch (Throwable e) { System.err.println(e); } return o2; } public static void main(String[] args) throws Exception { ReflectTest t = new ReflectTest(); t.test1(); Customer customer = new Customer(); customer.setAge(20); customer.setName("张三"); System.out.println("调用前name: " + customer.getName()); System.out.println("调用前age: " + customer.getAge()); t.test2(customer); System.out.println("调用后name: " + customer.getName()); System.out.println("调用后age: " + customer.getAge()); Customer customer2 = (Customer)t.test3(customer); System.out.println("克隆对象的name: " + customer2.getName()); System.out.println("克隆对象的age: " + customer2.getAge()); } } class Customer { private long id; private String name; private int age; public Customer() { } public Customer(String name, int age) { this.name = name; this.age = age; } public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } } 运行结果： 属性： id name age 方法： public java.lang.String demo1.client.Customer.getName() public long demo1.client.Customer.getId() public void demo1.client.Customer.setName(java.lang.String) public void demo1.client.Customer.setAge(int) public int demo1.client.Customer.getAge() public void demo1.client.Customer.setId(long) 调用前name: 张三 调用前age: 20 the Customer age is: 25 调用后name: 李四 调用后age: 25 克隆对象的name: 李四 克隆对象的age: 25
