关于Java反射破坏封装的问题

今天看ITEYE，一片关于Java反射破话封装的问题，摘录如下：

一般情况下，我们并不能对类的私有字段进行操作，利用反射也不例外，但有的时候，例如要序列化的时候，我们又必须有能力去处理这些字段，这时候，我们就需要调用AccessibleObject上的setAccessible()方法来允许这种访问，而由于反射类中的Field，Method和Constructor继承自AccessibleObject，因此，通过在这些类上调用setAccessible()方法，我们可以实现对这些字段的操作。但有的时候这将会成为一个安全隐患，为此，我们可以启用java.security.manager来判断程序是否具有调用setAccessible()的权限。默认情况下，内核API和扩展目录的代码具有该权限，而类路径或通过URLClassLoader加载的应用程序不拥有此权限 。

?

package com.dream.reflection;     /**   * Created by IntelliJ IDEA.   * User: Zhong Gang   * Date: 11-9-24   * Time: 下午7:02   */  public class User {       private Integer id;       private int number;       private String name = "zhong_gang";         private User(Integer id) {           this.id = id;       }         private User(int number) {           this.number = number;       }         protected User(String name) {           this.name = name;       }         private User(Integer id, String name) {           this.id = id;           this.name = name;       }         public User() {         }         public String upperName() {           return name.toUpperCase();       }         public Integer getId() {           return id;       }         public String getName() {           return name;       }         public int getNumber() {           return number;       }   }  

?

package com.dream.reflection;     import junit.framework.TestCase;     import java.lang.reflect.Constructor;   import java.lang.reflect.Field;   import java.lang.reflect.Method;     /**   * Created by IntelliJ IDEA.   * User: Zhong Gang   * Date: 11-9-24   * Time: 下午7:03   */  public class UserRelectionTest extends TestCase {         public void testIntegerReflection() throws Exception {           Class<User> clazz = User.class;           Constructor<User> constructor = clazz.getDeclaredConstructor(Integer.class);           constructor.setAccessible(true);           User user = constructor.newInstance(Integer.valueOf("1"));           assertEquals(Integer.valueOf("1"), user.getId());       }         public void testIntReflection() throws Exception {           Class<User> clazz = User.class;           Constructor<User> constructor = clazz.getDeclaredConstructor(int.class);           constructor.setAccessible(true);           User user = constructor.newInstance(1);           assertEquals(1, user.getNumber());       }         public void testStringReflection() throws Exception {           Class<User> clazz = User.class;           Constructor<User> constructor = clazz.getDeclaredConstructor(String.class);   //        constructor.setAccessible(true);           User user = constructor.newInstance("ZhongGang");           assertEquals("ZhongGang", user.getName());       }         public void testFiledReflection() throws Exception {           Class<User> clazz = User.class;           Field id = clazz.getDeclaredField("id");           id.setAccessible(true);           User user = new User();           id.set(user, Integer.valueOf("3"));           assertEquals(Integer.valueOf("3"), user.getId());       }         public void testMethodReflection() throws Exception {           Class<User> clazz = User.class;           Method method = clazz.getDeclaredMethod("upperName");   //        method.setAccessible(true);           User user = new User();           String invoke = (String) method.invoke(user);           assertEquals("ZHONG_GANG", invoke);       }   }  

?

另一篇关于反射int.class 与 Integer.class的：

?

http://www.iteye.com/problems/72276