Java使用序列化流实现对List泛型的深拷贝

我会带着你远行 2023-07-11 12:39 15阅读 0赞

# 使用序列化流实现对List泛型的深拷贝 #

### 深拷贝 ###

*  为新的对象重新开辟一个内存空间，拷贝原有对象的数据结构和值；新的对象的值修改不会涉及原对象的值（请注意性能问题）。

### 实现序列化拷贝的前提条件 ###

*  实体对象实现Serializable接口
    
        /**
         * 用户实体类
         */
        public class UserEntity implements Serializable { 
        
            private int id;
        
            private String username;
        
            private String sex;
        
            private int age;
        
            private String address;
        
            private String birthday;
        
            //get、set方法省略
        	
            public UserEntity(int id, String username, String sex, int age, String address) { 
                this.id = id;
                this.username = username;
                this.sex = sex;
                this.age = age;
                this.address = address;
            }
        
            @Override
            public String toString() { 
                return "UserEntity{" +
                        "id=" + id +
                        ", username='" + username + '\'' +
                        ", sex='" + sex + '\'' +
                        ", age=" + age +
                        ", address='" + address + '\'' +
                        '}';
            }
        }

### 序列化拷贝方法 ###

*      private static final Logger LOGGER = LoggerFactory.getLogger(DeepCopyDemo.class);
        
        public static <T> List<T> deepCopy(List<T> list) { 
                //判断是否实现序列化
                if (list instanceof Serializable){ 
                    ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
                    try { 
                        ObjectOutputStream out = new ObjectOutputStream(byteOut);
                        out.writeObject(list);
        
                        ByteArrayInputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());
                        ObjectInputStream inStream = new ObjectInputStream(byteIn);
                        List<T> ts = (List<T>) inStream.readObject();
                        return ts;
                    } catch (Exception e) { 
                        LOGGER.error("序列化Copy失败", e);
                        e.printStackTrace();
                    }
                }
                return null;
            }

### 序列化拷贝测试 ###

*      public static Integer INDEX  = 0;
        
            public static void main(String[] args) { 
                UserEntity userEntity1 = new UserEntity(0, "张无忌","女",1 , "beijignshi");
                UserEntity userEntity2 = new UserEntity(1, "李寻欢","女",4 , "tianjinshi");
                UserEntity userEntity3 = new UserEntity(3, "项羽","男",0 , "chuguo");
                UserEntity userEntity4 = new UserEntity(4, "刘邦","男",8 , "hanchao");
        
                List<UserEntity> list = new ArrayList<>();
                list.add(userEntity2);
                list.add(userEntity1);
                list.add(userEntity4);
                list.add(userEntity3);
        
                System.out.println("----deep copy front----");
                for (UserEntity userEntity: list) { 
                    System.out.println(userEntity.toString());
                }
        
                List<UserEntity> copyResult = deepCopy(list);
                System.out.println("----deep copy after----");
                copyResult.get(INDEX).setUsername("夷陵老祖");
                for (UserEntity userEntity: copyResult) { 
                    System.out.println(userEntity.toString());
                }
        
            }

### 拷贝结果 ###

*      ----deep copy front----
        UserEntity{ id=1, username='李寻欢', sex='女', age=4, address='tianjinshi'}
        UserEntity{ id=0, username='张无忌', sex='女', age=1, address='beijignshi'}
        UserEntity{ id=4, username='刘邦', sex='男', age=8, address='hanchao'}
        UserEntity{ id=3, username='项羽', sex='男', age=0, address='chuguo'}
        ----deep copy after----
        UserEntity{ id=1, username='夷陵老祖', sex='女', age=4, address='tianjinshi'}
        UserEntity{ id=0, username='张无忌', sex='女', age=1, address='beijignshi'}
        UserEntity{ id=4, username='刘邦', sex='男', age=8, address='hanchao'}
        UserEntity{ id=3, username='项羽', sex='男', age=0, address='chuguo'}