Java的对象序列化

1，什么是序列化，及序列化的作用？

序列化就是讲对象转为一组字节,用于持久化和网络传输。持久化不难理解,对象会随着程序结束而结束,如果我们要存储对象中的数据信息时，可以使用数据库,也可以使用文件，而序列化就是将对象压缩成一组字节更便于存储。

网络传输也是同样的道理。对象序列在要使用的时候反序列化就可以转为对象。不过序列化只将成员变量转化为相应的序列，静态的变量会被忽视掉。

2,如何实现序列化

类实现java.io.Serializable接口,就可以实现序列化了,如:

import java.io.Serializable;public class Student implements Serializable{private Integer sid;private String name;private String sex;public Integer getSid() {return sid;}public void setSid(Integer sid) {this.sid = sid;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public Student(Integer sid, String name, String sex) {super();this.sid = sid;this.name = name;this.sex = sex;}public Student() {super();}@Overridepublic String toString() {return "Student [sid=" + sid + ", name=" + name + ", sex=" + sex + "]";}}

import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;public class SerializableUtil {public static byte[] serialize(Object obj){//对象输出流ObjectOutputStream oos=null;//字节输出流ByteArrayOutputStream baos=null;//序列化后的字节数组byte[] bs=null;try {baos=new ByteArrayOutputStream();oos=new ObjectOutputStream( baos);//将对象输出到ObjectOutputStream里oos.writeObject(  obj );//将输出到对象输出流的数据转为字节数组bs=baos.toByteArray();} catch (IOException e) {e.printStackTrace();}finally{if(  baos!=null){try {baos.close();} catch (IOException e) {e.printStackTrace();}}}return bs;}public static Object  unSerialize(byte[] bs){//字节输入流ByteArrayInputStream bais=null;//转化的对象Object obj=null;try {//读取字节数组的信息bais=new ByteArrayInputStream( bs  );//创建对象输入流,并将读取到的字节流传入ObjectInputStream ois=new ObjectInputStream( bais);//将字节流信息转为对象obj= ois.readObject();} catch (Exception e) {e.printStackTrace();}finally{if(  bais!=null){try {bais.close();} catch (IOException e) {e.printStackTrace();}}}return obj;}}

public class Test {public static void main(String[] args) {Student stu = new Student(1001,"SeanLeong","男");byte[] bs = SerializableUtil.serialize(stu);for(int i=0, n = bs.length; i<n; i++){System.out.print(bs[i]);}System.out.println();Student s = (Student) SerializableUtil.unSerialize(bs);System.out.println(s.toString());}}

运行结果-84-1905115114078311611710010111011647-81122103-12084-352520376041109710910111601876106971189747108971101034783116114105110103597603115101120113012601760311510510011601976106971189747108971101034773110116101103101114591201121160983101971107610111111010311603-25-108-7311511401710697118974610897110103467311011610110310111418-30-96-92-9-127-1215620173051189710811710112011401610697118974610897110103467811710998101114-122-84-1072911-108-32-117200120112003-23Student [sid=1001, name=SeanLeong, sex=男]

存在一种情况,我们不需要将对象所有的成员变量都序列化。这个时候我们就要采用transient关键字，比如上面的案例中我不想将name序列化,那就将 private String name 前添加transient关键字  transient private String name;

其他不变。

运行结果：-84-190511511407831161171001011101164284-58607628-40113202760311510112011601876106971189747108971101034783116114105110103597603115105100116019761069711897471089711010347731101161011031011145912011211603-25-108-7311511401710697118974610897110103467311011610110310111418-30-96-92-9-127-1215620173051189710811710112011401610697118974610897110103467811710998101114-122-84-1072911-108-32-117200120112003-23Student [sid=1001, name=null, sex=男]