基本概念:
序列化是將對象狀態轉換爲可保持或傳輸的格式的過程。與序列化相對的是反序列化,它將流轉換爲對象。這兩個過程結合起來,可以輕鬆地存儲和傳輸數據。
昨天在一本書上看到了,好好實踐了一下,序列化爲一般文件,也序列化爲XML文件(使用XStream)。
用於序列化的實體類Person.java 代碼如下(記得需要實現Serializable接口):
import java.io.Serializable;
@SuppressWarnings("serial")
public class Person implements Serializable{
private String name;
private int age;
public Person(){
}
public Person(String str, int n){
System.out.println("Inside Person's Constructor");
name = str;
age = n;
}
String getName(){
return name;
}
int getAge(){
return age;
}
}
序列化、反序列化爲一般的文件,SerializeToFlatFile.java類的代碼如下:
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class SerializeToFlatFile {
public static void main(String[] args) {
SerializeToFlatFile ser = new SerializeToFlatFile();
ser.savePerson();
ser.restorePerson();
}
public void savePerson(){
Person myPerson = new Person("Jay",24);
try {
FileOutputStream fos = new FileOutputStream("E:\\workspace\\2010_03\\src\\myPerson.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
System.out.println("Person--Jay,24---Written");
System.out.println("Name is: "+myPerson.getName());
System.out.println("Age is: "+myPerson.getAge());
oos.writeObject(myPerson);
oos.flush();
oos.close();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
public void restorePerson() {
try {
FileInputStream fis = new FileInputStream("E:\\workspace\\2010_03\\src\\myPerson.txt");
ObjectInputStream ois = new ObjectInputStream(fis);
Person myPerson = (Person)ois.readObject();
System.out.println("\n--------------------\n");
System.out.println("Person--Jay,24---Restored");
System.out.println("Name is: "+myPerson.getName());
System.out.println("Age is: "+myPerson.getAge());
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
運行結果爲(console輸出),當然可以查看到myPerson.txt文件已經生成:
Inside Person's Constructor
Person--Jay,24---Written
Name is: Jay
Age is: 24
--------------------
Person--Jay,24---Restored
Name is: Jay
Age is: 24
序列化、反序列化爲XML文件,我使用了XStream來序列化,需要引入xstream-1.3.1.jar包的支持,
http://xstream.codehaus.org/download.html 處可以下載jar,然後引入到Eclipse中的build path中。
Serialize.java的代碼如下:
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import com.thoughtworks.xstream.*;
public class Serialize {
public static void main(String[] args) {
Serialize ser = new Serialize();
ser.serializeToXml();
ser.deSerializeFromXml();
}
public void serializeToXml(){
Person[] myPerson = new Person[2];
myPerson[0] = new Person("Jay",24);
myPerson[1] = new Person("Tom",23);
XStream xstream = new XStream();
try {
FileOutputStream fos = new FileOutputStream("E:\\workspace\\2010_03\\src\\myPerson.xml");
xstream.toXML(myPerson,fos);
} catch (FileNotFoundException ex) {
ex.printStackTrace();
}
System.out.println(xstream.toXML(myPerson));
}
public void deSerializeFromXml(){
XStream xs = new XStream();
Person[] myPerson = null;
try {
FileInputStream fis = new FileInputStream("E:\\workspace\\2010_03\\src\\myPerson.xml");
myPerson=(Person[])xs.fromXML(fis);
if (myPerson != null)
{
int len = myPerson.length;
for (int i=0;i<len;i++)
{
System.out.println(myPerson[i].getName());
System.out.println(myPerson[i].getAge());
}
}
} catch (FileNotFoundException ex) {
ex.printStackTrace();
}
}
}
運行結果爲(console輸出),當然可以查看到myPerson.xml文件已經生成:
Inside Person's Constructor
Inside Person's Constructor
<Person-array>
<Person>
<name>Jay</name>
<age>24</age>
</Person>
<Person>
<name>Tom</name>
<age>23</age>
</Person>
</Person-array>
Jay
24
Tom
23
參考資料:
http://developer.51cto.com/art/200908/147650.htm
http://www.ibm.com/developerworks/cn/xml/x-xstream/#resources
http://www.cnblogs.com/stephencat/archive/2007/06/05/772520.html
轉載:http://renyongjie668.blog.163.com/blog/static/1600531201022105142865/
這次我們講的是控制對象的序列化和反序列化
控制序列化就是有選擇的序列化對象,而不是把對象的所以內容都序列化,前篇我們的例子中介紹了transit變量和類變量(static)不被序列化,現在我們還有一種更爲靈活的控制對象序列化和反序列方法,可以在序列化過程中儲存其他非this對象包含的數據
我們現在再來介紹一個接口 java.io.Externalizable 。當對象實現了這個接口時,就可以靈活的控制它的序列化和反序列過程,這個接口繼承了java.io.Serializable
Externalizable 接口定義了兩個方法,writerExternal方法在序列化時被調用,可以再該方法中控制序列化內容,readExternal方法在反序列時被調用,可以在該方法中控制反序列的內容
好了,現在我們改寫上例的UserInfo
- import java.io.*;
- import java.util.*;
- //本程序通過實現Externalizable接口控制對象序列化和反序列
- public class UserInfo implements Externalizable {
- public String userName;
- public String userPass;
- public int userAge;
- public UserInfo(){
- }
- public UserInfo(String username,String userpass,int userage){
- this.userName=username;
- this.userPass=userpass;
- this.userAge=userage;
- }
- //當序列化對象時,該方法自動調用
- public void writeExternal(ObjectOutput out) throws IOException{
- System.out.println("現在執行序列化方法");
- //可以在序列化時寫非自身的變量
- Date d=new Date();
- out.writeObject(d);
- //只序列化userName,userPass變量
- out.writeObject(userName);
- out.writeObject(userPass);
- }
- //當反序列化對象時,該方法自動調用
- public void readExternal(ObjectInput in) throws IOException,ClassNotFoundException{
- System.out.println("現在執行反序列化方法");
- Date d=(Date)in.readObject();
- System.out.println(d);
- this.userName=(String)in.readObject();
- this.userPass=(String)in.readObject();
- }
- public String toString(){
- return "用戶名: "+this.userName+";密碼:"+this.userPass+
- ";年齡:"+this.userAge;
- }
- }
import java.io.*;
import java.util.*;
//本程序通過實現Externalizable接口控制對象序列化和反序列
public class UserInfo implements Externalizable {
public String userName;
public String userPass;
public int userAge;
public UserInfo(){
}
public UserInfo(String username,String userpass,int userage){
this.userName=username;
this.userPass=userpass;
this.userAge=userage;
}
//當序列化對象時,該方法自動調用
public void writeExternal(ObjectOutput out) throws IOException{
System.out.println("現在執行序列化方法");
//可以在序列化時寫非自身的變量
Date d=new Date();
out.writeObject(d);
//只序列化userName,userPass變量
out.writeObject(userName);
out.writeObject(userPass);
}
//當反序列化對象時,該方法自動調用
public void readExternal(ObjectInput in) throws IOException,ClassNotFoundException{
System.out.println("現在執行反序列化方法");
Date d=(Date)in.readObject();
System.out.println(d);
this.userName=(String)in.readObject();
this.userPass=(String)in.readObject();
}
public String toString(){
return "用戶名: "+this.userName+";密碼:"+this.userPass+
";年齡:"+this.userAge;
}
}
改寫測試類
- import java.io.ObjectOutputStream;
- import java.io.ObjectInputStream;
- import java.io.FileInputStream;
- import java.io.FileOutputStream;
- import java.util.Date;
- import java.lang.management.*;
- public class Test {
- //序列化對象到文件
- public static void serialize(String fileName){
- try
- {
- //創建一個對象輸出流,講對象輸出到文件
- ObjectOutputStream out=new ObjectOutputStream(new FileOutputStream(fileName));
- UserInfo user=new UserInfo("renyanwei","888888",20);
- out.writeObject(user); //序列化一個會員對象
- out.close();
- }
- catch (Exception x)
- {
- System.out.println(x.toString());
- }
- }
- //從文件反序列化到對象
- public static void deserialize(String fileName){
- try
- {
- //創建一個對象輸入流,從文件讀取對象
- ObjectInputStream in=new ObjectInputStream(new FileInputStream(fileName));
- //讀取UserInfo對象並調用它的toString()方法
- UserInfo user=(UserInfo)(in.readObject());
- System.out.println(user.toString());
- in.close();
- }
- catch (Exception x)
- {
- System.out.println(x.toString());
- }
- }
- public static void main(String[] args) {
- serialize("D:\\test.txt");
- System.out.println("序列化完畢");
- deserialize("D:\\test.txt");
- System.out.println("反序列化完畢");
- }
- }
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Date;
import java.lang.management.*;
public class Test {
//序列化對象到文件
public static void serialize(String fileName){
try
{
//創建一個對象輸出流,講對象輸出到文件
ObjectOutputStream out=new ObjectOutputStream(new FileOutputStream(fileName));
UserInfo user=new UserInfo("renyanwei","888888",20);
out.writeObject(user); //序列化一個會員對象
out.close();
}
catch (Exception x)
{
System.out.println(x.toString());
}
}
//從文件反序列化到對象
public static void deserialize(String fileName){
try
{
//創建一個對象輸入流,從文件讀取對象
ObjectInputStream in=new ObjectInputStream(new FileInputStream(fileName));
//讀取UserInfo對象並調用它的toString()方法
UserInfo user=(UserInfo)(in.readObject());
System.out.println(user.toString());
in.close();
}
catch (Exception x)
{
System.out.println(x.toString());
}
}
public static void main(String[] args) {
serialize("D:\\test.txt");
System.out.println("序列化完畢");
deserialize("D:\\test.txt");
System.out.println("反序列化完畢");
}
}
執行結果
現在執行序列化方法
序列化完畢
現在執行反序列化方法
Thu Oct 23 22:18:12 CST 2008
用戶名: renyanwei;密碼:888888;年齡:0
反序列化完畢
通過一張圖來看程序流程
首先,我們在序列化UserInfo對象的時候,由於這個類實現了Externalizable 接口,在writeExternal()方法裏定義了哪些屬性可以序列化,哪些不可以序列化,所以,對象在經過這裏就把規定能被序列化的序列化保存文件,不能序列化的不處理,然後在反序列的時候自動調用readExternal()方法,根據序列順序挨個讀取進行反序列,並自動封裝成對象返回,然後在測試類接收,就完成了反序列