Serialize

　　源代码：

 

package com.serialize;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 9/26/11
 * Time: 11:42 AM
 */
public enum Level {
    INFO,
    DEBUG,
    ERROR
}

 

package com.serialize;

import java.io.Serializable;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 9/26/11
 * Time: 11:42 AM
 */
public class BasicInfo implements Serializable{
    private String city;
    private String country;

    public BasicInfo(String city, String country) {
        this.city = city;
        this.country = country;
    }

    public String getCity() {
        return city;
    }

    public String getCountry() {
        return country;
    }
}

 

package com.serialize;

import java.io.Serializable;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 9/26/11
 * Time: 11:38 AM
 */
public class Information implements Serializable{
    private int number;
    private Integer count;
    private String name;
    private Level level;
    private int[] numbers;
    private transient BasicInfo basicInfo;

    public Information(int number, Integer count, String name, Level level,int[] numbers, BasicInfo basicInfo) {
        this.number = number;
        this.count = count;
        this.name = name;
        this.level = level;
        this.numbers = numbers;
        this.basicInfo = basicInfo;
    }

    public int getNumber() {
        return number;
    }

    public Integer getCount() {
        return count;
    }

    public String getName() {
        return name;
    }

    public Level getLevel() {
        return level;
    }

    public BasicInfo getBasicInfo() {
        return basicInfo;
    }

    public int[] getNumbers() {
        return numbers;
    }
}

 

package com.serialize;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 9/26/11
 * Time: 1:43 PM
 */
public class ExtendInformation extends Information {
    private String description;

    public ExtendInformation(int number, Integer count, String name, Level level,int[] numbers, BasicInfo basicInfo, String description) {
        super(number, count, name, level,numbers, basicInfo);
        this.description = description;
    }

    public String getDescription() {
        return description;
    }
}

 

package com.serialize;

import junit.framework.TestCase;

import java.io.*;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 9/26/11
 * Time: 11:43 AM
 */
public class SerializeTest extends TestCase {

    public void testSerializable() throws Exception {
        File file = new File("D:\\information.txt");
        if (!file.exists()) {
            file.createNewFile();
        }

        BasicInfo basicInfo = new BasicInfo("Chengdu", "China");
        Information information = new Information(100, Integer.valueOf("100"), "ZhongGang", Level.ERROR, new int[]{1, 2, 3, 4, 5,}, basicInfo);

        ExtendInformation extendInformation = new ExtendInformation(100, Integer.valueOf("100"), "ZhongGang", Level.ERROR, new int[]{1, 2, 3, 4, 5,}, basicInfo, "Ma Ma Mi Ya");

        OutputStream outputStream = new FileOutputStream(file);
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);

        objectOutputStream.writeObject(information);
        objectOutputStream.writeObject(extendInformation);

        InputStream inputStream = new FileInputStream(file);
        ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);
        Information info = (Information) objectInputStream.readObject();
        assertEquals(100, info.getNumber());
        assertEquals(Integer.valueOf("100"), info.getCount());
        assertEquals("ZhongGang", info.getName());
        assertEquals(Level.ERROR, info.getLevel());
        assertEquals(5, info.getNumbers().length);

        BasicInfo basic = info.getBasicInfo();
        assertNull(basic);
//        assertEquals("Chengdu", basic.getCity());
//        assertEquals("China", basic.getCountry());
    }

}

　　结论：

　　１。序列化适用的情况为当出现系统崩溃或程序运行停止等特殊情况时，为了保存类的实例到磁盘，待下次系统重启或程序再次运行时，重新构造类的实例，或都还原类的实例状态，也适用于在网络中传输类的实例，即在网络中的不同机器上还原类的实例状态。

　　２。为了实现序列化，需要实现Serializable接口，该接口为一标记接口，没有任何方法，实现该接口的类，表明该项类可以进行序列化与反序列化，通俗地说即是，可以将类的实例即对象转化为流或字节，或者将相应的流或字节转化为相应的对象，前者叫做序列化，而后者叫做反序列化。

　　３。父类实例了Serializable接口，那么它的子类不需要再次实现Serializable接口，就可以实现序列化。

　　４。如果某个类的某个属性为非基本类型，基本类型的封装对象，枚举或可序列化数组等对象时，如果该对象没有实现Serializable接口，即没有实例化，那么会导致NoSerialzableException，为了避免此种情况的发生，可以为该对象实现Serializable接口，或者加上transient修饰符，表明在进行序列化时，此属性不会进行序列化。

　　５。通过序列化保存的类的实例状态为二进制数据，其中不仅包含实例的状态值，还包含序列化号，以及类的名称等必要信息，其中的一些附加信息是为反序列化提供足够的信息。

　　６。通过序列化实现的功能也可以通过其它一些方式来实现，如通过xml文件等，在xml文件中以特定格式来表述类的实例状态值，这样通过分析xml文件来还原当时的类的实例状态，并且这样的实现，当在网络中进行传输时，还可以对文件进行加密处理，使用起来更加安全。

　　７。序列化后的信息不包含类的方法