Java中Serializable接口的用法
今天学习了Serializable接口的用法，以及
private static final long serialVersionUID的具体用法
如下
如果今天你的类Serialized存到硬盘里,
可是後来你却更改了类别的field(增加或减少或改名).
当你Deserialize时,就会出现Exception.这样就会做成不兼容性的问题.
但当serialVersionUID相同时,它就会将不一样的field以type的预设值Deserialize.
这个可以避开不兼容性的问题.
例子：
public class User implements Serializable {
private static final long serialVersionUID = -7020619477594468968L;
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
User类实现了serializable接口，里面有一个name域。
public class SerialzeTest {
public static void main(String[] args)
{
try {
File test = new File("test.seri");
FileOutputStream out = new FileOutputStream(test);
ObjectOutputStream oout = new ObjectOutputStream(out);
User user = new User();
user.setName("example1");
oout.writeObject(user);
FileInputStream in = new FileInputStream(test);
ObjectInputStream oin = new ObjectInputStream(in);
User user = (User)oin.readObject();
System.out.println(user.getName());
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
该类将User类输入到test.seri文件中，再从中读取出来。
假如现在将User类改变
public class User implements Serializable {
private static final long serialVersionUID = -7020619477594468968L;
private String name;
private String pass;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPass() {
return pass;
}
public void setPass(String pass) {
this.pass = pass;
}
}
添加了一个password域，这里并没有改变serialVersionUID
再使用serialtest类
public class SerialzeTest {
public static void main(String[] args)
{
try {
File test = new File("test.seri");
// FileOutputStream out = new FileOutputStream(test);
// ObjectOutputStream oout = new ObjectOutputStream(out);
// User user = new User();
// user.setName("example1");
// oout.writeObject(user);
FileInputStream in = new FileInputStream(test);
ObjectInputStream oin = new ObjectInputStream(in);
User user = (User)oin.readObject();
System.out.println(user.getName());
System.out.println(user.getPass());
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
从test.seri文件中读取该类就不会抛出异常，输出为
example1
null
即会将password域认为空。
假如在新的User类中修改了serialVersionUID值，就会抛出异常