transient关键字小议

当你实现Serializable接口的时候，预示着你在使用序列化与反序列化，此时你会考虑如果对于大对象是不是也需要进行序列化，如果不需要，那怎么避免他们在实现Serializable接口后不序列化这个属性对象那？OK，java提供了关键字transient，它的意思是瞬间，它会避免被她修饰的属性被序列化。
下边是一个例子：

package javabeat.samples;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

class NameStore implements Serializable{
	private String firstName;
	private transient String middleName;
	private String lastName;
	public NameStore (String fName, String mName, String lName){
		this.firstName = fName;
		this.middleName = mName;
		this.lastName = lName;
	}
	public String toString(){
		StringBuffer sb = new StringBuffer(40);
		sb.append("First Name : ");
		sb.append(this.firstName);
		sb.append("Middle Name : ");
		sb.append(this.middleName);
		sb.append("Last Name : ");
		sb.append(this.lastName);
		return sb.toString();
	}
}
public class TransientExample{
	public static void main(String args[]) throws Exception {
		NameStore nameStore = new NameStore("Steve","Middle","Jobs");
		ObjectOutputStream o = new ObjectOutputStream(new FileOutputStream(
				"nameStore"));
		// writing to object
		o.writeObject(nameStore);
		o.close();
		
		// reading from object
		ObjectInputStream in =new ObjectInputStream( 
                new FileInputStream("nameStore")); 
		NameStore nameStore1 = (NameStore)in.readObject();
		System.out.println(nameStore1);
	}
}

// output will be : First Name : SteveMiddle Name : nullLast Name : Jobs

虽然set了middlename的值，但是通过序列化，它被忽略了，所以当反序列化后，它就为null。