自定義序列化實現Externalizable接口需要注意的問題

package com.zhen.demo;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

public class Person5 implements Externalizable{

	private String name;
	
	private int age;
	
	public Person5(){}
	
	public Person5(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public void writeExternal(ObjectOutput out) throws IOException {
		out.writeObject(new StringBuffer(name).reverse());
		out.writeInt(age);
	}

	@Override
	public void readExternal(ObjectInput in) throws IOException,
			ClassNotFoundException {
		this.name = ((StringBuffer)in.readObject()).reverse().toString();
		this.age = in.readInt();
	}

	@Override
	public String toString() {
		return "Person5 [name=" + name + ", age=" + age + "]";
	}

}

實現該接口與實現Serializable接口的情況不太一樣，需要序列化的類要提供無參構造器，且訪問修飾符不能是private和protected和默認的修飾符，只能是public，否則會報錯；

Exception in thread "main" java.io.InvalidClassException: com.zhen.demo.Person5; no valid constructor
	at java.io.ObjectStreamClass$ExceptionInfo.newInvalidClassException(ObjectStreamClass.java:150)
	at java.io.ObjectStreamClass.checkDeserialize(ObjectStreamClass.java:790)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1782)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1353)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:373)
	at com.zhen.demo.WriteObject.main(WriteObject.java:44)