Java序列化深入剖析和总结（精华）

1、什么是序列化和反序列化

2.序列化的目的

1)对象序列化的目标是将对象保存到磁盘上，或允许在网络中直接传输对象、进程间传输对象（RPC是分布式框架hadoop实现的基础就用到了对象的序列化）

2)序列化是 RMI（Remote Method Invoke – 远程方法调用）过程的参数和返回值都必须实现的机制

2、什么情况下需要序列化

3、ransient关键字

可以让序列化对象的某些属性放弃序列化的机会

4、对于序列化对象中有引用对象的情况

5、实现序列化的方式

6.Externalizable的API

void

readExternal(ObjectInput in)

void

writeExternal(ObjectOutput out)

7、对比

参考代码：

package com.test;

import java.io.Serializable;

public class Person implements Serializable {
private static final long serialVersionUID = 1L;

//transient关键字：可以让序列化对象的某些属性放弃序列化的机会  此时，测试结果为 null : 29
//private transient String name;

private String name;
private int age;
//序列化对象中有引用对象的情况
private OtherClass otherClass = new OtherClass();

public OtherClass getOtherClass() {
return otherClass;
}

public Person(String name, int age) {
this.name = name;
this.age = age;
}

public String getName() {
return name;
}

public int getAge() {
return age;
}
}

package com.test;

import java.io.Serializable;

public class OtherClass implements Serializable {

}

 package com.test;

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

public class ObjectStreamDemo {

public staticvoid test() throws Exception {
Person person= new Person("watchemen",29);
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("C:/javaTest/person.txt"));
os.writeObject(person);
os.close();

ObjectInputStream ios = new ObjectInputStream(new FileInputStream("C:/javaTest/person.txt"));
Person person1 = (Person)ios.readObject();
System.out.println(person1.getName()+" : "+person1.getAge());

//OtherClass没有实现序列化时会报错
//OtherClass实现序列化后显示：com.test.OtherClass@35718057
System.out.println(person1.getOtherClass());

ios.close();
}
public staticvoid main(String[] args) throws Exception {
test();
}

}

 package com.test;
/**
* 实现Externalizable接口实现序列化
*/
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Date;

public class Person1 implements Externalizable {

private static final long serialVersionUID = 1L;
private String name;
private int age;

public Person1() {
}

public Person1(String name, int age) {
this.name = name;
this.age = age;
}

public String getName() {
return name;
}

public int getAge() {
return age;
}

@Override
publicvoid readExternal(ObjectInput in) throws IOException,ClassNotFoundException {
this.name = (String) in.readObject();
this.age = in.readInt();
Date date = (Date) in.readObject();
System.out.println("date: " + date);
}

@Override
publicvoid writeExternal(ObjectOutput out) throws IOException {
//可以附加一些额外的功能
Date date = new Date();
out.writeObject(name);
out.writeInt(age);
out.writeObject(date);
}

}

 package com.test;

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

public class ObjectStreamDemo1 {

public staticvoid test() throws Exception {
Person1 person1= new Person1("watchemen",29);
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("C:/javaTest/person1.txt"));
os.writeObject(person1);
os.close();

ObjectInputStream ios = new ObjectInputStream(new FileInputStream("C:/javaTest/person1.txt"));
Person1 person2 = (Person1)ios.readObject();
System.out.println(person2.getName()+" : "+person2.getAge());
ios.close();
}
public staticvoid main(String[] args) throws Exception {
test();
}

}