//简单定义一个Student类
public class Student {

 private String name;
 private int age;

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

 public void setName(String name){
 this.name = name;
 }
 public void setAge(int age){
 this.age = age;
 }
 public String getName(){
 return this.name;
 }
 public int getAge(){
 return this.age;
 }
 //重写toString
 @Override
 public String toString(){
 return ("my name is:"+this.name+" age is:"+this.age);
 }
}

//main方法实现了将对象写入文件并读取出来
public static void main(String[] args) throws IOException{

 DataOutputStream dot = new DataOutputStream(new FileOutputStream("hello.txt"));
 Student stuW = new Student("walker",21);
 //将此对象写入到文件中
 dot.writeUTF(stuW.getName());
 dot.writeInt(stuW.getAge());
 dot.close();

 //将对象从文件中读出
 DataInputStream din = new DataInputStream(new FileInputStream("hello.txt"));
 Student stuR = new Student();
 stuR.setName(din.readUTF());
 stuR.setAge(din.readInt());
 din.close();

 System.out.println(stuR);
 }

public static void main(String[] args) throws IOException, ClassNotFoundException {

 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("hello.txt"));
 Student stuW = new Student("walker",21);
 oos.writeObject(stuW);
 oos.close();

 //从文件中读取该对象返回
 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("hello.txt"));
 Student stuR = (Student)ois.readObject();
 System.out.println(stuR);
 }

public ObjectOutputStream(OutputStream out)

public class Student implements Serializable {

 String name;
 int age;
 Teacher t; //另外一个对象类型

 public Student(){}
 public Student(String name,int age,Teacher t){
 this.name = name;
 this.age=age;
 this.t = t;
 }

 public void setName(String name){this.name = name;}
 public void setAge(int age){this.age = age;}
 public void setT(Teacher t){this.t = t;}
 public String getName(){return this.name;}
 public int getAge(){return this.age;}
 public Teacher getT(){return this.t;}
}

public class Teacher implements Serializable {
 String name;

 public Teacher(String name){
 this.name = name;
 }
}

public static void main(String[] args) throws IOException, ClassNotFoundException {

 Teacher t = new Teacher("li");
 Student stu1 = new Student("walker",21,t);
 Student stu2 = new Student("yam",22,t);
 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("hello.txt"));
 oos.writeObject(stu1);
 oos.writeObject(stu2);

 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("hello.txt"));
 Student stuR1 = (Student)ois.readObject();
 Student stuR2 = (Student)ois.readObject();

 if (stuR1.getT() == stuR2.getT())
  System.out.println("相同对象");
 }

public class Student implements Serializable {

 String name;
 Teacher t;

}

public class Teacher implements Serializable {
 String name;
 Student stu;

}

public static void main(String[] args) throws IOException, ClassNotFoundException {

 Teacher t = new Teacher();
 Student s =new Student();
 t.name = "walker";
 t.stu = s;
 s.name = "yam";
 s.t = t;

 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("hello.txt"));
 oos.writeObject(t);
 oos.writeObject(s);
 oos.close();

 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("hello.txt"));
 Teacher tR = (Teacher)ois.readObject();
 Student sR = (Student)ois.readObject();
 if(tR == sR.t && sR == tR.stu)System.out.println("ok");

 }

public class Student implements Serializable {

 String name;
 transient int age;

 public String toString(){
 return this.name + ":" + this.age;
 }
}

public static void main(String[] args) throws IOException, ClassNotFoundException {

 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("hello.txt"));
 Student stu = new Student();
 stu.name = "walker";stu.age = 21;
 oos.writeObject(stu);

 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("hello.txt"));
 Student stuR = (Student)ois.readObject();

 System.out.println(stuR);
 }

//改动过的student类，main方法没有改动，大家可以往上看
public class Student implements Serializable {

 String name;
 transient int age;

 private void writeObject(ObjectOutputStream oos) throws IOException {
 oos.defaultWriteObject();

 oos.writeInt(25);
 }

 private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
 ois.defaultReadObject();

 age = ois.readInt();
 }

 public String toString(){
 return this.name + ":" + this.age;
 }
}