Java编程思想：序列化基础部分

 import java.io.*;
 import java.util.Date;
 import java.util.Random;

 public class Test {
     public static void main(String[] args){
 //        Worm.test();
 //        Blip.test();
 //        Login.test();
         SerialCtl.test();
     }
 }

 class Data implements Serializable {
     private int n;

     public Data(int n) {
         this.n = n;
     }

     public String toString() {
         return Integer.toString(n);
     }
 }

 class Worm implements Serializable {
     private static final int SIZE = 1024;
     private static Random random = new Random(47);
     private Data[] datas = new Data[]{
             new Data(random.nextInt(10)),
             new Data(random.nextInt(10)),
             new Data(random.nextInt(10))
     };

     private Worm next;
     private char c;

     public Worm(int i, char c) {
         System.out.println("Worm Constructor: " + i);
         this.c=c;
         if (--i > 0) {
             next=new Worm(i,(char)(c+1));
         }
     }

     public Worm() {
         System.out.println("Default Constructor");
     }

     public String toString() {
         StringBuilder sb = new StringBuilder(":");
         sb.append("c");
         sb.append("(");
         for (Data data : datas) {
             sb.append(data);
         }
         sb.append(")");
         if (next != null) {
             sb.append(next);
         }
         return sb.toString();
     }

     public static void test() {
         try{
             Worm w = new Worm(6, 'a');
             System.out.println("w  = "+w);

             /*

             //创建ObjectOutputStream用于储存序列化结果
             ObjectOutputStream out = new ObjectOutputStream(
                     new FileOutputStream("worm.out"));

             out.writeObject("Worm Storage\n");
             out.writeObject(w);
             out.close();

             //创建ObjectInputStream用于读取序列化数据
             ObjectInputStream in = new ObjectInputStream(
                     new FileInputStream("worm.out"));

             //从序列化数据恢复时，需要按照序列化顺序
             String s = (String)in.readObject();
             Worm w2 = (Worm)in.readObject();
             System.out.println(s+"w2 = "+w);

             */

             //测试，将序列化数据储存在ByteArrayOutputStream中

             //这个地方这样写，不便于后面操作
             /*
             ObjectOutputStream out2 = new ObjectOutputStream(
                     new ByteArrayOutputStream());
             */

             ByteArrayOutputStream bs = new ByteArrayOutputStream();
             ObjectOutputStream out2 = new ObjectOutputStream(bs);
             out2.writeObject("Worm Storage In Bytes...\n");
             out2.writeObject(w);
             out2.flush();

             ObjectInputStream in2 = new ObjectInputStream(
                     new ByteArrayInputStream(bs.toByteArray()));

             String s2 = (String)in2.readObject();
             Worm w3 = (Worm)in2.readObject();

             System.out.println(s2 + "w3 = "+w3);

         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         }
     }
 }

 /*
     Serializable序列化时，对象完全以它存储的二进制为为基础来构造，而不调用构造器
     Externnlizable序列化时，所有普通的默认构造器都会被调用（包括字段定义时的初始
     化），然后调用readExternal()
  */
 class Blip implements Externalizable {
     private int i;
     private String s;

     public Blip() {
         System.out.println("Constructor: Blip()");
     }

     public Blip(String s, int i) {
         System.out.println("Constructor: Blip(String s, int i)");

         this.s=s;
         this.i=i;
     }

     public String toString() {
         return s + i;
     }

     @Override
     public void writeExternal(ObjectOutput out) throws IOException {
         System.out.println("Blip.writeExternal...");
         out.writeObject(s);
         //这个地方写了一个BUG，用Object会造成自动装箱，导致readInt()读不出来结果
         //out.writeObject(i);
         out.writeInt(i);
     }

     @Override
     public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
         System.out.println("Blip.readExternal...");
         this.s = (String)in.readObject();
         this.i = in.readInt();
     }

     public static void test() {
         try{
             Blip b = new Blip("A String...", 47);
             System.out.println(b);

             //创建输出流
             ObjectOutputStream out = new ObjectOutputStream(
                     new FileOutputStream("Blip.out"));
             out.writeObject(b);
             out.close();

             //创建输入流
             ObjectInputStream in = new ObjectInputStream(
                     new FileInputStream("Blip.out"));
             Blip b2 = (Blip)in.readObject();
             System.out.println(b2);

         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         }

     }
 }

 /*
     测试 Transient关键字
  */
 class Login implements Serializable {
     private Date date = new Date();
     private String username;
     private transient String password;

     public Login(String name, String password) {
         this.username = name;
         this.password=password;
     }

     public String toString() {
         return "Login info:"+
                 "\n   username:"+username+
                 "\n   password:"+password+
                 "\n   date:"+date;
     }

     public static void test() {
         try{
             Login l = new Login("zhangshan", "123456");
             System.out.println("Login l = "+l);

             //创建输出流
             ObjectOutputStream out = new ObjectOutputStream(
                     new FileOutputStream("login.out"));
             out.writeObject(l);

             //创建输入流
             ObjectInputStream in = new ObjectInputStream(
                     new FileInputStream("login.out"));
             Login m = (Login)in.readObject();
             System.out.println("Login m = "+m);

         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         }

     }
 }

 /*
     Externalizable的替代方案，非常混乱的一个方案，没有研究的价值
  */
 class SerialCtl implements Serializable {
     private String username;
     private transient String password;

     public SerialCtl(String name, String password) {
         this.username=name;
         this.password=password;
     }

     public String toString() {
         return username+"\n"+password;
     }

     private void writeObject(ObjectOutputStream outputStream)
         throws IOException{
         outputStream.defaultWriteObject();
         outputStream.writeObject(password);
     }

     private void readObject(ObjectInputStream inputStream)
         throws IOException,ClassNotFoundException{
         inputStream.defaultReadObject();
         password=(String)inputStream.readObject();
     }

     public static void test() {
         SerialCtl sc = new SerialCtl("Test1", "Test2");
         System.out.println("Before:\n"+sc);

         try{
             //创建输出流
             ObjectOutputStream out = new ObjectOutputStream(
                     new FileOutputStream("SerialCtl.out"));
             out.writeObject(sc);

             //创建输入流
             ObjectInputStream in = new ObjectInputStream(
                     new FileInputStream("SerialCtl.out"));
             SerialCtl sc2 = (SerialCtl)in.readObject();
             System.out.println("Now:\n"+sc2);
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         }
     }
 }