一道關於java序列化的問題，看大家知多少————

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問題先放在這裡，稍後我會做出解答

 

已知類有Test和Test2，問兩次主程式的輸出結果是多少（SerializeUtil只是序列化的工具類）

類Test

public class Test implements Serializable{    private static final long serialVersionUID = 1L;    private int num;    private transient String str;    public Test(){        this.num = 0xFFFF;        this.str = "string";    }    public Test(int num, String str) {        this.num = num;        this.str = str;    }    @Override    public String toString() {        return num + ","+str;    }}

類Test2

public class Test2 implements Externalizable,Serializable{    private static final long serialVersionUID = 1L;    private int num;    private transient String str;    public Test2() {        this.num = 0xFFFF;        this.str = "hello";    }    public Test2(int num, String str) {        this.num = num;        this.str = str;    }    @Override    public void writeExternal(ObjectOutput out) throws IOException {        out.write(num);    }    @Override    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {        this.num = in.read();    }    @Override    public String toString() {        return num + ","+str;    }}

兩個主程式：

    public static void main(String[] args) {        Test test = new Test();        File file = new File("d:/test.bin");        SerializeUtil.writeObject(file,test);        Test test2 = (Test) SerializeUtil.readObject(file);        System.out.println(test);        System.out.println(test2);    }

 

    public static void main(String[] args) {        Test2 test2 = new Test2();        File file = new File("d:/test2.bin");        SerializeUtil.writeObject(file,test2);        Test2 t = (Test2) SerializeUtil.readObject(file);        System.out.println(test2);        System.out.println(t);    }

 

附SerializeUtil的代碼，可無視——

 1 public class SerializeUtil { 2  3     public static void writeObject(File file,Object object){ 4         FileOutputStream fileOutputStream = null; 5         try { 6             fileOutputStream = new FileOutputStream(file); 7             ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream); 8             objectOutputStream.writeObject(object); 9             objectOutputStream.flush();10         }catch (IOException e){11             e.printStackTrace();12         }finally {13             if(fileOutputStream!=null){14                 try {15                     fileOutputStream.close();16                 } catch (IOException e) {}17             }18         }19     }20 21     public static Object readObject(File file){22         FileInputStream fileInputStream = null;23         try {24             fileInputStream = new FileInputStream(file);25             ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);26             return objectInputStream.readObject();27         }catch (ClassNotFoundException|IOException e){28             e.printStackTrace();29         }finally {30             if(fileInputStream!=null){31                 try {32                     fileInputStream.close();33                 } catch (IOException e) {}34             }35         }36         return null;37     }38 39 }

序列化工具類

 

答案如下：

/*第一個主程式：65535,string65535,null第二個主程式：65535,hello255,hello*/

答案

 

一道關於java序列化的問題，看大家知多少————