blip3.java

Thinking in JAVA第四版源代码

//: io/Blip3.java
// Reconstructing an externalizable object.
import java.io.*;
import static net.mindview.util.Print.*;

public class Blip3 implements Externalizable {
  private int i;
  private String s; // No initialization
  public Blip3() {
    print("Blip3 Constructor");
    // s, i not initialized
  }
  public Blip3(String x, int a) {
    print("Blip3(String x, int a)");
    s = x;
    i = a;
    // s & i initialized only in non-default constructor.
  }
  public String toString() { return s + i; }
  public void writeExternal(ObjectOutput out)
  throws IOException {
    print("Blip3.writeExternal");
    // You must do this:
    out.writeObject(s);
    out.writeInt(i);
  }
  public void readExternal(ObjectInput in)
  throws IOException, ClassNotFoundException {
    print("Blip3.readExternal");
    // You must do this:
    s = (String)in.readObject();
    i = in.readInt();
  }
  public static void main(String[] args)
  throws IOException, ClassNotFoundException {
    print("Constructing objects:");
    Blip3 b3 = new Blip3("A String ", 47);
    print(b3);
    ObjectOutputStream o = new ObjectOutputStream(
      new FileOutputStream("Blip3.out"));
    print("Saving object:");
    o.writeObject(b3);
    o.close();
    // Now get it back:
    ObjectInputStream in = new ObjectInputStream(
      new FileInputStream("Blip3.out"));
    print("Recovering b3:");
    b3 = (Blip3)in.readObject();
    print(b3);
  }
} /* Output:
Constructing objects:
Blip3(String x, int a)
A String 47
Saving object:
Blip3.writeExternal
Recovering b3:
Blip3 Constructor
Blip3.readExternal
A String 47
*///:~