79 lines
2.0 KiB
Java
79 lines
2.0 KiB
Java
// serialization/Blips.java
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// (c)2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Simple use of Externalizable & a pitfall
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import java.io.*;
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class Blip1 implements Externalizable {
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public Blip1() {
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System.out.println("Blip1 Constructor");
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}
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@Override
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public void writeExternal(ObjectOutput out)
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throws IOException {
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System.out.println("Blip1.writeExternal");
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}
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@Override
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public void readExternal(ObjectInput in)
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throws IOException, ClassNotFoundException {
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System.out.println("Blip1.readExternal");
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}
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}
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class Blip2 implements Externalizable {
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Blip2() {
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System.out.println("Blip2 Constructor");
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}
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@Override
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public void writeExternal(ObjectOutput out)
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throws IOException {
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System.out.println("Blip2.writeExternal");
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}
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@Override
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public void readExternal(ObjectInput in)
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throws IOException, ClassNotFoundException {
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System.out.println("Blip2.readExternal");
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}
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}
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public class Blips {
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public static void
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main(String[] args) throws IOException,
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ClassNotFoundException {
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System.out.println("Constructing objects:");
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Blip1 b1 = new Blip1();
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Blip2 b2 = new Blip2();
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try(
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ObjectOutputStream o = new ObjectOutputStream(
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new FileOutputStream("Blips.serialized"))
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) {
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System.out.println("Saving objects:");
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o.writeObject(b1);
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o.writeObject(b2);
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}
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// Now get them back:
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System.out.println("Recovering b1:");
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try(
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ObjectInputStream in = new ObjectInputStream(
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new FileInputStream("Blips.serialized"))
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) {
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b1 = (Blip1)in.readObject();
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}
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// OOPS! Throws an exception:
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//- System.out.println("Recovering b2:");
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//- b2 = (Blip2)in.readObject();
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}
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}
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/* Output:
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Constructing objects:
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Blip1 Constructor
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Blip2 Constructor
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Saving objects:
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Blip1.writeExternal
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Blip2.writeExternal
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Recovering b1:
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Blip1 Constructor
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Blip1.readExternal
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*/
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