通过序列化举办深层复制(java)

若研究一下第10章先容的谁人Java 1.1工具序列化示例，大概发明若在一个工具序列化今后再除掉对它的序列化，可能说举办装配，那么实际经验的正是一个“克隆”的进程。
那么为什么不消序列化举办深层复制呢？下面这个例子通过计较执行时间比拟了这两种要领：
 

//: Compete.java
import java.io.*;

class Thing1 implements Serializable {}
class Thing2 implements Serializable {
  Thing1 o1 = new Thing1();
}

class Thing3 implements Cloneable {
  public Object clone() {
    Object o = null;
    try {
      o = super.clone();
    } catch (CloneNotSupportedException e) {
      System.out.println("Thing3 can't clone");
    }
    return o;
  }
}

class Thing4 implements Cloneable {
  Thing3 o3 = new Thing3();
  public Object clone() {
    Thing4 o = null;
    try {
      o = (Thing4)super.clone();
    } catch (CloneNotSupportedException e) {
      System.out.println("Thing4 can't clone");
    }
    // Clone the field, too:
    o.o3 = (Thing3)o3.clone();
    return o;
  }
}

public class Compete {
  static final int SIZE = 5000;
  public static void main(String[] args) {
    Thing2[] a = new Thing2[SIZE];
    for(int i = 0; i < a.length; i++)
      a[i] = new Thing2();
    Thing4[] b = new Thing4[SIZE];
    for(int i = 0; i < b.length; i++)
      b[i] = new Thing4();
    try {
      long t1 = System.currentTimeMillis();
      ByteArrayOutputStream buf = 
        new ByteArrayOutputStream();
      ObjectOutputStream o =
        new ObjectOutputStream(buf);
      for(int i = 0; i < a.length; i++)
        o.writeObject(a[i]);
      // Now get copies:
      ObjectInputStream in =
        new ObjectInputStream(
          new ByteArrayInputStream(
            buf.toByteArray()));
      Thing2[] c = new Thing2[SIZE];
      for(int i = 0; i < c.length; i++)
        c[i] = (Thing2)in.readObject();
      long t2 = System.currentTimeMillis();
      System.out.println(
        "Duplication via serialization: " +
        (t2 - t1) + " Milliseconds");
      // Now try cloning:
      t1 = System.currentTimeMillis();
      Thing4[] d = new Thing4[SIZE];
      for(int i = 0; i < d.length; i++)
        d[i] = (Thing4)b[i].clone();
      t2 = System.currentTimeMillis();
      System.out.println(
        "Duplication via cloning: " +
        (t2 - t1) + " Milliseconds");
    } catch(Exception e) {
      e.printStackTrace();
    }
  }
} ///:~

个中，Thing2和Thing4包括了成员工具，所以需要举办一些深层复制。一个有趣的处所是尽量Serializable类很容易配置，但在复制它们时却要做多得多的事情。克隆涉及到大量的类配置事情，但实际的工具复制是相当简朴的。功效很好地说明白一切。下面是屡次运行别离获得的功效：
简直
 

Duplication via serialization: 3400 Milliseconds
Duplication via cloning: 110 Milliseconds

Duplication via serialization: 3410 Milliseconds
Duplication via cloning: 110 Milliseconds

Duplication via serialization: 3520 Milliseconds
Duplication via cloning: 110 Milliseconds

除了序列化和克隆之间庞大的时间差别以外，我们也留意到序列化技能的运行功效并不不变，而克隆每一次耗费的时间都是沟通的。