Java基础之序列化对象——将对象写入到文件中（SerializeObjects）

控制台程序。

首先定义一个含有任意不同数据类型域的可序列化类：

import java.io.Serializable;

public class Junk implements Serializable {
  private static java.util.Random generator = new java.util.Random();
  private int answer;                                                  // The answer
  private double[] numbers;                                            // Valuable data
  private String thought;                                              // A unique thought
  private static final long serialVersionUID = 9001L;

  public Junk(String thought) {
    this.thought = thought;
    answer = 42;                                                       // Answer always 42

    numbers = new double[3 + generator.nextInt(4)];                    // Array size 3 to 6
    for(int i = 0 ; i < numbers.length ; ++i) {                        // Populate with
      numbers[i] = generator.nextDouble();                             // random values
   }
  }

  @Override
  public String toString() {
    StringBuffer strBuf = new StringBuffer(thought);
    strBuf.append('
').append(String.valueOf(answer));
    for(int i = 0 ; i < numbers.length ; i++) {
      strBuf.append("
numbers[")
            .append(String.valueOf(i))
            .append("] = ")
            .append(numbers[i]);
    }
    return strBuf.toString();
  }
}

然后使用如下程序能将这个类类型的对象写入到文件中：

import java.io.*;
import java.nio.file.*;
import java.io.IOException;

public class SerializeObjects {
  public static void main(String[] args) {
    Junk obj1 = new Junk("A green twig is easily bent.");
    Junk obj2 = new Junk("A little knowledge is a dangerous thing.");
    Junk obj3 = new Junk("Flies light on lean horses.");

    Path file = Paths.get(System.getProperty("user.home")).resolve("Beginning Java Struff").resolve("JunkObjects.bin");
    try {
      Files.createDirectories(file.getParent());    // Make sure we have the directory
    } catch (IOException e) {
      e.printStackTrace();
      System.exit(1);
    }

    try (ObjectOutputStream objectOut = new ObjectOutputStream(new BufferedOutputStream(Files.newOutputStream(file)))){
      // Write three objects to the file
      objectOut.writeObject(obj1);                                     // Write object
      objectOut.writeObject(obj2);                                     // Write object
      objectOut.writeObject(obj3);                                     // Write object
      System.out.println("

obj1:
" + obj1
                        +"

obj2:
" + obj2
                        +"

obj3:
" + obj3);

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