对象的序列化

下面将实现一个序列化对象的例子，也就是将对象保存到文件中，在从文件中读出对象
步骤：
1确保要保存的对象实现了Serializeable 接口
2通过创建一个ObjectOutputStream()对象来打开文件
3通过writeObject（）将对象写入文件
4完成后关闭输入流。

从文件中读取对象
1通过一个ObjectInputStream（）对象来打开文件
2通过调用readObject（）来读取对象，并将对像强制转换为读取对象的实际类型
3关闭流。

一：定义一个类My.class 作为序列化的对象
/**
 *
 */
package hust.ophoneclub.SerialDemo;

import java.io.File;
import java.io.Serializable;

/**
 * @author chenhao
 *
 */
public class MyClass implements Serializable {
    String str;
    double[] vals;
    File file;
   
    public MyClass(String str, double[] numbers, String fileName){
        this.str = str;
        vals = numbers;
        file = new File(fileName);
    }
   
    public String toString(){
        String data = " str:" + str + "\n" + "vlas ";
        for(double d: vals) {
            data += d + " ";
        }
        data += "\nfile name " + file.getName();
        return data;
    }
}

定义一个类来实现这个序列化的过程
/**
 *
 */
package hust.ophoneclub.SerialDemo;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/**
 * @author chenhao
 *
 */
public class SerialDemo {
    public static void main(String args[] ){
        saveObj();
        readObj();
        //
    }

    /**
     *
     */
    private static void saveObj() {
        double v1[] = {1.1, 2.2, 3.3};
        double v2[] = {1.2, 2.3, 3.4};
       
        MyClass object1 = new MyClass("first obj", v1, "firstObj.txt");
        MyClass object2 = new MyClass("first obj", v2, "secondObj.txt");
       
        //open the output file
        ObjectOutputStream out;
        try {
            out = new ObjectOutputStream(new FileOutputStream("obj.dat"));
        } catch (Exception e) {
            printError(e);
            return;
        }
       
        //write the obj to the file
        try {
            writeObjToFile(object1, out);
            writeObjToFile(object2, out);
           
        } catch (Exception e) {
            printError(e);
        }
       
        try{
            out.close();
        }catch (Exception e) {
            printError(e);
        }
    }

    /**
     * @param e
     */
    private static void printError(Exception e) {
        System.out.println(e.getMessage());
    }

    /**
     *
     */
    private static void readObj() {
        //read the object from the file
        ObjectInputStream in = null;
        try {
            in = new ObjectInputStream(new FileInputStream("obj.dat"));
        } catch (Exception e) {
            printError(e);
            return;
        }
        System.out.println("\nreading obj from the file ");
        try {
            MyClass inputObj;
            inputObj = (MyClass)in.readObject();
            System.out.println("First Objetct" + inputObj);
           
            inputObj = (MyClass)in.readObject();
            System.out.println("second Objetct" + inputObj);
        } catch (Exception e) {
           printError(e);
        }
       
        try {
            in.close();
        } catch (Exception e) {
            printError(e);
        }
       
    }
    /**
     * @param object1
     * @param out
     * @throws IOException
     */
    private static void writeObjToFile(MyClass object1, ObjectOutputStream out)
            throws IOException {
        System.out.println("write the obj to the file");
        System.out.println(object1);
        out.writeObject(object1);
    }
}

输出的结果
write the obj to the file
 str:first obj
vlas 1.1 2.2 3.3
file name firstObj.txt
write the obj to the file
 str:first obj
vlas 1.2 2.3 3.4
file name secondObj.txt

reading obj from the file
First Objetct str:first obj
vlas 1.1 2.2 3.3
file name firstObj.txt
second Objetct str:first obj
vlas 1.2 2.3 3.4
file name secondObj.txt