问题现象：使用ObjectOutputStream向同一个文件写入多个对象，
A). 当ObjectOutputStream在打开后连续写入多个对象再关闭，可通过ObjectInputStream正常读取写入的多个对象；
B). 当每写入一个对象即关闭ObjectOutputStream并在写入下一个对象时重新打开，通过ObjectInputStream读取对象时，可以正常读取第一个对象，但读取第二个对象时报错。典型的报错信息如下：

Exception in thread "main" java.io.StreamCorruptedException: invalid type code: AC
	at java.io.ObjectInputStream.readObject0(Unknown Source)
	at java.io.ObjectInputStream.readObject(Unknown Source)
	at com.demo.ObjectSerializationDemo.writeObjectsSeparately(ObjectSerializationDemo.java:69)
	at com.demo.ObjectSerializationDemo.main(ObjectSerializationDemo.java:17)
		

问题原因：创建ObjectOutputStream对象时，会向输出流中写入标志数据“AC ED 00 05”；创建ObjectInputStream对象时，会自动解析输入流中开始的这些标志数据，因此采用方法A操作可以正常读取写入的对象。

但当采用方法B)时，由于ObjectOutputStream创建了两次，因此写入第二个对象时，会再次添加标志数据；ObjectInputStream仅能解析第一个对象前的标志数据，后面的标志数据当作对象数据处理，导致处理错误。

可参考这篇文章的内容。

方法A)示例程序：

public static void writeObjectsContinually() throws FileNotFoundException, IOException, ClassNotFoundException  {
	System.out.println("Write 2 Objects in one ObjectOutputStream:");
	
	String[] array1 = {"this", "is", "a", "demo", "program"};
	String[] array2 = {"this", "is", "also", "a", "demo", "program"}; 
	File f1 = new File("object.out_1");
	File f2 = new File("object.out_2");
		
	/**
	 * 在一个OutputStream中写入array1和array2
	 */
	ObjectOutputStream outputStream;
	outputStream = new ObjectOutputStream(new FileOutputStream(f1));
	outputStream.writeObject(array1);
	outputStream.writeObject(array2);
	outputStream.flush();
	outputStream.close();

	/**
	 * 读取array1和array2
	 */
	ObjectInputStream inputStream;
	inputStream = new ObjectInputStream(new FileInputStream(f1));
	String[] arrayOut1 = (String[]) inputStream.readObject();
	String[] arrayOut2 = (String[]) inputStream.readObject();
	inputStream.close();

	System.out.printf("==>>%s\n==>>before:%s\n==>>after:%s\n", "array1", Arrays.toString(array1), Arrays.toString(arrayOut1));
	System.out.printf("==>>%s\n==>>before:%s\n==>>after:%s\n", "array2", Arrays.toString(array2), Arrays.toString(arrayOut2));
}
		

方法B)示例程序：

public static void writeObjectsSeparately() throws FileNotFoundException, IOException, ClassNotFoundException  {
	System.out.println("Write 2 Objects in two ObjectOutputStreams:");
	
	String[] array1 = {"this", "is", "a", "demo", "program"};
	String[] array2 = {"this", "is", "also", "a", "demo", "program"}; 
	File f1 = new File("object.out_1");
	File f2 = new File("object.out_2");
	
	ObjectOutputStream outputStream;
	/**
	 * 打开OutputStream，写入array1
	 */
	outputStream = new ObjectOutputStream(new FileOutputStream(f2, true));
	outputStream.writeObject(array1);
	outputStream.flush();
	outputStream.close();
	/**
	 * 打开OutputStream，写入array2
	 */
	outputStream = new ObjectOutputStream(new FileOutputStream(f2, true));
	outputStream.writeObject(array2);
	outputStream.flush();
	outputStream.close();
	
	/**
	 * 读取array1和array2
	 */
	ObjectInputStream inputStream;
	inputStream = new ObjectInputStream(new FileInputStream(f2));
	String[] arrayOut11 = (String[]) inputStream.readObject();	// 第一个对象读取成功
	String[] arrayOut22 = (String[]) inputStream.readObject();	// 第二个对象读取时抛出异常
	inputStream.close();

	System.out.printf("==>>%s\n==>>before:%s\n==>>after:%s\n", "array1", Arrays.toString(array1), Arrays.toString(arrayOut11));
	System.out.printf("==>>%s\n==>>before:%s\n==>>after:%s\n", "array2", Arrays.toString(array2), Arrays.toString(arrayOut22));
}