先来看看java的ObjectOutputStream和ObjectInputStream源码好了

public ObjectOutputStream(OutputStream out) throws IOException {  
        verifySubclass();  
        bout = new BlockDataOutputStream(out);  
        handles = new HandleTable(10, (float) 3.00);  
        subs = new ReplaceTable(10, (float) 3.00);  
        enableOverride = false;  
        writeStreamHeader();  
        bout.setBlockDataMode(true);  
        if (extendedDebugInfo) {  
            debugInfoStack = new DebugTraceInfoStack();  
        } else {  
            debugInfoStack = null;  
        }  
    }  

public ObjectInputStream(InputStream in) throws IOException {  
        verifySubclass();  
        bin = new BlockDataInputStream(in);  
        handles = new HandleTable(10);  
        vlist = new ValidationList();  
        enableOverride = false;  
        readStreamHeader();  
        bin.setBlockDataMode(true);  
    }  

不难发现在序列化new的时候调用了writeStreamHeader()方法写入了4个字节的StreamHeader

但是呢在读取的时候只有读取一次StreamHeader的,所以导致出错

贴图:

这里我们可以看下StreamHeader的内容：

protected void writeStreamHeader() throws IOException {  
        bout.writeShort(STREAM_MAGIC);  
        bout.writeShort(STREAM_VERSION);  
    }  

很简单，一个魔数，一个版本号。两个都是short类型，占4个字节。

解决方法就是把StreamHeader给去掉就行了啦,使用以下方法:

public static void writeObj(File file, Object obj) throws IOException {
		boolean isexit = false;
		if (file.exists()) {
			isexit = true;// 序列化文件存在,追加内容
		}
		FileOutputStream fileOutputStream = new FileOutputStream(file,true);
		// 每次new的时候都会写入一个StreamHeader,所以要把屁股后面的StreamHeader去掉
		ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
		long pos = 0;// 可以说是文件的长度
		if (isexit) {
			// getChannel()返回此通道的文件位置，这是一个非负整数，它计算从文件的开始到当前位置之间的字节数
			pos = fileOutputStream.getChannel().position() - 4;// StreamHeader有4个字节所以减去
			// 将此通道的文件截取为给定大小
			fileOutputStream.getChannel().truncate(pos);
			System.out.println("追加成功~");
		}

		objectOutputStream.writeObject(obj);
		// 关闭流
		objectOutputStream.close();
		fileOutputStream.close();

	}

（反序列化）读取多个对象:

		FileInputStream fileInputStream = null;
		ObjectInputStream objectInputStream = null;
		java.util.List<Student> list = new ArrayList<Student>();
		try {
			fileInputStream = new FileInputStream(file);
			objectInputStream = new ObjectInputStream(fileInputStream);
			while (fileInputStream.available() > 0) {
				list.add((Student) objectInputStream.readObject());
			}
			System.out.println("读取~");
			for (int i = 0; i < list.size(); i++) {
				System.out.println(list.get(i));
			}

		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 

参考博客:点击打开链接