使用 try-with-resources 重写此代码

Question

此代码用于通过java序列化复制一个实例。它采用传统的try-catch-finally写法。可以改成try-with-resources形式吗？（代码中的DeepConcretePrototype是一个普通的java对象）

    /**
     * Clone an instance through java serialization
     * @return
     */
    public DeepConcretePrototype deepCloneBySerializable() {
        DeepConcretePrototype clone = null;
        ByteArrayOutputStream byteArrayOutputStream = null;
        ObjectOutputStream objectOutputStream = null;
        ByteArrayInputStream byteArrayInputStream = null;
        ObjectInputStream objectInputStream = null;
        try {
            //Output an instance to memory
            byteArrayOutputStream = new ByteArrayOutputStream();
            objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
            objectOutputStream.writeObject(this);
            objectOutputStream.flush();
            //Read instance from memory
            byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
            objectInputStream = new ObjectInputStream(byteArrayInputStream);
            clone = (DeepConcretePrototype)objectInputStream.readObject();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (byteArrayOutputStream != null) {
                try {
                    byteArrayOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (objectOutputStream != null) {
                try {
                    objectOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (byteArrayInputStream != null) {
                try {
                    byteArrayInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (objectInputStream != null) {
                try {
                    objectInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return clone;
    }

Answer 1

是的，您可以使用 try-with-resources，但这有点棘手，因为 read 的成功取决于 write 的成功。一种编写方法是使用嵌套 try:

public DeepConcretePrototype deepCloneBySerializable() {
    DeepConcretePrototype clone = null;

    try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
         ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream)) {
        //Output an instance to memory
        objectOutputStream.writeObject(this);
        objectOutputStream.flush();

        try (ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
             ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream)) {
            //Read instance from memory
            clone = (DeepConcretePrototype) objectInputStream.readObject();
        }

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

    return clone;
}

使用 try-with-resources 重写此代码

Rewrite this code using try-with-resources

java

io

try-catch

try-with-resources