java - 是否有任何理由将异常的原因设置为自身？

Question

我在我正在构建的 Java 库中遇到过一些地方，在这些地方异常的原因被设置为异常本身。

异常是否有任何理由将自身作为其原因？

编辑

根据要求，这里有一个具体的例子:

Answer 1

我经常看到 Hibernate 或 Spring 等框架或库抛出的异常将自身作为原因(混淆了过程中的调试器 GUI)。

我一直想知道他们为什么这样做，因为这似乎是个坏主意。今天，当我尝试将一个序列化为 JSON 时，它实际上导致了一个问题:bam，enless cycle。

所以我进一步调查了一下:

在 Throwable 的源代码中(这里列出的所有源代码都来自 JDK 1.7)我们有这个:

 /**
     * The throwable that caused this throwable to get thrown, or null if this
     * throwable was not caused by another throwable, or if the causative
     * throwable is unknown.  If this field is equal to this throwable itself,
     * it indicates that the cause of this throwable has not yet been
     * initialized.
     *
     * @serial
     * @since 1.4
     */
    private Throwable cause = this;

现在我特别遇到了扩展 RuntimeException 的异常类的问题，所以我从那里开始。 RuntimeException 的构造函数之一:

/** Constructs a new runtime exception with the specified detail message.
     * The cause is not initialized, and may subsequently be initialized by a
     * call to {@link #initCause}.
     *
     * @param   message   the detail message. The detail message is saved for
     *          later retrieval by the {@link #getMessage()} method.
     */
    public RuntimeException(String message) {
        super(message);
    }

上面调用的Exception的构造函数:

 /**
     * Constructs a new exception with the specified detail message.  The
     * cause is not initialized, and may subsequently be initialized by
     * a call to {@link #initCause}.
     *
     * @param   message   the detail message. The detail message is saved for
     *          later retrieval by the {@link #getMessage()} method.
     */
    public Exception(String message) {
        super(message);
    }

上面调用的Throwable的构造函数:

/**
     * Constructs a new throwable with the specified detail message.  The
     * cause is not initialized, and may subsequently be initialized by
     * a call to {@link #initCause}.
     *
     * <p>The {@link #fillInStackTrace()} method is called to initialize
     * the stack trace data in the newly created throwable.
     *
     * @param   message   the detail message. The detail message is saved for
     *          later retrieval by the {@link #getMessage()} method.
     */
public Throwable(String message) {
    fillInStackTrace();
    detailMessage = message;
}

fillInStackTrace 是一种 native 方法，似乎不会修改 cause 字段。

如您所见，除非随后调用 initCause 方法，否则 cause 字段永远不会更改 this 的原始值.

结论:如果您使用不采用 cause 参数，并且您不调用 initCause 方法，异常的原因将是它本身!

所以我想这应该使它成为一种非常普遍的现象。