URL解码：Java中的UnsupportedEncodingException [英] URL decoding: UnsupportedEncodingException in Java

问题描述

我从文档中了解到， UnsupportedEncodingException 只能指定一个错误的编码作为URLDecoder.decode（String，String）方法的第二个参数。是这样吗？我需要知道可以抛出这个异常的情况。

What I understand from the documentation is that UnsupportedEncodingException can only be thrown if I specify a wrong encoding as the second parameter to URLDecoder.decode(String, String) method. Is it so? I need to know cases where this exception can be thrown.

基本上，我在我的一个功能中有这个代码段：

Basically, I have this code segment in one of my functions:

if (keyVal.length == 2) {
    try {
        value = URLDecoder.decode(
            keyVal[1],
            "UTF-8");
    } catch (UnsupportedEncodingException e) {
          // Will it ever be thrown?
    }
}

由于我明确提到UTF-8有什么办法可以抛出这个异常吗？我需要在catch块中做任何事情吗？或者，如果我的理解是完全错误的，请让我知道。

Since I am explicitly mentioning "UTF-8", is there any way this exception can be thrown? Do I need to do anything in the catch block? Or, if my understanding is completely wrong, please let me know.

推荐答案

不可能发生，除非有根本的破坏你的JVM但是我认为你应该写成：

It cannot happen, unless there is something fundamentally broken in your JVM. But I think you should write this as:

try {
    value = URLDecoder.decode(keyVal[1], "UTF-8");
} catch (UnsupportedEncodingException e) {
    throw new AssertionError("UTF-8 is unknown");
    // or 'throw new AssertionError("Impossible things are happening today. " +
    //                              "Consider buying a lottery ticket!!");'
}

这样做的代价是永远不会执行的几个字节的代码，一个永远不会被执行的字符串用过的。那个小的价格是为了保护你可能误读/误解了javadocs（你没有在这种情况下）...或者规范可能会改变的可能性（在这种情况下不会）...

The cost of doing this is a few bytes of code that will "never" be executed, and one String literal that will never be used. That a small price for the protecting against the possibility that you may have misread / misunderstood the javadocs (you haven't in this case ...) or that the specs might change (they won't in this case ...)

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