我什么时候应该使用Java的StringWriter？

问题描述：

什么是Java StringWriter ，我应该何时使用它？

What is a Java StringWriter, and when should I use it?

我已阅读文档和看了这里，但我不知道什么时候我应该使用它。

I have read the documentation and looked here, but I do not understand when I should use it.

答

这是一个专门的 Writer 写字符到 StringBuffer ，然后我们使用像 toString（）这样的方法来获取字符串结果。

It is a specialized Writer that writes characters to a StringBuffer, and then we use method like toString() to get the string result.

当使用 StringWriter 时，您要写入字符串，但API期望 Writer 或 Stream 。这是一个妥协，只有当你需要时才使用 StringWriter ，因为 StringBuffer / StringBuilder 写字符更自然，更容易，这应该是你的首选。

When StringWriter is used is that you want to write to a string, but the API is expecting a Writer or a Stream. It is a compromised, you use StringWriter only when you have to, since StringBuffer/StringBuilder to write characters is much more natural and easier,which should be your first choice.

这是两个典型的好用例 StringWriter

Here is two of a typical good case to use StringWriter

1.将堆栈跟踪转换为 String ，因此我们可以轻松地记录它。

1.Converts the stack trace into String, so that we can log it easily.

StringWriter sw = new StringWriter();//create a StringWriter
PrintWriter pw = new PrintWriter(sw);//create a PrintWriter using this string writer instance
t.printStackTrace(pw);//print the stack trace to the print writer(it wraps the string writer sw)
String s=sw.toString(); // we can now have the stack trace as a string

2.另一种情况是我们需要的时候从 InputStream 复制到 Writer 上的字符，以便我们可以获得 String 稍后，使用 Apache commons IOUtils #copy ：

2.Another case will be when we need to copy from an InputStream to chars on a Writer so that we can get String later, using Apache commons IOUtils#copy :

StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, encoding);//copy the stream into the StringWriter
String result = writer.toString();

我什么时候应该使用Java的StringWriter？

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