当使用StringWriter时,您希望写入字符串,但API需要Writer或Stream.它是一个妥协的,你只有在必须时才使用StringWriter,因为StringBuffer / StringBuilder写字符更加自然和容易,这应该是你的首选.

以下是使用StringWriter的两个典型案例

1.将堆栈跟踪转换为String,以便我们可以轻松记录.

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.另一种情况是当我们需要从InputStream复制到Writer上的字符时,以便我们以后可以使用Apache commons IOUtils#copy获取String：

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