IllegalStateException：PWC3990：已为此响应调用 getWriter()
java.lang.IllegalStateException: PWC3990: getWriter() has already been called for this response
如何解决这个错误？我运行一个简单的 servlet 代码来显示条形图。
java.lang.IllegalStateException: PWC3990: getWriter() has already been called for this response
How to solve this error? I run a simple servlet code to display the bar graph.
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您不能在同一个响应上同时调用
getOutputStream()和getWriter()。请记住，JSP隐式使用getWriter()。You cannot call both
getOutputStream()andgetWriter()on the same response. Keep in mind that JSP implicitly usesgetWriter().还要确保请求没有从其他地方重定向到当前 servlet。如果是，则很有可能已经调用了
getOutputStream()或getWriter()之一。Also make sure that the request is not being redirected to current servlet from some place else. If it is, then there is a high probability that one of
getOutputStream()orgetWriter()has already been called on it.