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서버의 출력을 변경하는 필터를 작성해야합니다. 여기 내 코드입니다 :서버 출력을 가로채는 필터
@WebServlet("/ServerClass")
public class ServerClass extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String text = request.getParameter("text");
PrintWriter pw = new PrintWriter(response.getOutputStream());
pw.write(text);
pw.close();
}
}
필터 구현 :
java.lang.IllegalStateException: getWriter() has already been called for this response
at org.apache.catalina.connector.Response.getOutputStream(Response.java:604)
at org.apache.catalina.connector.ResponseFacade.getOutputStream(ResponseFacade.java:197)
at javax.servlet.ServletResponseWrapper.getOutputStream(ServletResponseWrapper.java:96)
at ServerClass.doPost(ServerClass.java:19)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at TextFilter.doFilter(TextFilter.java:33)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
:
@WebFilter("/TextFilter")
public class TextFilter implements Filter {
public TextFilter() {
}
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
PrintWriter out = response.getWriter();
TextResponseWrapper wrapper = new TextResponseWrapper((HttpServletResponse)response);
chain.doFilter(request, wrapper);
String responseText = wrapper.toString();
responseText.replaceAll("text", "****");
response.setContentLength(responseText.getBytes().length);
out.println(responseText);
out.close();
}
public void init(FilterConfig fConfig) throws ServletException {
}
}
class TextResponseWrapper extends HttpServletResponseWrapper {
private CharArrayWriter output;
public String toString() {
return output.toString();
}
public TextResponseWrapper(HttpServletResponse response){
super(response);
output = new CharArrayWriter();
}
public PrintWriter getWriter(){
return new PrintWriter(output);
}
}
web.xml의 문제는 나는 다음과 같은 오류가 발생하고 있다는 점이다
<filter>
<filter-name>TextFilter</filter-name>
<filter-class>TextFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>TextFilter</filter-name>
<servlet-name>ServerClass</servlet-name>
</filter-mapping>
그래서 나는 약간의 연구 후 이해했던 것에서 ch,이 오류는 ServerClass와 TextFilter 모두에서 OutputStream을 열었 기 때문에 발생합니다. 그러나 그렇게하지 않고 어떻게 서버 출력을 가로 챌 수 있습니까? 이 상황에서 올바른 접근법은 무엇입니까?