在使用String的replaceFirst(regex,replacement)的时候出现java.lang.IllegalArgumentException: Illegal group
reference错误，错误信息如下：
2012-8-7 15:03:34 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet default threw exception
java.lang.IllegalArgumentException: Illegal group reference
at java.util.regex.Matcher.appendReplacement(Unknown Source)
at java.util.regex.Matcher.replaceFirst(Unknown Source)
at java.lang.String.replaceFirst(Unknown Source)
at com.redmoon.forum.plugin.DefaultRender.AddShading(DefaultRender.java:612)
at com.redmoon.forum.plugin.DefaultRender.RendContentFormat(DefaultRender.java:580)
at com.redmoon.forum.plugin.DefaultRender.RenderContent(DefaultRender.java:105)
at org.apache.jsp.showtopic_jsp._jspService(showtopic_jsp.java:1709)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
at com.redmoon.forum.LinkFilter.doFilter(LinkFilter.java:83)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
at java.lang.Thread.run(Unknown Source)
原因是第一个参数支持正则表达式，replacement中出现“$”,会按照$1$2的分组模式进行匹配，当编译器发现“$”后跟的不是整数的时候，就会抛出“非法的组引用”的异常。所以我们在使用replaceAll(regex, replacement)函数的时候要特别小心。如果真的要把String中的字符替换成"$AAA"的话，可以对replacement 进行“$”的转义处理。
解决方法：
替换掉replacement里面的$字符： s=s.replaceAll("\\$", "\\\\\\$");
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2012-8-7 15:12:33 |
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