org.apache.jasper.JasperException: /WEB-INF/view/../../../common/common1.jsp (line: 7, column: 1) Page directive must not have multiple occurrences of pageencoding

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先还原错误：

org.apache.jasper.JasperException: /WEB-INF/view/../../../../common/common1.jsp (line: 7, column: 1) Page directive must not have multiple occurrences of pageencoding
    org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:41)
    org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:275)
    org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:107)
    org.apache.jasper.compiler.Validator$DirectiveVisitor.visit(Validator.java:196)
    org.apache.jasper.compiler.Node$PageDirective.accept(Node.java:571)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2428)
    org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2434)
    org.apache.jasper.compiler.Node$Root.accept(Node.java:464)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2428)
    org.apache.jasper.compiler.Validator$DirectiveVisitor.visit(Validator.java:101)
    org.apache.jasper.compiler.Node$IncludeDirective.accept(Node.java:635)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2428)
    org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2434)
    org.apache.jasper.compiler.Node$Root.accept(Node.java:464)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Validator.validateDirectives(Validator.java:1813)
    org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:196)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:356)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:336)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:323)
    org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:585)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:363)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1286)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1041)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:984)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    com.allcam.rss.system.filter.SystemFilter.doFilter(SystemFilter.java:102)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

解决及分析：

页面使用了多次页面编码。
问题所在：
页面引用公用的头，两个都使用了：pageEncoding="UTF-8"，
即：<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
去掉其他页面的pageEncoding="UTF-8",只留下一个就可以解决问题。