Root cause of ServletException.

weblogic.utils.ParsingException: nested TokenStreamException: antlr.TokenStreamIOException

        at weblogic.servlet.jsp.JspLexer.parse(JspLexer.java(Compiled Code))

        at weblogic.servlet.jsp.JspParser.doit(JspParser.java:106)

        at weblogic.servlet.jsp.JspParser.parse(JspParser.java:234)

        at weblogic.servlet.jsp.Jsp2Java.outputs(Jsp2Java.java:125)

        at weblogic.utils.compiler.CodeGenerator.generate(CodeGenerator.java:258)

        at weblogic.servlet.jsp.JspStub.compilePage(JspStub.java:388)

        at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:238)

        at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:188)

        at weblogic.servlet.internal.ServletStubImpl.getServlet(ServletStubImpl.java(Compiled Code))

        at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java(Compiled Code))

        at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java(Compiled Code))

        at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:322)

        at edu.yale.its.tp.cas.servlet.Login.doGet(Login.java:188)

        at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)

        at javax.servlet.http.HttpServlet.service(HttpServlet.java(Compiled Code))

        at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java(Inlined Compiled Code))

        at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java(Compiled Code))

        at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java(Inlined Compiled Code))

        at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java(Compiled Code))

        at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java(Compiled Code))

        at weblogic.security.service.SecurityManager.runAs(SecurityManager.java(Inlined Compiled Code))

        at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java(Compiled Code))

        at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java(Compiled Code))

        at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java(Compiled Code))

        at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)

> 

原因：中文编码问题

解决：在web.xml里加上过滤:

<filter>

     <filter-name>Set Character Encoding</filter-name>

     <filter-class>edu.yale.its.tp.cas.SetCharacterEncodingFilter</filter-class>

     <init-param>

              <param-name>encoding</param-name>

              <param-value>GB2312</param-value>

         </init-param>

     </filter>

     <filter-mapping>

         <filter-name>Set Character Encoding</filter-name>

         <url-pattern>/*</url-pattern>

     </filter-mapping>

--------------//SetCharacterEncodingFilter类是中文过滤类

package edu.yale.its.tp.cas;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/**
 * Example filter that sets the character encoding to be used in parsing the

 * incoming request, either unconditionally or only if the client did not

 * specify a character encoding.

 * 如果原来没有设置request的编码，就设置；否则保持不变

 */

public class SetCharacterEncodingFilter
    implements Filter {

  protected String encoding = null;

  protected FilterConfig filterConfig = null;

  protected boolean ignore = true;

  /**
   * Take this filter out of service.

   */

  public void destroy() {

    this.encoding = null;

    this.filterConfig = null;

  }

  /**
   * Select and set (if specified) the character encoding to be used to

   * interpret request parameters for this request.

   */

  public void doFilter(ServletRequest request, ServletResponse response,

                       FilterChain chain)

      throws IOException, ServletException {

// Conditionally select and set the character encoding to be used

    if (ignore || (request.getCharacterEncoding() == null)) {

      String encoding = selectEncoding(request);

      if (encoding != null) {

        request.setCharacterEncoding(encoding); //设置request编码的地方

      }else
      {

        request.setCharacterEncoding("gb2312"); //强制设置编码
      }

    }

// Pass control on to the next filter

// 传递控制到下一个过滤器

   chain.doFilter(request, response);

  }

  /**
   * Place this filter into service.

   * 从web-app的web.xml文件中读取初始参数的值

   */

  public void init(FilterConfig filterConfig) throws ServletException {

    this.filterConfig = filterConfig;

    this.encoding = filterConfig.getInitParameter("encoding");

    String value = filterConfig.getInitParameter("ignore");

    if (value == null) {

      this.ignore = true;
    }

    else if (value.equalsIgnoreCase("true")) {

      this.ignore = true;
    }

    else if (value.equalsIgnoreCase("yes")) {

      this.ignore = true;
    }

    else {

      this.ignore = false;
    }

  }

  /**
   * Select an appropriate character encoding to be used, based on the

   * characteristics of the current request and/or filter initialization

   * parameters. If no character encoding should be set, return

   * <code>null</code>.

   * 选择request原来的编码

   */

  protected String selectEncoding(ServletRequest request) {

    return (this.encoding);

  }

}