errorbean.java

struts框架的jsf组件的核心实用例子集合

package com.corejsf;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.sql.SQLException;
import java.util.Map;
import javax.faces.context.FacesContext;
import javax.servlet.ServletException;

public class ErrorBean {
   public String getStackTrace() {
      FacesContext context = FacesContext.getCurrentInstance();
      Map request = context.getExternalContext().getRequestMap();
      Throwable ex = (Throwable) request.get("javax.servlet.error.exception");
      StringWriter sw = new StringWriter();
      PrintWriter pw = new PrintWriter(sw);
      fillStackTrace(ex, pw);
      return sw.toString();
   }

   private static void fillStackTrace(Throwable t, PrintWriter w) {
      if (t == null) return;
      t.printStackTrace(w);
      if (t instanceof ServletException) {
         Throwable cause = ((ServletException) t).getRootCause();
         if (cause != null) {
            w.println("Root cause:");
            fillStackTrace(cause, w);
         }
      } else if (t instanceof SQLException) {
         Throwable cause = ((SQLException) t).getNextException();
         if (cause != null) {
            w.println("Next exception:");
            fillStackTrace(cause, w);
         }
      } else {
         Throwable cause = t.getCause();
         if (cause != null) {
            w.println("Cause:");
            fillStackTrace(cause, w);
         }
      }
   }
}