又遇到问题了HTML/Servlet/class

ILI90 2012-02-28 10:51:53

创建了一个Dynamic Web Project
HelloLet.java:

package aaa;

import java.util.Calendar;
import java.io.PrintWriter;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloLet extends HttpServlet {
private static final long serialVersionUID = 1L;

public HelloLet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("GB18030");
String user = request.getParameter("user");
user = user.trim();
if(user.length()<=0)
user = null;
System.out.println("user=" + user);
Calendar now = Calendar.getInstance();
String w = "欢迎您访问我的网站！";

if(now.get(Calendar.HOUR_OF_DAY)<12)
w = (user == null)?"早上好！" + w:user + "，早上好！" + w;
else if(now.get(Calendar.HOUR_OF_DAY)>=18)
w = (user == null)?"晚上好！" + w:user + "，晚上好！" + w;
else if(now.get(Calendar.HOUR_OF_DAY)<18)
w = (user == null)?"下午好！" + w:user + "，下午好！" + w;

response.setContentType("text/html;charest=gb18030");

PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<meta http-equiv=\"Content-Type\"content=\"text/html\">");
out.println("</head>");
out.println("<body>");
out.println(w);
out.println("</body>");
out.println("</html>");
out.close();
}

}

index-let.html:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>
<form action="HelloLet" method="post">
欢迎您，请输入您的名字：<input type="text" name="user">
<input type="submit" value="提交">
</form>
</body>
</html>

我已经把servlet-api.jar复制到WEB-INF下的lib下了
我把这个项目是发布到tomcat的webapps下的HelloWeb.war，然后用tomcat7.x来Debug As后就会弹出以下内容：
'Launching HelloWeb on Tomcat 7.x' has encountered a proble.
Errors occurred during the build.
Errors running builder 'DeploymentBuilding' on project 'HelloWeb'.
java.lang.NullPointerException

怎么解决呢？

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码无边 2012-02-28

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楼主环境有问题不？貌似楼主这句才是关键啊。

if(now.get(Calendar.HOUR_OF_DAY)<12)

w = (user == null)?"早上好！" + w:user + "，早上好！" + w;

else if(now.get(Calendar.HOUR_OF_DAY)>=18)

w = (user == null)?"晚上好！" + w:user + "，晚上好！" + w;

else if(now.get(Calendar.HOUR_OF_DAY)<18)

w = (user == null)?"下午好！" + w:user + "，下午好！" + w;