Java EE(常见问题）—— Servlet.service() for servlet [jsp] in context with path [/web04] threw exception-优快云博客

在实现Java EE中的findPwd功能时遇到Servlet.service()异常，提示无法为JSP编译类。问题根源在于未对s1和s2变量进行初始化。修正代码后问题解决，但对不初始化变量导致的JSP编译错误原因仍有疑问。

在写findPwd(找回密码）时会出现这样子的错误： Servlet.service() for servlet [jsp] in context with path [/web04] threw exception [Unable to compile class for JSP:；

翻译一下：[/web04]抛出异常[无法为jsp编译类:

但是一直不知道为什么错了，后来仔细看了看，终于发现了自己的错误。

原代码

           String s1;//注意要赋值，不赋值会有错
             String s2;
             while(rs.next()){
            	  s1=rs.getString(1);
                  s2=rs.getString(2);
         
             }
 %>
  <center>
	<font face="楷体" size="6" color="#000">找回密码界面</font>
	<table width="300" height = "180" border="5" bordercolor="#A0A0A0">
  	  <tr>
		<th>用户名：</th>
		<td><input type="text" name="username" value="<%= s1 %>"></td>
 	  </tr>
 	   <tr>
		<th>密    码：</th>
		<td><input type="text" name="password" value="<%= s2 %>"></td>
 	  </tr>
 	</table>
 	</center>

修改后代码1

             String s1=null;//注意要赋值，不赋值会有错
             String s2=null;
             while(rs.next()){
            	  s1=rs.getString(1);
                  s2=rs.getString(2);
         
             }
 %>
  <center>
	<font face="楷体" size="6" color="#000">找回密码界面</font>
	<table width="300" height = "180" border="5" bordercolor="#A0A0A0">
  	  <tr>
		<th>用户名：</th>
		<td><input type="text" name="username" value="<%= s1 %>"></td>
 	  </tr>
 	   <tr>
		<th>密    码：</th>
		<td><input type="text" name="password" value="<%= s2 %>"></td>
 	  </tr>
 	</table>
 	</center>
</body>

原因是没有给s1和s2赋初值。

全部代码：

<%@ page language="java" import="java.util.*,java.sql.*,java.net.*" pageEncoding="utf-8"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <base href="<%=basePath%>">

    

    <title>taobao findPwd page</title>

    

	<meta http-equiv="pragma" content="no-cache">

	<meta http-equiv="cache-control" content="no-cache">

	<meta http-equiv="expires" content="0">    

	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

	<meta http-equiv="description" content="This is my page">

	<!--

	<link rel="stylesheet" type="text/css" href="styles.css">

	-->

 

  </head>

  <body>
<% 
        //接收用户名和密码  

            String user = new String(request.getParameter("name").getBytes("ISO-8859-1"),"UTF-8");  

            
       //连接数据库

            Class.forName("com.mysql.cj.jdbc.Driver");

            String url = "jdbc:mysql://localhost:3306/db_01?serverTimezone=GMT%2B8";

          

            

             Connection conn = DriverManager.getConnection(url,"root","guanhong520");//这步错可能是因为数据库属性安全中的名、密码不对或SQL的IP端口不是‘3306’
             PreparedStatement pStmt = conn.prepareStatement("select * from user where uername = '" + user);
             String sql = "select * from user where uername ='";
             sql += user + "'";
             ResultSet rs = pStmt.executeQuery(sql);
             String s1=null;//注意要赋值，不赋值会有错
             String s2=null;
             while(rs.next()){
            	  s1=rs.getString(1);
                  s2=rs.getString(2);
         
             }
 %>
  <center>
	<font face="楷体" size="6" color="#000">找回密码界面</font>
	<table width="300" height = "180" border="5" bordercolor="#A0A0A0">
  	  <tr>
		<th>用户名：</th>
		<td><input type="text" name="username" value="<%= s1 %>"></td>
 	  </tr>
 	   <tr>
		<th>密    码：</th>
		<td><input type="text" name="password" value="<%= s2 %>"></td>
 	  </tr>
 	</table>
 	</center>
</body>

</html>

但是还是不知道为什么不赋初值，会导致无法为jsp编译类，有大佬知道吗

欢迎大家在下面留言呀