package Student;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.*;
import Student.student;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
Class.forName("org.gjt.mm.mysql.Driver");
String url = "jdbc:mysql://localhost:3306/tset";
String username = "root";
String password = "123456";
Connection conn = DriverManager.getConnection(url, username, password);
Statement stmt = conn.createStatement();
String sql = "select * from student ";
ResultSet rs = stmt.executeQuery(sql);
List<student> list = new ArrayList<student>();
while(rs.next()){
student stu=new student();
stu.setUser(rs.getString("user"));
stu.setPass(rs.getString("pass"));
stu.setNick(rs.getString("nick"));
list.add(stu);
}
request.setAttribute("list", list);
rs.close();
stmt.close();
conn.close();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
request.getRequestDispatcher("output.jsp").forward(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
<%@ page import="java.sql.Connection" %><%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2017/11/7
Time: 16:07
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="java.sql.*" %>
<%@ page import="java.util.*" %>
<%@ page import="Student.student"%>
<%
List list=(List)request.getAttribute("list");
String nickname="sss";
if (list == null) {
nickname="不存在这人";
}
else {
for (student student : list) {
if (request.getParameter("username").equals(student.getUser()) && request.getParameter("password").equals(student.getPass()) ) {
nickname = student.getNick();
}
else{
nickname="密码错误";
}
}
}
%>
<%=nickname%>
List<student> list=(List)request.getAttribute("list");
你这里应该带泛型啊
楼上正解，还有你这代码写的不规则啊，后台的代码最好在前台不要出现，还有你数据库加载，用配置文件就行了。当然刚开始接触java的例外。
while(rs.next()){ student stu=new student(); stu.setUser(rs.getString("user")); stu.setPass(rs.getString("pass")); stu.setNick(rs.getString("nick")); list.add(stu); } student stu=new student(); stu.setUser("jack"); stu.setPass("123456"); stu.setNick("sasa"); list.add(stu); request.setAttribute("list", list);
你用el表达式获取看看，比如：${list} 或者${request.list}
<%
List list=(List)request.getAttribute("list");
String nickname="sss";
if (list == null) {
nickname="不存在";
}
else {
for (student student : list) {
if (request.getParameter("username").equals(student.getUser()) && request.getParameter("password").equals(student.getPass()) ) {
nickname = student.getNick();
}
else{
nickname="密码错误";
}
}
}
%>
<%=nickname%>
org.apache.jasper.JasperException: Unable to compile class for JSP:
An error occurred at line: [30] in the jsp file: [/output.jsp]
Syntax error, insert "}" to complete Statement
27: if (request.getParameter("username").equals(student.getUser()) && request.getParameter("password").equals(student.getPass()) ) {
28: {
29: nickname = student.getNick();
30: }
31: else{
32: nickname="瀵嗙爜閿欒";
33: }
An error occurred at line: [172] in the generated java file: [C:\Users\Administrator.IntelliJIdea2017.2\system\tomcat_untitled\work\Catalina\localhost\ROOT\org\apache\jsp\output_jsp.java]
Syntax error on token "}", delete this token
An error occurred at line: [173] in the generated java file: [C:\Users\Administrator.IntelliJIdea2017.2\system\tomcat_untitled\work\Catalina\localhost\ROOT\org\apache\jsp\output_jsp.java]
Syntax error, insert "}" to complete ClassBody
Stacktrace:
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:103)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:213)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:458)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:389)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:361)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:345)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:603)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Student.MyServlet.doPost(MyServlet.java:60)
javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Type Exception Report
Message An exception occurred processing [/output.jsp] at line [27]
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
org.apache.jasper.JasperException: An exception occurred processing [/output.jsp] at line [27]
24: }
25: else {
26: for (student student : list) {
27: if (request.getParameter("username").equals(student.getUser()) && request.getParameter("password").equals(student.getPass()) )
28: {
29: nickname = student.getNick();
30: }
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:593)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:482)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Student.MyServlet.doPost(MyServlet.java:60)
javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Root Cause
java.lang.NullPointerException
org.apache.jsp.output_jsp._jspService(output_jsp.java:137)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:444)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Student.MyServlet.doPost(MyServlet.java:60)
javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Note The full stack trace of the root cause is available in the server logs.
Apache Tomcat/9.0.1
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2017/11/6
Time: 14:15
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>