jsp提交参数给Servlet实现简单登录测试 但是无响应

Question

用jsp提交name和ps给Servlet 提交后Servlet没能实现跳转 是什么原因 Servlet代码如下:
package ccut;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;public class doLoginServlet extends HttpServlet{
public void init(ServletConfig config) throws ServletException{
super.init(config);
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
} public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name=request.getParameter("name");
String ps=request.getParameter("ps");

try {
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/testlogin","root","123456");
String sql="select * from user where name="+name+" and ps="+ps;
System.out.println(sql);
Statement stmt=con.createStatement();
ResultSet rs=stmt.executeQuery(sql);
if(rs.next()){
RequestDispatcher dispatcher=request.getRequestDispatcher("showLogin.jsp");
dispatcher.forward(request, response);
}else{
response.sendRedirect("login1.jsp");
}
} catch (Exception e) {
e.printStackTrace();
}

} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
web.xml和类文件都无误请各位帮帮忙,先谢谢大家了

Answer 1

 String sql="select * from user where name="+name+" and ps="+ps;这个语句是不是不太对？name和ps是字符串类型吗？是的话没有单引号。数据库查询不会成功才对。

Answer 2

SQL语句是不对 但是我该了之后还是提示数据库连接不上
com.mysql.jdbc.CommunicationsException: Communications link failure due to under
lying exception:** BEGIN NESTED EXCEPTION **java.net.SocketException
MESSAGE: java.net.ConnectException: Connection refused: connectSTACKTRACE:java.net.SocketException: java.net.ConnectException: Connection refused: connect        at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.ja
va:151)
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:280)
        at com.mysql.jdbc.Connection.createNewIO(Connection.java:1774)
        at com.mysql.jdbc.Connection.<init>(Connection.java:437)
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java
:268)
        at java.sql.DriverManager.getConnection(Unknown Source)
        at java.sql.DriverManager.getConnection(Unknown Source)
        at ccut.doLoginServlet.doGet(doLoginServlet.java:24)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:175)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:128)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:102)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:263)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:844)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.proce
ss(Http11Protocol.java:584)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:44
7)
        at java.lang.Thread.run(Unknown Source)
** END NESTED EXCEPTION **
        at com.mysql.jdbc.Connection.createNewIO(Connection.java:1839)
        at com.mysql.jdbc.Connection.<init>(Connection.java:437)
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java
:268)
        at java.sql.DriverManager.getConnection(Unknown Source)
        at java.sql.DriverManager.getConnection(Unknown Source)
        at ccut.doLoginServlet.doGet(doLoginServlet.java:24)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:175)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:128)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:102)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:263)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:844)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.proce
ss(Http11Protocol.java:584)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:44
7)
        at java.lang.Thread.run(Unknown Source)

Answer 3

    从你Servlet的代码来看，没有什么问题，你标题是说没实现跳转，那问题就是出现在form表单的action的跳转上了action="loginSevlet",那你应该在web.xml里面去配置一下
  <servlet>
   <servlet-name></servlet-name>
   <servlet-class></servlet-class>
  </servlet>
  <servlet-mapping>
   <servlet-name></servlet-name>
   <url-pattern></url-pattern>
  </servlet-mapping>
记得要你action要跳转的loginServlet名字一样
好了去试试吧！

Answer 4

看提示信息，应该是下面这句有问题，建议好好检查一下端口号，用户名，数据库名神马的。
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/testlogin","root","123456");

Answer 5

web.xml 和 类文件都配置正确 jsp能提交到 servlet中 但是servlet无法实现跳转

Answer 6

噢！不好意思没看清楚你下面还有web.xml配置无误，算路过顶下了。

Answer 7

mysql服务开了吗，端口、数据库名对不

Answer 8

还是把web.xml配置贴出来大家看看吧