从HTML表单调用servlet，但从不调用servlet [英] Calling servlet from HTML form, but servlet is never invoked
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问题描述
我的servlet代码：
import javax.servlet.http.HttpServlet;
import java.io. *;
import java.sql。*;
import javax.servlet。*;
import javax.servlet.http。*;
$ b public class Loginservlet extends HttpServlet {
public void doPost（HttpServletRequest req，HttpServletResponse res）throws ServletException，IOException
{
System.out.println（login servlet）;
String connectionURL =jdbc：mysql：// localhost：3306 / mysql;
连接连接=空;
res.setContentType（text / html）;
PrintWriter out = res.getWriter（）;
字符串用户名= req.getParameter（用户名）;
String password = req.getParameter（password）;
尝试{
Class.forName（com.mysql.jdbc.Driver）;
connection = DriverManager.getConnection（connectionURL，root，root）;
String sql =插入注册值（？，？）;
PreparedStatement pst = connection.prepareStatement（sql）;
pst.setString（1，username）;
pst.setString（2，password）;
int numRowsChanged = pst.executeUpdate（）;
out.println（Data has been submitted）;
pst.close（）;
catch（ClassNotFoundException e）{
out.println（无法加载数据库驱动程序：+ e.getMessage（））;
}
catch（SQLException e）{
out.println（SQLException caught：+ e.getMessage（））;
}
catch（Exception e）{
out.println（e）;
}
finally {
try {
if（connection！= null）
connection.close（）;
}
catch（忽略SQLException）{
out.println（忽略）;
}
}
}
}
我的html代码：
注册
< form action =servlet / Loginservletmethod =post>
< font size ='5'>建立您的帐户：< / font>< br />< br>
< label for =usernameaccesskey =ustyle =padding-left：3px;>用户名：< / label>
< input type =textstyle =background-color：#ffffff; margin-left：14px; padding-top：7px; border-width：0px; margin-top：6px;填充右：85px; id =usernamename =usernametabindex =1>< br />< br>
< label for =passwordaccesskey =pstyle =padding-left：4px;>密码：< / label>
< input type =passwordstyle =background-color：#ffffff; margin-left：14px; padding-top：7px; border-width：0px; padding-right：85px; id =passwordname =paswordtabindex =2>< br />< br>
< input type =submitvalue =Submitstyle =margin-left：164px;/>
< input type =resetvalue =Resetstyle =margin-left：17px;/>
< / form>
web.xml文件：
<？xml version =1.0encoding = UTF-8\" >？;
< web-app version =2.5
xmlns =http://java.sun.com/xml/ns/javaee
xmlns：xsi =http：// www.w3.org/2001/XMLSchema-instance
xsi：schemaLocation =http://java.sun.com/xml/ns/javaee
http://java.sun.com/ XML / NS / JavaEE的/网络app_2_5.xsd>
< servlet>
< servlet-name>登录< / servlet-name>
< servlet-class> Loginservlet< / servlet-class>
< / servlet>
< servlet-mapping>
< servlet-name>登录< / servlet-name>
< url-pattern> / login< / url-pattern>
< / servlet-mapping>
请帮忙
解决方案
当您查看您的servlet类时，没有定义 package 需要。并在< servlet-class /> 标记中将该类与包（意思是完全限定名）映射。
另一件事是你将动作设置为url servlet / LogininServlet ，但在< url-pattern /> 标签，这是错误的。您可以简单地将表单操作设置为 login
Iam calling servlet from html form,servlet takes the form data and it will insert that form data into database.But when i click the submit button error page is coming.please help whats wrong in my servlet code.
my servlet code:
import javax.servlet.http.HttpServlet;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Loginservlet extends HttpServlet {
public void doPost(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException
{
System.out.println("login servlet");
String connectionURL = "jdbc:mysql://localhost:3306/mysql";
Connection connection=null;
res.setContentType("text/html");
PrintWriter out = res.getWriter();
String username= req.getParameter("username");
String password = req.getParameter("password");
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(connectionURL, "root", "root");
String sql = "insert into signup values (?,?)";
PreparedStatement pst = connection.prepareStatement(sql);
pst.setString(1, username);
pst.setString(2, password);
int numRowsChanged = pst.executeUpdate();
out.println(" Data has been submitted ");
pst.close();
}
catch(ClassNotFoundException e){
out.println("Couldn't load database driver: "+ e.getMessage());
}
catch(SQLException e){
out.println("SQLException caught: " + e.getMessage());
}
catch (Exception e){
out.println(e);
}
finally {
try {
if (connection != null)
connection.close();
}
catch (SQLException ignored){
out.println(ignored);
}
}
}
}
my html code:
Sign Up
<form action="servlet/Loginservlet" method="post" >
<font size='5'>Create your Account:</font><br/><br>
<label for="username" accesskey="u" style="padding-left:3px;">User Name: </label>
<input type="text" style="background-color:#ffffff;margin-left:14px;padding-top:7px;border-width:0px;margin-top:6px;padding-right:85px;" id="username" name="username" tabindex="1"><br/><br>
<label for="password" accesskey="p" style="padding-left:4px;">Password: </label>
<input type="password" style="background-color:#ffffff;margin-left:14px;padding-top:7px;border-width:0px;padding-right:85px;" id="password" name="pasword" tabindex="2"><br/><br>
<input type="submit" value="Submit" style="margin-left:164px;"/>
<input type="reset" value="Reset" style="margin-left:17px;"/>
</form>
web.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>Loginservlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
please help
解决方案
As you look into your servlet class, there is no package defined, which is required. And map that class with package(mean fully qualified name) in <servlet-class/> tag.
Another thing is you are setting action to url servlet/LogininServlet, but given different url in <url-pattern/> tag, which is wrong. you can simply set the form action to login
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