“ HTTP状态404请求的资源不可用”

Question

I'm newbie to servlet programming. 我是servlet编程的新手。 I have checked various other links about the Http 404 error but nothing helped me. 我检查了有关Http 404错误的各种其他链接，但没有任何帮助。 So I'm posting my code here. 所以我在这里发布我的代码。

I have three html forms in WebContent/ folder form1.html , form2.html , form3.html , all these forms have same url pattern because accessing three different forms in the same Http session. 我在WebContent/文件夹form1.html ， form2.html ， form3.html有三种html表单，所有这些表单都具有相同的url模式，因为在同一Http会话中访问了三种不同的表单。

form1.html form1.html

 <html> <head> <title>Adhar Registration Form</title> </head> <body style="background-color:orange"> <h1>FORM 1</h1> <form action="./reg" method="get"> <table> <tr><td>NAME:</td><td><input type="text" name="id"/></td></tr> <tr><td>F_NAME:</td><td><input type="text" name="name"/></td></tr> <tr><td>M_NAME:</td><td><input type="text" name="email"/></td></tr> <tr><td><input type="submit" name= "NEXT"> </td></tr> </table> <input type="hidden" name="fno" value="1"> </form> </body> </html>

form2.html form2.html

 <html> <head> <title>Adhar Registration Form</title> </head> <body style="background-color:orange"> <h1>FORM 2</h1> <form action="./reg" method="get"> <table> <tr><td>CONTACT:</td><td><input type="text" name="id"/></td></tr> <tr><td>EMAIL:</td><td><input type="text" name="name"/></td></tr> <tr><td>ADDRESS:</td><td><textarea rows ="10" cols="5" name="address"></textarea></td></tr> <tr><td><input type="submit" name= "NEXT"> </td></tr> </table> <input type="hidden" name="fno" value="2"> </form> </body> </html>

 <html> <head> <title>Adhar Registration Form</title> </head> <body style="background-color:orange"> <h1>FORM 3</h1> <form action="./reg" method="get"> <table> <tr><td>QUALIFICATION:</td><td><input type="text" name="id"/></td></tr> <tr><td>PAN NO:</td><td><input type="text" name="name"/></td></tr> <tr><td><input type="submit" name= "Register"> </td></tr> </table> <input type="hidden" name="fno" value="3"> </form> </body> </html>

web.xml web.xml中

 <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <display-name>Adhar</display-name> <welcome-file-list> <welcome-file>form1.html</welcome-file> </welcome-file-list> <servlet> <servlet-name>login</servlet-name> <servlet-class>container.RegistrationServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>login</servlet-name> <url-pattern>/reg</url-pattern> </servlet-mapping> </web-app>

RegistrationServlet.java RegistrationServlet.java

package container;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class RegistrationServlet
 */
@WebServlet("/reg")
public class RegistrationServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public static final String URL = "jdbc:mysql://localhost/db";
    public static final String USER = "root";
    public static final String PASSWORD = "12345";
    public static final String DRIVER_CLASS = "com.mysql.jdbc.Driver";

    /**
     * @see HttpServlet#HttpServlet()
     */
    public RegistrationServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        PrintWriter out = response.getWriter();

        HttpSession hs = request.getSession();
        String fno = request.getParameter("fno");

        if(fno.equals("1")){
            String name = request.getParameter("name");
            String f_name = request.getParameter("f_name");
            String m_name = request.getParameter("m_name");

            hs.setAttribute("name", name);
            hs.setAttribute("f_name", f_name);
            hs.setAttribute("m_name", m_name);

            response.sendRedirect("./Form2.html");
        }
        if(fno.equals("2")){

            String contact = request.getParameter("contact");
            String email = request.getParameter("email");
            String address = request.getParameter("address");

            hs.setAttribute("contact", contact);
            hs.setAttribute("email", email);
            hs.setAttribute("address", address);

            response.sendRedirect("./Form3.html");
        }
        if(fno.equals("3")){

            String qual = request.getParameter("qual");
            String pan = request.getParameter("pan");

            String name = (String)hs.getAttribute("name");
            String f_name = (String)hs.getAttribute("f_name");
            String m_name = (String)hs.getAttribute("m_name");

            String contact = (String)hs.getAttribute("contact");
            String email = (String)hs.getAttribute("email");
            String address = (String)hs.getAttribute("address");

            try {
                Class.forName(DRIVER_CLASS);
                System.out.println("Loaded the driver");

                Connection con = DriverManager.getConnection(URL,USER,PASSWORD);
                PreparedStatement ps = con.prepareStatement("INSERT into adharReg values(?,?,?,?,?,?,?,?)");

                ps.setString(1, name);
                ps.setString(2, f_name);
                ps.setString(3, m_name);
                ps.setString(4, contact);
                ps.setString(5, email);
                ps.setString(6, address);
                ps.setString(7, qual);
                ps.setString(8, pan);

                int i = ps.executeUpdate();

                if(i!=0){
                    out.println("<h1>REGISTRATION SUCCESS</h1>");
                }
                else{
                    out.println("<h1>REGISTRATION FAILED</h1>");
                }

            } catch (Exception e) {
                // TODO: handle exception
                out.println("<h1>REGISTRATION FAILED" + e.getMessage() + " </h1>");
            }

        }
    }

}

I'm using tomcat server 8.0. 我正在使用Tomcat服务器8.0。 I checked this Link and my tomcat server has exact same settings. 我检查了此链接，并且我的tomcat服务器具有完全相同的设置。 And followed this link for any possible mistakes but, I don't know the exact reason why i'm getting Http 404 error. 并遵循此链接的任何可能的错误，但是，我不知道我收到Http 404错误的确切原因。 Help me out why i'm getting this error. 帮助我，为什么我会收到此错误。

Thanks. 谢谢。

Answer 1

check web.xml is exist into WEB-INF folder. 检查web.xml是否存在于WEB-INF文件夹中。

and use servlet mapping into web.xml 并使用servlet映射到web.xml

And register the servlet instead in web.xml like this: 然后像这样在web.xml中注册servlet：

<servlet>
<servlet-name>yourServlet</servlet-name>
<servlet-class>com.example.YourServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>yourServlet</servlet-name>
<url-pattern>/servlet</url-pattern>  
</servlet-mapping>

for more refer bellow link :- 有关更多信息，请参见波纹管链接：-

http://www.beingjavaguys.com/2013/08/jsp-servlet-hello-world-example.html http://www.beingjavaguys.com/2013/08/jsp-servlet-hello-world-example.html

https://www.javatpoint.com/servlet-with-annotation https://www.javatpoint.com/servlet-with-annotation

Answer 2

The issue is caused by a conflict between web.xml configuration and the WebServlet annotation. 该问题是由web.xml配置和WebServlet批注之间的冲突引起的。 The web.xml is delcaring a servlet called login that target to the /reg url, but also in the RegistrationServlet there is a declaration throught @WebServlet annotation that reference to the same url /reg. web.xml正在传送一个名为login的servlet，该servlet的目标是/ reg url，但在RegistrationServlet中，也有一个@WebServlet批注声明，该声明引用了相同的URL / reg。

One possible solution is to remove the servlet declaration from the web.xml, that means that the web.xml content should be like this. 一种可能的解决方案是从web.xml中删除servlet声明，这意味着web.xml内容应如下所示。

web.xml web.xml中

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>Adhar</display-name>
  <welcome-file-list>
    <welcome-file>form1.html</welcome-file>
  </welcome-file-list>

</web-app>

Just let the Servlet declared by annotation only. 只需让Servlet仅通过注释声明即可。 Hope this helps. 希望这可以帮助。

“ HTTP状态404请求的资源不可用”

问题描述

2 个解决方案

解决方案1
0 2017-07-16 17:26:18

解决方案2
0 已采纳 2017-07-16 17:51:31

“ HTTP状态404请求的资源不可用”

问题描述

2 个解决方案

解决方案1 0 2017-07-16 17:26:18

解决方案2 0 已采纳 2017-07-16 17:51:31

解决方案1
0 2017-07-16 17:26:18

解决方案2
0 已采纳 2017-07-16 17:51:31