Question

在我填写表单并提交后，我收到404错误。我希望在点击提交按钮后显示提交数据的表格。我还发现我的提交没有在数据库中录制，我不知道为什么？

错误：HTTP状态404 - / Lab5 / ShowParameters
我正在使用Tomcat 8.0.24

DBentry.java

package db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;

//import com.mysql.jdbc.Connection;
//import com.mysql.jdbc.PreparedStatement;

public class DBentry {
    static DBentry instance = new DBentry();
    Connection dbconn;
    ResultSet results = null;
    java.sql.PreparedStatement sql;
    String dpwd = null;
    StringBuilder sb = new StringBuilder();
    java.sql.Statement stmt = null;

    //change URL to your database server as needed
    String dbPath="jdbc:mysql://localhost:8889/cs485_lab5";

    public static DBentry getInstance() {
        if (instance==null) {
            instance = new DBentry();
        }
        return instance;
    }

    //Establish connection to MySQL server
    public Connection newConnection() {
        try {
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            try {           
                dbconn = DriverManager.getConnection(dbPath,"root","root");
                System.out.println("gain the connection");
                return dbconn;
            }
            catch (Exception s){
                System.out.println(s.getStackTrace().toString());}
        }
        catch (Exception err){
            System.out.println(err.getStackTrace().toString());
        }
        return null;
    }

    public ResultSet selectStatement( String query ) {
        try {

            dbconn=instance.newConnection();
            sql= dbconn.prepareStatement(query);
            ResultSet results;
            results=sql.executeQuery();
            System.out.println("query="+query);


            //WARNING!
            //Need to process ResultSet before closing connection
            dbconn.close();
            return results;
        }
        catch (Exception err) {
            System.out.println(err.getMessage());
            return null;
        }
    }

    public boolean DBentry( String query ) {
        try {
            System.out.println("query="+query);
            instance.newConnection();
            sql= dbconn.prepareStatement(query);
            sql.executeUpdate(query);
            dbconn.close();
            return true;
        }
        catch ( Exception err ) {
            err.getStackTrace();
            return false;
        }
    }

    public boolean entry(String itemNum,String price,String fName,String lName,String shipAdd,String cardType, String ccn ) {
        try {
            instance.DBentry("INSERT INTO cs485_lab5.Orders ( `Item Number`, `Price`, 'FirstName', 'LastName', 'ShippingAddress', 'CreditCard', 'CCN') " +  
                                "VALUES ('"+itemNum+"','"+price+"','"+fName+"','"+lName+"','"+shipAdd+"','"+cardType+"',  '"+ccn+"');");    
            return true;
        }
        catch ( Exception err ) {
            err.getStackTrace();
            return false;
        }
    }


    public static void main(String[] args) {    
        //instance.entry("123wdr", "1234.00", "Bill", "Bob", "1234 jon doe street", "Visa", "12345677");
    }
}

ShowParameters.java

package db;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;

public class ShowParameters extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {


        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        String docType =
                "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " +
                "Transitional//EN\">\n";
        String title = "Reading All Request Parameters";

        out.println(docType +
                "<HTML>\n" +
                "<HEAD><TITLE>" + title + "</TITLE></HEAD>\n" +
                "<BODY BGCOLOR=\"#FDF5E6\">\n" +
                "<H1 ALIGN=CENTER>" + title + "</H1>\n" +
                "<TABLE BORDER=1 ALIGN=CENTER>\n" +
                "<TR BGCOLOR=\"#FFAD00\">\n" +
                "<TH>Parameter Name<TH>Parameter Value(s)");

        Enumeration paramNames = request.getParameterNames();
        while(paramNames.hasMoreElements()) {
            String paramName = (String)paramNames.nextElement();
            out.print("<TR><TD>" + paramName + "\n<TD>");
            String[] paramValues =
                    request.getParameterValues(paramName);
            if (paramValues.length == 1) {
                String paramValue = paramValues[0];
                if (paramValue.length() == 0)
                    out.println("<I>No Value</I>");
                else
                    out.println(paramValue);
            } else {
                out.println("<UL>");
                for(int i=0; i<paramValues.length; i++) {
                    out.println("<LI>" + paramValues[i]);
                }
                out.println("</UL>");
            }
        }

        out.println("</TABLE>\n</BODY></HTML>");
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        System.out.println("STOP1\n");
        doGet(request, response);
    }

}

的index.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Lab 5</title>
</head>
<body>
<%@ page import="db.*" %>
<body BGCOLOR="#FDF5E6">

<h1 align="center"> Customer Order Form</h1>
<form action="ShowParameters" method="post">
    Item Number: <input type="text" name="itemNum"> <br>
    Price Each: <input value="$" type="text" name="price"> <br>
    <hr>
    First Name: <input type = "text" name = "fname"> <br>
    Last Name: <input type = "text" name = "lname"> <br>
    Shipping Address: <textarea name = "shipadd" style ="resize:none "></textarea> <br>
    Credit Card: <br>
    <input name="creditcard" value ="visa" type="radio">Visa <br>
    <input name="creditcard" value ="mastercard" type="radio">MasterCard <br>
    Credit Card Number: <input name = "ccn" type="text">
    <center><input type="submit" value="Submit Order"></center>
</form>
<%
String itemNum=request.getParameter("itemNum");
String price=request.getParameter("price");
String fName=request.getParameter("fname");
String lName=request.getParameter("lname");
String shipAdd=request.getParameter("shipadd");
String cardType=request.getParameter("creditcard");
String ccn=request.getParameter("ccn");

if (itemNum!= null&&!itemNum.trim().equals("")){
    DBentry DBentry = new DBentry();
    boolean flag=DBentry.entry(itemNum, price, fName, lName, shipAdd, cardType, ccn);
    if(flag){%><script type="text/javascript">alert("Entry Success");</script><%
    }
    else { %><script type="text/javascript">alert("Entry Failure");</script><%}
}

%>
</body>

</html>

的web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:web="http://java.sun.com/xml/ns/javaee" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>Lab5</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>

Answer 1

您需要将servlet映射添加到web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:web="http://java.sun.com/xml/ns/javaee" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>Lab5</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>showParameters</servlet-name>
    <servlet-class>db.ShowParameters</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>showParameters</servlet-name>
    <url-pattern>/ShowParameters</url-pattern>
  </servlet-mapping>
</web-app>

第一个标记<servlet>及其内部告诉Tomcat在哪个类中查找servlet并为servlet命名。下一个标记<servlet-mapping>用该名称标识servlet并将其映射到url。

Answer 2

使用

在web.xml中添加servlet映射

<servlet>

和

<servlet-mapping>

或者只是在servlet顶部添加@WebServlet注释。

我提交jsp页面后收到404错误

2 个答案: