Question

我正在尝试连接数据库并写一些记录，但我收到此错误任何人都可以帮助我纠正它我真的很感激我是java编程的新手这是我的jsp文件：NewFile.jsp

<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; 
          charset=ISO-8859-1">
    <title>Insert title here</title>
  </head>
  <body>
     <form action="/Add" method="post" enctype="multipart/form-data">
        Enter news ID: <br> 
           <input type="text" name="id"><br><br>
        Enter title :<br> 
           <input type="text" name="title"><br><br>
        Choose an image : 
           <input type="file" name="image" required="required">
           <br><br>
         <input type="submit" value="add news">
    </form>
  </body>
</html>

这是我的Add.java

package com.example.saeid;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

public class Add extends HttpServlet
{
  private static final long serialVersionUID = 1L;
  private String db_userName = "root";
  private String db_Password = "uyhgbv098";
  private String db_Name = "my_demo_database";
  private String driver = "com.mysql.jdbc.Driver";
  private String url = "jdbc:mysql://localhost:3306/";

  private Connection getConnection() 
  {
    Connection conn = null;
    try 
    {
         Class.forName(driver);
         conn = DriverManager.getConnection(
               url + db_Name,
               db_userName,
               db_Password);
    } 
    catch (Exception e) 
    {
      throw new RuntimeException("Failed to obtain database connection.", e);
    }
    return conn;
}

public void doPost( HttpServletRequest request, HttpServletResponse response)  
        throws ServletException, IOException 
{ 
    String newsId = request.getParameter("id");
    int newsID = Integer.parseInt(newsId);
    String newsTitle = request.getParameter("title");
    String body = "body";
    InputStream inputStream = null;
    Part part = request.getPart("image");
    inputStream = part.getInputStream();
    Connection conn = null;
    try
    {
        conn = getConnection();
        String query = "INSERT INTO news (id , title , subm_date , text , image ) values (?, ?, NOW() ,? ,?)";
        PreparedStatement ps = conn.prepareStatement(query);
        ps.setInt(1, newsID);
        ps.setString(2,newsTitle );
        ps.setString(3, body);
        ps.setBlob(4, inputStream);
        int row = ps.executeUpdate();
        if (row > 0) 
        {
            RequestDispatcher rd = request.getRequestDispatcher("NewFile.jsp");
            rd.include(request,response);
        }
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }
    finally
    {
        try 
        {
            conn.close();
        }
        catch(SQLException e)
        {
            e.printStackTrace();
        }
    }
}

}

和web.xml：

<?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>12</display-name>
   <welcome-file-list>
     <welcome-file>NewFile.jsp</welcome-file>
   </welcome-file-list>

   <servlet>
     <servlet-name>addServlet</servlet-name>
     <servlet-class>com.example.saeid.Add</servlet-class>
   </servlet>

  <servlet-mapping>
    <servlet-name>addServlet</servlet-name>
    <url-pattern>NewFile</url-pattern> 
  </servlet-mapping>

Answer 1

404的原因之一是URL写得不正确，链接不正确。如果在访问localhost：8080 / NewFile.jsp页面或单击Add时得到404响应，则表单操作指向/ Add但是url-pattern是NewFile。将url-pattern更改为 /添加

为什么我得到这个错误？ HTTP状态404 - 未找到

1 个答案: