Question

这里我遇到一个问题，通常我必须在Bean类中获取并设置值，因此必须传递给Dbconnection类和servlet，但是我无法在servlet中调用bean / dbconnect方法来插入值在databases.can一些指南，以正确的方式获得jsp传递

豆 - ＆GT; DBCONNECT --- ---的servlet register.jsp

的welcome.jsp：

<body>
<%  
Bean bean=(Bean)request.getAttribute("bean");  
out.print("Welcome, "+bean.getUsername());  
%>
<p>You are successfully logged in!</p>  
</body>

的index.jsp：

<form action="Controller" method="post">
    User name:<input type="text" name="username">
    Password:<input type="password" name="password">
    <input type="submit" name="Login"> <a href="Register.jsp">Register</a>
</form>

Register.jsp

<form action="Controller" method="post">
User name:<input type="text" name="name" >
Password:<input type="password" name="pass">
Email-id<input type="text" name="emailid">
phone number:<input type="text" name="phone">
<input type="submit" value="submit"><a href="index.jsp">Login</a>
</form>

Bean.java

package Databases;

public class Bean
{

    private   String username;
    private   String password;
    private   String emailid;
    private   String phone;
   /**
     * @return the username
     */
    public String getUsername()
    {
        return username;
    }
    /**
     * @param username the username to set
     */
    public void setUsername(String username)
    {
        this.username = username;
    }
    /**
     * @return the password
     */
    public String getPassword()
    {
        return password;
    }
    /**
     * @param password the password to set
     */
    public void setPassword(String password)
    {
        this.password = password;
    }
    /**
     * @return the emailid
     */
    public String getEmailid()
    {
        return emailid;
    }
    /**
     * @param emailid the emailid to set
     */
    public void setEmailid(String emailid)
    {
        this.emailid = emailid;
    }
    /**
     * @return the phone
     */
    public String getPhone()
    {
        return phone;
    }
    /**
     * @param phone the phone to set
     */
    public void setPhone(String phone)
    {
        this.phone = phone;
    }

}

Dbconnect.java

package Databases;

import java.io.*;
import java.sql.*;
import java.util.ArrayList;
import java.util.Iterator;

public class Dbconnect
{
    public static void main(String args[]) throws ClassNotFoundException
    {
        Dbconnect db = new Dbconnect();
        db.dbconnect();
    }

    public Connection dbconnect() throws ClassNotFoundException
    {

        try
        {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/mine", "root", "android");

        } catch (SQLException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;

    }

    public String user(Bean bean)
    {
        Connection con = null;
        PreparedStatement prep = null;
        try
        {
            con = dbconnect();
            String sql = "SELECT * user WHERE name = ? AND password = ?";
            prep = con.prepareStatement(sql);

            prep.setString(1, bean.getUsername());
            prep.setString(2, bean.getPassword());

        } 
        catch (Exception e)
        {
            System.out.println("cannot connect");
            e.printStackTrace();
        }
        return "user login";
    }

    public String insertDetail(Bean bean) throws SQLException
    {

        String sql = "insert into user(name,password,email,phone) values(?,?,?,?)";
        Connection con = null;
        PreparedStatement prep = null;

        try
        {
            con = dbconnect();
            prep = con.prepareStatement(sql);

        } catch (ClassNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        prep.setString(1, bean.getUsername());
        prep.setString(2, bean.getPassword());
        prep.setString(3, bean.getEmailid());
        prep.setString(4, bean.getPhone());
        prep.executeUpdate();
        prep.close();

        return "successfully added";

    }
}

Controller.java

    package servlet;

import java.io.IOException;
import java.io.PrintWriter;

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

import com.mysql.jdbc.PreparedStatement;

import Databases.Dbconnect;

import Databases.*;

/**
 * Servlet implementation class Loginservlet
 */
public class Controller extends HttpServlet
{
    private static final long serialVersionUID = 1L;

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

    }

    protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
    {

        response.setContentType("text/html");
        //PrintWriter out = response.getWriter();

        String name = request.getParameter("name");
        String pass = request.getParameter("pass");
        String email = request.getParameter("emailid");
        String pn = request.getParameter("phone");
        System.out.println("Name :" + name);
        System.out.println("pass :" + pass);
        System.out.println("emailid :" + email);
        System.out.println("phone:" + pn);


        Bean bean=new Bean();  
        bean.setUsername(name);  
        bean.setPassword(pass);  
        bean.setEmailid(email);
        bean.setPhone(pn);

        request.setAttribute("bean",bean);  

        request.getRequestDispatcher("index.jsp");
        request.getRequestDispatcher("Register.jsp");


    }



}

的web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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>WebprojectTry</display-name>
  <welcome-file-list>

    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>Controller</display-name>
    <servlet-name>Controller</servlet-name>
    <servlet-class>servlet.Controller</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Controller</servlet-name>
    <url-pattern>/Controller</url-pattern>
  </servlet-mapping>
</web-app>

Answer 1

好的，您可以在GitHub account浏览完整的代码。它正在运行，但我个人会将JPA用于持久性。

让我们从包含doPost方法的控制器开始。它只需要请求参数，构造一些bean并调用DAO将其持久化到数据库。完成后，它将bean设置为请求属性并调用jsp调用。这意味着一旦你再次打开这个jsp，这个bean就不会消失。使用会话将其存储在多个调用中。

public class Controller extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = request.getParameter("name");
        String phone = request.getParameter("phone");
        // todo check parameters

        User user = new User(name, phone);
        DAO dao = new DAO();
        dao.saveUser(user);
        request.setAttribute("USER", user);// consider using session
        // TODO handle errors

        RequestDispatcher dispatcher = request.getRequestDispatcher("register/index.jsp");
        dispatcher.forward(request, response);
    }
}

web.xml很简单：

<servlet>
    <servlet-name>RegistrationController</servlet-name>
    <servlet-class>cz.literak.sandbox.so.register.Controller</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>RegistrationController</servlet-name>
    <url-pattern>/RegistrationController</url-pattern>
</servlet-mapping>

DAO使用旧的普通JDBC将对象存储在数据库表中。我赞成使用DataSource。

static {
    try {
        Class.forName("org.mariadb.jdbc.Driver");

// Class.forName（＆＃34; com.mysql.jdbc.Driver＆＃34;）; } catch（ClassNotFoundException e）{ e.printStackTrace（）; } }

public User findUser(String phone) {
    // todo
    return null;
}

//  DDL: CREATE TABLE user (name VARCHAR(100), phone VARCHAR(100))
public boolean saveUser(User user) throws ServletException {
    try (
         Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "secret");
         PreparedStatement ps = con.prepareStatement("INSERT INTO user VALUES(?,?)"))
    {
        ps.setString(1, user.getName());
        ps.setString(2, user.getPhone());
        return ps.execute();
    } catch (SQLException e) {
        throw new ServletException("DB operation failed", e);
    }
}

最后是jsp。它只检查USER是否存在，然后显示注册表单或欢迎消息。

<c:choose>
    <c:when test="${USER == null}">
        <form action="${pageContext.request.contextPath}/RegistrationController" method="post">
            <table>
                <tr>
                    <td>User name</td>
                    <td><input type="text" name="name" ></td>
                </tr>
                <tr>
                    <td>Phone</td>
                    <td><input type="text" name="phone"></td>
                </tr>
                <tr>
                    <td></td>
                    <td><input type="submit" value="submit"></td>
                </tr>
            </table>
        </form>
    </c:when>
    <c:otherwise>
        Welcome <c:out value="${USER.name}"/>
    </c:otherwise>
</c:choose>

我希望你不会删除这个问题，因为我花了很多时间来回答。

将值bean / java传递给servlet

1 个答案: