记录-Hibernate+servlet实现简单的增、删、查、改

由于需要对Hibernate作个了解，所以写了个简单的实现

以上是大概目录

1.新建Hibernate.cfg.xml配置文件

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

<session-factory>
    <property name="connection.username">root</property>
    <property name="connection.url">
        jdbc:mysql://localhost:3306/hiber?characterEncoding=utf8
    </property>
    <property name="dialect">
        org.hibernate.dialect.MySQLDialect
    </property>
    <property name="myeclipse.connection.profile">
        mysqlJdbcDriver
    </property>
    <property name="connection.password">123456</property>
    <property name="connection.driver_class">
        com.mysql.jdbc.Driver
    </property>
    <property name="show_sql">true</property>
    <property name="format_sql">true</property>
    <property name="hbm2ddl.auto">update</property>
    <mapping resource="/entity/User.hbm.xml"/>

</session-factory>

</hibernate-configuration>

2.修改web.xml 路径映射

<?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_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>tHIbe</display-name>
  <servlet>
      <servlet-name>userServlet</servlet-name>
      <servlet-class>servlet.userServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>userServlet</servlet-name>
      <url-pattern>*.do</url-pattern>
  </servlet-mapping>
  <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>

3.路径跳转的servlet类

package servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

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

import com.sun.org.apache.bcel.internal.generic.Select;

import entity.User;
import service.UserService;
import service.impl.UserServiceImpl;

public class userServlet extends HttpServlet{

    /**
     *
     */
    private static final long serialVersionUID = 1L;
    UserService userService=new UserServiceImpl();
    public void execute(HttpServletRequest request, HttpServletResponse response ) throws IOException{
        System.out.println("进入次类");
        String path = request.getServletPath();
        path = path.substring(0, path.indexOf("."));
        request.setCharacterEncoding("utf8");
        response.setContentType("text/html;charset=utf8");

        if (path.equals("/goReg")) {
            RequestDispatcher dispatcher=request.getRequestDispatcher("/WEB-INF/jsp/reg.jsp");
            try {
                dispatcher.forward(request, response);
            } catch (ServletException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }else if(path.equals("/reg")){
            regUser(request,response);
            try {
                request.getRequestDispatcher("/WEB-INF/jsp/index.jsp").forward(request, response);
            } catch (ServletException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }else if(path.equals("/select")){
            select(request,response);
            try {
                request.getRequestDispatcher("/WEB-INF/jsp/index.jsp").forward(request, response);
            } catch (ServletException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }else if(path.equals("/delete")){
            delete(request,response);
            try {
                request.getRequestDispatcher("/WEB-INF/jsp/index.jsp").forward(request, response);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

    public void regUser(HttpServletRequest req,HttpServletResponse resp){
        System.out.println("进行注册");
        String name=req.getParameter("name");
        String pwd=req.getParameter("pwd");
        User user=new User();
        user.setName(name);
        user.setPwd(pwd);
        userService.addUser(user);
        req.setAttribute("user", user);
    }

    public void select(HttpServletRequest req,HttpServletResponse resp){

        System.out.println("查询中");
        List<User> list=new ArrayList<>();
        list=userService.select();
        req.setAttribute("list", list);
    }

    public void delete(HttpServletRequest req,HttpServletResponse resp){
        Integer id=Integer.parseInt(req.getParameter("name"));
        int result=userService.delete(id);
        if(result==1){
            req.setAttribute("msg", "成功kill");
        }
        System.out.println(result);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("haha ");
        execute(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(req, resp);
    }
}

4.新建Hibernate工具类（主要用来在dao的实现类里面创建session、关闭session等）

package util;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {
private static final SessionFactory sessionFactory;

    static
    {
        try
        {
            Configuration config = new Configuration().configure("hibernate.cfg.xml");
            sessionFactory = config.buildSessionFactory();
        }
        catch(Throwable e)
        {
            throw new ExceptionInInitializerError(e);
        }
    }

    public static final ThreadLocal session = new ThreadLocal();

    public static Session currentSession() throws HibernateException
    {
        Session s = (Session)session.get();
        //Open a new Session,if this Thread has none yet
        if(s == null || !s.isOpen())
        {
            s = sessionFactory.openSession();
            session.set(s);
        }
        return s;
    }

    public static void closeSession() throws HibernateException
    {
        Session s = (Session)session.get();
        session.set(null);
        if(s != null)
            s.close();
    }
}

5.dao层实现类代码参考

package dao.impl;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;

import dao.UserDao;
import entity.User;
import util.HibernateUtil;

public class UserDaoImpl implements UserDao {

    @Override
    public void addUser(User user) {
        // TODO Auto-generated method stub
        Session session = HibernateUtil.currentSession();
        Transaction tx=session.beginTransaction();

        try {
            session.save(user);//保存次酒类对象
            tx.commit();//提交到数据库
            session.close();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        }
    }

    @Override
    public List<User> select() {
        Session session = HibernateUtil.currentSession();
        //Transaction tx=session.beginTransaction();
        List<User> list=null;
        try {
             String hql="from User";//使用命名参数，推荐使用，易读。
               Query query=session.createQuery(hql);
               list=query.list();
               //tx.commit();//提交到数据库
               session.close();
               return list;

        } catch (Exception e) {
            e.printStackTrace();
        }
        return list;
    }

    @Override
    public int delete(Integer id) {
        Session session=HibernateUtil.currentSession();
        Transaction tx=session.beginTransaction();
        try {
            User user=(User)session.get(User.class, id);
            session.delete(user);
            tx.commit();
            session.close();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
            return 0;
        }
        return 1;
    }

}

6.User实体类的映射文件User.hbm.xml，和数据的关联文件（需要在Hibernate.cfg.xml配置文件中引入）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="entity">
    <class name="User" table="user">
       <id name="id" column="id">
          <generator class="identity"></generator>
       </id>
       <property name="name" column="name" unique="true"></property>
       <property name="pwd" column="pwd"></property>
    </class>
</hibernate-mapping>    

7.User实体类（注意要实现 implements Serializable）

package entity;

import java.io.Serializable;

/**
 * 持久化user类
 * @author Administrator
 *
 */
public class User implements Serializable{

    private int id;
    private String name;
    private String pwd;

    public User(int id, String name, String pwd) {
        super();
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public User() {
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

}

8.jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>主页</title>
<script type="text/javascript">
    function dianji(){
        window.location.href='select.do'
    };

    function kill(){
        window.location.href='delete.do?name=${list.get(1).id}'
    }

    function ok(){
        var name=document.getElementById("newName").value;
        window.location.href='update.do?name='+name
    }
</script>
</head>
<body>
欢迎你：${suser.name},你将走向最强王者之路<br/>
点击下方按钮：<br/>
<input type="button" value="查询最强王者" onclick="dianji()"/><br/>
最强王者是：${list.get(1).name}<br/>

看我的<br/>
<input type="button" value="kill you!" onclick="kill()"/>
<p>${msg}</p>

你已成为最强王者请修改你的名称：<input type="text" name="name" id="newName" placeholder="请输入你的新昵称" /><input type="button" value="确定" onclick="ok()"/>
</body>
</html>

在项目遇到的问题有：

1.启动tomcat时 报无法启动的错误，错误可能在xml配置文件

2.xml配置的路径跳转不能跳转，同样的代码，重新建项目后又可以了，不知道什么原因