java web课程管理系统开发实例（从数据库连接到代码）
以下是几个简单知识：
JavaBean：用于传递数据，拥有与数据相关的逻辑处理
JSP：从Model接收数据并生成HTML
Servlet：接收HTTP请求并控制Model和View
jdbc：用于配置环境
前言：相关的软件下载和环境配置
1、下载并配置JDK。
2、下载eclipse。
3、下载并配置apache-tomcat（服务器）。
4、下载MySQL（数据库）。
5、下载Navicat for MySQL（数据库可视化工具），方便对数据库的操作。
6、下载jdbc用来实现eclipse中的项目与数据库实现连接。
（看网上教程就好）
一、【建立数据库】
库中设有课程，教师，教室三个值
二、【新建web项目】
打开eclipse，点击File—》New—》other—》Dynamic Web Project
点击Next
需要输入项目名，最好用英文填写，完成之后eclipse左侧会有刚刚创建的项目出现下图
在我的电脑中，打开你下载的jdbc（也就是mysql-connector-java-8.0.13）所在的文件夹中的
将mysql-connector-java-8.0.13文件复制
粘贴在eclipse中，你所建立的项目下的 WebContent/WEB-INF/lib 文件夹下，如下图
接下来便是jsp文件和java文件的写入了.
代码如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>
.a{
margin-top: 20px;
}
.b{
font-size: 20px;
width: 160px;
color: white;
background-color: greenyellow;
}
</style>
</head>
<body>
<%
Object message = request.getAttribute("message");
if(message!=null && !"".equals(message)){ %>
<script type="text/javascript">
alert("<%=request.getAttribute("message")%>");
</script>
<%} %>
<div align="center">
<h1 style="color: red;">课程信息录入</h1>
<a href="index.jsp">返回主页</a>
<form action="CourseServlet?method=add" method="post" onsubmit="return check()">
<div class="a">
课程名称<input type="text" id="name" name="name"/>
</div>
<div class="a">
任课教师<input type="text" id="teacher" name="teacher" />
</div>
<div class="a">
上课地点<input type="text" id="classroom" name="classroom" />
</div>
<div class="a">
<button type="submit" class="b">保 存</button>
</div>
</form>
</div>
<script type="text/javascript">
function check() {
var name = document.getElementById("name");;
var teacher = document.getElementById("teacher");
var classroom = document.getElementById("classroom"); //非空
if(name.value == '') {
alert('课程名称为空');
name.focus();
return false;
}
if(teacher.value == '') {
alert('教师为空');
teacher.focus();
return false;
}
if(classroom.value == '') {
alert('上课地点为空');
classroom.focus();
return false;
} //教师
if(teacher.value != '王建民' && teacher.value != '王辉' && teacher.value != '刘丹' && teacher.value != '刘立嘉' && teacher.value != '杨子光'){
alert('教师名称错误');
return false;
} //教室
if(!/^基教/.test(classroom.value) && !/^一教/.test(classroom.value) && !/^二教/.test(classroom.value) && !/^三教/.test(classroom.value)) {
alert('上课地点错误');
return false;
}
}
</script>
</body>
</html>
add.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>
.a{
margin-top: 20px;
}
.b{
font-size: 20px;
width: 160px;
color: white;
background-color: greenyellow;
}
</style>
</head>
<body>
<%
Object message = request.getAttribute("message");
if(message!=null && !"".equals(message)){ %>
<script type="text/javascript">
alert("<%=request.getAttribute("message")%>");
</script>
<%} %>
<div align="center">
<h1 style="color: red;">课程信息删除</h1>
<a href="index.jsp">返回主页</a>
<form action="CourseServlet?method=getcoursebyname" method="post" onsubmit="return check()">
<div class="a">
课程名称<input type="text" id="name" name="name"/>
</div>
<div class="a">
<button type="submit" class="b">查 找</button>
</div>
</form>
</div>
<script type="text/javascript">
function check() {
var name = document.getElementById("name");; //非空
if(name.value == '') {
alert('课程名称为空');
name.focus();
return false;
}
}
</script>
</body>
</html>
del.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>
.a{
margin-top: 20px;
}
.b{
font-size: 20px;
width: 160px;
color: white;
background-color: greenyellow;
}
.tb, td {
border: 1px solid black;
font-size: 22px;
}
</style>
</head>
<body>
<div align="center">
<h1 style="color: red;">课程信息删除</h1>
<a href="index.jsp">返回主页</a>
<table class="tb">
<tr>
<td>课程名称</td>
<td>${course.name}</td>
</tr>
<tr>
<td>任课教师</td>
<td>${course.teacher}</td>
</tr>
<tr>
<td>上课地点</td>
<td>${course.classroom}</td>
</tr>
</table>
<div class="a">
<a onclick="return check()" href="CourseServlet?method=del&id=${course.id}">删 除</a>
</div>
</div>
<script type="text/javascript">
function check() {
if (confirm("真的要删除吗？")){
return true;
}else{
return false;
}
}
</script>
</body>
</html>
detail.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>
.a{
margin-top: 20px;
}
.b{
font-size: 20px;
width: 160px;
color: white;
background-color: greenyellow;
}
</style>
</head>
<body>
<%
Object message = request.getAttribute("message");
if(message!=null && !"".equals(message)){ %>
<script type="text/javascript">
alert("<%=request.getAttribute("message")%>");
</script>
<%} %>
<div align="center">
<h1 style="color: red;">课程信息修改</h1>
<a href="index.jsp">返回主页</a>
<form action="CourseServlet?method=update" method="post" onsubmit="return check()">
<div class="a">
课程名称<input type="text" id="name" name="name" value="${course.name}"/>
</div>
<div class="a">
任课教师<input type="text" id="teacher" name="teacher" value="${course.teacher}"/>
</div>
<div class="a">
上课地点<input type="text" id="classroom" name="classroom" value="${course.classroom}"/>
</div>
<input type="hidden" id="id" name="id" value="${course.id}"/>
<div class="a">
<button type="submit" class="b">修 改</button>
</div>
</form>
</div>
<script type="text/javascript">
function check() {
var name = document.getElementById("name");;
var teacher = document.getElementById("teacher");
var classroom = document.getElementById("classroom"); //非空
if(name.value == '') {
alert('课程名称为空');
name.focus();
return false;
}
if(teacher.value == '') {
alert('教师为空');
teacher.focus();
return false;
}
if(classroom.value == '') {
alert('上课地点为空');
classroom.focus();
return false;
} //教师
if(teacher.value != '王建民' && teacher.value != '王辉' && teacher.value != '刘丹' && teacher.value != '刘立嘉' && teacher.value != '杨子光'){
alert('教师名称错误');
return false;
} //教室
if(!/^基教/.test(classroom.value) && !/^一教/.test(classroom.value) && !/^二教/.test(classroom.value) && !/^三教/.test(classroom.value)) {
alert('上课地点错误');
return false;
}
}
</script>
</body>
</html>
detail2.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>首页</title>
<style>
.a{
font-size: 26px;
margin-top: 20px;
}
</style>
</head>
<body>
<div align="center">
<h1 style="color: red;">课程基本信息管理系统</h1>
<div class="a">
<a href="add.jsp">课程信息录入</a>
</div>
<div class="a">
<a href="CourseServlet?method=list">课程信息修改</a>
</div>
<div class="a">
<a href="del.jsp">课程信息删除</a>
</div>
<div class="a">
<a href="search.jsp">课程信息查询</a>
</div>
</div>
</body>
</html>
index
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>
.a{
margin-top: 20px;
}
.b{
font-size: 20px;
width: 160px;
color: white;
background-color: greenyellow;
}
.tb, td {
border: 1px solid black;
font-size: 22px;
}
</style>
</head>
<body>
<%
Object message = request.getAttribute("message");
if(message!=null && !"".equals(message)){ %>
<script type="text/javascript">
alert("<%=request.getAttribute("message")%>");
</script>
<%} %>
<div align="center">
<h1 style="color: red;">课程信息列表</h1>
<a href="index.jsp">返回主页</a>
<table class="tb">
<tr>
<td>id</td>
<td>课程名称</td>
<td>任课教师</td>
<td>上课地点</td>
<td align="center" colspan="2">操作</td>
</tr>
<c:forEach items="${courses}" var="item">
<tr>
<td>${item.id}</td>
<td>${item.name}</td>
<td>${item.teacher}</td>
<td>${item.classroom}</td>
<td><a href="CourseServlet?method=getcoursebyid&id=${item.id}">修改</a></td>
</tr>
</c:forEach>
</table>
</div>
</body>
</html>
list.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>
.a{
margin-top: 20px;
}
.b{
font-size: 20px;
width: 160px;
color: white;
background-color: greenyellow;
}
</style>
</head>
<body>
<div align="center">
<h1 style="color: red;">课程信息查询</h1>
<a href="index.jsp">返回主页</a>
<form action="CourseServlet?method=search" method="post" onsubmit="return check()">
<div class="a">
课程名称<input type="text" id="name" name="name"/>
</div>
<div class="a">
任课教师<input type="text" id="teacher" name="teacher" />
</div>
<div class="a">
上课地点<input type="text" id="classroom" name="classroom" />
</div>
<div class="a">
<button type="submit" class="b">查 询</button>
</div>
</form>
</div>
<script type="text/javascript">
function check() {
var name = document.getElementById("name");;
var teacher = document.getElementById("teacher");
var classroom = document.getElementById("classroom"); //非空
if(name.value == '' && teacher.value == '' && classroom.value == '') {
alert('请填写一个条件');
return false;
}
}
</script>
</body>
</html>
search.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>
.a{
margin-top: 20px;
}
.b{
font-size: 20px;
width: 160px;
color: white;
background-color: greenyellow;
}
.tb, td {
border: 1px solid black;
font-size: 22px;
}
</style>
</head>
<body>
<div align="center">
<h1 style="color: red;">课程信息列表</h1>
<a href="index.jsp">返回主页</a>
<table class="tb">
<tr>
<td>id</td>
<td>课程名称</td>
<td>任课教师</td>
<td>上课地点</td>
</tr>
<!-- forEach遍历出adminBeans -->
<c:forEach items="${courses}" var="item" varStatus="status">
<tr>
<td>${item.id}</td>
<td><a>${item.name}</a></td>
<td>${item.teacher}</td>
<td>${item.classroom}</td>
</tr>
</c:forEach>
</table>
</div>
</body>
</html>
searchlist.jsp
直接在上图中一起建立包和类
package com.hjf;
public class Course {
private int id;
private String name;
private String teacher;
private String classroom;
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 getTeacher() {
return teacher;
}
public void setTeacher(String teacher) {
this.teacher = teacher;
}
public String getClassroom() {
return classroom;
}
public void setClassroom(String classroom) {
this.classroom = classroom;
}
public Course() {}
public Course(int id, String name, String teacher, String classroom) {
this.id = id;
this.name = name;
this.teacher = teacher;
this.classroom = classroom;
}
public Course(String name, String teacher, String classroom) {
this.name = name;
this.teacher = teacher;
this.classroom = classroom;
}
}
Course.java
package com.hjf; import java.sql.Connection; import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List; /**
* 课程Dao
* Dao层操作数据
* @author Hu
*
*/
public class CourseDao { /**
* 添加
* @param course
* @return
*/
public boolean add(Course course) {
String sql = "insert into course(name, teacher, classroom) values('" + course.getName() + "','" + course.getTeacher() + "','" + course.getClassroom() + "')";
Connection conn = DBUtil.getConn();
Statement state = null;
boolean f = false;
int a = 0; try {
state = conn.createStatement();
state.executeUpdate(sql);
} catch (Exception e) {
e.printStackTrace();
} finally {
DBUtil.close(state, conn);
} if (a > 0) {
f = true;
}
return f;
} /**
* 删除
*
* @param id
* @return
*/
public boolean delete (int id) {
boolean f = false;
String sql = "delete from course where id='" + id + "'";
Connection conn = DBUtil.getConn();
Statement state = null;
int a = 0; try {
state = conn.createStatement();
a = state.executeUpdate(sql);
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.close(state, conn);
} if (a > 0) {
f = true;
}
return f;
} /**
* 修改
* @param name
* @param pass
*/
public boolean update(Course course) {
String sql = "update course set name='" + course.getName() + "', teacher='" + course.getTeacher() + "', classroom='" + course.getClassroom()
+ "' where id='" + course.getId() + "'";
Connection conn = DBUtil.getConn();
Statement state = null;
boolean f = false;
int a = 0; try {
state = conn.createStatement();
a = state.executeUpdate(sql);
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.close(state, conn);
} if (a > 0) {
f = true;
}
return f;
} /**
* 验证课程名称是否唯一
* true --- 不唯一
* @param name
* @return
*/
public boolean name(String name) {
boolean flag = false;
String sql = "select name from course where name = '" + name + "'";
Connection conn = DBUtil.getConn();
Statement state = null;
ResultSet rs = null; try {
state = conn.createStatement();
rs = state.executeQuery(sql);
while (rs.next()) {
flag = true;
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.close(rs, state, conn);
}
return flag;
} /**
* 通过ID得到类
* @param id
* @return
*/
public Course getCourseById(int id) {
String sql = "select * from course where id ='" + id + "'";
Connection conn = DBUtil.getConn();
Statement state = null;
ResultSet rs = null;
Course course = null; try {
state = conn.createStatement();
rs = state.executeQuery(sql);
while (rs.next()) {
String name = rs.getString("name");
String teacher = rs.getString("teacher");
String classroom = rs.getString("classroom");
course = new Course(id, name, teacher, classroom);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
DBUtil.close(rs, state, conn);
} return course;
} /**
* 通过name得到Course
* @param name
* @return
*/
public Course getCourseByName(String name) {
String sql = "select * from course where name ='" + name + "'";
Connection conn = DBUtil.getConn();
Statement state = null;
ResultSet rs = null;
Course course = null; try {
state = conn.createStatement();
rs = state.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("id");
String teacher = rs.getString("teacher");
String classroom = rs.getString("classroom");
course = new Course(id, name, teacher, classroom);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
DBUtil.close(rs, state, conn);
} return course;
} /**
* 查找
* @param name
* @param teacher
* @param classroom
* @return
*/
public List<Course> search(String name, String teacher, String classroom) {
String sql = "select * from course where ";
if (name != "") {
sql += "name like '%" + name + "%'";
}
if (teacher != "") {
sql += "teacher like '%" + teacher + "%'";
}
if (classroom != "") {
sql += "classroom like '%" + classroom + "%'";
}
List<Course> list = new ArrayList<>();
Connection conn = DBUtil.getConn();
Statement state = null;
ResultSet rs = null; try {
state = conn.createStatement();
rs = state.executeQuery(sql);
Course bean = null;
while (rs.next()) {
int id = rs.getInt("id");
String name2 = rs.getString("name");
String teacher2 = rs.getString("teacher");
String classroom2 = rs.getString("classroom");
bean = new Course(id, name2, teacher2, classroom2);
list.add(bean);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.close(rs, state, conn);
} return list;
} /**
* 全部数据
* @param name
* @param teacher
* @param classroom
* @return
*/
public List<Course> list() {
String sql = "select * from course";
List<Course> list = new ArrayList<>();
Connection conn = DBUtil.getConn();
Statement state = null;
ResultSet rs = null; try {
state = conn.createStatement();
rs = state.executeQuery(sql);
Course bean = null;
while (rs.next()) {
int id = rs.getInt("id");
String name2 = rs.getString("name");
String teacher2 = rs.getString("teacher");
String classroom2 = rs.getString("classroom");
bean = new Course(id, name2, teacher2, classroom2);
list.add(bean);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.close(rs, state, conn);
} return list;
} }
CourseDao.java
package com.hjf; import java.util.List; /**
* CourseService
* 服务层
* @author Hu
*
*/
public class CourseService { CourseDao cDao = new CourseDao(); /**
* 添加
* @param course
* @return
*/
public boolean add(Course course) {
boolean f = false;
if(!cDao.name(course.getName())) {
cDao.add(course);
f = true;
}
return f;
} /**
* 删除
*/
public void del(int id) {
cDao.delete(id);
} /**
* 修改
* @return
*/
public void update(Course course) {
cDao.update(course);
} /**
* 通过ID得到一个Course
* @return
*/
public Course getCourseById(int id) {
return cDao.getCourseById(id);
} /**
* 通过Name得到一个Course
* @return
*/
public Course getCourseByName(String name) {
return cDao.getCourseByName(name);
} /**
* 查找
* @return
*/
public List<Course> search(String name, String teacher, String classroom) {
return cDao.search(name, teacher, classroom);
} /**
* 全部数据
* @return
*/
public List<Course> list() {
return cDao.list();
}
}
CourseService
package com.hjf; import java.io.IOException; import java.util.List; import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; @WebServlet("/CourseServlet")
public class CourseServlet extends HttpServlet { private static final long serialVersionUID = 1L; CourseService service = new CourseService(); /**
* 方法选择
*/
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
String method = req.getParameter("method");
if ("add".equals(method)) {
add(req, resp);
} else if ("del".equals(method)) {
del(req, resp);
} else if ("update".equals(method)) {
update(req, resp);
} else if ("search".equals(method)) {
search(req, resp);
} else if ("getcoursebyid".equals(method)) {
getCourseById(req, resp);
} else if ("getcoursebyname".equals(method)) {
getCourseByName(req, resp);
} else if ("list".equals(method)) {
list(req, resp);
}
} /**
* 添加
* @param req
* @param resp
* @throws IOException
* @throws ServletException
*/
private void add(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
req.setCharacterEncoding("utf-8");
String name = req.getParameter("name");
String teacher = req.getParameter("teacher");
String classroom = req.getParameter("classroom");
Course course = new Course(name, teacher, classroom); //添加后消息显示
if(service.add(course)) {
req.setAttribute("message", "添加成功");
req.getRequestDispatcher("add.jsp").forward(req,resp);
} else {
req.setAttribute("message", "课程名称重复，请重新录入");
req.getRequestDispatcher("add.jsp").forward(req,resp);
}
} /**
* 全部
* @param req
* @param resp
* @throws ServletException
*/
private void list(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
req.setCharacterEncoding("utf-8");
List<Course> courses = service.list();
req.setAttribute("courses", courses);
req.getRequestDispatcher("list.jsp").forward(req,resp);
} /**
* 通过ID得到Course
* @param req
* @param resp
* @throws ServletException
*/
private void getCourseById(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
req.setCharacterEncoding("utf-8");
int id = Integer.parseInt(req.getParameter("id"));
Course course = service.getCourseById(id);
req.setAttribute("course", course);
req.getRequestDispatcher("detail2.jsp").forward(req,resp);
} /**
* 通过名字查找
* 跳转至删除
* @param req
* @param resp
* @throws IOException
* @throws ServletException
*/
private void getCourseByName(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
req.setCharacterEncoding("utf-8");
String name = req.getParameter("name");
Course course = service.getCourseByName(name);
if(course == null) {
req.setAttribute("message", "查无此课程！");
req.getRequestDispatcher("del.jsp").forward(req,resp);
} else {
req.setAttribute("course", course);
req.getRequestDispatcher("detail.jsp").forward(req,resp);
}
} /**
* 删除
* @param req
* @param resp
* @throws IOException
* @throws ServletException
*/
private void del(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
req.setCharacterEncoding("utf-8");
int id = Integer.parseInt(req.getParameter("id"));
service.del(id);
req.setAttribute("message", "删除成功！");
req.getRequestDispatcher("del.jsp").forward(req,resp);
} /**
* 修改
* @param req
* @param resp
* @throws IOException
* @throws ServletException
*/
private void update(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
req.setCharacterEncoding("utf-8");
int id = Integer.parseInt(req.getParameter("id"));
String name = req.getParameter("name");
String teacher = req.getParameter("teacher");
String classroom = req.getParameter("classroom");
Course course = new Course(id, name, teacher, classroom); service.update(course);
req.setAttribute("message", "修改成功");
req.getRequestDispatcher("CourseServlet?method=list").forward(req,resp);
} /**
* 查找
* @param req
* @param resp
* @throws ServletException
*/
private void search(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
req.setCharacterEncoding("utf-8");
String name = req.getParameter("name");
String teacher = req.getParameter("teacher");
String classroom = req.getParameter("classroom");
List<Course> courses = service.search(name, teacher, classroom);
req.setAttribute("courses", courses);
req.getRequestDispatcher("searchlist.jsp").forward(req,resp);
}
}
CourseServlet.java
package com.hjf; import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement; /**
* 数据库连接工具
* @author Hu
*
*/
public class DBUtil { public static String db_url = "jdbc:mysql://localhost:3306/course?useSSL=false&useUnicode=true&characterEncoding=UTF-8";
public static String db_user = "root";
public static String db_pass = "123"; public static Connection getConn () {
Connection conn = null; try {
Class.forName("com.mysql.jdbc.Driver");//加载驱动
conn = DriverManager.getConnection(db_url, db_user, db_pass);
} catch (Exception e) {
e.printStackTrace();
} return conn;
} /**
* 关闭连接
* @param state
* @param conn
*/
public static void close (Statement state, Connection conn) {
if (state != null) {
try {
state.close();
} catch (SQLException e) {
e.printStackTrace();
}
} if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
} public static void close (ResultSet rs, Statement state, Connection conn) {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
} if (state != null) {
try {
state.close();
} catch (SQLException e) {
e.printStackTrace();
}
} if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
} }
DBUtil.java
关于为什么有的类需要单独一个包
为了不同项目间更好的对接.
附：
目录说明
com.astar
- config 用于放置配置文件，资源文件等。如Spring配置文件applicationContext.xml
- background 后台管理层结构
- common 项目中公用的文件，如下
- constant 常量
- enumeration 枚举类
- util 工具类
- dao 抽象接口及实现类，用于放置封装好的底层数据访问操作。如JPA的CURD
- service 抽象业务接口及实现类，用于调用同层dao目录中的DAO对象，便于被实现和继承
- controller 控制层，通过SpringMVC 实现请求处理，并转发。
- entity 实体层，用于放置项目中的公用实体
- filter 过滤层，放置过滤器
- center/finance/printer/keeper/editor 这是项目中的角色，每个角色作为一个独立层，便于分工和解耦，使每层中的业务功能内聚
- service 独立的，特有的业务
- dao 通过该层自己来处理DAO
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