servlet+mybatis实现crud(增删改查)
目的：使用servlet+mybatis+Mysql完成对学生信息表的增删改查操作，并结合jsp展示效果
项目结构
准备工作>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
1.建表
附上建表代码：
附上SQL代码：
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
`id` bigint(11) NOT NULL AUTO_INCREMENT,
`name` varchar(150) DEFAULT NULL,
`age` int(3) DEFAULT NULL,
`birthday` date DEFAULT NULL,
`address` varchar(255) DEFAULT NULL,
`phone` varchar(11) DEFAULT NULL,
`email` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;
2.所需jar包
引入mybatis
1.将mybatis-3.4.1.jar,mysql-connector-java-5.1.38.jar放到lib目录下，并buildPath。
2.鼠标右键点击项目名，新建一个名为resource的资源文件，注意是这种图标
资源文件放到这里才能被识别。在resource文件夹下新建一个db.properties文件
放连接数据库信息
db.properties
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///student?characterEncoding=UTF8&useSSL=true&serverTimezone=UTC
username=root
password=root
再在该目录下建一个名为Mybatis-config.xml的xml配置文件
Mybatis-config.xml
src下创建domain包存放实体类，domain下新建一个名为Student的java类
Student.java
/**
* 学生实体类
* @author 红烛
*
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student implements Serializable{
private static final long serialVersionUID = 1L;
private Long id;
private String name;
private Integer age;
private Date birthday;
private String address;
private String phone;
private String email;
}
src下创建mapper包，新建StudentMapper接口和StudentMapper.xml文件
StudentMapper接口中什么都不用写，我们把接口写在dao层
StudentMapper.java
/**
*
* @author 红烛
*
*/
public interface StudentMapper {
}
StudentMapper.xml
id,name,age,birthday,address,phone,email
insert into student(id,name,age,birthday,address,phone,email)values(#{id},#{name},#{age},#{birthday},#{address},#{phone},#{email})
delete from student where id=#{id}
update student
name=#{name},
age=#{age},
birthday=#{birthday},
address=#{address},
phone=#{phone},
email=#{email},
where id=#{id}
StudentMapper.xml文件写完后注意，在主配置文件mybatis-config.xml中配置资源扫描
在src下创建dao.impl包，在dao包下创建IStudentDAO接口，在dao.impl下创建StudentDAOImpl实现类。
IStudentDAO.java
/**
*
* @author 红烛
*
*/
public interface IStudentDAO {
/**
* 添加学生信息
* @param stu
*/
void insert(Student stu);
/**
* 删除学生信息
* @param id
*/
void delete(Long id);
/**
* 修改学生信息
* @param stu
*/
void update(Student stu);
/**
* 查询某个学生信息
* @param id
* @return
*/
Student select(Long id);
/**
* 查询所有学生信息
* @return
*/
List selectAll();
}
StudentDAOImpl.java
/**
*
* @author 红烛
*
*/
public class StudentDAOImpl implements IStudentDAO {
@Override
public void insert(Student stu) {
SqlSession session=MybatisUtil.getSession();
session.insert("cn.wolfcode.mapper.StudentMapper.insert",stu);
session.commit();
session.close();
}
@Override
public void delete(Long id) {
SqlSession session=MybatisUtil.getSession();
session.delete("cn.wolfcode.mapper.StudentMapper.delete",id);
session.commit();
session.close();
}
@Override
public void update(Student stu) {
SqlSession session=MybatisUtil.getSession();
session.update("cn.wolfcode.mapper.StudentMapper.update",stu);
session.commit();
session.close();
}
@Override
public Student select(Long id) {
SqlSession session=MybatisUtil.getSession();
Student stu=session.selectOne("cn.wolfcode.mapper.StudentMapper.select",id);
session.close();
return stu;
}
@Override
public List selectAll() {
SqlSession session=MybatisUtil.getSession();
List list=session.selectList("cn.wolfcode.mapper.StudentMapper.selectAll");
session.close();
return list;
}
}
这里面的MybatisUtil是一个工具类，用于获取数据库连接，在src下新建一个名为util包，用于存放工具类。
MybatisUtil.java
/**
*
- @author 红烛
*/
public class MybatisUtil {
private static SqlSessionFactory factory;
private MybatisUtil(){};
static{
try {
factory=new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("Mybatis-config.xml"));
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSession(){
SqlSession session=factory.openSession();
return session;
}
}
src下创建创建service.impl包。在service包下新建IStudentService.java接口。在impl包下创建StudentServiceImplement.java类
IStudentService
/**
* 这部分和dao包下接口代码一样
* @author 红烛
*
*/
public interface IStudentService {
/**
* 添加学生信息
* @param stu
*/
void insert(Student stu);
/**
* 删除学生信息
* @param id
*/
void delete(Long id);
/**
* 修改学生信息
* @param stu
*/
void update(Student stu);
/**
* 查询某个学生信息
* @param id
* @return
*/
Student select(Long id);
/**
* 查询所有学生信息
* @return
*/
List selectAll();
}
StudentServiceImplement
/**
* 实现接口
* @author 红烛
*
*/
public class StudentServiceImpl implements IStudentService {
//采用面向接口编程方式
private IStudentDAO dao=new StudentDAOImpl();
@Override
public void insert(Student stu) {
dao.insert(stu);
}
@Override
public void delete(Long id) {
dao.delete(id);
}
@Override
public void update(Student stu) {
dao.update(stu);
}
@Override
public Student select(Long id) {
Student stu=dao.select(id);
return stu;
}
@Override
public List selectAll() {
List list=dao.selectAll();
return list;
}
}
准备阶段完成：在src下快速创建StudentServiceImplement.java的测试类，测试对数据库student表的增删改查是否正确。
servlet增删改查
添加功能
这是通过查找所有学生信息在jsp上进行页面展示
思路：在servlet的service方法中，
1.通过调用service的selectAll()方法拿到所有的学生信息
2.使用request.setAttribute();方法将数据放到request请求域中
3.转发跳转到student.jsp页面
4.student.jsp页面通el表达式从request请求域中取得数据
servlet相关部分代码
protected void findAll(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取数据
List list=studentService.selectAll();
//将数据放到request请求域中
request.setAttribute("list", list);
//跳转到student.jsp页面
request.getRequestDispatcher("/WEB-INF/view/student.jsp").forward(request, response);
}
student.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
学生信息页
删除功能
点击删除，跳转到删除这一模块。那么问题来了，servlet怎么识别你传过来的地址是要执行什么功能呢？解决方案是在链接中传递一个参数，在servlet中接收参数，如果传过来的参数cmd=delete，就调用delete方法，如果传过来的参数cmd=update,则跳转到update方法，这样就解决了。代码如下：
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//解决乱码问题
request.setCharacterEncoding("utf-8");
//接收地址中的参数值
String cmd=request.getParameter("cmd");
if("insertOrUpdate".equals(cmd)){
insertOrUpdate(request,response);
}else if("insert".equals(cmd)){
insert(request,response);
}else if("delete".equals(cmd)){
delete(request,response);
}else if("update".equals(cmd)){
update(request,response)；
}else{
findAll(request, response);
}
}
实现删除的思路：点击删除
1.删除
我们需要在路径中将要删除的这一条数据的id传递过去，
2.在servlet中接收id的值
3.调用service中delete方法，通过id将这条数据删除
4.重定向到student.jsp页面 （我们需要看到是否数据被删除）
protected void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//接收传过来的id值
String id=request.getParameter("id");
//StringUtil是判断字符串是否为空的工具类，代码下面贴出
if(StringUtil.hasLength(id)){
studentService.delete(Long.valueOf(id));
}
//重定向到显示页面
response.sendRedirect("/student");
}
StringUtil.java
/***
*
* @author 红烛
*
*/
public class StringUtil {
private StringUtil(){};
public static boolean hasLength(String val){
return val!=null&&!"".equals(val.trim());
}
}
增加,修改操作
增加和修改操作在这四个功能中是相对比较难的部分
增加修改所用的jsp页面
edit.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
${empty stu?'添加':'修改' }页面
实现思路：
-
1.点击student.jsp中的添加按钮 添加进入servlet的insert()方法模块。
2.在insert（）方法中跳转到edit.jsp页面
3.填好数据后点击提交 进入到servlet的insertOrUpdate模块，对用户提交的数据进行处理
4.使用request.getParameter();方法将数据一一接收
5.将接受的数据进行封装 Student stu=new Student(); stu.set… 调用service的insert()实现数据插入数据库
6.重定向到student.jsp页面 -
增加和修改操作基本一致，主要区别在于，增加操作从edit页面点击提交到servlet，id值是没有的，因为id是设置的自增长，添加时不需要填写id项。而修改操作需要通过id进行修改，点击修改时，需要将id值传到servlet，servlet接收到后就可以通过调用service的select方法查询出这个id的student的所有信息。然后通过将得到的student对象信息放到请求域（request）中，再跳转到edit页面，edit页面通过el表达式${}给输入框赋值实现数据回显。修改完成也是提交到servlet的insertOrUpdate模块，而这时id是有数据的；所以可以通过id值是否为空判断是添加还是修改操作，从而调用相应的方法。
protected void insertOrUpdate(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Student stu=new Student(); String id=request.getParameter("id"); if(StringUtil.hasLength(id)){ stu.setId(Long.valueOf(id)); p2Stu(request,response,stu); studentService.update(stu); }else{ p2Stu(request,response,stu); studentService.insert(stu); } response.sendRedirect("/student"); } //点击修改 实现数据回显，并跳转到edit页面 protected void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String id=request.getParameter("id"); Student stu=studentService.select(Long.valueOf(id)); request.setAttribute("stu", stu); request.getRequestDispatcher("/WEB-INF/view/edit.jsp").forward(request, response); } //接收参数并封装 protected void insert(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.getRequestDispatcher("/WEB-INF/view/edit.jsp").forward(request, response); } private static void p2Stu(HttpServletRequest request, HttpServletResponse response,Student stu)throws ServletException, IOException{ String name=request.getParameter("name"); String birthday=request.getParameter("birthday"); String age=request.getParameter("age"); String address=request.getParameter("address"); String email=request.getParameter("email"); String phone=request.getParameter("phone"); stu.setAddress(address); if(StringUtil.hasLength(age)){ stu.setAge(Integer.valueOf(age)); } SimpleDateFormat sft=new SimpleDateFormat("yyyy-MM-dd"); Date date; try { date = sft.parse(birthday); stu.setBirthday(date); } catch (ParseException e) { e.printStackTrace(); } stu.setEmail(email); stu.setName(name); stu.setPhone(phone);}
servlet代码总览
/**
*
* @author 红烛
*
*/
@WebServlet("/student")
public class StudentServlet extends HttpServlet{
private IStudentService studentService=new StudentServiceImpl();
private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
String cmd=request.getParameter("cmd");
if("insertOrUpdate".equals(cmd)){
insertOrUpdate(request,response);
}else if("insert".equals(cmd)){
insert(request,response);
}else if("delete".equals(cmd)){
delete(request,response);
}else if("update".equals(cmd)){
update(request,response);
}else{
findAll(request, response);
}
}
protected void insertOrUpdate(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Student stu=new Student();
String id=request.getParameter("id");
if(StringUtil.hasLength(id)){
stu.setId(Long.valueOf(id));
p2Stu(request,response,stu);
studentService.update(stu);
}else{
p2Stu(request,response,stu);
studentService.insert(stu);
}
response.sendRedirect("/student");
}
protected void insert(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.getRequestDispatcher("/WEB-INF/view/edit.jsp").forward(request, response);
}
protected void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String id=request.getParameter("id");
if(StringUtil.hasLength(id)){
studentService.delete(Long.valueOf(id));
}
response.sendRedirect("/student");
}
protected void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String id=request.getParameter("id");
Student stu=studentService.select(Long.valueOf(id));
request.setAttribute("stu", stu);
request.getRequestDispatcher("/WEB-INF/view/edit.jsp").forward(request, response);
}
protected void findAll(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
List list=studentService.selectAll();
request.setAttribute("list", list);
request.getRequestDispatcher("/WEB-INF/view/student.jsp").forward(request, response);
}
private static void p2Stu(HttpServletRequest request, HttpServletResponse response,Student stu)throws ServletException, IOException{
String name=request.getParameter("name");
String birthday=request.getParameter("birthday");
String age=request.getParameter("age");
String address=request.getParameter("address");
String email=request.getParameter("email");
String phone=request.getParameter("phone");
stu.setAddress(address);
if(StringUtil.hasLength(age)){
stu.setAge(Integer.valueOf(age));
}
SimpleDateFormat sft=new SimpleDateFormat("yyyy-MM-dd");
Date date;
try {
date = sft.parse(birthday);
stu.setBirthday(date);
} catch (ParseException e) {
e.printStackTrace();
}
stu.setEmail(email);
stu.setName(name);
stu.setPhone(phone);
}
}