Spring MVC CRUD用法示例图解 _MVC

本文概述

建立表格
Spring MVC CRUD示例

CRUD(创建, 读取, 更新和删除)应用程序是用于创建任何项目的最重要的应用程序。它提供了开发大型项目的想法。在Spring MVC中, 我们可以开发一个简单的CRUD应用程序。
在这里, 我们使用JdbcTemplate进行数据库交互。
建立表格在这里, 我们正在使用MySQL数据库中存在的emp99表。它有4个字段：ID, 姓名, 薪水和名称。在此, id由序列自动生成。

文章图片
Spring MVC CRUD示例 1.将依赖项添加到pom.xml文件。
pom.xml

< !-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc --> < dependency> < groupId> org.springframework< /groupId> < artifactId> spring-webmvc< /artifactId> < version> 5.1.1.RELEASE< /version> < /dependency> < !-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-jasper --> < dependency> < groupId> org.apache.tomcat< /groupId> < artifactId> tomcat-jasper< /artifactId> < version> 9.0.12< /version> < /dependency> < !-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api --> < dependency> < groupId> javax.servlet< /groupId> < artifactId> servlet-api< /artifactId> < version> 3.0-alpha-1< /version> < /dependency> < !-- https://mvnrepository.com/artifact/javax.servlet/jstl --> < dependency> < groupId> javax.servlet< /groupId> < artifactId> jstl< /artifactId> < version> 1.2< /version> < /dependency> < !-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --> < dependency> < groupId> mysql< /groupId> < artifactId> mysql-connector-java< /artifactId> < version> 8.0.11< /version> < /dependency> < !-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc --> < dependency> < groupId> org.springframework< /groupId> < artifactId> spring-jdbc< /artifactId> < version> 5.1.1.RELEASE< /version> < /dependency>

2.创建bean类
在这里, bean类包含与数据库中存在的字段相对应的变量(以及setter和getter方法)。
Emp.java

package com.srcmini.beans; public class Emp { private int id; private String name; private float salary; private String designation; 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 float getSalary() { return salary; } public void setSalary(float salary) { this.salary = salary; } public String getDesignation() { return designation; } public void setDesignation(String designation) { this.designation = designation; }}

3.创建控制器类
EmpController.java

package com.srcmini.controllers; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import com.srcmini.beans.Emp; import com.srcmini.dao.EmpDao; @Controller public class EmpController { @Autowired EmpDao dao; //will inject dao from XML file/*It displays a form to input data, here "command" is a reserved request attribute *which is used to display object data into form */ @RequestMapping("/empform") public String showform(Model m){ m.addAttribute("command", new Emp()); return "empform"; } /*It saves object into database. The @ModelAttribute puts request data *into model object. You need to mention RequestMethod.POST method *because default request is GET*/ @RequestMapping(value="http://www.srcmini.com/save", method = RequestMethod.POST) public String save(@ModelAttribute("emp") Emp emp){ dao.save(emp); return "redirect:/viewemp"; //will redirect to viewemp request mapping } /* It provides list of employees in model object */ @RequestMapping("/viewemp") public String viewemp(Model m){ List< Emp> list=dao.getEmployees(); m.addAttribute("list", list); return "viewemp"; } /* It displays object data into form for the given id. * The @PathVariable puts URL data into variable.*/ @RequestMapping(value="http://www.srcmini.com/editemp/{id}") public String edit(@PathVariable int id, Model m){ Emp emp=dao.getEmpById(id); m.addAttribute("command", emp); return "empeditform"; } /* It updates model object. */ @RequestMapping(value="http://www.srcmini.com/editsave", method = RequestMethod.POST) public String editsave(@ModelAttribute("emp") Emp emp){ dao.update(emp); return "redirect:/viewemp"; } /* It deletes record for the given id in URL and redirects to /viewemp */ @RequestMapping(value="http://www.srcmini.com/deleteemp/{id}", method = RequestMethod.GET) public String delete(@PathVariable int id){ dao.delete(id); return "redirect:/viewemp"; } }

4.创建DAO类
让我们创建一个DAO类来访问数据库中所需的数据。
EmpDao.java

package com.srcmini.dao; import java.sql.ResultSet; import java.sql.SQLException; import java.util.List; import org.springframework.jdbc.core.BeanPropertyRowMapper; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.jdbc.core.RowMapper; import com.srcmini.beans.Emp; public class EmpDao { JdbcTemplate template; public void setTemplate(JdbcTemplate template) { this.template = template; } public int save(Emp p){ String sql="insert into Emp99(name, salary, designation) values('"+p.getName()+"', "+p.getSalary()+", '"+p.getDesignation()+"')"; return template.update(sql); } public int update(Emp p){ String sql="update Emp99 set name='"+p.getName()+"', salary="+p.getSalary()+", designation='"+p.getDesignation()+"' where id="+p.getId()+""; return template.update(sql); } public int delete(int id){ String sql="delete from Emp99 where id="+id+""; return template.update(sql); } public Emp getEmpById(int id){ String sql="select * from Emp99 where id=?"; return template.queryForObject(sql, new Object[]{id}, new BeanPropertyRowMapper< Emp> (Emp.class)); } public List< Emp> getEmployees(){ return template.query("select * from Emp99", new RowMapper< Emp> (){ public Emp mapRow(ResultSet rs, int row) throws SQLException { Emp e=new Emp(); e.setId(rs.getInt(1)); e.setName(rs.getString(2)); e.setSalary(rs.getFloat(3)); e.setDesignation(rs.getString(4)); return e; } }); } }

5.在web.xml文件中提供控制器的条目
【Spring MVC CRUD用法示例图解】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_3_0.xsd" id="WebApp_ID" version="3.0"> < display-name> SpringMVC< /display-name> < servlet> < servlet-name> spring< /servlet-name> < servlet-class> org.springframework.web.servlet.DispatcherServlet< /servlet-class> < load-on-startup> 1< /load-on-startup> < /servlet> < servlet-mapping> < servlet-name> spring< /servlet-name> < url-pattern> /< /url-pattern> < /servlet-mapping> < /web-app>

6.在xml文件中定义bean
spring-servlet.xml

< ?xml version="1.0" encoding="UTF-8"?> < beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> < context:component-scan base-package="com.srcmini.controllers"> < /context:component-scan> < bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> < property name="prefix" value="http://www.srcmini.com/WEB-INF/jsp/"> < /property> < property name="suffix" value="http://www.srcmini.com/.jsp"> < /property> < /bean> < bean id="ds" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> < property name="driverClassName" value="http://www.srcmini.com/com.mysql.jdbc.Driver"> < /property> < property name="url" value="http://www.srcmini.com/jdbc:mysql://localhost:3306/test"> < /property> < property name="username" value=""> < /property> < property name="password" value=""> < /property> < /bean> < bean id="jt" class="org.springframework.jdbc.core.JdbcTemplate"> < property name="dataSource" ref="ds"> < /property> < /bean> < bean id="dao" class="com.srcmini.dao.EmpDao"> < property name="template" ref="jt"> < /property> < /bean> < /beans>

7.创建请求的页面
index.jsp

< a href="http://www.srcmini.com/empform"> Add Employee< /a> < a href="http://www.srcmini.com/viewemp"> View Employees< /a>

8.创建其他视图组件
empform.jsp

< %@ taglib uri="http://www.springframework.org/tags/form" prefix="form"%> < %@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> < h1> Add New Employee< /h1> < form:form method="post" action="save"> < table > < tr> < td> Name : < /td> < td> < form:input path="name"/> < /td> < /tr> < tr> < td> Salary :< /td> < td> < form:input path="salary" /> < /td> < /tr> < tr> < td> Designation :< /td> < td> < form:input path="designation" /> < /td> < /tr> < tr> < td> < /td> < td> < input type="submit" value="http://www.srcmini.com/Save" /> < /td> < /tr> < /table> < /form:form>

empeditform.jsp
这里的” / SpringMVCCRUDSimple” 是项目名称, 如果你有不同的项目名称, 请更改此名称。对于实时应用程序, 你可以提供完整的URL。

< %@ taglib uri="http://www.springframework.org/tags/form" prefix="form"%> < %@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> < h1> Edit Employee< /h1> < form:form method="POST" action="/SpringMVCCRUDSimple/editsave"> < table > < tr> < td> < /td> < td> < form:hiddenpath="id" /> < /td> < /tr> < tr> < td> Name : < /td> < td> < form:input path="name"/> < /td> < /tr> < tr> < td> Salary :< /td> < td> < form:input path="salary" /> < /td> < /tr> < tr> < td> Designation :< /td> < td> < form:input path="designation" /> < /td> < /tr> < tr> < td> < /td> < td> < input type="submit" value="http://www.srcmini.com/Edit Save" /> < /td> < /tr> < /table> < /form:form>

viewemp.jsp

< %@ taglib uri="http://www.springframework.org/tags/form" prefix="form"%> < %@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> < h1> Employees List< /h1> < table border="2" width="70%" cellpadding="2"> < tr> < th> Id< /th> < th> Name< /th> < th> Salary< /th> < th> Designation< /th> < th> Edit< /th> < th> Delete< /th> < /tr> < c:forEach var="emp" items="${list}"> < tr> < td> ${emp.id}< /td> < td> ${emp.name}< /td> < td> ${emp.salary}< /td> < td> ${emp.designation}< /td> < td> < a href="http://www.srcmini.com/editemp/${emp.id}"> Edit< /a> < /td> < td> < a href="http://www.srcmini.com/deleteemp/${emp.id}"> Delete< /a> < /td> < /tr> < /c:forEach> < /table> < br/> < a href="http://www.srcmini.com/empform"> Add New Employee< /a>

输出