个性化阅读
专注于IT技术分析

Spring MVC CRUD用法示例图解

本文概述

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。

Spring MVC CRUD示例

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="/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="/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="/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="/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

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="/WEB-INF/jsp/"></property>  
<property name="suffix" value=".jsp"></property>  
</bean>  
  
<bean id="ds" class="org.springframework.jdbc.datasource.DriverManagerDataSource">  
<property name="driverClassName" value="com.mysql.jdbc.Driver"></property>  
<property name="url" value="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="empform">Add Employee</a>
<a href="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="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:hidden  path="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="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>${emp.designation}</td>
    <td><a href="editemp/${emp.id}">Edit</a></td>
    <td><a href="deleteemp/${emp.id}">Delete</a></td>
    </tr>
    </c:forEach>
    </table>
    <br/>
    <a href="empform">Add New Employee</a>

输出

Spring MVC CRUD示例

单击添加员工后, 你将看到以下表格。

Spring MVC CRUD示例

填写表单, 然后单击”保存”以将条目添加到数据库中。

Spring MVC CRUD示例

现在, 单击”编辑”以对提供的数据进行一些更改。

Spring MVC CRUD示例

现在, 单击”编辑保存”以将具有更改的条目添加到数据库中。

Spring MVC CRUD示例

现在, 单击”删除”以从数据库中删除条目。

Spring MVC CRUD示例

下载此示例(使用Eclipse开发)


下载SQL文件

下载SQL文件

下载MYSQL-connector.jar文件

如果你不使用maven, 请下载MYSQL-connector.jar。

赞(0) 打赏
未经允许不得转载:srcmini » Spring MVC CRUD用法示例图解
分享到: 更多 (0)

评论 抢沙发

评论前必须登录!

 

觉得文章有用就打赏一下文章作者

微信扫一扫打赏