spring mvc crud示例

crud(創(chuàng)建，讀取，更新和刪除)應(yīng)用程序是用于創(chuàng)建任何項目的最重要的應(yīng)用程序。它提供了開發(fā)大型項目的想法。在springmvc中，我們可以開發(fā)一個簡單的crud應(yīng)用程序。

在這里，我們使用 jdbctemplate 進行數(shù)據(jù)庫交互。

創(chuàng)建一個表

在這里，我們使用的是mysql數(shù)據(jù)庫中存在的emp99表。它具有4個字段: id，名稱，薪水和名稱。

spring mvc crud示例

1、將依賴項添加到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、創(chuàng)建bean類

在這里，bean類包含對應(yīng)于數(shù)據(jù)庫中存在的字段的變量(以及setter和getter方法)。

emp.java

package com.yapf.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、創(chuàng)建控制器類

empcontroller.java

package com.yapf.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.yapf.beans.emp;  
import com.yapf.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、創(chuàng)建dao類

讓我們創(chuàng)建一個dao類以訪問數(shù)據(jù)庫中所需的數(shù)據(jù)。

empdao.java

package com.yapf.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.yapf.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條目

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文件中定義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.yapf.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.yapf.dao.empdao">  
<property name="template" ref="jt"></property>  
</bean>     
</beans>

7、創(chuàng)建請求的頁面

index.jsp

<a href="empform">add employee</a>
<a href="viewemp">view employees</a>

8、創(chuàng)建其他視圖組件

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

此處"/springmvccrudsimple"是項目名稱，如果您使用其他項目名稱，請更改此名稱。對于實時應(yīng)用程序，您可以提供完整的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>

輸出:

點擊 添加員工時，您將看到以下表格。

填寫表格，然后 單擊保存以將條目添加到數(shù)據(jù)庫中。

現(xiàn)在，點擊 編輯以對提供的內(nèi)容進行一些更改數(shù)據(jù)。

現(xiàn)在，單擊 編輯保存，將具有更改的條目添加到數(shù)據(jù)庫中。

現(xiàn)在，單擊 刪除從數(shù)據(jù)庫中刪除條目。