Spring MVC 分页示例

分页用于在不同部分中显示大量记录。在这种情况下，我们在一页中显示10、20或50条记录。对于剩余的记录，我们提供链接。

我们可以在Spring MVC中简单地创建分页示例。在这个分页示例中，我们使用MySQL数据库来获取记录。

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创建表格或导入SQL文件

在这里，我们在“test”数据库中创建了“emp”表。emp表有三个字段：id、name和salary。要么创建一个表并手动插入记录，要么导入我们的SQL文件。

Java中的多态性 | 动态方法调度

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Spring MVC 分页示例

1. 在pom.xml文件中添加依赖项。

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对应的变量（以及setter和getter方法）。

Emp.java

package cn.javatiku.beans;    
    
public class Emp {    
private int id;    
private String name;    
private float salary;    
    
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;    
}    
    
}  

3. 创建控制器类

在控制器类中，@PathVariable注解将方法参数绑定到临时URL。例如：

@RequestMapping(value="/viewemp/{pageid}")

在这里，大括号 {} 包含了临时的值。

EmpController.java

package cn.javatiku.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.PathVariable;    
import org.springframework.web.bind.annotation.RequestMapping;      
import cn.javatiku.beans.Emp;    
import cn.javatiku.dao.EmpDao;    
@Controller    
public class EmpController {    
    @Autowired    
    EmpDao dao;    
        
    @RequestMapping(value="/viewemp/{pageid}")    
    public String edit(@PathVariable int pageid,Model m){    
        int total=5;    
        if(pageid==1){}    
        else{    
            pageid=(pageid-1)*total+1;    
        }    
        System.out.println(pageid);  
        List<Emp> list=dao.getEmployeesByPage(pageid,total);    
          m.addAttribute("msg", list);  
        return "viewemp";    
    }    
}   

4. 创建DAO类

我们创建一个DAO类来从数据库中访问所需的数据。

EmpDao.java

package cn.javatiku.dao;    
   
import java.sql.ResultSet;    
import java.sql.SQLException;    
import java.util.List;    
import org.springframework.jdbc.core.JdbcTemplate;    
import org.springframework.jdbc.core.RowMapper;    
import cn.javatiku.beans.Emp;    
    
public class EmpDao {    
JdbcTemplate template;    
    
public void setTemplate(JdbcTemplate template) {    
    this.template = template;    
}    
    
public List<Emp> getEmployeesByPage(int pageid,int total){    
    String sql="select * from emp limit "+(pageid-1)+","+total;    
    return template.query(sql,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));    
            return e;    
        }    
    });    
}    
}    

5. 在web.xml文件中提供控制器的入口

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="cn.javatiku.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="cn.javatiku.dao.EmpDao">    
<property name="template" ref="jt"></property>    
</bean>       
</beans>  

7. 创建所请求的页面

index.jsp

<!DOCTYPE html>  
<html>  
<body>  
<a href="viewemp/1">View Employees</a>   
</body>  
</html>  

8. 创建视图组件

viewemp.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>      
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">  
<html>  
<body>  
<h1>Employees List</h1>    
<table border="2" width="70%" cellpadding="2">    
<tr><th>Id</th><th>Name</th><th>Salary</th></tr>    
   <c:forEach var="emp" items="${msg}">     
   <tr>    
   <td>${emp.id}</td>    
   <td>${emp.name}</td>    
   <td>${emp.salary}</td>    
   </tr>    
   </c:forEach>    
   </table>    
   <br/>    
   <a href="/SpringMVCPaginationExample/viewemp/1">1</a>     
   <a href="/SpringMVCPaginationExample/viewemp/2">2</a>     
   <a href="/SpringMVCPaginationExample/viewemp/3">3</a>    
</body>  
</html>  

输出：