前几天在这里分享了手写 sql 分页查询实现分页，现在来看看使用 mybatis 分页插件 pagehepler 来实现分页
使用分页插件的原因，简化了sql代码的写法，实现较好的物理分页，比写一段完整的分页sql代码，也能减少了误差性。
Mybatis分页插件 demo 项目地址：https://gitee.com/free/Mybatis_PageHelper
我这里使用 maven 工程实现：
1.首先导入分页插件的依赖：
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>5.0.0</version>
</dependency>
2.配置分页拦截器插件
官方文档有两种配置分页拦截器插件
1. 在 MyBatis 配置 xml 中配置拦截器插件
<!--
plugins在配置文件中的位置必须符合要求，否则会报错，顺序如下:
properties?, settings?,
typeAliases?, typeHandlers?,
objectFactory?,objectWrapperFactory?,
plugins?,
environments?, databaseIdProvider?, mappers?
-->
<plugins>
<!-- com.github.pagehelper为PageHelper类所在包名 -->
<plugin interceptor="com.github.pagehelper.PageInterceptor">
<!-- 使用下面的方式配置参数，后面会有所有的参数介绍 -->
<property name="param1" value="value1"/>
</plugin>
</plugins>
2. 在 Spring 配置文件中配置拦截器插件
使用 spring 的属性配置方式，可以使用 plugins 属性像下面这样配置：
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 注意其他配置 -->
<property name="plugins">
<array>
<bean class="com.github.pagehelper.PageInterceptor">
<property name="properties">
<!--使用下面的方式配置参数，一行配置一个 -->
<value>
params=value1
</value>
</property>
</bean>
</array>
</property>
</bean>
这里我项目中使用的是第二种，里面的参数根据实际情况配置，也可以不配置
3.调用方法
mapper 层 sql 语句按照一般查询写法，不用写分页：
<!-- 分页查询 -->
<select id="finds" resultType="country">
SELECT
id,
countryname,
countrycode
FROM
country
</select>
mapper 层接口：
/**
* 查询
* @param params
* @return
*/
public List<Country> finds();
service 业务层接口：
/**
* 分页查询
* @param params 分页参数 pageNo（页码），pageSize（每页查询数目）
* @return
*/
public PageInfo<Country> finds(Params params);
service 业务层实现类：PageHelper.startPage(1, 10);第一个参数表示第几页，第二个参数表示每页显示的记录数
执行完 PageHelper.startPage(1, 10);语句后，紧跟着的第一个select方法会被分页：List<Country> blogs = countryMapper.finds();
然后再用 PageInfo 对查询结果进行包装，PageInfo<Country> pageInfo = new PageInfo<Country>(blogs);
并将 pageInfo 返回到控制层
/**
* 查询
*/
public PageInfo<Country> finds(Params params) { //查询
int pageNo = params.getPageNo();
int pageSize = params.getPageSize(); PageHelper.startPage(pageNo, pageSize);
List<Country> blogs = countryMapper.finds();
//用PageInfo对结果进行包装
PageInfo<Country> pageInfo = new PageInfo<Country>(blogs); return pageInfo; }
这里返回 pageInfo 后，在 controller 层传入 params 分页参数 和 解析 pageInfo：
List<Country> clist = pageInfo.getList(); 再将 clist 放进作用域，在前台页面利用<c:forEach></c:forEach>可循环获得分页数据
/**
* 首页，并且分页查询
* @return
*/
@RequestMapping("/index")
public ModelAndView index(Params params){ ModelAndView modelAndView = new ModelAndView();
//一开始第一页，查询10条
params.setPageNo(1);
params.setPageSize(10);
PageInfo<Country> pageInfo = countryService.finds(params); List<Country> clist = pageInfo.getList(); //查询数量
long couts = countryService.counts(); modelAndView.addObject("clist", clist);
modelAndView.addObject("couts", couts);
modelAndView.setViewName("index"); return modelAndView;
}
上面说的都是关键分页的实现代码，现在看看全部配置和实现的代码：
pom.xml
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.krry</groupId>
<artifactId>maven_pagehepler_ora</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>maven_pagehepler_ora</name>
<url>http://maven.apache.org</url> <properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!-- MyBatis Generator -->
<!-- Java接口和实体类 -->
<targetJavaProject>${basedir}/src/main/java</targetJavaProject>
<targetMapperPackage>com.isea533.mybatis.mapper</targetMapperPackage>
<targetModelPackage>com.isea533.mybatis.model</targetModelPackage>
<!-- XML生成路径 -->
<targetResourcesProject>${basedir}/src/main/resources</targetResourcesProject>
<targetXMLPackage>mapper</targetXMLPackage>
<!-- 编译jdk版本 -->
<jdk.version>1.6</jdk.version>
<!-- 依赖版本 -->
<mybatis.version>3.3.1</mybatis.version>
<mapper.version>3.3.6</mapper.version>
<pagehelper.version>5.0.0</pagehelper.version>
<mysql.version>5.1.29</mysql.version>
<spring.version>4.1.2.RELEASE</spring.version>
<mybatis.spring.version>1.2.4</mybatis.spring.version>
</properties> <dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency> <!--web-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>javax.ws.rs</groupId>
<artifactId>javax.ws.rs-api</artifactId>
<version>2.0</version>
</dependency>
<dependency>
<groupId>javax.websocket</groupId>
<artifactId>javax.websocket-api</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>javax.annotation</groupId>
<artifactId>javax.annotation-api</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>javax.transaction</groupId>
<artifactId>javax.transaction-api</artifactId>
<version>1.2</version>
</dependency> <!--Spring-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-oxm</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
</dependency> <!--spring-oxm依赖-->
<dependency>
<groupId>org.codehaus.castor</groupId>
<artifactId>castor-xml</artifactId>
<version>1.3.3</version>
</dependency>
<!--spring-json依赖-->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.4.2</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-xml</artifactId>
<version>2.4.2</version>
</dependency>
<!--spring-aop依赖-->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.8.2</version>
</dependency> <!--上传文件-->
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.1</version>
</dependency> <!--mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency> <!--druid-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.11</version>
</dependency> <!--Mybatis-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>${mybatis.spring.version}</version>
</dependency>
<!-- Mybatis Generator -->
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-core</artifactId>
<version>1.3.2</version>
<scope>compile</scope>
<optional>true</optional>
</dependency>
<!--分页插件-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>${pagehelper.version}</version>
</dependency>
<!--通用Mapper-->
<dependency>
<groupId>tk.mybatis</groupId>
<artifactId>mapper</artifactId>
<version>${mapper.version}</version>
</dependency> <dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.3.2</version>
</dependency> </dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-framework-bom</artifactId>
<version>${spring.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<repositories>
<repository>
<id>nexus</id>
<name>local private nexus</name>
<url>http://maven.oschina.net/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>sonatype-nexus-releases</id>
<name>Sonatype Nexus Releases</name>
<url>http://oss.sonatype.org/content/repositories/releases</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>sonatype-nexus-snapshots</id>
<name>Sonatype Nexus Snapshots</name>
<url>http://oss.sonatype.org/content/repositories/snapshots</url>
<releases>
<enabled>false</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
applicationContext.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:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:util="http://www.springframework.org/schema/util" xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-3.0.xsd
"> <!-- 配置包扫描 -->
<context:component-scan base-package="com.krry"></context:component-scan> <!-- 导入外部资源文件 -->
<context:property-placeholder location="classpath:jdbc.properties" /> <!-- 配置druid数据源 -->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
init-method="init" destroy-method="close">
<property name="driverClassName" value="${db.driver}" />
<property name="url" value="${db.url}" />
<property name="username" value="${db.username}" />
<property name="password" value="${db.password}" />
</bean> <!-- 注册事务管理器 -->
<bean id="txMgr"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"></property>
</bean> <!-- 开启事务注解驱动 -->
<tx:annotation-driven transaction-manager="txMgr" /> <!-- 配置mybatis的sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="configLocation" value="classpath:mybatis-config.xml"></property>
<property name="typeAliasesPackage" value="com.krry.entity"/>
<property name="plugins">
<array>
<bean class="com.github.pagehelper.PageInterceptor">
<!-- 这里的几个配置主要演示如何使用，如果不理解，一定要去掉下面的配置 -->
<property name="properties">
<value> </value>
</property>
</bean>
</array>
</property>
</bean> <!-- 配置可以整体扫描Mapper的一个扫描器 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<!--如果有多个报路径,用逗号分开即可 -->
<property name="basePackage" value="com.krry.mapper"></property>
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
</bean> </beans>
mybatis-config.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration>
<settings>
<!-- 全局映射器启用缓存 -->
<setting name="cacheEnabled" value="true" />
<!-- 查询时，关闭关联对象即时加载以提高性能 -->
<setting name="lazyLoadingEnabled" value="true" />
<!-- 设置关联对象加载的形态，此处为按需加载字段(加载字段由SQL指 定)，不会加载关联表的所有字段，以提高性能 -->
<setting name="aggressiveLazyLoading" value="false" />
<!-- 对于未知的SQL查询，允许返回不同的结果集以达到通用的效果 -->
<setting name="multipleResultSetsEnabled" value="true" />
<!-- 允许使用列标签代替列名 -->
<setting name="useColumnLabel" value="true" />
<!-- 允许使用自定义的主键值(比如由程序生成的UUID 32位编码作为键值)，数据表的PK生成策略将被覆盖 -->
<setting name="useGeneratedKeys" value="true" />
<!-- 给予被嵌套的resultMap以字段-属性的映射支持 -->
<setting name="autoMappingBehavior" value="FULL" />
<!-- 对于批量更新操作缓存SQL以提高性能 -->
<setting name="defaultExecutorType" value="BATCH" />
<!-- 数据库超过25000秒仍未响应则超时 -->
<setting name="defaultStatementTimeout" value="25" />
<setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString"/>
</settings> <typeAliases>
<!--自定义user对象的别名 -->
<!-- <typeAlias type="com.krry.mybatis.sysmanage.entity.User" alias="user"/> -->
<!-- 批量定义别名 -->
<package name="com.krry.entity" />
</typeAliases> </configuration>
springmvc.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:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-3.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
"> <!-- 开启注解模式驱动 -->
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />
<!-- 开启mvc的注解模式 user 还会注册一个ConversionService 子类FormattingConversionServiceFactoryBean-->
<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<bean class="com.krry.core.UTF8StringHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/plain;charset=UTF-8</value>
<value>text/html;charset=UTF-8</value>
</list>
</property>
</bean>
<bean class="org.springframework.http.converter.BufferedImageHttpMessageConverter"/>
<bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="prefixJson" value="false" />
<property name="objectMapper">
<bean class="com.fasterxml.jackson.databind.ObjectMapper">
<!-- 处理responseBody 里面日期类型 -->
<property name="dateFormat">
<bean class="java.text.SimpleDateFormat">
<constructor-arg type="java.lang.String" value="yyyy-MM-dd HH:mm:ss" />
</bean>
</property>
<!-- 为null字段时不显示 -->
<property name="serializationInclusion">
<value type="com.fasterxml.jackson.annotation.JsonInclude.Include">NON_NULL</value>
</property>
</bean>
</property>
<property name="supportedMediaTypes">
<list>
<value>application/json;charset=UTF-8</value>
<value>application/x-www-form-urlencoded;charset=UTF-8</value>
</list>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven> <!-- 扫包 -->
<context:component-scan base-package="com.krry.controller"></context:component-scan> <!--对静态资源文件的访问 必须要设置，因为在springmvc的配置中配置了/匹配所有请求，
此工程所有的请求(.do ,addUser,js/image/css)都会被springmvc解析,
必须对所有的静态资源文件进行过滤放行 -->
<!-- 静态资源过滤 下面二选一-->
<!--<mvc:default-servlet-handler/> -->
<mvc:resources mapping="/resource/**" location="/resource/" /> <!-- 视图渲染 jsp/freemaker/velocity-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 制定页面存放的路径 -->
<property name="prefix" value="/WEB-INF/pages/"></property>
<!-- 文件的后缀 -->
<property name="suffix" value=".jsp"></property>
</bean> </beans>
jdbc.properties 和 log4j.properties 就不用展示了，都差不多的
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_2_5.xsd" version="2.5">
<display-name>maven_pagehepler</display-name>
<welcome-file-list>
<welcome-file>index/index</welcome-file>
</welcome-file-list>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<listener>
<listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>
</listener>
<filter>
<filter-name>encoding</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>maven_pagehepler</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>maven_pagehepler</servlet-name>
<url-pattern>/index/index</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>maven_pagehepler</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
实体类：Country.java
package com.krry.entity;
public class Country {
/**
* 主键
*/
private Integer id;
/**
* 名称
*/
private String countryname;
/**
* 代码
*/
private String countrycode;
public Country(Integer id, String countryname, String countrycode) {
this.id = id;
this.countryname = countryname;
this.countrycode = countrycode;
}
/**
* 获取主键
*
* @return Id - 主键
*/
public Integer getId() {
return id;
}
/**
* 设置主键
*
* @param id 主键
*/
public void setId(Integer id) {
this.id = id;
}
/**
* 获取名称
*
* @return countryname - 名称
*/
public String getCountryname() {
return countryname;
}
/**
* 设置名称
*
* @param countryname 名称
*/
public void setCountryname(String countryname) {
this.countryname = countryname;
}
/**
* 获取代码
*
* @return countrycode - 代码
*/
public String getCountrycode() {
return countrycode;
}
/**
* 设置代码
*
* @param countrycode 代码
*/
public void setCountrycode(String countrycode) {
this.countrycode = countrycode;
}
}
Params.java
package com.krry.entity; /**
*
* Params
* @author krry
* @version 1.0.0
*
*/
public class Params { private Integer pageSize = 10;
private Integer pageNo = 0; public Integer getPageNo() {
return pageNo;
} public void setPageNo(Integer pageNo) {
this.pageNo = pageNo;
} public Integer getPageSize() {
return pageSize;
} public void setPageSize(Integer pageSize) {
this.pageSize = pageSize;
} }
持久层：CountryMapper.java
package com.krry.mapper; import java.util.List; import com.krry.entity.Country; /**
*
* Mapper：操作数据库
* @author krry
* @version 1.0.0
*
*/
public interface CountryMapper { /**
* 查询
* @param params
* @return
*/
public List<Country> finds(); /**
* 计算
* com.krry.dao.admin
* 方法名：countBlogs
* @author krry
* @param params
* @return int
* @exception
* @since 1.0.0
*/
public long counts(); }
CountryMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.krry.mapper.CountryMapper" > <!-- 分页查询 -->
<select id="finds" resultType="country">
SELECT
id,
countryname,
countrycode
FROM
country
</select> <!-- 查询博客数量 -->
<select id="counts" resultType="long">
SELECT
count(*)
FROM
country
</select> </mapper>
业务层接口：
package com.krry.service; import java.util.HashMap;
import java.util.List; import javax.servlet.http.HttpServletRequest; import org.apache.ibatis.annotations.Param; import com.github.pagehelper.PageInfo;
import com.krry.entity.Country;
import com.krry.entity.Params; /**
* service层：处理业务逻辑（impl里面实现）
* @author asusaad
*
*/
public interface ICountryService { /**
* 分页查询所有博客
* @param params 分页参数 pageNo（页码），pageSize（每页查询数目）
* @return
*/
public PageInfo<Country> finds(Params params); /**
* 计算博客数量
* @param params
* @return
*/
public long counts(); }
业务层实现类
package com.krry.service.impl; import java.util.HashMap;
import java.util.List; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.servlet.ModelAndView; import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.krry.entity.Country;
import com.krry.entity.Params;
import com.krry.mapper.CountryMapper;
import com.krry.service.ICountryService; /**
* 实现service层接口
* @author asusaad
*
*/
@Service
public class CountryService implements ICountryService{ @Autowired
private CountryMapper countryMapper; /**
* 查询
*/
public PageInfo<Country> finds(Params params) { //查询
int pageNo = params.getPageNo();
int pageSize = params.getPageSize(); PageHelper.startPage(pageNo, pageSize);
List<Country> blogs = countryMapper.finds();
//用PageInfo对结果进行包装
PageInfo<Country> pageInfo = new PageInfo<Country>(blogs); return pageInfo; } /**
* 计算
* @param params
* @return
*/
public long counts(){ long couts = countryMapper.counts(); return couts;
} }
控制层：KrryController.java
package com.krry.controller; import java.util.ArrayList;
import java.util.HashMap;
import java.util.List; import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView; import com.github.pagehelper.PageInfo;
import com.krry.entity.Country;
import com.krry.entity.Params;
import com.krry.service.ICountryService; /**
* KrryController
* controller层，作为请求转发
* @author asusaad
*
*/
@Controller //表示是多例模式，每个用户返回的web层是不一样的
@RequestMapping("/index")
public class KrryController { @Autowired
private ICountryService countryService; /**
* 首页，并且分页查询
* @return
*/
@RequestMapping("/index")
public ModelAndView index(Params params){ ModelAndView modelAndView = new ModelAndView();
//一开始第一页，查询10条
params.setPageNo(1);
params.setPageSize(10);
PageInfo<Country> pageInfo = countryService.finds(params); List<Country> clist = pageInfo.getList(); //查询数量
long couts = countryService.counts(); modelAndView.addObject("clist", clist);
modelAndView.addObject("couts", couts);
modelAndView.setViewName("index"); return modelAndView;
} /**
* ajax请求 的 分页查询
* @param params
* @return
*/
@ResponseBody
@RequestMapping("/loadData")
public HashMap<String, Object> loadData(Params params){ HashMap<String, Object> map = new HashMap<String, Object>();
PageInfo<Country> pageInfo = countryService.finds(params);
List<Country> clist = pageInfo.getList();
map.put("clist", clist); return map;
}
// }