SSM使用mybatis分頁插件pagehepler實現分頁示例

2024-07-14 08:40:08

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前幾天在這里分享了手寫 sql 分頁查詢實現分頁，現在來看看使用 mybatis 分頁插件 pagehepler 來實現分頁

使用分頁插件的原因，簡化了sql代碼的寫法，實現較好的物理分頁，比寫一段完整的分頁sql代碼，也能減少了誤差性。

Mybatis分頁插件 demo 項目地址：free-Mybatis_PageHelper.rar

我這里使用 maven 工程實現：

1.首先導入分頁插件的依賴：

<dependency>  <groupId>com.github.pagehelper</groupId>  <artifactId>pagehelper</artifactId>  <version>5.0.0</version> </dependency>

2.配置分頁攔截器插件

官方文檔有兩種配置分頁攔截器插件

1. 在 MyBatis 配置 xml 中配置攔截器插件

<!--  plugins在配置文件中的位置必須符合要求，否則會報錯，順序如下: properties?, settings?,  typeAliases?, typeHandlers?,  objectFactory?,objectWrapperFactory?,  plugins?,  environments?, databaseIdProvider?, mappers?--><plugins> <!-- com.github.pagehelper為PageHelper類所在包名 --> <plugin interceptor="com.github.pagehelper.PageInterceptor">  <!-- 使用下面的方式配置參數，后面會有所有的參數介紹 -->  <property name="param1" value="value1"/> </plugin></plugins>

2. 在 Spring 配置文件中配置攔截器插件

使用 spring 的屬性配置方式，可以使用 plugins 屬性像下面這樣配置：

<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參數，一行配置一個 -->   <value>   params=value1   </value>  </property>  </bean> </array> </property></bean>

這里我項目中使用的是第二種，里面的參數根據實際情況配置，也可以不配置

3.調用方法

mapper 層 sql 語句按照一般查詢寫法，不用寫分頁：

<!-- 分頁查詢 --> <select id="finds" resultType="country">  SELECT   id,   countryname,   countrycode  FROM   country </select>

mapper 層接口：

/** * 查詢 * @param params * @return*/public List<Country> finds();

service 業務層接口：

 /** * 分頁查詢 * @param params 分頁參數 pageNo（頁碼），pageSize（每頁查詢數目） * @return */ public PageInfo<Country> finds(Params params);

service 業務層實現類：PageHelper.startPage(1, 10);第一個參數表示第幾頁，第二個參數表示每頁顯示的記錄數

執行完 PageHelper.startPage(1, 10);語句后，緊跟著的第一個select方法會被分頁：List<Country> blogs = countryMapper.finds();

然后再用 PageInfo 對查詢結果進行包裝，PageInfo<Country> pageInfo = new PageInfo<Country>(blogs);

并將 pageInfo 返回到控制層

/**  * 查詢  */ public PageInfo<Country> finds(Params params)     //查詢  int pageNo = params.getPageNo();  int pageSize = params.getPageSize();    PageHelper.startPage(pageNo, pageSize);  List<Country> blogs = countryMapper.finds();  //用PageInfo對結果進行包裝  PageInfo<Country> pageInfo = new PageInfo<Country>(blogs);  return pageInfo;  }

這里返回 pageInfo 后，在 controller 層傳入 params 分頁參數和解析 pageInfo：

List<Country> clist = pageInfo.getList(); 再將 clist 放進作用域，在前臺頁面利用<c:forEach></c:forEach>可循環獲得分頁數據/**  * 首頁，并且分頁查詢  * @return  */ @RequestMapping("/index") public ModelAndView index(Params params){  ModelAndView modelAndView = new ModelAndView();  //一開始第一頁，查詢10條  params.setPageNo(1);  params.setPageSize(10);  PageInfo<Country> pageInfo = countryService.finds(params);  List<Country> clist = pageInfo.getList();  //查詢數量  long couts = countryService.counts();  modelAndView.addObject("clist", clist);  modelAndView.addObject("couts", couts);  modelAndView.setViewName("index");    return modelAndView; }

上面說的都是關鍵分頁的實現代碼，現在看看全部配置和實現的代碼：

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接口和實體類 -->  <targetJavaProject>${basedir}/src/main/java</targetJavaProject>  <targetMapperPackage>com.isea533.mybatis.mapper</targetMapperPackage>  <targetModelPackage>com.isea533.mybatis.model</targetModelPackage>  <!-- XML生成路徑 -->  <targetResourcesProject>${basedir}/src/main/resources</targetResourcesProject>  <targetXMLPackage>mapper</targetXMLPackage>  <!-- 編譯jdk版本 -->  <jdk.version>1.6</jdk.version>  <!-- 依賴版本 -->  <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依賴-->  <dependency>   <groupId>org.codehaus.castor</groupId>   <artifactId>castor-xml</artifactId>   <version>1.3.3</version>  </dependency>  <!--spring-json依賴-->  <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依賴-->  <dependency>   <groupId>org.aspectj</groupId>   <artifactId>aspectjweaver</artifactId>   <version>1.8.2</version>  </dependency>  <!--上傳文件-->  <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>${mybatis.spring.version}</version>  </dependency>  <!-- Mybatis Generator -->  <dependency>   <groupId>org.mybatis.generator</groupId>   <artifactId>mybatis-generator-core</artifactId>   <version>1.3.2</version>   <scope>compile</scope>   <optional>true</optional>  </dependency>  <!--分頁插件-->  <dependency>   <groupId>com.github.pagehelper</groupId>   <artifactId>pagehelper</artifactId>   <version>${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 ">  <!-- 配置包掃描 --> <context:component-scan base-package="com.krry"></context:component-scan>   <!-- 導入外部資源文件 --> <context:property-placeholder location="classpath:jdbc.properties" />   <!-- 配置druid數據源 --> <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>  <!-- 注冊事務管理器 --> <bean id="txMgr"  class="org.springframework.jdbc.datasource.DataSourceTransactionManager">  <property name="dataSource" ref="dataSource"></property> </bean> <!-- 開啟事務注解驅動 --> <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">     <!-- 這里的幾個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>  <!-- 配置可以整體掃描Mapper的一個掃描器 --> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">  <!--如果有多個報路徑,用逗號分開即可 -->  <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>    <!-- 全局映射器啟用緩存 -->   <setting name="cacheEnabled" value="true" />    <!-- 查詢時，關閉關聯對象即時加載以提高性能 -->   <setting name="lazyLoadingEnabled" value="true" />   <!-- 設置關聯對象加載的形態，此處為按需加載字段(加載字段由SQL指    定)，不會加載關聯表的所有字段，以提高性能 -->   <setting name="aggressiveLazyLoading" value="false" />   <!-- 對于未知的SQL查詢，允許返回不同的結果集以達到通用的效果 -->   <setting name="multipleResultSetsEnabled" value="true" />   <!-- 允許使用列標簽代替列名 -->   <setting name="useColumnLabel" value="true" />   <!-- 允許使用自定義的主鍵值(比如由程序生成的UUID 32位編碼作為鍵值)，數據表的PK生成策略將被覆蓋 -->   <setting name="useGeneratedKeys" value="true" />    <!-- 給予被嵌套的resultMap以字段-屬性的映射支持 -->   <setting name="autoMappingBehavior" value="FULL" />   <!-- 對于批量更新操作緩存SQL以提高性能 -->   <setting name="defaultExecutorType" value="BATCH" />    <!-- 數據庫超過25000秒仍未響應則超時 -->   <setting name="defaultStatementTimeout" value="25" />    <setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString"/> </settings>   <typeAliases>  <!--自定義user對象的別名 -->  <!-- <typeAlias type="com.krry.mybatis.sysmanage.entity.User" alias="user"/> -->  <!-- 批量定義別名 -->  <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  ">   <!-- 開啟注解模式驅動 -->   <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />   <!-- 開啟mvc的注解模式 user 還會注冊一個ConversionService 子類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">        <!-- 處理responseBody 里面日期類型 -->         <property name="dateFormat">          <bean class="java.text.SimpleDateFormat">           <constructor-arg type="java.lang.String" value="yyyy-MM-dd HH:mm:ss" />          </bean>         </property>         <!-- 為null字段時不顯示 -->        <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>     <!-- 掃包 -->   <context:component-scan base-package="com.krry.controller"></context:component-scan>     <!--對靜態資源文件的訪問 必須要設置，因為在springmvc的配置中配置了/匹配所有請求，  此工程所有的請求(.do ,addUser,js/image/css)都會被springmvc解析,  必須對所有的靜態資源文件進行過濾放行 -->  <!-- 靜態資源過濾 下面二選一-->  <!--<mvc:default-servlet-handler/> -->  <mvc:resources mapping="/resource/**" location="/resource/" />   <!-- 視圖渲染 jsp/freemaker/velocity-->  <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">    <!-- 制定頁面存放的路徑 -->    <property name="prefix" value="/WEB-INF/pages/"></property>    <!-- 文件的后綴 -->    <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>

實體類：Country.java

package com.krry.entity;public class Country {  /**  * 主鍵  */ private Integer id;  /**  * 名稱  */ private String countryname; /**  * 代碼  */ private String countrycode; public Country(Integer id, String countryname, String countrycode) {  this.id = id;  this.countryname = countryname;  this.countrycode = countrycode; } /**  * 獲取主鍵  *  * @return Id - 主鍵  */ public Integer getId() {  return id; } /**  * 設置主鍵  *  * @param id 主鍵  */ public void setId(Integer id) {  this.id = id; }  /**  * 獲取名稱  *  * @return countryname - 名稱  */ public String getCountryname() {  return countryname; } /**  * 設置名稱  *  * @param countryname 名稱  */ public void setCountryname(String countryname) {  this.countryname = countryname; } /**  * 獲取代碼  *  * @return countrycode - 代碼  */ public String getCountrycode() {  return countrycode; } /**  * 設置代碼  *  * @param countrycode 代碼  */ 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; }}

持久層：CountryMapper.java

package com.krry.mapper;import java.util.List;import com.krry.entity.Country;/** *  * Mapper：操作數據庫 * @author krry * @version 1.0.0 * */public interface CountryMapper { /**  * 查詢  * @param params  * @return  */ public List<Country> finds();  /**  * 計算  * 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" >  <!-- 分頁查詢 --> <select id="finds" resultType="country">  SELECT   id,   countryname,   countrycode  FROM   country </select>  <!-- 查詢博客數量 --> <select id="counts" resultType="long">  SELECT   count(*)  FROM   country </select> </mapper>

業務層接口：

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層：處理業務邏輯（impl里面實現） * @author asusaad * */public interface ICountryService {  /**  * 分頁查詢所有博客  * @param params 分頁參數 pageNo（頁碼），pageSize（每頁查詢數目）  * @return  */ public PageInfo<Country> finds(Params params);  /**  * 計算博客數量  * @param params  * @return  */ public long counts(); }

業務層實現類

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;/** * 實現service層接口 * @author asusaad * */@Servicepublic class CountryService implements ICountryService{ @Autowired private CountryMapper countryMapper;  /**  * 查詢  */ public PageInfo<Country> finds(Params params) {    //查詢  int pageNo = params.getPageNo();  int pageSize = params.getPageSize();    PageHelper.startPage(pageNo, pageSize);  List<Country> blogs = countryMapper.finds();  //用PageInfo對結果進行包裝  PageInfo<Country> pageInfo = new PageInfo<Country>(blogs);  return pageInfo;   }  /**  * 計算  * @param params  * @return  */ public long counts(){    long couts = countryMapper.counts();    return couts; }}

控制層：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層，作為請求轉發 * @author asusaad * */@Controller //表示是多例模式，每個用戶返回的web層是不一樣的@RequestMapping("/index")public class KrryController {  @Autowired private ICountryService countryService;  /**  * 首頁，并且分頁查詢  * @return  */ @RequestMapping("/index") public ModelAndView index(Params params){    ModelAndView modelAndView = new ModelAndView();  //一開始第一頁，查詢10條  params.setPageNo(1);  params.setPageSize(10);  PageInfo<Country> pageInfo = countryService.finds(params);    List<Country> clist = pageInfo.getList();  //查詢數量  long couts = countryService.counts();  modelAndView.addObject("clist", clist);  modelAndView.addObject("couts", couts);  modelAndView.setViewName("index");    return modelAndView; }  /**  * ajax請求 的 分頁查詢  * @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; }//  }

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