自定义mybatis分页插件
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Mybatis实现自定义分页内容返回需要2个插件（相当于struts的拦截器），一个拦截StatementHandler接口，用于对查询的sql做分页封装和分页对象的一些参数设置，另一个拦截ResultSetHandler接口，在mybatis执行完查询之后返回的数据进行封装到分页对象中。整个分页就自动完成了。
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PageInterceptor.java（用于拦截StatementHandler接口）
package com.util;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.Iterator;import java.util.Map;import java.util.Map.Entry;import java.util.Properties;import org.apache.ibatis.executor.parameter.DefaultParameterHandler;import org.apache.ibatis.executor.parameter.ParameterHandler;import org.apache.ibatis.executor.statement.PreparedStatementHandler;import org.apache.ibatis.executor.statement.StatementHandler;import org.apache.ibatis.mapping.BoundSql;import org.apache.ibatis.mapping.MappedStatement;import org.apache.ibatis.plugin.Interceptor;import org.apache.ibatis.plugin.Intercepts;import org.apache.ibatis.plugin.Invocation;import org.apache.ibatis.plugin.Plugin;import org.apache.ibatis.plugin.Signature;import org.apache.ibatis.reflection.MetaObject;import org.springframework.util.StringUtils;@Intercepts({@Signature(type=StatementHandler.class,method="prepare",args=Connection.class)})public class PageInterceptor implements Interceptor {private String DBType;public Object intercept(Invocation invocation) throws Throwable {StatementHandler statementHandler = (StatementHandler)invocation.getTarget();MetaObject delegateMetaObject =MetaObject.forObject(statementHandler);PreparedStatementHandler delegate = (PreparedStatementHandler)delegateMetaObject.getValue("delegate");BoundSql boundSql = delegate.getBoundSql();Object parame = boundSql.getParameterObject();Connection connection = (Connection)invocation.getArgs()[0];if(parame instanceof Map){Map<?, ?> parameMap = (Map<?, ?>)parame;Iterator<?> iterator = parameMap.entrySet().iterator();boolean flag = true;while(iterator.hasNext()){Object object = ((Entry<?, ?>)iterator.next()).getValue();if(object instanceof Page && flag){String pageSql = this.getPageSql(boundSql.getSql(), (Page<?>)object);this.countTotal(parameMap, delegate,connection);flag = false;MetaObject boundSqlMetaObject = MetaObject.forObject(boundSql); boundSqlMetaObject.setValue("sql", pageSql);}}}return invocation.proceed();}public Object plugin(Object target) {if(target instanceof StatementHandler){return Plugin.wrap(target, this);}else {return target;}}public void setProperties(Properties properties) {this.DBType = properties.getProperty("DBType");}private void countTotal(Map<?, ?> Map,PreparedStatementHandler statementHandler,Connection connection){Page<?> page = null;Iterator<?> iterator = Map.values().iterator();while(iterator.hasNext()){Object object = iterator.next();if(object instanceof Page){page = (Page<?>)object;}}MetaObject metaObject = MetaObject.forObject(statementHandler);MappedStatement mappedStatement = (MappedStatement)metaObject.getValue("mappedStatement");BoundSql boundSql = statementHandler.getBoundSql();String sql = boundSql.getSql();sql = this.getCountSql(sql);BoundSql countBoundSql = new BoundSql(mappedStatement.getConfiguration(), sql, boundSql.getParameterMappings(), Map);ParameterHandler parameterHandler = new DefaultParameterHandler(mappedStatement, Map, countBoundSql);PreparedStatement pstmt = null; ResultSet rs = null; try { pstmt =connection.prepareStatement(sql); parameterHandler.setParameters(pstmt); rs = pstmt.executeQuery(); if (rs.next()) { int totalRecord = rs.getInt(1); page.setTotal(totalRecord); page.setPageCount((totalRecord-1)/page.getPageSize()+1); } } catch (SQLException e) { e.printStackTrace(); } finally { try { if (rs != null) rs.close(); if (pstmt != null) pstmt.close(); } catch (SQLException e) { e.printStackTrace(); } }}private String getCountSql(String sql){int beginIndex = sql.indexOf("from");sql = sql.substring(beginIndex);sql = "select count(1)"+sql;return sql;}private String getPageSql(String sql,Page<?> page){StringBuffer sqlBuffer = new StringBuffer(sql);if(DBType.equalsIgnoreCase("mysql")){return getMysqlPageSql(sqlBuffer, page);}else if(DBType.equalsIgnoreCase("oralce")){return getOralcePageSql(sqlBuffer, page);}else{return sql.toString();}}private String getMysqlPageSql(StringBuffer sql,Page<?> page){if(null!=page.getOrder() && !page.getOrder().equals("0")){String[] order = page.getOrder().split(",");String[] sorts = page.getSort().split(",");int i=0;sql.append(" order by ");for(String sort :sorts){sql.append(sort).append(" ").append(order[i]).append(",");i++;}sql.deleteCharAt(sql.length()-1);}sql.append(" limit ").append(page.getStartIndex()).append(",").append(page.getEndIndex());return sql.toString();}private String getOralcePageSql(StringBuffer sql,Page<?> page){if(null!=page.getOrder() && !page.getOrder().equals("0")){String[] order = StringUtils.split(page.getOrder(),",");int i=0;sql.append(" order by ");for(String sort :StringUtils.split(page.getSort(), ",") ){sql.append(sort).append(" ").append(order[i]);i++;}}sql.insert(0, "select u.*, rownum r from (").append(") u where rownum <= ").append(page.getEndIndex());sql.insert(0, "select * from (").append(") where r > ").append(page.getStartIndex()); return sql.toString();}}ResultInterceptor,java（拦截ResultSetHandler接口，将查询结果进行封装到分页对象中）
package com.util;import java.sql.Statement;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import java.util.Map;import java.util.Properties;import org.apache.ibatis.executor.resultset.FastResultSetHandler;import org.apache.ibatis.executor.resultset.ResultSetHandler;import org.apache.ibatis.mapping.BoundSql;import org.apache.ibatis.plugin.Interceptor;import org.apache.ibatis.plugin.Intercepts;import org.apache.ibatis.plugin.Invocation;import org.apache.ibatis.plugin.Plugin;import org.apache.ibatis.plugin.Signature;import org.apache.ibatis.reflection.MetaObject;@Intercepts({@Signature(args = { Statement.class }, method = "handleResultSets", type = ResultSetHandler.class)})public class ResultInterceptor implements Interceptor {public Object intercept(Invocation invocation) throws Throwable {FastResultSetHandler resultSetHandler = (FastResultSetHandler)invocation.getTarget();MetaObject metaObject = MetaObject.forObject(resultSetHandler);BoundSql boundSql = (BoundSql)metaObject.getValue("boundSql");Object parameterObject = boundSql.getParameterObject();List result = new ArrayList();if(parameterObject instanceof Map<?, ?>){Iterator<?> iterator = ((Map<?, ?>) parameterObject).values().iterator();while(iterator.hasNext()){Object object = iterator.next();if(object instanceof Page<?>){List<?> list = (List<?>) invocation.proceed();Page<?> page = (Page<?>)object;page.setResult(list);result.add(page); break;}}}else{result = (List)invocation.proceed();}return result;}public Object plugin(Object target) {if(target instanceof ResultSetHandler){return Plugin.wrap(target, this);}else{return target;}}public void setProperties(Properties properties) {}}package com.util;import java.util.List;public class Page<T> {private final int PAGE_SIZE_DEFAULT=10; private int page=1;private int pageSize=PAGE_SIZE_DEFAULT;private int total;private int pageCount;private int startIndex;private int endIndex;private String sort;private String order;private List<?> result; public List<?> getRows() {return result;}public void setRows(List<?> rows) {//this.rows = rows;pageSize = Integer.valueOf((String)rows.get(0));}public String toString() {return "Page [PAGE_SIZE_DEFAULT=" + PAGE_SIZE_DEFAULT + ", pageNum="+ page + ", pageSize=" + pageSize + ", total=" + total+ ", pageCount=" + pageCount + ", startIndex=" + startIndex+ ", endIndex=" + endIndex + ", result=" + result + "]";}public int getPage() {return page;}public void setPage(int pageNum) {this.page = pageNum;}public int getPageSize() {return pageSize;}public void setPageSize(int pageSize) {this.pageSize = pageSize;}public int getTotal() {return total;}public void setTotal(int total) {this.total = total;}public int getStartIndex() {this.startIndex = (this.page-1)*this.pageSize;return startIndex;}public int getEndIndex() {this.endIndex = this.page*this.pageSize;return endIndex;}public List<?> getResult() {return result;}public void setResult(List<?> result) {this.result = result;}public int getPageCount() {return pageCount;}public void setPageCount(int pageCount) {this.pageCount = pageCount;}public void setRows(int rows) {this.pageSize = rows;}public String getSort() {return sort;}public void setSort(String sort) {this.sort = sort;}public String getOrder() {return order;}public void setOrder(String order) {this.order = order;}}conf.xml(mybatis配置插件)
<?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> <plugins> <plugin interceptor="com.util.PageInterceptor"> <property name="DBType" value="mysql"/> </plugin> <plugin interceptor="com.util.ResultInterceptor"></plugin> </plugins> </configuration>
applicationContext.xml（mybatis自动扫描dao与实现对接）
<?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" xmlns:security="http://www.springframework.org/schema/security" 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/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.1.xsd" > <!--创建jdbc数据源 --> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/sushe" /> <property name="username" value="root" /> <property name="password" value="123456" /> </bean> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="mapperLocations" value="classpath:com/dao/Impl/*.xml" /> <property name="configLocation" value="classpath:conf.xml"></property> </bean> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.dao"></property></bean> </beans>
testDao.java
package com.dao;import com.bean.Student;import com.util.Page;public interface TestDao {public Student getStudentById(int id);public Page<Student> getStudentsByClassId(int classId,Page<Student> page);}testDao.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"><!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的例如namespace="me.gacl.mapping.userMapper"就是me.gacl.mapping(包名)+userMapper(userMapper.xml文件去除后缀) --><mapper namespace="com.dao.TestDao"> <!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，id属性值必须是唯一的，不能够重复 使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型 resultType="me.gacl.domain.User"就表示将查询结果封装成一个User类的对象返回 User类就是users表所对应的实体类 --> <!-- 根据id查询得到一个user对象 --> <resultMap type="com.bean.Student" id="student"> <id property="id" column="ID"/> <result column="Student_Name" property="name"/> <result column="Student_Sex" property="sex"/> </resultMap> <select id="getStudentById" parameterType="int" resultMap="student"> select *,Student_ID id from student where student_id=#{id} </select> <select id="getStudentsByClassId" resultMap="student"> select * from student where class_id=#{0} </select></mapper><?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-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/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd "> <context:annotation-config /> <!-- 自动扫面com目录及其子目录下面所有类文件，自动注入所有带注解的类 --> <context:component-scan base-package="com.*" /> <bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"/> <!-- 处理请求response返回值，如下配置能正确返回字符串型返回值,如返回值为对象，则自动转为json --><bean id="handleAdapter" class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"><property name="messageConverters"> <list> <ref bean="mappingJacksonHttpMessageConverter" /><!-- json转换器 --> <ref bean="mappingStringHttpMessageConverter" /> </list> </property></bean><bean id="mappingJacksonHttpMessageConverter" class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" /> <bean id="mappingStringHttpMessageConverter" class="org.springframework.http.converter.StringHttpMessageConverter" /><!-- 对模型视图名称的解析，即在模型视图名称添加前后缀 --><bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/jsp/" /> <property name="suffix" value=".jsp"></property> <property name="order" value="1"></property></bean></beans>
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