MyBatis拦截器实现分页功能的实现方法

/** * 分页对应的实体类 */public class Page {  /**   * 总条数   */  private int totalNumber;  /**   * 当前第几页   */  private int currentPage;  /**   * 总页数   */  private int totalPage;  /**   * 每页显示条数   */  private int pageNumber = 5;  /**   * 数据库中limit的参数，从第几条开始取   */  private int dbIndex;  /**   * 数据库中limit的参数，一共取多少条   */  private int dbNumber;  /**   * 根据当前对象中属性值计算并设置相关属性值   */  public void count() {    // 计算总页数    int totalPageTemp = this.totalNumber / this.pageNumber;    int plus = (this.totalNumber % this.pageNumber) == 0 ? 0 : 1;    totalPageTemp = totalPageTemp + plus;    if(totalPageTemp <= 0) {      totalPageTemp = 1;    }    this.totalPage = totalPageTemp;    // 设置当前页数    // 总页数小于当前页数，应将当前页数设置为总页数    if(this.totalPage < this.currentPage) {      this.currentPage = this.totalPage;    }    // 当前页数小于1设置为1    if(this.currentPage < 1) {      this.currentPage = 1;    }    // 设置limit的参数    this.dbIndex = (this.currentPage - 1) * this.pageNumber;    this.dbNumber = this.pageNumber;  }  public int getTotalNumber() {    return totalNumber;  }  public void setTotalNumber(int totalNumber) {    this.totalNumber = totalNumber;    this.count();  }  public int getCurrentPage() {    return currentPage;  }  public void setCurrentPage(int currentPage) {    this.currentPage = currentPage;  }  public int getTotalPage() {    return totalPage;  }  public void setTotalPage(int totalPage) {    this.totalPage = totalPage;  }  public int getPageNumber() {    return pageNumber;  }  public void setPageNumber(int pageNumber) {    this.pageNumber = pageNumber;    this.count();  }  public int getDbIndex() {    return dbIndex;  }  public void setDbIndex(int dbIndex) {    this.dbIndex = dbIndex;  }  public int getDbNumber() {    return dbNumber;  }  public void setDbNumber(int dbNumber) {    this.dbNumber = dbNumber;  }}

package com.imooc.interceptor;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.util.Map;import java.util.Properties;import org.apache.ibatis.executor.parameter.ParameterHandler;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.DefaultReflectorFactory;import org.apache.ibatis.reflection.MetaObject;import org.apache.ibatis.reflection.SystemMetaObject;import com.imooc.entity.Page;/** * 分页拦截器 *  * @author Skye * */@Intercepts({    @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class, Integer.class }) })public class PageInterceptor implements Interceptor {  public Object intercept(Invocation invocation) throws Throwable {    StatementHandler statementHandler = (StatementHandler) invocation.getTarget();    MetaObject metaObject = MetaObject.forObject(statementHandler, SystemMetaObject.DEFAULT_OBJECT_FACTORY,        SystemMetaObject.DEFAULT_OBJECT_WRAPPER_FACTORY, new DefaultReflectorFactory());    MappedStatement mappedStatement = (MappedStatement) metaObject.getValue("delegate.mappedStatement");    //通过MetaObject元数据取得方法名id：com.XXX.queryMessageListByPage    String id = mappedStatement.getId();    //匹配在mybatis中定义的与分页有关的查询id    if (id.matches(".+ByPage$")) {      //BoundSql中有原始的sql语句和对应的查询参数      BoundSql boundSql = statementHandler.getBoundSql();      Map<String, Object> params = (Map<String, Object>) boundSql.getParameterObject();      Page page = (Page) params.get("page");      String sql = boundSql.getSql();      String countSql = "select count(*)from (" + sql + ")a";      Connection connection = (Connection) invocation.getArgs()[0];      PreparedStatement countStatement = connection.prepareStatement(countSql);      ParameterHandler parameterHandler = (ParameterHandler) metaObject.getValue("delegate.parameterHandler");      parameterHandler.setParameters(countStatement);      ResultSet rs = countStatement.executeQuery();      if (rs.next()) {        //为什么是getInt（1）? 因为数据表的列是从1开始计数        page.setTotalNumber(rs.getInt(1));        System.out.println("拦截器得知page的记录总数为：" + page.getTotalNumber());      }      String pageSql = sql + " limit " + page.getDbIndex() + "," + page.getDbNumber();      metaObject.setValue("delegate.boundSql.sql", pageSql);    }    return invocation.proceed();  }  /**   * @param target   * 被拦截的对象   */  public Object plugin(Object target) {    // 如果将拦截器类比喻为代购票的公司，那this就是代购业务员（进入方法前是无代理购票能力业务员，进入后成为有代理能力的业务员）    // 通过注解获取拦截目标的信息，如果不符合拦截要求就返回原目标，如果符合则使用动态代理生成代理对象    return Plugin.wrap(target, this);  }  public void setProperties(Properties properties) {    // TODO Auto-generated method stub  }}

 <!-- 自定义的分页拦截器 -->  <plugins>    <plugin interceptor="你写的拦截器全类名">    </plugin>  </plugins>

<!--pagination需要的脚本--><%  // 获取请求的上下文  String context = request.getContextPath();%><link href="../css/pagination.css" rel="external nofollow" rel="stylesheet" type="text/css"/><script type="text/javascript" src="../js/jquery-1.11.3.js"></script><script type="text/javascript" src="../js/jquery.pagination.js"></script><script type="text/javascript">// 点击分页按钮以后触发的动作function handlePaginationClick(new_page_index, pagination_container) {<!--从stuForm表单提交当前页的参数.可以使用restful方式，让springmvc使用@PathVariable关键字定义的形参去接。这2个参数是分页控件自己提供的，不需要我们去自己找，但是计数从0开始，而我们后台分页计数从1开始，因此要手动加1。 -->  $("#stuForm").attr("action", "你定义的分页查询url/"+(new_page_index+1));  $("#stuForm").submit();  return false;}$(function(){  $("#News-Pagination").pagination(${result.totalRecord}, {    items_per_page:${result.pageSize}, // 每页显示多少条记录    current_page:${result.currentPage} - 1, // 当前显示第几页数据    num_display_entries:8, // 分页显示的条目数    next_text:"下一页",    prev_text:"上一页",    num_edge_entries:2, // 连接分页主体，显示的条目数    callback:handlePaginationClick(当前页，分页div的id), //执行的回调函数    load_first_page:false //防止页面一直刷新( 这条非常重要！)  });});</script><!-- 这部分用c:forEach标签打印查询结果的表格--><!--分页控件名称--><div id="News-Pagination"></div>