Mybatis拦截器分页

这里做的是以ByPage结尾的，使用mysql数据库
一、page类：

package com.ming.util;

/**
 * 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;
    }
}

二、拦截器

package com.ming.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.MetaObject;
import org.apache.ibatis.reflection.SystemMetaObject;

import com.ming.util.Page;

/**
 * 
 * 拦截器签名:要拦截的目标类型是StatementHandler（注意：type只能配置成接口类型），
 * 拦截的方法是名称为prepare参数为Connection类型的方法
 *
 */
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })
public class PageInterceptor1 implements Interceptor {

    public Object intercept(Invocation invocation) throws Throwable {
        // 拦截获取statement处理类
        StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
        // 把statement处理类交给MetaObject代理类代理
        MetaObject metaObject = MetaObject.forObject(statementHandler, SystemMetaObject.DEFAULT_OBJECT_FACTORY,
                SystemMetaObject.DEFAULT_OBJECT_WRAPPER_FACTORY);
        MappedStatement mappedStatement = (MappedStatement) metaObject.getValue("delegate.mappedStatement");
        String id = mappedStatement.getId();
        //以ByPage结尾的才操作
        if (id.matches(".+ByPage$")) {
            BoundSql boundSql = statementHandler.getBoundSql();
            String sql = boundSql.getSql();
            String countSql = "select count(*) from (" + sql + ")a";
            // 获取connection
            Connection connection = (Connection) invocation.getArgs()[0];
            // 通过connection获取prepareStatement
            PreparedStatement countStatement = connection.prepareStatement(countSql);
            // 获取参数处理类
            ParameterHandler parameterHandler = (ParameterHandler) metaObject.getValue("delegate.parameterHandler");
            // 通过参数处理类 把参数设置进去
            parameterHandler.setParameters(countStatement);
            // 开始查询
            ResultSet rs = countStatement.executeQuery();
            // 获取传过来的参数
            Map<?, ?> parameter = (Map<?, ?>) boundSql.getParameterObject();
            // 获取page参数
            Page page = (Page) parameter.get("page");
            if (rs.next()) {
                // 为page设置查询出来的所有数据条数
                page.setTotalNumber(rs.getInt(1));
            }
            // 改造后带分页查询的SQL语句
            String pageSql = sql + " limit " + page.getDbIndex() + "," + page.getDbNumber();
            // 代理类设置改装好sql语句
            metaObject.setValue("delegate.boundSql.sql", pageSql);
        }
        return invocation.proceed();
    }

    public Object plugin(Object target) {
        //不合条件的 直接放行
        return Plugin.wrap(target, this);
    }

    public void setProperties(Properties properties) {
    }

}

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