weaver-hrm-salary/src/com/engine/salary/component/PageInterceptor.java

package com.engine.salary.component;


import com.github.pagehelper.Page;
import org.apache.commons.lang3.StringUtils;
import org.apache.ibatis.binding.MapperMethod;
import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.statement.RoutingStatementHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.scripting.defaults.DefaultParameterHandler;
import weaver.conn.RecordSet;

import javax.xml.bind.PropertyException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Properties;


@Intercepts({@Signature(method = "prepare", type = StatementHandler.class, args = {Connection.class,Integer.class})})
@SuppressWarnings("rawtypes")
public class PageInterceptor implements Interceptor {
    private static String databaseType = "";// 数据库类型，不同的数据库有不同的分页方法

    /**
     * 拦截后要执行的方法
     */
    public Object intercept(Invocation invocation) throws Throwable {

        RoutingStatementHandler handler = (RoutingStatementHandler) invocation
                .getTarget();
        StatementHandler delegate = (StatementHandler) ReflectUtil.getFieldValue(handler, "delegate");
        BoundSql boundSql = delegate.getBoundSql();
        Object params = boundSql.getParameterObject();
        Page page = null;
        if (params instanceof Page) {
            page = (Page) params;
        } else if (params instanceof MapperMethod.ParamMap) {
            MapperMethod.ParamMap paramMap = (MapperMethod.ParamMap) params;
            for (Object key : paramMap.keySet()) {
                if (paramMap.get(key) instanceof Page) {
                    page = (Page) paramMap.get(key);
                    break;
                }
            }
        }

        if (page != null) {
            MappedStatement mappedStatement = (MappedStatement) ReflectUtil
                    .getFieldValue(delegate, "mappedStatement");
            Connection connection = (Connection) invocation.getArgs()[0];
            String sql = boundSql.getSql();
            this.setTotalRecord(page, (MapperMethod.ParamMap) params,
                    mappedStatement, connection);
            String pageSql = this.getPageSql(page, sql);
            ReflectUtil.setFieldValue(boundSql, "sql", pageSql);
        }
        return invocation.proceed();
    }

    /**
     * 拦截器对应的封装原始对象的方法
     */
    public Object plugin(Object target) {
        return Plugin.wrap(target, this);
    }

    public void setProperties(Properties p) {
        databaseType = p.getProperty("databaseType");
        if (StringUtils.isEmpty(databaseType)) {
            try {
                throw new PropertyException("databaseType is not found!");
            } catch (PropertyException e) {
                e.printStackTrace();
            }
        }
    }

    private String getPageSql(Page<?> page, String sql) {
        StringBuffer sqlBuffer = new StringBuffer(sql);
        RecordSet recordSet = new RecordSet();

        String dbType = recordSet.getDBType();
        if ("mysql".equalsIgnoreCase(dbType)) {
            return getMysqlPageSql(page, sqlBuffer);
        } else if ("oracle".equalsIgnoreCase(dbType)) {
            return getOraclePageSql(page, sqlBuffer);
        } else if ("sqlserver".equalsIgnoreCase(dbType)) {
            return getSqlserverPageSql(page, sqlBuffer);
        }
        return sqlBuffer.toString();
    }

    private String getSqlserverPageSql(Page<?> page, StringBuffer sqlBuffer) {
        // 计算第一条记录的位置，Sqlserver中记录的位置是从0开始的。
        int startRowNum = (page.getPageNum() - 1) * page.getPageSize() + 1;
        int endRowNum = startRowNum + page.getPageSize();
        String sql = "select appendRowNum.row,* from (select ROW_NUMBER() OVER (order by (select 0)) AS row,* from ("
                + sqlBuffer.toString()
                + ") as innerTable"
                + ")as appendRowNum where appendRowNum.row >= "
                + startRowNum
                + " AND appendRowNum.row <= " + endRowNum;
        return sql;
    }

    private String getMysqlPageSql(Page<?> page, StringBuffer sqlBuffer) {
        // 计算第一条记录的位置，Mysql中记录的位置是从0开始的。
        int offset = (page.getPageNum() - 1) * page.getPageSize();
        sqlBuffer.append(" limit ").append(offset).append(",").append(page.getPageSize());
        return sqlBuffer.toString();
    }

    private String getOraclePageSql(Page<?> page, StringBuffer sqlBuffer) {
        // 计算第一条记录的位置，Oracle分页是通过rownum进行的，而rownum是从1开始的
        int offset = (page.getPageNum() - 1) * page.getPageSize() + 1;
        sqlBuffer.insert(0, "select u.*, rownum r from (").append(") u where rownum < ")
                .append(offset + page.getPageSize());
        sqlBuffer.insert(0, "select * from (").append(") where r >= ").append(offset);
        return sqlBuffer.toString();
    }

    /**
     * 给当前的参数对象page设置总记录数
     *
     * @param page            Mapper映射语句对应的参数对象
     * @param mappedStatement Mapper映射语句
     * @param connection
     */
    private void setTotalRecord(Page<?> page, MapperMethod.ParamMap params,
                                MappedStatement mappedStatement, Connection connection) {
        BoundSql boundSql = mappedStatement.getBoundSql(params);
        String sql = boundSql.getSql();
        String countSql = this.getCountSql(sql);
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
        BoundSql countBoundSql = new BoundSql(mappedStatement.getConfiguration(), countSql, parameterMappings, params);
        ParameterHandler parameterHandler = new DefaultParameterHandler(
                mappedStatement, params, countBoundSql);
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            pstmt = connection.prepareStatement(countSql);
            parameterHandler.setParameters(pstmt);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                int totalRecord = rs.getInt(1);
//                page.setTotalRecord(totalRecord);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null) rs.close();
                if (pstmt != null) pstmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 根据原Sql语句获取对应的查询总记录数的Sql语句
     *
     * @param sql
     * @return
     */
    private String getCountSql(String sql) {
        return "select count(*) from (" + sql + ") as countRecord";
    }

}