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package com.mgear.samering.util;import java.lang.reflect.Field;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.List;import java.util.Properties;import org.apache.ibatis.executor.parameter.ParameterHandler;import org.apache.ibatis.executor.resultset.ResultSetHandler;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 org.apache.ibatis.scripting.defaults.DefaultParameterHandler;import org.apache.log4j.Logger;import com.alibaba.fastjson.JSONObject;/** * Mybatis - 分页拦截器 * * @author c.c. */@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }), @Signature(type = ResultSetHandler.class, method = "handleResultSets", args = { Statement.class }) })public class PageInterceptor implements Interceptor { private static final Logger logger = Logger.getLogger(PageInterceptor.class); public static final ThreadLocal localPage = new ThreadLocal (); private static Page mypage; /** * 开始分页 * @param pageNum * @param pageSize */ public static void startPage(int pageNum, int pageSize) { localPage.set(new Page(pageNum, pageSize)); } /** * 结束分页并返回结果，该方法必须被调用，否则localPage会一直保存下去，直到下一次startPage * @return */ public static Page endPage() {// Page page = localPage.get();// localPage.remove(); return mypage; } @Override public Object intercept(Invocation invocation) throws Throwable { if (localPage.get() == null) { return invocation.proceed(); } if (invocation.getTarget() instanceof StatementHandler) { StatementHandler statementHandler = (StatementHandler) invocation.getTarget(); MetaObject metaStatementHandler = SystemMetaObject.forObject(statementHandler); // 分离代理对象链(由于目标类可能被多个拦截器拦截，从而形成多次代理，通过下面的两次循环 // 可以分离出最原始的的目标类) while (metaStatementHandler.hasGetter("h")) { Object object = metaStatementHandler.getValue("h"); metaStatementHandler = SystemMetaObject.forObject(object); } // 分离最后一个代理对象的目标类 while (metaStatementHandler.hasGetter("target")) { Object object = metaStatementHandler.getValue("target"); metaStatementHandler = SystemMetaObject.forObject(object); } MappedStatement mappedStatement = (MappedStatement) metaStatementHandler.getValue("delegate.mappedStatement"); //分页信息if (localPage.get() != null) { Page page = localPage.get(); BoundSql boundSql = (BoundSql) metaStatementHandler.getValue("delegate.boundSql"); // 分页参数作为参数对象parameterObject的一个属性 String sql = boundSql.getSql(); // 重写sql String pageSql = buildPageSql(sql, page); //重写分页sql metaStatementHandler.setValue("delegate.boundSql.sql", pageSql); Connection connection = (Connection) invocation.getArgs()[0]; // 重设分页参数里的总页数等 setPageParameter(sql, connection, mappedStatement, boundSql, page); // 将执行权交给下一个拦截器 return invocation.proceed(); } else if (invocation.getTarget() instanceof ResultSetHandler) { Object result = invocation.proceed(); Page page = localPage.get(); page.setResult((List) result); mypage=page; localPage.remove(); return result; } return null; } /** * 只拦截这两种类型的 * StatementHandler * ResultSetHandler * @param target * @return */ @Override public Object plugin(Object target) { if (target instanceof StatementHandler || target instanceof ResultSetHandler) { return Plugin.wrap(target, this); } else { return target; } } @Override public void setProperties(Properties properties) { } /** * 修改原SQL为分页SQL * @param sql * @param page * @return */ private String buildPageSql(String sql, Page page) { StringBuilder pageSql = new StringBuilder(200);// pageSql.append("select rn.* from ( select temp.*, rownum XH from ( "); pageSql.append(sql); pageSql.append(" limit ").append(page.getStartRow()).append(" , ").append(page.getPageRecord());// pageSql.append(" ) temp where rownum <= ").append(page.getEndRow());// pageSql.append(") rn where XH > ").append(page.getStartRow()); return pageSql.toString();// return sql; } /** * 获取总记录数 * @param sql * @param connection * @param mappedStatement * @param boundSql * @param page */ private void setPageParameter(String sql, Connection connection, MappedStatement mappedStatement, BoundSql boundSql, Page page) { // 记录总记录数 String countSql = "select count(0) from (" + sql + ") t";// System.out.println(sql); PreparedStatement countStmt = null; ResultSet rs = null; try { countStmt = connection.prepareStatement(countSql); BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), countSql, boundSql.getParameterMappings(), boundSql.getParameterObject()); //使用反射注入参数 Field metaParamsField = ReflectUtil.getFieldByFieldName(boundSql, "metaParameters"); if (metaParamsField != null) { MetaObject mo = (MetaObject) ReflectUtil.getValueByFieldName(boundSql, "metaParameters"); ReflectUtil.setValueByFieldName(countBS, "metaParameters", mo); } setParameters(countStmt, mappedStatement, countBS, boundSql.getParameterObject()); rs = countStmt.executeQuery(); int totalCount = 0; if (rs.next()) { totalCount = rs.getInt(1); } page.setRecordCount(totalCount); int totalPage = totalCount==0?0:(totalCount-1)/page.getPageRecord()+1; page.setPageCount(totalPage); } catch (Exception e) { } finally { try { rs.close(); } catch (SQLException e) { } try { countStmt.close(); } catch (SQLException e) { } } } /** * 代入参数值 * @param ps * @param mappedStatement * @param boundSql * @param parameterObject * @throws SQLException */ private void setParameters(PreparedStatement ps, MappedStatement mappedStatement, BoundSql boundSql, Object parameterObject) throws SQLException { ParameterHandler parameterHandler = new DefaultParameterHandler(mappedStatement, parameterObject, boundSql); parameterHandler.setParameters(ps); } /** * Description: 分页 * Author: liuzh * Update: liuzh(2014-04-16 10:56) */ public static class Page { private int CurrentPage; private int PageRecord; private int startRow; private int endRow; private long RecordCount; private int PageCount; private List result; public Page(int pageNum, int pageSize) { this.CurrentPage = pageNum; this.PageRecord = pageSize; this.startRow = pageNum > 0 ? (pageNum - 1) * pageSize : 0; this.endRow = pageNum * pageSize; } public String toString() { JSONObject count = new JSONObject(); count.put("RecordCount", RecordCount); count.put("PageCount", PageCount); count.put("CurrentPage",CurrentPage); count.put("PageRecord", PageRecord); return count.toString(); } public int getCurrentPage() { return CurrentPage; } public void setCurrentPage(int currentPage) { CurrentPage = currentPage; } public int getPageRecord() { return PageRecord; } public void setPageRecord(int pageRecord) { PageRecord = pageRecord; } public int getStartRow() { return startRow; } public void setStartRow(int startRow) { this.startRow = startRow; } public int getEndRow() { return endRow; } public void setEndRow(int endRow) { this.endRow = endRow; } public long getRecordCount() { return RecordCount; } public void setRecordCount(long recordCount) { RecordCount = recordCount; } public int getPageCount() { return PageCount; } public void setPageCount(int pageCount) { PageCount = pageCount; } public List getResult() { return result; } public void setResult(List result) { this.result = result; } }}