java分页拦截类实现sql自动分页
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2024-03-12 07:58:55
本文实例为大家分享了完整的java分页拦截类,供大家参考,具体内容如下
package com.opms.interceptor;
import j...
本文实例为大家分享了完整的java分页拦截类,供大家参考,具体内容如下
package com.opms.interceptor; import java.sql.connection; import java.sql.preparedstatement; import java.sql.resultset; import java.sql.sqlexception; import java.util.properties; import org.apache.ibatis.executor.parameter.parameterhandler; import org.apache.ibatis.executor.statement.statementhandler; import org.apache.ibatis.logging.log; import org.apache.ibatis.logging.logfactory; 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.factory.defaultobjectfactory; import org.apache.ibatis.reflection.factory.objectfactory; import org.apache.ibatis.reflection.wrapper.defaultobjectwrapperfactory; import org.apache.ibatis.reflection.wrapper.objectwrapperfactory; import org.apache.ibatis.scripting.defaults.defaultparameterhandler; import org.apache.ibatis.session.rowbounds; import com.wifi.core.page.page; /** * 通过拦截<code>statementhandler</code>的<code>prepare</code>方法,重写sql语句实现物理分页。 * 老规矩,签名里要拦截的类型只能是接口。 * * @author 湖畔微风 * */ @intercepts({@signature(type = statementhandler.class, method = "prepare", args = {connection.class})}) public class pageinterceptor implements interceptor { /** * 日志 */ private static final log logger = logfactory.getlog(pageinterceptor.class); /** * 声明对象 */ private static final objectfactory default_object_factory = new defaultobjectfactory(); /** * 声明对象 */ private static final objectwrapperfactory default_object_wrapper_factory = new defaultobjectwrapperfactory(); /** * 数据库类型(默认为mysql) */ private static string defaultdialect = "mysql"; /** * 需要拦截的id(正则匹配) */ private static string defaultpagesqlid = ".*4page$"; /** * 数据库类型(默认为mysql) */ private static string dialect = ""; /** * 需要拦截的id(正则匹配) */ private static string pagesqlid = ""; /** * @param invocation 参数 * @return object * @throws throwable 抛出异常 */ public object intercept(invocation invocation) throws throwable { statementhandler statementhandler = (statementhandler) invocation.gettarget(); metaobject metastatementhandler = metaobject.forobject(statementhandler, default_object_factory, default_object_wrapper_factory); // 分离代理对象链(由于目标类可能被多个拦截器拦截,从而形成多次代理,通过下面的两次循环可以分离出最原始的的目标类) while (metastatementhandler.hasgetter("h")) { object object = metastatementhandler.getvalue("h"); metastatementhandler = metaobject.forobject(object, default_object_factory, default_object_wrapper_factory); } // 分离最后一个代理对象的目标类 while (metastatementhandler.hasgetter("target")) { object object = metastatementhandler.getvalue("target"); metastatementhandler = metaobject.forobject(object, default_object_factory, default_object_wrapper_factory); } dialect=defaultdialect;pagesqlid=defaultpagesqlid; /* configuration configuration = (configuration) metastatementhandler.getvalue("delegate.configuration"); dialect = configuration.getvariables().getproperty("dialect"); if (null == dialect || "".equals(dialect)) { logger.warn("property dialect is not setted,use default 'mysql' "); dialect = defaultdialect; } pagesqlid = configuration.getvariables().getproperty("pagesqlid"); if (null == pagesqlid || "".equals(pagesqlid)) { logger.warn("property pagesqlid is not setted,use default '.*page$' "); pagesqlid = defaultpagesqlid; }*/ mappedstatement mappedstatement = (mappedstatement) metastatementhandler.getvalue("delegate.mappedstatement"); // 只重写需要分页的sql语句。通过mappedstatement的id匹配,默认重写以page结尾的mappedstatement的sql if (mappedstatement.getid().matches(pagesqlid)) { boundsql boundsql = (boundsql) metastatementhandler.getvalue("delegate.boundsql"); object parameterobject = boundsql.getparameterobject(); if (parameterobject == null) { throw new nullpointerexception("parameterobject is null!"); } else { object obj = metastatementhandler .getvalue("delegate.boundsql.parameterobject.page"); // 传入了page参数且需要开启分页时 if(obj!=null&&obj instanceof page &&((page)obj).ispagination()){ page page = (page) metastatementhandler .getvalue("delegate.boundsql.parameterobject.page"); string sql = boundsql.getsql(); // 重写sql string pagesql = buildpagesql(sql, page); metastatementhandler.setvalue("delegate.boundsql.sql", pagesql); // 采用物理分页后,就不需要mybatis的内存分页了,所以重置下面的两个参数 metastatementhandler.setvalue("delegate.rowbounds.offset", rowbounds.no_row_offset); metastatementhandler.setvalue("delegate.rowbounds.limit", rowbounds.no_row_limit); 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(); } /** * 从数据库里查询总的记录数并计算总页数,回写进分页参数<code>pageparameter</code>,这样调用者就可用通过 分页参数 * <code>pageparameter</code>获得相关信息。 * * @param sql 参数 * @param connection 连接 * @param mappedstatement 参数 * @param boundsql 绑定sql * @param page 页 */ 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 + ") as total"; preparedstatement countstmt = null; resultset rs = null; try { countstmt = connection.preparestatement(countsql); boundsql countbs = new boundsql(mappedstatement.getconfiguration(), countsql, boundsql.getparametermappings(), boundsql.getparameterobject()); setparameters(countstmt, mappedstatement, countbs, boundsql.getparameterobject()); rs = countstmt.executequery(); int totalcount = 0; if (rs.next()) { totalcount = rs.getint(1); } page.settotalcount(totalcount); page.init(page.getcurpage(), page.getpagesize(), totalcount); } catch (sqlexception e) { logger.error("ignore this exception", e); } finally { try { rs.close(); } catch (sqlexception e) { logger.error("ignore this exception", e); } try { countstmt.close(); } catch (sqlexception e) { logger.error("ignore this exception", e); } } } /** * 对sql参数(?)设值 * * @param ps 参数 * @param mappedstatement 参数 * @param boundsql 绑定sql * @param parameterobject 参数对象 * @throws sqlexception 抛出sql异常 */ private void setparameters(preparedstatement ps, mappedstatement mappedstatement, boundsql boundsql, object parameterobject) throws sqlexception { parameterhandler parameterhandler = new defaultparameterhandler(mappedstatement, parameterobject, boundsql); parameterhandler.setparameters(ps); } /** * 根据数据库类型,生成特定的分页sql * * @param sql 餐宿 * @param page 页 * @return string */ private string buildpagesql(string sql, page page) { if (page != null) { stringbuilder pagesql = new stringbuilder(); if ("mysql".equals(dialect)) { pagesql = buildpagesqlformysql(sql, page); } else if ("oracle".equals(dialect)) { pagesql = buildpagesqlfororacle(sql, page); } else { return sql; } return pagesql.tostring(); } else { return sql; } } /** * mysql的分页语句 * * @param sql 参数 * @param page 页 * @return string */ public stringbuilder buildpagesqlformysql(string sql, page page) { stringbuilder pagesql = new stringbuilder(100); string beginrow = string.valueof((page.getcurpage() - 1) * page.getpagesize()); pagesql.append(sql); pagesql.append(" limit " + beginrow + "," + page.getpagesize()); return pagesql; } /** * 参考hibernate的实现完成oracle的分页 * * @param sql 参数 * @param page 参数 * @return string */ public stringbuilder buildpagesqlfororacle(string sql, page page) { stringbuilder pagesql = new stringbuilder(100); string beginrow = string.valueof((page.getcurpage() - 1) * page.getpagesize()); string endrow = string.valueof(page.getcurpage() * page.getpagesize()); pagesql.append("select * from ( select temp.*, rownum row_id from ( "); pagesql.append(sql); pagesql.append(" ) temp where rownum <= ").append(endrow); pagesql.append(") where row_id > ").append(beginrow); return pagesql; } /** * @param target 参数 * @return object */ public object plugin(object target) { // 当目标类是statementhandler类型时,才包装目标类,否者直接返回目标本身,减少目标被代理的次数 if (target instanceof statementhandler) { return plugin.wrap(target, this); } else { return target; } } /** * @param properties 参数 */ public void setproperties(properties properties) { } }
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