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java分页拦截类实现sql自动分页

2019-11-26 13:31:41
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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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