PageInterceptor.java@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })pub ...
PageInterceptor.java
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })public class PageInterceptor implements Interceptor { private static final Logger logger = Logger .getLogger(PageInterceptor.class); private static final ObjectFactory DEFAULT_OBJECT_FACTORY = new DefaultObjectFactory(); private static final ObjectWrapperFactory DEFAULT_OBJECT_WRAPPER_FACTORY = new DefaultObjectWrapperFactory(); private static String defaultPageSqlId = ".*Page$"; // 需要拦截的ID(正则匹配) private static String pageSqlId = ""; // 需要拦截的ID(正则匹配) @Override 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,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); } Configuration configuration = (Configuration) metaStatementHandler .getValue("delegate.configuration"); Properties properties = configuration.getVariables(); if (null != properties && StringUtils.isNotBlank(properties.getProperty("pageSqlId"))) { pageSqlId = properties.getProperty("pageSqlId"); } else { 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!"); } Map<String, Object> paramMap = (Map) parameterObject; PageParameter page = (PageParameter) paramMap.get("0"); String sql = boundSql.getSql(); // 重写sql String pageSql = buildPageSqlForMysql(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** return invocation.proceed(); } @Override 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; } } @Override public void setProperties(Properties properties) { // TODO Auto-generated method stub } /** * mysql的分页语句 * * @param sql * @param page * @return String */ public String buildPageSqlForMysql(String sql, PageParameter page) { StringBuilder pageSql = new StringBuilder(100); String beginrow = String.valueOf((page.getCurrentPage() - 1) * page.getPageSize()); pageSql.append(sql); pageSql.append(" limit " + beginrow + "," + page.getPageSize()); return pageSql.toString(); } private void setPageParameter(String sql, Connection connection, MappedStatement mappedStatement, BoundSql boundSql, PageParameter 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); int totalPage = totalCount / page.getPageSize() + ((totalCount % page.getPageSize() == 0) ? 0 : 1); page.setTotalPage(totalPage); } 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); } } } private void setParameters(PreparedStatement ps, MappedStatement mappedStatement, BoundSql boundSql, Object parameterObject) throws SQLException { ParameterHandler parameterHandler = new DefaultParameterHandler( mappedStatement, parameterObject, boundSql); parameterHandler.setParameters(ps); }}
原标题:springMVC分页,interceptor实现
关键词:Spring
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