/** 将0=1/1=1/true的恒等式进行优化 */ private static IFilter shortestFilter(IFilter root) throws EmptyResultFilterException { IFilter filter = FilterUtils.toDNFAndFlat(root); List<List<IFilter>> DNFfilter = FilterUtils.toDNFNodesArray(filter); List<List<IFilter>> newDNFfilter = new ArrayList<List<IFilter>>(); for (List<IFilter> andDNFfilter : DNFfilter) { boolean isShortest = false; List<IFilter> newAndDNFfilter = new ArrayList<IFilter>(); for (IFilter one : andDNFfilter) { if (one.getOperation() == OPERATION.CONSTANT) { boolean flag = false; if (((IBooleanFilter) one).getColumn() instanceof ISelectable) { // 可能是个not函数 newAndDNFfilter.add(one); // 不能丢弃 } else { String value = ((IBooleanFilter) one).getColumn().toString(); if (StringUtils.isNumeric(value)) { flag = BooleanUtils.toBoolean(Integer.valueOf(value)); } else { flag = BooleanUtils.toBoolean(((IBooleanFilter) one).getColumn().toString()); } if (!flag) { isShortest = true; break; } } } else { newAndDNFfilter.add(one); } } if (!isShortest) { if (newAndDNFfilter.isEmpty()) { // 代表出现为true or xxx,直接返回true IBooleanFilter f = ASTNodeFactory.getInstance().createBooleanFilter(); f.setOperation(OPERATION.CONSTANT); f.setColumn("1"); f.setColumnName(ObjectUtils.toString("1")); return f; } else { // 针对非false的情况 newDNFfilter.add(newAndDNFfilter); } } } if (newDNFfilter.isEmpty()) { throw new EmptyResultFilterException("空结果"); } return FilterUtils.DNFToOrLogicTree(newDNFfilter); }