用JSON这么久，刚发现JSONObject的getString()暗藏炸弹！！！
public Map<String, Object> queryalmMonitorInfo(@RequestBody String jsonStr) ???{ ???????JSONObject json = JSONObject.fromObject(jsonStr); ???????// 当前页码 ???????int currentPage = json.getInt(SysConstant.PAGE); ???????// 每页条数 ???????int pageSize = json.getInt(SysConstant.ROWS); ???????Map<String, Object> mape = new HashMap<String, Object>(); ???????String areaid = json.getString("areaids"); ???????JSONArray areaids = JSONArray.fromObject(areaid); ???????@SuppressWarnings("unchecked") ???????List<String> areaIdlist = (List<String>) JSONArray.toCollection(areaids, ???????????????String.class); ???????String sysAndeqp = json.getString("eqpLists"); ???????List<String> eqpLists; ???????if ("".equals(sysAndeqp)) { ???????????eqpLists = null; ???????} ???????else { ???????????JSONArray eqpList = JSONArray.fromObject(sysAndeqp); ???????????eqpLists = (List<String>) JSONArray.toCollection(eqpList, ???????????????????String.class); ???????} ???????String sysEmsId = json.getString("sysEmsId"); ???????String techType = json.getString("techType"); ???????List<String> sysEmsIds; ???????if ("".equals(sysEmsId)) { ???????????sysEmsIds = null; ???????} ???????else { ???????????/* ????????????* JSONArray sysEmsIdList = JSONArray.fromObject(sysEmsId); ????????????* sysEmsIds = (List<String>) JSONArray.toCollection(sysEmsIdList, ????????????* String.class); ????????????*/ ???????????String[] arr = sysEmsId.split(","); ???????????sysEmsIds = Arrays.asList(arr); ???????} ???????List<String> techTypes; ???????if ("".equals(techType)) { ???????????techTypes = null; ???????} ???????else { ???????????/* ????????????* JSONArray techTypeList = JSONArray.fromObject(techType); ????????????* techTypes = (List<String>) JSONArray.toCollection(techTypeList, ????????????* String.class); ????????????*/ ???????????String[] arr1 = techType.split(","); ???????????techTypes = Arrays.asList(arr1); ???????} ???????String keyword = json.getString("keyword"); ???????String alarmLevel = json.getString("alarmLevel"); ???????String neEmsId = json.getString("neEmsId"); ???????String shelfEmsId = json.getString("shelfEmsId"); ???????String slotEmsId = json.getString("slotEmsId"); ???????int cardEmsId = json.getInt("cardEmsId"); ???????String isConf = json.getString("isConf"); ???????String portEmsId = json.getString("portEmsId"); ???????PageVo pageVo = PageUtil.assemblePageVo(currentPage, pageSize); ???????mape.put("keyword", keyword); ???????mape.put("alarmLevel", alarmLevel); ???????mape.put("techType", techTypes); ???????mape.put("areaId", areaIdlist); ???????mape.put("sysEmsId", sysEmsIds); ???????mape.put("neEmsId", neEmsId); ???????mape.put("shelfEmsId", shelfEmsId); ???????mape.put("slotEmsId", slotEmsId); ???????mape.put("cardEmsId", cardEmsId); ???????mape.put("portEmsId", portEmsId); ???????mape.put("sysAndeqp", eqpLists); ???????mape.put("isConf", isConf); ???????//新加条件20180628 ???????mape.put("isDamage", json.optString("isDamage")); ???????mape.put("techTypeName", json.optString("techTypeName")); ???????mape.put("sysName", json.optString("sysName")); ???????mape.put("neTypeName", json.optString("neTypeName")); ???????mape.put("alarmLevelOriginal", json.optString("alarmLevelOriginal")); ???????mape.put("alarmNeTimeStar", json.optString("alarmNeTimeStar")); ???????mape.put("alarmNeTimeEnd", json.optString("alarmNeTimeEnd")); ???????mape.put("ruleDesc", json.optString("ruleDesc")); ???????mape.put("projectName", json.optString("projectName")); ???????PageVo resPageVo = almMonitorService.getNetworkScaleAnalysis(pageVo, mape); ???????Map<String, Object> map = new HashMap<String, Object>(); ???????map.put(SysConstant.ROWS, resPageVo.getVoList()); ???????map.put(SysConstant.TOTAL, resPageVo.getRecordCount()); ???????return map; ???}项目用的SpringMVC，前端报错经过调试为此方法没有返回值，由于这是别人写的代码并没有try catch（这里表示气愤！！！），经过一点一点debug发现getString()方法无缘无故抛异常了，问了下度娘发现这个方法有雷：当JSONObject中不存在某key的时候就抛异常，而optString()不会，前端写的是自定义条件查询，JSONObject中的key并不是固定不变的，所以这里改为用optString()方法，mybatis配置的sql中有判断，不会影响查询。
关于JSONObject取值方法getString()与optString()
原文地址：https://www.cnblogs.com/vingewu/p/9300366.html