java遍历json字符串，取得相应KV值时，各种麻烦，比如将json中的list取出来转为JSONArray，再将list中的object转化为map，再取值（之前的做法），仙子啊通过阿里的fastjson，可以很方便的直接将str转化为JSONArray，再将里面的object强转为JSONObject，然后再通过obj.getInteger(“key”)和obj.getString(“key”)等取值。

? 1 2 3 4 5 6 7 JSONArray json = (JSONArray) JSONArray.parse(str); for (Object obj : json) { JSONObject jo = (JSONObject)obj; int status = jo.getInteger("status"); String message= jo.getString("message"); System.out.println("status---" + status + "---message---" + message); }

1.当json字符串中有数组和map对象，遍历数据，数据格式如下：

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 [ { "status":0, "tags":[ "check:ntp" ], "timestamp":1492151922.198, "check":"datadog.agent.check_status", "host_name":"song-2", "message":null, "id":2 }, { "status":0, "tags":null, "timestamp":1492151922.2325, "check":"datadog.agent.up", "host_name":"song-2", "message":null, "id":5 } ]

解析上面json字符串数据，如果不使用如fastjson或者Gson时，解析方法如下：

方法一

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 /** * 主机详情中，异常错误信息的报错的平台服务状态和message * @param str * @return * @throws Exception */ private List<Map<String,String>> operStr(String str) throws Exception{ List<Map<String,String>> mList = new ArrayList<Map<String,String>>();//探针开启的服务名list JSONArray json = (JSONArray) JSONArray.parse(str); Map<String,Object> objMap = null; Map<String,String> resMap = null; for (Object obj : json) { objMap = Obj2Map(obj); @SuppressWarnings("unchecked") Map<String,Object> mObj = (Map<String, Object>) objMap.get("map"); int status = (Integer) mObj.get("status"); if(status != 0){ resMap = new HashMap<String,String>(); switch (status) { case 1: resMap.put("status","WARNING"); break; case 2: resMap.put("status","ERROR"); break; case 3: resMap.put("status","CRIT"); break; default: break; } resMap.put("serviceName", ((String) mObj.get("check")).split("\\.")[0]); resMap.put("msg", (String)mObj.get("message")); mList.add(resMap); } } return mList; } /** * object转map * @param obj * @return * @throws Exception */ public Map<String,Object> Obj2Map(Object obj) throws Exception{ if(obj == null){ return null; } Map<String,Object> map=new HashMap<String, Object>(); Field[] fields = obj.getClass().getDeclaredFields(); for(Field field:fields){ field.setAccessible(true); map.put(field.getName(), field.get(obj)); } return map; }

方法二

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 /** * 主机详情中，异常错误信息的报错的平台服务状态和message * @param str * @return * @throws Exception */ private List<Map<String,String>> operStr(String str) throws Exception{ List<Map<String,String>> mList = new ArrayList<Map<String,String>>();//探针开启的服务名list JSONArray json = (JSONArray) JSONArray.parse(str); Map<String,String> resMap = null; for (Object obj : json) { JSONObject jo = (JSONObject)obj; int status = jo.getInteger("status"); if(status != 0){ resMap = new HashMap<String,String>(); switch (status) { case 1: resMap.put("status","WARNING"); break; case 2: resMap.put("status","ERROR"); break; case 3: resMap.put("status","CRIT"); break; default: break; } resMap.put("serviceName", (jo.getString("check")).split("\\.")[0]); resMap.put("msg", jo.getString("message")); mList.add(resMap); } } return mList; }

2.当json字符串中是数组包含数组时候，遍历数据，数据格式如下：

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 [ [ "haproxy", "haproxy", 0, "ERROR", "swdfghyjuikl", { } ], [ "gearmand", "gearmand", 0, "ERROR", "'Found no valid connections in list: [<GearmanConnection localhost:4730 connected=False>]'", { "version":"[8, 4, 20]" } ] ]

方法一

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 /** * 通过查询agentChecksStr解析得到异常信息 * @param agentChecksStr * @return */ private List<Map<String,String>> getExceptInfoFromAgentChecks(String agentChecksStr){ List<Map<String,String>> mList = new ArrayList<Map<String,String>>();//探针开启的服务名list //mList 主机详情中，异常错误信息的报错的平台服务状态和message Object jsonArray = JSONArray.parse(agentChecksStr); @SuppressWarnings("unchecked") List<List<Object>> list= (List<List<Object>>) jsonArray; Map<String,String> map = null; for(int i=0;i<list.size();i++){ map = new HashMap<String,String>(); String status = list.get(i).get(3).toString(); if(!status.equals("OK")){ String serviceName = list.get(i).get(0).toString(); String msg = list.get(i).get(4).toString(); map.put("serviceName", serviceName); map.put("status", status); map.put("msg", msg); mList.add(map); } } return mList; }

方法二

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 /** * 通过查询agentChecksStr解析得到异常信息 * @param agentChecksStr * @return */ private List<Map<String,String>> getExceptInfoFromAgentChecks(String agentChecksStr){ //探针开启的服务名list List<Map<String,String>> mList = new ArrayList<Map<String,String>>(); JSONArray jsonArray = (JSONArray) JSONArray.parse(agentChecksStr); Map<String,String> map = null; for (Object obj : jsonArray) { map = new HashMap<String,String>(); JSONArray ja = (JSONArray)obj; String status = ja.getString(3); if(!status.equals("OK")){ String serviceName = ja.getString(0); String msg = ja.getString(4); map.put("serviceName", serviceName); map.put("status", status); map.put("msg", msg); mList.add(map); } } return mList; }

Gson将json字符串转化为json对象：

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 import com.google.gson.Gson; import com.google.gson.JsonArray; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonParser; public class MainTest { public static void main(String[] args) throws Exception{ String jsonstr0 = "{\"alarmDetails\":{\"conditionDetails\":{\"alarmId\":7,\"alarmNodataNotifyTime\":1,\"alarmNowSeriesWaitTime\":2},\"conditionStatic\":{\"alarmId\":7,\"conditionAggregate\":\"avg\",\"conditionOperator\":1,\"conditionThresholdTime\":5,\"conditionThresholdValue\":\"123\"},\"metricDetails\":{\"alarmId\":7,\"metricAggregater\":\"avg\",\"metricBy\":\"host\",\"metricExcludeTag\":\"host:paas-177\",\"metricName\":\"system.cpu.user\",\"metricQ\":\"avg:system.cpu.user{#address:wuhan,!host:paas-177}by{host}\",\"metricTag\":\"#address:wuhan\"},\"notify\":[{\"alarmId\":7,\"notifyChannel\":5,\"notifyUserId\":1},{\"alarmId\":7,\"notifyChannel\":5,\"notifyUserId\":2}],\"view\":{\"alarmExpression\":\"avg(last_5m)avg:system.cpu.user{#address:wuhan,!host:paas-177}by{host}>123.0\",\"alarmId\":7,\"alarmLastValue\":\"UP\",\"alarmName\":\"static_metric\",\"alarmStatus\":1,\"alarmType\":2,\"alarmTypeJoin\":3,\"createTime\":\"2017-06-28 17:25:52.0\",\"createUserId\":1,\"isDisable\":false,\"lastAlarmTime\":\"2017-06-28 17:25:27.0\",\"metricName\":\"system.cpu.user\",\"metricTag\":\"#address:wuhan\",\"updateTime\":\"2017-06-29 15:49:18.0\"}},\"alarmId\":7,\"allMark\":{\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\":{\"changePutTime\":true,\"lastPutTsdbTime\":1499655343,\"lastSuccessCheckTime\":1499655349,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"tagMap\":{\"host\":\"cfeng-4\",\"#address\":\"wuhan\",\"!host\":\"paas-177\"}}},\"joinType\":3,\"useMetricUnit\":\"percent\",\"validataDetails\":{\"status\":0,\"validataMerges\":[{\"alarmMarkDto\":{\"changePutTime\":true,\"lastPutTsdbTime\":1499655343,\"lastSuccessCheckTime\":1499655349,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"tagMap\":{\"host\":\"cfeng-4\",\"#address\":\"wuhan\",\"!host\":\"paas-177\"}},\"status\":0,\"tag\":\"host:cfeng-4\",\"validataNodata\":{\"currentTime\":1499655349,\"isNodata\":false,\"lastSuccessCheckTime\":1499655349,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"tag\":{\"host\":\"cfeng-4\",\"#address\":\"wuhan\",\"!host\":\"paas-177\"},\"thresholdTime\":60},\"validataStatic\":{\"converToThresholdValue\":123.0,\"end\":1499655343,\"intervalAggregator\":\"avg\",\"isAlart\":true,\"operator\":1,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"start\":1499655043,\"sysUnit\":\"percent\",\"tag\":{\"#address\":\"wuhan\",\"host\":\"cfeng-4\",\"!host\":\"paas-177\"},\"thresholdTime\":300,\"thresholdValue\":\"123\",\"value\":5.715769243240357}}],\"validataTimeSeconds\":1499655349}}"; String jsonstr1 = "{\"alarmDetails\":{\"conditionDetails\":{\"alarmId\":7,\"alarmNodataNotifyTime\":1,\"alarmNowSeriesWaitTime\":2},\"conditionStatic\":{\"alarmId\":7,\"conditionAggregate\":\"avg\",\"conditionOperator\":1,\"conditionThresholdTime\":5,\"conditionThresholdValue\":\"123\"},\"metricDetails\":{\"alarmId\":7,\"metricAggregater\":\"avg\",\"metricBy\":\"host\",\"metricExcludeTag\":\"host:paas-177\",\"metricName\":\"system.cpu.user\",\"metricQ\":\"avg:system.cpu.user{#address:wuhan,!host:paas-177}by{host}\",\"metricTag\":\"#address:wuhan\"},\"notify\":[{\"alarmId\":7,\"notifyChannel\":5,\"notifyUserId\":1},{\"alarmId\":7,\"notifyChannel\":5,\"notifyUserId\":2}],\"view\":{\"alarmExpression\":\"avg(last_5m)avg:system.cpu.user{#address:wuhan,!host:paas-177}by{host}>123.0\",\"alarmId\":7,\"alarmLastValue\":\"UP\",\"alarmName\":\"static_metric\",\"alarmStatus\":1,\"alarmType\":2,\"alarmTypeJoin\":3,\"createTime\":\"2017-06-28 17:25:52.0\",\"createUserId\":1,\"isDisable\":false,\"lastAlarmTime\":\"2017-06-28 17:25:27.0\",\"metricName\":\"system.cpu.user\",\"metricTag\":\"#address:wuhan\",\"updateTime\":\"2017-06-29 15:49:18.0\"}},\"alarmId\":7,\"allMark\":{\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\":{\"changePutTime\":true,\"lastPutTsdbTime\":1499655374,\"lastSuccessCheckTime\":1499655379,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"tagMap\":{\"host\":\"cfeng-4\",\"#address\":\"wuhan\",\"!host\":\"paas-177\"}}},\"joinType\":3,\"useMetricUnit\":\"percent\",\"validataDetails\":{\"status\":0,\"validataMerges\":[{\"alarmMarkDto\":{\"changePutTime\":true,\"lastPutTsdbTime\":1499655374,\"lastSuccessCheckTime\":1499655379,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"tagMap\":{\"host\":\"cfeng-4\",\"#address\":\"wuhan\",\"!host\":\"paas-177\"}},\"status\":0,\"tag\":\"host:cfeng-4\",\"validataNodata\":{\"currentTime\":1499655379,\"isNodata\":false,\"lastSuccessCheckTime\":1499655379,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"tag\":{\"host\":\"cfeng-4\",\"#address\":\"wuhan\",\"!host\":\"paas-177\"},\"thresholdTime\":60},\"validataStatic\":{\"converToThresholdValue\":123.0,\"end\":1499655374,\"intervalAggregator\":\"avg\",\"isAlart\":true,\"operator\":1,\"series\":\"avg:system.cpu.user{host:cfeng-4,#address:wuhan,!host:paas-177}\",\"start\":1499655074,\"sysUnit\":\"percent\",\"tag\":{\"#address\":\"wuhan\",\"host\":\"cfeng-4\",\"!host\":\"paas-177\"},\"thresholdTime\":300,\"thresholdValue\":\"123\",\"value\":5.089640821729388}}],\"validataTimeSeconds\":1499655379}}"; Set<String> set = new HashSet<String>(); set.add(jsonstr0); set.add(jsonstr1); Gson gs = new Gson(); List<Object> eventList = new ArrayList<Object>(); for (String str : set) { JsonObject returnData = new JsonParser().parse(str).getAsJsonObject(); JsonObject ad = returnData.get("alarmDetails").getAsJsonObject(); JsonObject vd = returnData.get("validataDetails").getAsJsonObject(); JsonArray vm = vd.get("validataMerges").getAsJsonArray(); JsonArray nf = ad.get("notify").getAsJsonArray(); JsonObject v = ad.get("view").getAsJsonObject(); String validataTimeSeconds = vd.get("validataTimeSeconds").toString(); for (JsonElement je : vm) { je.getAsJsonObject().add("view", v); je.getAsJsonObject().add("notify", nf); je.getAsJsonObject().addProperty("validataTimeSeconds", Long.parseLong(validataTimeSeconds)); eventList.add(je); } } for (Object obj : eventList) { String inParam = gs.toJson(obj); System.out.println(inParam); } System.out.println(gs.toJson(eventList)); } } ? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 //获取设备信息（只有硬件设备和虚拟设备有） HashMap<String,String> paramMap = new HashMap<String,String>(); paramMap.put("hostid", mHostId); paramMap.put("ptype", dto.getPtype()); paramMap.put("type_flag", dto.getTypeFlag()); paramMap.put("api_key", apikey); String resStr = HttpUtils.get(DEVICE_INFO_URL, paramMap); JSONObject jobj = JSON.parseObject(resStr); JSONObject obj = (JSONObject)jobj.get("result"); if(obj.size() != 0){ String restr = jobj.get("result").toString(); DeviceInfoDto deviceInfoDto = new Gson().fromJson(restr, DeviceInfoDto.class); dto.setDeviceInfo(deviceInfoDto); } ? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 List<Map<Integer, Long>> result = new ArrayList<Map<Integer, Long>>(); Map<String, String> timeMap = null; List<Map<String, String>> timeArr = new ArrayList<Map<String, String>>(); for (int j = 0; j < result.size(); j++) { timeMap = new HashMap<String, String>(); if (j == result.size() - 1) { timeMap.put("startTime",result.get(j).get(result.get(j).keySet().iterator().next()) + ""); timeMap.put("endTime", System.currentTimeMillis() + ""); } else { timeMap.put("startTime", result.get(j).get(result.get(j).keySet().iterator().next()) + ""); timeMap.put("endTime", (result.get(j+1).get(result.get(j+1).keySet().iterator().next()) - 1) + ""); } timeMap.put("hostName", "*"); //1:info,2:error,3:success,4:warning Integer key = result.get(j).keySet().iterator().next(); if (key == 1) { timeMap.put("status", "info"); } else if (key == 2) { timeMap.put("status", "error"); } else if (key == 3) { timeMap.put("status", "success"); } else if (key == 4) { timeMap.put("status", "warning"); } timeArr.add(timeMap); }

以上这篇Java遍历json字符串取值的实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持服务器之家。

原文链接：https://blog.csdn.net/u010466329/article/details/72416892