如何使用Jackson和JSON Pointer查詢解析任何JSON節點
阿新 • • 發佈:2021-09-17
目錄
- Jackson和ON Pointer查詢解析任何JSON節點
- 1.示例Json文件
- 2. 解析文件
- Jackson 通用解析JSON方法
Jackson和JSON Pointer查詢解析任何JSON節點
JSON Pointer是字串表示式,用於標識JSON文件特定節點。RFC 6901規範有定義,用於查詢複雜Json文件結構。
1.示例Json文件
{ "firstName": "John","lastName": "Doe","address": { "street": "21 2nd Street","city": "New York","postalCode": "10021-3100","coordinates": { "latitude": 40.7250387,"longitude": -73.9932568 } },"phone": [ "139","137" ],"grade": [ { "name": "math","score": 99 },{ "name": "english","score": 97 } ] }
該文件包括複雜的巢狀,其中巢狀型別有物件,陣列,陣列物件。下面使用JSON Pointer進行解析。
2. 解析文件
使用Jackson的核心物件ObjectMapper,首先解析json字串未JsonNode。
String json = "{\n" + " \"firstName\": \"John\",\n" + " \"lastName\": \"Doe\",\n" + " \"address\": {\n" + " \"street\": \"21 2nd Street\",\n" + " \"city\": \"New York\",\n" + " \"postalCode\": \"10021-3100\",\n" + " \"coordinates\": {\n" + " \"latitude\": 40.7250387,\n" + " \"longitude\": -73.9932568\n" + " }\n" + " },\n" + " \"phone\":[\"139\",\"137\"],\n" + " \"grade\":[\n" + " {\"name\":\"math\",\"score\":99},\n" + " {\"name\":\"english\",\"score\":97}\n" + " ]\n" + " }"; ObjectMapper mapper = new ObjectMapper(); JsonNode node = mapper.readTree(json);
2.1 獲取屬性
JsonNode firstName = node.at("/firstName"); print("firstName",firstName.toString());
必須以/開頭,表示當前起始節點。
輸出結果:
firstName:"John"
2.2 獲取物件屬性
JsonNode coordinatesNode = node.at("/address/coordinates"); print("coordinatesNode",coordinatesNode.toString());
輸出結果:
coordinatesNode:{"latitude":40.7250387,"longitude":-73.9932568}
2.3 獲取陣列屬性
JsonNode phoneNode = node.at("/phone"); print("phoneNode",phoneNode.toString());
輸出結果:
phoneNode:["139","137"]
2.4 獲取陣列屬性元素
JsonNode phone1Node = node.at("/phone/0"); print("phone1Node",phone1Node.toString());
輸出結果:
phone1Node:"139"
2.4 獲取陣列物件屬性
JsonNode nameNode = node.at("/grade/0/name"); print("name",nameNode.toString()); JsonNode scoreNode = node.at("/grade/0/score"); print("score",scoreNode.toString());
輸出結果:
name:"math"
score:99
Jackson 通用解析JSON方法
package com.util; import com.fasterxml.jackson.annotation.JsonAutoDetect; import com.fasterxml.jackson.annotation.PropertyAccessor; import com.fasterxml.jackson.databind.DeserializationFeature; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.SerializationFeature; import com.fasterxml.jackson.databind.type.TypeFactory; import com.google.common.collect.Lists; import lombok.extern.slf4j.Slf4j; import org.apache.commons.lang3.StringUtils; import .io.IOException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; /** * json 解析類,通用於全專案 * <p/> * Created by 劉一波 on 15/7/24. * E-Mail:[email protected] */ @Slf4j public class JsonUtils { private static ObjectMapper objectMapper = new ObjectMapper(); static { objectMapper.setVisibility(PropertyAccessor.FIELD,JsonAutoDetect.Visibility.ANY); objectMapper.configure(SerializationFeature.INDENT_OUTPUT,true); objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,false); www.cppcns.com objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); objectMapper.setDateFormat(sdf); } /** * 提供給elasticsearch使用,把bean轉換成list map 集合型別,否則不能存入索引 * *客棧 @param o * @return */ public static Object beanToJsonObject(Object o) { return jsonStrToList(objectToJsonStr(o),Map.class); } public static String objectToJsonStr(Object o) { try { return objectMapper.writeValueAsString(o); } catch (IOException e) { log.error("object can not objectTranslate to json",e); } return null; } public static <T> T jsonStrToObject(String json,Class<T> cls) { try { return objectMapper.readValue(json,cls); } catch (IOException e) { log.error("json cant be objectTranslate to object",e); return null; } } public static <T> T jsonDataToObject(String jsonStr,Class<T> cls) { if (!StringUtils.isEmpty(jsonStr)) { T data = JsonUtils.jsonStrToObject(jsonStr,cls); return data; } else { return null; } } public static <T> List<T> jsonStrToList(String jsonStr,Class<?> clazz) { List<T> list = Lists.newArrayList(); try { // 指定容器結構和型別(這裡是ArrayList和clazz) TypeFactory t = TypeFactory.defaultInstance(); list = objectMapper.readValue(jsonStr,t.constructCollectionType(ArrayList.class,clazz)); } catch (IOException e) { log.error("反序列化序列化attributes,從Json到List報錯",e); } return list; } public static Map jsonStrToMap(String attributes) { try { return objectMapper.readValue(attributes,HashMap.class); } catch (IOException e) { log.error("反序列化序列化attributes,從Json到HashMap報錯",e); } return new HashMap(); } }
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