Jackson和JSON Pointer查询解析任何JSON节点
JSON Pointer是字符串表达式，用于标识JSON文档特定节点。RFC 6901规范有定义，用于查询复杂Json文档结构。
1.示例Json文档
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{ "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 } ] } |
该文档包括复杂的嵌套，其中嵌套类型有对象，数组，数组对象。下面使用JSON Pointer进行解析。
2. 解析文档
使用Jackson的核心对象ObjectMapper，首先解析json字符串未JsonNode。
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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 获取属性
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JsonNode firstName = node.at( "/firstName" ); print( "firstName" ,firstName.toString()); |
必须以/开头，表示当前起始节点。
输出结果：
firstName:"John"
2.2 获取对象属性
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JsonNode coordinatesNode = node.at( "/address/coordinates" ); print( "coordinatesNode" ,coordinatesNode.toString()); |
输出结果：
coordinatesNode:{"latitude":40.7250387,"longitude":-73.9932568}
2.3 获取数组属性
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JsonNode phoneNode = node.at( "/phone" ); print( "phoneNode" , phoneNode.toString()); |
输出结果：
phoneNode:["139","137"]
2.4 获取数组属性元素
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JsonNode phone1Node = node.at( "/phone/0" ); print( "phone1Node" ,phone1Node.toString()); |
输出结果：
phone1Node:"139"
2.4 获取数组对象属性
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JsonNode nameNode = node.at( "/grade/0/name" ); print( "name" ,nameNode.toString()); JsonNode scoreNode = node.at( "/grade/0/score" ); print( "score" ,scoreNode.toString()); |
输出结果：
name:"math"
score:99
Jackson 通用解析JSON方法
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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测试数据mon.collect.Lists; import lombok.extern.slf4j.Slf4j; import org.apache测试数据mons.lang3.StringUtils; import java.io.IOException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; /** * json 解析类，通用于全项目 * <p/> * Created by 刘一波 on 15/7/24. * E-Mail:zhanlanstar@163测试数据 */ @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 ); objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false ); SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" ); objectMapper.setDateFormat(sdf); } /** * 提供给elasticsearch使用，把bean转换成list map 集合类型，否则不能存入索引 * * @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 { // 指定容器结构和类型（这里是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，从Json到List报错" , 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，从Json到HashMap报错" , e); } return new HashMap(); } } |
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
原文链接：https://blog.csdn.net/neweastsun/article/details/106530134
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