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.common.collect.Lists;import lombok.extern.slf4j.Slf4j;import org.apache.commons.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.com */@Slf4jpublic 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服务器之家。
原文链接：https://blog.csdn.net/neweastsun/article/details/106530134
