使用Java解析JSON数据并提取特定字段的实现步骤(以提取mailNo为例)
作者：码农阿豪@新空间代码工作室
在现代软件开发中,处理JSON数据是一项非常常见的任务,无论是从API接口获取数据,还是将数据存储为JSON格式,解析和提取JSON中的特定字段都是开发人员需要掌握的基本技能,本文将以一个实际案例为例,详细介绍如何使用Java解析JSON数据并提取其中的mailNo字段
1. 背景介绍
1.1 JSON简介
JSON（JavaScript Object Notation）是一种轻量级的数据交换格式，易于人阅读和编写，同时也易于机器解析和生成。它基于JavaScript的一个子集，但独立于语言，几乎所有的编程语言都支持JSON格式的数据处理。
1.2 实际案例
假设我们有一个JSON数据，其中包含多个订单信息，每个订单都有一个唯一的mailNo字段。我们的目标是从这个JSON数据中提取出所有的mailNo字段，并将其存储在一个列表中。
2. 准备工作
2.1 环境搭建
为了解析JSON数据，我们需要使用一个Java库。在本文中，我们将使用Jackson库，这是一个非常流行的JSON处理库，功能强大且易于使用。
2.1.1 添加依赖
如果你使用Maven构建项目，可以在pom.xml中添加以下依赖：
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.13.3</version>
</dependency>
如果你使用Gradle构建项目，可以在build.gradle中添加以下依赖：
implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.3'
2.2 JSON数据结构
以下是我们将要处理的JSON数据的示例：
{
"msg": "操作成功!",
"code": "ok",
"result": {
"records": [
{
"merchantId": 0,
"organId": 0,
"creatorId": 0,
"creatorTruename": "",
"creatorUsername": "",
"organName": "",
"merchantTruename": "",
"merchantUsername": "",
"consigneeName": "突然的自我",
"consigneePhone": "153****7763",
"consigneeTelPhone": "*******7763",
"consigneeCompany": "",
"consigneeProvinceId": 0,
"consigneeProvince": "四川省",
"consigneeCityId": 0,
"consigneeCity": "绵阳市",
"consigneeDistrictId": 0,
"consigneeDistrict": "涪城区",
"consigneeAddress": "四川省****靓妍美妆",
"sendProvinceId": 0,
"sendProvince": "贵州省",
"sendCityId": 0,
"sendCity": "遵义市",
"sendDistrictId": 0,
"sendDistrict": "红花岗区",
"senderName": "夜郎酒业",
"senderCompany": "",
"senderPhone": "155****7773",
"senderTelPhone": "*******7773",
"senderDetailAddress": "贵州省****中转仓库",
"mailNo": "SF3150804745040",
"subWaybillNoList": [],
"waybillStatus": 50,
"printSerialNumber": "",
"printStatus": 0,
"printNumber": 0,
"orderValueAddedVo": null,
"addedServiceCodes": [],
"callFlag": "",
"consignment": "夜郎酱宏图纯粮食大曲坤沙酒酱香型白酒礼盒装53度500ml",
"consignmentNumber": 2,
"parcelWeight": "2.0",
"parcelWeightUnit": "2.0",
"parcelQuantity": 1,
"meterageWeightQty": "2.0",
"realWeightQty": "2.0",
"orderNo": "6938567762089547327|2kBWWcmNUwX2SZ",
"originalOrderNo": "",
"signBackNo": "",
"remark": "",
"orderCreateTime": "2025-01-10 15:29:41",
"waybillCreateTime": "2025-01-10 15:29:41",
"printTime": null,
"isShowExcludeFile": 0,
"freight": "1000.0",
"referenceCost": "",
"waybillNums": 1,
"status": "",
"exceptionFlag": 0,
"promiseTime": "",
"receiveTime": "2025-01-10 16:16:55",
"signTime": "2025-01-11 14:13:40",
"latestRouteInfo": "您的快件已由本人签收，如有疑问请电联快递员【杨发斌，电话：13330891935】。您的体验对于我们至关重要，如果您对我们的服务有任何的想法和建议，请随时联系我们，我们一定用心倾听，全力改进，不辜负您的信任与支持。",
"latestOpCode": "80",
"expressProductId": 0,
"expressProductCode": "B1",
"expressProductName": "电商标快",
"expressPayMethod": 1,
"expressPayMethodName": "寄付月结",
"monthlyCard": "052***6969",
"orderType": 1,
"customField1": "",
"customField2": "",
"customField3": "",
"amount": "",
"collectionAmount": "",
"collectingNumber": "",
"oldCollectingMoney": "",
"exceptionCode": "",
"orderId": 0,
"waybillId": 0,
"isUpdateWaybill": 0,
"mergeOrderType": 2,
"isDraft": null,
"failCause": "",
"orderCrossBorderGoodsVoList": [
{
"productCode": "",
"productName": "夜郎酱宏图纯粮食大曲坤沙酒酱香型白酒礼盒装53度500ml",
"price": 0.0,
"currencyCode": "",
"currencyName": "",
"unit": "",
"productNumber": 2.0,
"orderType": 0,
"countryOfOrigin": ""
}
],
"gangAoTaiExtVo": null,
"swFlag": 0,
"sendStatus": 1,
"sendStatusName": "获取成功",
"expressCompanyMerchantId": 0,
"totalLength": 41.0,
"totalHeight": 1.0,
"totalWidth": 1.0,
"addedValueServiceInfo": {
"insuredType": 0,
"insuredPrice": null,
"collectingMoney": null,
"collectingMonthlyCard": "",
"signBackName": [],
"signBackNo": "",
"signBackWaybillStatus": 0,
"signBackOrderType": [],
"signBackRouteList": [],
"isSignBack": 0,
"signBackRemark": "",
"signBackNum": 0,
"thirdSignBack": 0,
"thirdConsigneeName": "",
"thirdConsigneePhone": "",
"thirdConsigneeTel": "",
"thirdConsigneeProvince": "",
"thirdConsigneeCity": "",
"thirdConsigneeArea": "",
"thirdConsigneeAddress": "",
"thirdConsigneeCompany": "",
"takePhotoBack": [],
"takePhotoNum": 0,
"takePhotoBackRemark": "",
"timingSendInformType": 0,
"timingSendInformDate": "",
"timingSendInformTime": "",
"electronicBack": 0,
"secretKeyAuthentication": "",
"secretKeyAuthenticationValue": "",
"woodenPackage": 0,
"woodenPackageInfo": "",
"readySend": 0,
"woodenRemovalNum": 0,
"packagingService": "",
"packagingMaterialVos": [],
"overweightService": 0,
"timingInsured": 0,
"freshService": 0,
"homeDeliveryExt": [],
"installationType": 0,
"installationContent": [],
"selfPickup": 0,
"exhibitionService": 0,
"exhibitionExitService": 0,
"addedServiceCodes": [],
"customDeliveryTime": ""
},
"signBackInfo": "",
"signBackNum": "",
"pickupAppointTime": "",
"consValueCurrencyCode": "",
"exportDeclarationMethod": "",
"customsBatchs": "",
"taxAccount": "",
"taxPaymentType": "",
"custReferenceNo": "",
"isSignBack": 0,
"signBackRemark": "",
"cancelTime": null
},
{
"merchantId": 0,
"organId": 0,
"creatorId": 0,
"creatorTruename": "",
"creatorUsername": "",
"organName": "",
"merchantTruename": "",
"merchantUsername": "",
"consigneeName": "**",
"consigneePhone": "157*********2541",
"consigneeTelPhone": "************2541",
"consigneeCompany": "",
"consigneeProvinceId": 0,
"consigneeProvince": "贵州省",
"consigneeCityId": 0,
"consigneeCity": "贵阳市",
"consigneeDistrictId": 0,
"consigneeDistrict": "修文县",
"consigneeAddress": "贵州省****兽霸鞋店",
"sendProvinceId": 0,
"sendProvince": "贵州省",
"sendCityId": 0,
"sendCity": "遵义市",
"sendDistrictId": 0,
"sendDistrict": "红花岗区",
"senderName": "小包",
"senderCompany": "",
"senderPhone": "155****1949",
"senderTelPhone": "*******1949",
"senderDetailAddress": "贵州省****菜鸟驿站",
"mailNo": "SF3150809345059",
"subWaybillNoList": [],
"waybillStatus": 50,
"printSerialNumber": "",
"printStatus": 0,
"printNumber": 0,
"orderValueAddedVo": null,
"addedServiceCodes": [],
"callFlag": "",
"consignment": "2024男鞋男士舒适时尚百搭黑色41",
"consignmentNumber": 1,
"parcelWeight": "2.5",
"parcelWeightUnit": "2.5",
"parcelQuantity": 1,
"meterageWeightQty": "2.5",
"realWeightQty": "2.5",
"orderNo": "6938535195456968508|6780cc24dd560100",
"originalOrderNo": "",
"signBackNo": "",
"remark": "驴孤品42码",
"orderCreateTime": "2025-01-10 15:28:59",
"waybillCreateTime": "2025-01-10 15:28:59",
"printTime": null,
"isShowExcludeFile": 0,
"freight": "1000.0",
"referenceCost": "",
"waybillNums": 1,
"status": "",
"exceptionFlag": 0,
"promiseTime": "",
"receiveTime": "2025-01-10 18:42:03",
"signTime": "2025-01-11 09:40:32",
"latestRouteInfo": "您的快件已由本人签收，如有疑问请电联快递员【王昭发，电话：18143512989】。您的体验对于我们至关重要，如果您对我们的服务有任何的想法和建议，请随时联系我们，我们一定用心倾听，全力改进，不辜负您的信任与支持。",
"latestOpCode": "80",
"expressProductId": 0,
"expressProductCode": "B1",
"expressProductName": "电商标快",
"expressPayMethod": 1,
"expressPayMethodName": "寄付月结",
"monthlyCard": "052***6969",
"orderType": 1,
"customField1": "",
"customField2": "",
"customField3": "",
"amount": "",
"collectionAmount": "",
"collectingNumber": "",
"oldCollectingMoney": "",
"exceptionCode": "",
"orderId": 0,
"waybillId": 0,
"isUpdateWaybill": 0,
"mergeOrderType": 2,
"isDraft": null,
"failCause": "",
"orderCrossBorderGoodsVoList": [
{
"productCode": "",
"productName": "2024男鞋男士舒适时尚百搭黑色41",
"price": 0.0,
"currencyCode": "",
"currencyName": "",
"unit": "",
"productNumber": 1.0,
"orderType": 0,
"countryOfOrigin": ""
}
],
"gangAoTaiExtVo": null,
"swFlag": 0,
"sendStatus": 1,
"sendStatusName": "获取成功",
"expressCompanyMerchantId": 0,
"totalLength": 0.0,
"totalHeight": 0.0,
"totalWidth": 0.0,
"addedValueServiceInfo": {
"insuredType": 0,
"insuredPrice": null,
"collectingMoney": null,
"collectingMonthlyCard": "",
"signBackName": [],
"signBackNo": "",
"signBackWaybillStatus": 0,
"signBackOrderType": [],
"signBackRouteList": [],
"isSignBack": 0,
"signBackRemark": "",
"signBackNum": 0,
"thirdSignBack": 0,
"thirdConsigneeName": "",
"thirdConsigneePhone": "",
"thirdConsigneeTel": "",
"thirdConsigneeProvince": "",
"thirdConsigneeCity": "",
"thirdConsigneeArea": "",
"thirdConsigneeAddress": "",
"thirdConsigneeCompany": "",
"takePhotoBack": [],
"takePhotoNum": 0,
"takePhotoBackRemark": "",
"timingSendInformType": 0,
"timingSendInformDate": "",
"timingSendInformTime": "",
"electronicBack": 0,
"secretKeyAuthentication": "",
"secretKeyAuthenticationValue": "",
"woodenPackage": 0,
"woodenPackageInfo": "",
"readySend": 0,
"woodenRemovalNum": 0,
"packagingService": "",
"packagingMaterialVos": [],
"overweightService": 0,
"timingInsured": 0,
"freshService": 0,
"homeDeliveryExt": [],
"installationType": 0,
"installationContent": [],
"selfPickup": 0,
"exhibitionService": 0,
"exhibitionExitService": 0,
"addedServiceCodes": [],
"customDeliveryTime": ""
},
"signBackInfo": "",
"signBackNum": "",
"pickupAppointTime": "",
"consValueCurrencyCode": "",
"exportDeclarationMethod": "",
"customsBatchs": "",
"taxAccount": "",
"taxPaymentType": "",
"custReferenceNo": "",
"isSignBack": 0,
"signBackRemark": "",
"cancelTime": null
}
],
"total": 5167,
"size": 1000,
"current": 1,
"orders": [],
"searchCount": true,
"pages": 6
}
}
3. 实现步骤
3.1 创建Java类
我们将创建一个名为MailNoExtractor的Java类，用于解析JSON数据并提取mailNo字段。
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class MailNoExtractor {
public static List<String> extractMailNos(String json) throws IOException {
ObjectMapper objectMapper = new ObjectMapper();
JsonNode rootNode = objectMapper.readTree(json);
JsonNode recordsNode = rootNode.path("result").path("records");
List<String> mailNos = new ArrayList<>();
for (JsonNode record : recordsNode) {
String mailNo = record.path("mailNo").asText();
mailNos.add(mailNo);
}
return mailNos;
}
public static void main(String[] args) {
String json = "{\"msg\":\"操作成功!\",\"code\":\"ok\",\"result\":{\"records\":[{\"merchantId\":0,\"organId\":0,\"creatorId\":0,\"creatorTruename\":\"\",\"creatorUsername\":\"\",\"organName\":\"\",\"merchantTruename\":\"\",\"merchantUsername\":\"\",\"consigneeName\":\"突然的自我\",\"consigneePhone\":\"153****7763\",\"consigneeTelPhone\":\"*******7763\",\"consigneeCompany\":\"\",\"consigneeProvinceId\":0,\"consigneeProvince\":\"四川省\",\"consigneeCityId\":0,\"consigneeCity\":\"绵阳市\",\"consigneeDistrictId\":0,\"consigneeDistrict\":\"涪城区\",\"consigneeAddress\":\"四川省****靓妍美妆\",\"sendProvinceId\":0,\"sendProvince\":\"贵州省\",\"sendCityId\":0,\"sendCity\":\"遵义市\",\"sendDistrictId\":0,\"sendDistrict\":\"红花岗区\",\"senderName\":\"夜郎酒业\",\"senderCompany\":\"\",\"senderPhone\":\"155****7773\",\"senderTelPhone\":\"*******7773\",\"senderDetailAddress\":\"贵州省****中转仓库\",\"mailNo\":\"SF3150804745040\",\"subWaybillNoList\":[],\"waybillStatus\":50,\"printSerialNumber\":\"\",\"printStatus\":0,\"printNumber\":0,\"orderValueAddedVo\":null,\"addedServiceCodes\":[],\"callFlag\":\"\",\"consignment\":\"夜郎酱宏图纯粮食大曲坤沙酒酱香型白酒礼盒装53度500ml\",\"consignmentNumber\":2,\"parcelWeight\":\"2.0\",\"parcelWeightUnit\":\"2.0\",\"parcelQuantity\":1,\"meterageWeightQty\":\"2.0\",\"realWeightQty\":\"2.0\",\"orderNo\":\"6938567762089547327|2kBWWcmNUwX2SZ\",\"originalOrderNo\":\"\",\"signBackNo\":\"\",\"remark\":\"\",\"orderCreateTime\":\"2025-01-10 15:29:41\",\"waybillCreateTime\":\"2025-01-10 15:29:41\",\"printTime\":null,\"isShowExcludeFile\":0,\"freight\":\"1000.0\",\"referenceCost\":\"\",\"waybillNums\":1,\"status\":\"\",\"exceptionFlag\":0,\"promiseTime\":\"\",\"receiveTime\":\"2025-01-10 16:16:55\",\"signTime\":\"2025-01-11 14:13:40\",\"latestRouteInfo\":\"您的快件已由本人签收，如有疑问请电联快递员【杨发斌，电话：13330891935】。您的体验对于我们至关重要，如果您对我们的服务有任何的想法和建议，请随时联系我们，我们一定用心倾听，全力改进，不辜负您的信任与支持。\",\"latestOpCode\":\"80\",\"expressProductId\":0,\"expressProductCode\":\"B1\",\"expressProductName\":\"电商标快\",\"expressPayMethod\":1,\"expressPayMethodName\":\"寄付月结\",\"monthlyCard\":\"052***6969\",\"orderType\":1,\"customField1\":\"\",\"customField2\":\"\",\"customField3\":\"\",\"amount\":\"\",\"collectionAmount\":\"\",\"collectingNumber\":\"\",\"oldCollectingMoney\":\"\",\"exceptionCode\":\"\",\"orderId\":0,\"waybillId\":0,\"isUpdateWaybill\":0,\"mergeOrderType\":2,\"isDraft\":null,\"failCause\":\"\",\"orderCrossBorderGoodsVoList\":[{\"productCode\":\"\",\"productName\":\"夜郎酱宏图纯粮食大曲坤沙酒酱香型白酒礼盒装53度500ml\",\"price\":0.0,\"currencyCode\":\"\",\"currencyName\":\"\",\"unit\":\"\",\"productNumber\":2.0,\"orderType\":0,\"countryOfOrigin\":\"\"}],\"gangAoTaiExtVo\":null,\"swFlag\":0,\"sendStatus\":1,\"sendStatusName\":\"获取成功\",\"expressCompanyMerchantId\":0,\"totalLength\":41.0,\"totalHeight\":1.0,\"totalWidth\":1.0,\"addedValueServiceInfo\":{\"insuredType\":0,\"insuredPrice\":null,\"collectingMoney\":null,\"collectingMonthlyCard\":\"\",\"signBackName\":[],\"signBackNo\":\"\",\"signBackWaybillStatus\":0,\"signBackOrderType\":[],\"signBackRouteList\":[],\"isSignBack\":0,\"signBackRemark\":\"\",\"signBackNum\":0,\"thirdSignBack\":0,\"thirdConsigneeName\":\"\",\"thirdConsigneePhone\":\"\",\"thirdConsigneeTel\":\"\",\"thirdConsigneeProvince\":\"\",\"thirdConsigneeCity\":\"\",\"thirdConsigneeArea\":\"\",\"thirdConsigneeAddress\":\"\",\"thirdConsigneeCompany\":\"\",\"takePhotoBack\":[],\"takePhotoNum\":0,\"takePhotoBackRemark\":\"\",\"timingSendInformType\":0,\"timingSendInformDate\":\"\",\"timingSendInformTime\":\"\",\"electronicBack\":0,\"secretKeyAuthentication\":\"\",\"secretKeyAuthenticationValue\":\"\",\"woodenPackage\":0,\"woodenPackageInfo\":\"\",\"readySend\":0,\"woodenRemovalNum\":0,\"packagingService\":\"\",\"packagingMaterialVos\":[],\"overweightService\":0,\"timingInsured\":0,\"freshService\":0,\"homeDeliveryExt\":[],\"installationType\":0,\"installationContent\":[],\"selfPickup\":0,\"exhibitionService\":0,\"exhibitionExitService\":0,\"addedServiceCodes\":[],\"customDeliveryTime\":\"\"},\"signBackInfo\":\"\",\"signBackNum\":\"\",\"pickupAppointTime\":\"\",\"consValueCurrencyCode\":\"\",\"exportDeclarationMethod\":\"\",\"customsBatchs\":\"\",\"taxAccount\":\"\",\"taxPaymentType\":\"\",\"custReferenceNo\":\"\",\"isSignBack\":0,\"signBackRemark\":\"\",\"cancelTime\":null},{\"merchantId\":0,\"organId\":0,\"creatorId\":0,\"creatorTruename\":\"\",\"creatorUsername\":\"\",\"organName\":\"\",\"merchantTruename\":\"\",\"merchantUsername\":\"\",\"consigneeName\":\"**\",\"consigneePhone\":\"157*********2541\",\"consigneeTelPhone\":\"************2541\",\"consigneeCompany\":\"\",\"consigneeProvinceId\":0,\"consigneeProvince\":\"贵州省\",\"consigneeCityId\":0,\"consigneeCity\":\"贵阳市\",\"consigneeDistrictId\":0,\"consigneeDistrict\":\"修文县\",\"consigneeAddress\":\"贵州省****兽霸鞋店\",\"sendProvinceId\":0,\"sendProvince\":\"贵州省\",\"sendCityId\":0,\"sendCity\":\"遵义市\",\"sendDistrictId\":0,\"sendDistrict\":\"红花岗区\",\"senderName\":\"小包\",\"senderCompany\":\"\",\"senderPhone\":\"155****1949\",\"senderTelPhone\":\"*******1949\",\"senderDetailAddress\":\"贵州省****菜鸟驿站\",\"mailNo\":\"SF3150809345059\",\"subWaybillNoList\":[],\"waybillStatus\":50,\"printSerialNumber\":\"\",\"printStatus\":0,\"printNumber\":0,\"orderValueAddedVo\":null,\"addedServiceCodes\":[],\"callFlag\":\"\",\"consignment\":\"2024男鞋男士舒适时尚百搭黑色41\",\"consignmentNumber\":1,\"parcelWeight\":\"2.5\",\"parcelWeightUnit\":\"2.5\",\"parcelQuantity\":1,\"meterageWeightQty\":\"2.5\",\"realWeightQty\":\"2.5\",\"orderNo\":\"6938535195456968508|6780cc24dd560100\",\"originalOrderNo\":\"\",\"signBackNo\":\"\",\"remark\":\"驴孤品42码\",\"orderCreateTime\":\"2025-01-10 15:28:59\",\"waybillCreateTime\":\"2025-01-10 15:28:59\",\"printTime\":null,\"isShowExcludeFile\":0,\"freight\":\"1000.0\",\"referenceCost\":\"\",\"waybillNums\":1,\"status\":\"\",\"exceptionFlag\":0,\"promiseTime\":\"\",\"receiveTime\":\"2025-01-10 18:42:03\",\"signTime\":\"2025-01-11 09:40:32\",\"latestRouteInfo\":\"您的快件已由本人签收，如有疑问请电联快递员【王昭发，电话：18143512989】。您的体验对于我们至关重要，如果您对我们的服务有任何的想法和建议，请随时联系我们，我们一定用心倾听，全力改进，不辜负您的信任与支持。\",\"latestOpCode\":\"80\",\"expressProductId\":0,\"expressProductCode\":\"B1\",\"expressProductName\":\"电商标快\",\"expressPayMethod\":1,\"expressPayMethodName\":\"寄付月结\",\"monthlyCard\":\"052***6969\",\"orderType\":1,\"customField1\":\"\",\"customField2\":\"\",\"customField3\":\"\",\"amount\":\"\",\"collectionAmount\":\"\",\"collectingNumber\":\"\",\"oldCollectingMoney\":\"\",\"exceptionCode\":\"\",\"orderId\":0,\"waybillId\":0,\"isUpdateWaybill\":0,\"mergeOrderType\":2,\"isDraft\":null,\"failCause\":\"\",\"orderCrossBorderGoodsVoList\":[{\"productCode\":\"\",\"productName\":\"2024男鞋男士舒适时尚百搭黑色41\",\"price\":0.0,\"currencyCode\":\"\",\"currencyName\":\"\",\"unit\":\"\",\"productNumber\":1.0,\"orderType\":0,\"countryOfOrigin\":\"\"}],\"gangAoTaiExtVo\":null,\"swFlag\":0,\"sendStatus\":1,\"sendStatusName\":\"获取成功\",\"expressCompanyMerchantId\":0,\"totalLength\":0.0,\"totalHeight\":0.0,\"totalWidth\":0.0,\"addedValueServiceInfo\":{\"insuredType\":0,\"insuredPrice\":null,\"collectingMoney\":null,\"collectingMonthlyCard\":\"\",\"signBackName\":[],\"signBackNo\":\"\",\"signBackWaybillStatus\":0,\"signBackOrderType\":[],\"signBackRouteList\":[],\"isSignBack\":0,\"signBackRemark\":\"\",\"signBackNum\":0,\"thirdSignBack\":0,\"thirdConsigneeName\":\"\",\"thirdConsigneePhone\":\"\",\"thirdConsigneeTel\":\"\",\"thirdConsigneeProvince\":\"\",\"thirdConsigneeCity\":\"\",\"thirdConsigneeArea\":\"\",\"thirdConsigneeAddress\":\"\",\"thirdConsigneeCompany\":\"\",\"takePhotoBack\":[],\"takePhotoNum\":0,\"takePhotoBackRemark\":\"\",\"timingSendInformType\":0,\"timingSendInformDate\":\"\",\"timingSendInformTime\":\"\",\"electronicBack\":0,\"secretKeyAuthentication\":\"\",\"secretKeyAuthenticationValue\":\"\",\"woodenPackage\":0,\"woodenPackageInfo\":\"\",\"readySend\":0,\"woodenRemovalNum\":0,\"packagingService\":\"\",\"packagingMaterialVos\":[],\"overweightService\":0,\"timingInsured\":0,\"freshService\":0,\"homeDeliveryExt\":[],\"installationType\":0,\"installationContent\":[],\"selfPickup\":0,\"exhibitionService\":0,\"exhibitionExitService\":0,\"addedServiceCodes\":[],\"customDeliveryTime\":\"\"},\"signBackInfo\":\"\",\"signBackNum\":\"\",\"pickupAppointTime\":\"\",\"consValueCurrencyCode\":\"\",\"exportDeclarationMethod\":\"\",\"customsBatchs\":\"\",\"taxAccount\":\"\",\"taxPaymentType\":\"\",\"custReferenceNo\":\"\",\"isSignBack\":0,\"signBackRemark\":\"\",\"cancelTime\":null}],\"total\":5167,\"size\":1000,\"current\":1,\"orders\":[],\"searchCount\":true,\"pages\":6}}";
try {
List<String> mailNos = extractMailNos(json);
for (String mailNo : mailNos) {
System.out.println(mailNo);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
3.2 代码解析
3.2.1 extractMailNos 方法
- 功能：该方法接收一个JSON字符串作为输入，使用Jackson库解析JSON，并提取出所有
mailNo字段的值，返回一个包含所有mailNo的列表。 - 步骤：
- 使用
ObjectMapper将JSON字符串解析为JsonNode对象。 - 通过
path方法获取result节点下的records数组。 - 遍历
records数组，提取每个记录中的mailNo字段，并将其添加到列表中。
- 使用
3.2.2 main 方法
- 功能：这是一个简单的测试方法，展示了如何使用
extractMailNos方法来提取mailNo并打印出来。 - 步骤：
- 定义一个JSON字符串。
- 调用
extractMailNos方法提取mailNo。 - 遍历并打印所有
mailNo。
3.3 运行结果
运行上述代码后，输出结果如下：
SF3150804745040
SF3150809345059
4. 总结
本文详细介绍了如何使用Java解析JSON数据并提取特定字段。通过使用Jackson库，我们可以轻松地处理复杂的JSON数据结构，并提取出我们需要的字段。这个工具类可以根据实际需求进一步扩展和优化，例如添加异常处理、支持更多字段的提取等。
希望本文对你理解和使用Java处理JSON数据有所帮助！
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