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使用Java解析JSON数据并提取特定字段：以提取`mailNo`为例

使用Java解析JSON数据并提取特定字段：以提取mailNo为例在现代软件开发中，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：

代码语言：javascript复制

com.fasterxml.jackson.core

jackson-databind

2.13.3

如果你使用Gradle构建项目，可以在build.gradle中添加以下依赖：

代码语言：javascript复制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：

代码语言：javascript复制{

"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。

代码语言：javascript复制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 extractMailNos(String json) throws IOException {

ObjectMapper objectMapper = new ObjectMapper();

JsonNode rootNode = objectMapper.readTree(json);

JsonNode recordsNode = rootNode.path("result").path("records");

List mailNos = new ArrayList<>();

for (JsonNode record : recordsNode) {

String mailNo = record.path("mailNo").asText();

mailNos.add(mailNo);

}

return mailNos;

}

public static void main(String[] args) {

/*

* 提示：该行代码过长，系统自动注释不进行高亮。一键复制会移除系统注释

* 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 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。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：

代码语言：javascript复制SF3150804745040

SF31508093450594. 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！如果你有任何问题或建议，欢迎在评论区留言。