如何在 Java 中修改 JSON 对象内的值答案

【问题标题】：How to modify values inside JSON object in Java如何在 Java 中修改 JSON 对象内的值
【发布时间】：2022-04-17 17:20:06
【问题描述】：

我有一个像这样的 JSON 对象。

{
   "result":{
      "issue_date":"20-02-2011",
      "father/husband":"Chopra",
      "name":"Variyar",
      
 "img":"/9j/4AAQSkZJRgABAQAABAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKS",
      "blood_group":"",
      "dob":"11-03-1981",
      "validity":{
         "non-transport":"24-03-2010 to 23-02-2030",
         "transport":""
      },
      "cov_details":[
         {
            "issue_date":"UNIT OFFICE,TRICHY",
            "cov":"NCWG"
         }
      ],
      "dl_number":"TN0290000784",
      "address":"PERIYA COLONY  KO PAVAZHANGUDI  VIRUDHACHALAM TK"
   },
   "request_id":"a2642ae9-2f10-4e9a-9f7e-c3ee1a9a2dbe",
   "status-code":"101"
}

我想使用 java 编辑“结果”中的“img”中的值。

obj.remove("img");
obj.put("img","N/A");

但它不起作用。我的预期输出是 Img 标签应该是这样的

 "img":"N/A",

关于如何实现这一点的任何建议？

【问题讨论】：

baeldung.com/jackson-object-mapper-tutorial
除了答案中的所有好的建议之外，您可以使用正则表达式的字符串替换，这不需要任何额外的包。虽然我不能给你确切的正则表达式来适合你的情况。
我同意@TomElias。有时，像 ObjectMapper 这样只更新 JSON 中的一个字符串值的工具是多余的。除了简单标准的字符串操作，大家可以看看这个stackoverflow.com/questions/64422516/…
对所有非常喜欢 JSON 解析器的人提出警告：1) JSON 映射严重依赖反射。这在高吞吐量系统中是非常糟糕的性能。 2) JSON 序列化器通常不是线程安全的。人们通常将对象映射器用作单例 bean，这可能是有风险的。

标签： java json

【解决方案1】：

试试这样的。以下是删除或更新数据的两个选项。使用 com.fasterxml.jackson

  String tt = "{   \"result\":{      \"issue_date\":\"20-02-2011\",      \"father/husband\":\"Chopra\",      \"name\":\"Variyar\",       \"img\":\"/9j/4AAQSkZJRgABAQAABAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKS\",      \"blood_group\":\"\",      \"dob\":\"11-03-1981\",      \"validity\":{         \"non-transport\":\"24-03-2010 to 23-02-2030\",         \"transport\":\"\"      },      \"cov_details\":[         {            \"issue_date\":\"UNIT OFFICE,TRICHY\",            \"cov\":\"NCWG\"         }      ],      \"dl_number\":\"TN0290000784\",      \"address\":\"PERIYA COLONY  KO PAVAZHANGUDI  VIRUDHACHALAM TK\"   },   \"request_id\":\"a2642ae9-2f10-4e9a-9f7e-c3ee1a9a2dbe\",   \"status-code\":\"101\"}";
         ObjectMapper mapper = new ObjectMapper();
         mapper.enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
         JsonFactory factory = mapper.getFactory();
         JsonParser createParser = factory.createParser(tt);
         JsonNode actualObj1 = mapper.readTree(createParser);
// if you just want to update
         ((ObjectNode)((ObjectNode)actualObj1).get("result")).put("img", "n/a"); 
// if you just want delete
         ((ObjectNode)((ObjectNode)actualObj1).get("result")).remove("img");
         System.out.println(actualObj1.toString());

【讨论】：

【解决方案2】：

您可以使用任何流行的 Json 序列化库将 Java 对象转换为 Json，反之亦然：

在 Jackson 的例子中，Java 中的对象看起来像这样：

package com.example;

import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
"issue_date",
"cov"
})
public class CovDetail {

@JsonProperty("issue_date")
private String issueDate;
@JsonProperty("cov")
private String cov;
@JsonIgnore
private Map<String, Object> additionalProperties = new HashMap<String, Object>();

@JsonProperty("issue_date")
public String getIssueDate() {
return issueDate;
}

@JsonProperty("issue_date")
public void setIssueDate(String issueDate) {
this.issueDate = issueDate;
}

@JsonProperty("cov")
public String getCov() {
return cov;
}

@JsonProperty("cov")
public void setCov(String cov) {
this.cov = cov;
}

@JsonAnyGetter
public Map<String, Object> getAdditionalProperties() {
return this.additionalProperties;
}

@JsonAnySetter
public void setAdditionalProperty(String name, Object value) {
this.additionalProperties.put(name, value);
}

}

package com.example;

import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
"result",
"request_id",
"status-code"
})
public class Result {

@JsonProperty("result")
private Result_ result;
@JsonProperty("request_id")
private String requestId;
@JsonProperty("status-code")
private String statusCode;
@JsonIgnore
private Map<String, Object> additionalProperties = new HashMap<String, Object>();

@JsonProperty("result")
public Result_ getResult() {
return result;
}

@JsonProperty("result")
public void setResult(Result_ result) {
this.result = result;
}

@JsonProperty("request_id")
public String getRequestId() {
return requestId;
}

@JsonProperty("request_id")
public void setRequestId(String requestId) {
this.requestId = requestId;
}

@JsonProperty("status-code")
public String getStatusCode() {
return statusCode;
}

@JsonProperty("status-code")
public void setStatusCode(String statusCode) {
this.statusCode = statusCode;
}

@JsonAnyGetter
public Map<String, Object> getAdditionalProperties() {
return this.additionalProperties;
}

@JsonAnySetter
public void setAdditionalProperty(String name, Object value) {
this.additionalProperties.put(name, value);
}

}

package com.example;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
"issue_date",
"father/husband",
"name",
"img",
"blood_group",
"dob",
"validity",
"cov_details",
"dl_number",
"address"
})
public class Result_ {

@JsonProperty("issue_date")
private String issueDate;
@JsonProperty("father/husband")
private String fatherHusband;
@JsonProperty("name")
private String name;
@JsonProperty("img")
private String img;
@JsonProperty("blood_group")
private String bloodGroup;
@JsonProperty("dob")
private String dob;
@JsonProperty("validity")
private Validity validity;
@JsonProperty("cov_details")
private List<CovDetail> covDetails = null;
@JsonProperty("dl_number")
private String dlNumber;
@JsonProperty("address")
private String address;
@JsonIgnore
private Map<String, Object> additionalProperties = new HashMap<String, Object>();

@JsonProperty("issue_date")
public String getIssueDate() {
return issueDate;
}

@JsonProperty("issue_date")
public void setIssueDate(String issueDate) {
this.issueDate = issueDate;
}

@JsonProperty("father/husband")
public String getFatherHusband() {
return fatherHusband;
}

@JsonProperty("father/husband")
public void setFatherHusband(String fatherHusband) {
this.fatherHusband = fatherHusband;
}

@JsonProperty("name")
public String getName() {
return name;
}

@JsonProperty("name")
public void setName(String name) {
this.name = name;
}

@JsonProperty("img")
public String getImg() {
return img;
}

@JsonProperty("img")
public void setImg(String img) {
this.img = img;
}

@JsonProperty("blood_group")
public String getBloodGroup() {
return bloodGroup;
}

@JsonProperty("blood_group")
public void setBloodGroup(String bloodGroup) {
this.bloodGroup = bloodGroup;
}

@JsonProperty("dob")
public String getDob() {
return dob;
}

@JsonProperty("dob")
public void setDob(String dob) {
this.dob = dob;
}

@JsonProperty("validity")
public Validity getValidity() {
return validity;
}

@JsonProperty("validity")
public void setValidity(Validity validity) {
this.validity = validity;
}

@JsonProperty("cov_details")
public List<CovDetail> getCovDetails() {
return covDetails;
}

@JsonProperty("cov_details")
public void setCovDetails(List<CovDetail> covDetails) {
this.covDetails = covDetails;
}

@JsonProperty("dl_number")
public String getDlNumber() {
return dlNumber;
}

@JsonProperty("dl_number")
public void setDlNumber(String dlNumber) {
this.dlNumber = dlNumber;
}

@JsonProperty("address")
public String getAddress() {
return address;
}

@JsonProperty("address")
public void setAddress(String address) {
this.address = address;
}

@JsonAnyGetter
public Map<String, Object> getAdditionalProperties() {
return this.additionalProperties;
}

@JsonAnySetter
public void setAdditionalProperty(String name, Object value) {
this.additionalProperties.put(name, value);
}

}

package com.example;

import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
"non-transport",
"transport"
})
public class Validity {

@JsonProperty("non-transport")
private String nonTransport;
@JsonProperty("transport")
private String transport;
@JsonIgnore
private Map<String, Object> additionalProperties = new HashMap<String, Object>();

@JsonProperty("non-transport")
public String getNonTransport() {
return nonTransport;
}

@JsonProperty("non-transport")
public void setNonTransport(String nonTransport) {
this.nonTransport = nonTransport;
}

@JsonProperty("transport")
public String getTransport() {
return transport;
}

@JsonProperty("transport")
public void setTransport(String transport) {
this.transport = transport;
}

@JsonAnyGetter
public Map<String, Object> getAdditionalProperties() {
return this.additionalProperties;
}

@JsonAnySetter
public void setAdditionalProperty(String name, Object value) {
this.additionalProperties.put(name, value);
}

}

然后您可以通过运行以下代码将 Json 序列化为 Java 对象：

final ObjectMapper objectMapper = new ObjectMapper();
final Result result = objectMapper.readValue(json, Result.class);

json 变量指的是您的 Json 数据。拥有 Java 对象后，您可以简单地使用 getter 和 setter 来根据需要调整对象。

result.setRequestId("Test");

如果您想编辑 img 属性：

result.getResult().setImg("N/A");

如果您想将 Java 对象转换回 Json，您可以执行以下操作：

final ObjectMapper mapper = new ObjectMapper();
final String jsonString = mapper.writeValueAsString(result);

Java 类的来源：http://www.jsonschema2pojo.org/

【讨论】：

【解决方案3】：

使用简单 org.json 库的解决方案（*不使用 POJO 类）

import org.json.JSONObject;

public class Test {

    public static void main(String[] args) {
        String jsonArray = "{\n" +
                "   \"result\":{\n" +
                "      \"issue_date\":\"20-02-2011\",\n" +
                "      \"father/husband\":\"Chopra\",\n" +
                "      \"name\":\"Variyar\",\n" +
                "      \n" +
                " \"img\":\"/9j/4AAQSkZJRgABAQAABAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKS\",\n" +
                "      \"blood_group\":\"\",\n" +
                "      \"dob\":\"11-03-1981\",\n" +
                "      \"validity\":{\n" +
                "         \"non-transport\":\"24-03-2010 to 23-02-2030\",\n" +
                "         \"transport\":\"\"\n" +
                "      },\n" +
                "      \"cov_details\":[\n" +
                "         {\n" +
                "            \"issue_date\":\"UNIT OFFICE,TRICHY\",\n" +
                "            \"cov\":\"NCWG\"\n" +
                "         }\n" +
                "      ],\n" +
                "      \"dl_number\":\"TN0290000784\",\n" +
                "      \"address\":\"PERIYA COLONY  KO PAVAZHANGUDI  VIRUDHACHALAM TK\"\n" +
                "   },\n" +
                "   \"request_id\":\"a2642ae9-2f10-4e9a-9f7e-c3ee1a9a2dbe\",\n" +
                "   \"status-code\":\"101\"\n" +
                "}";
        JSONObject jObject = new JSONObject(jsonArray);
        jObject.getJSONObject("result").put("img", "N/A");
        System.out.println(jObject);
    }

}

输出：

 {
   "result":{
      "cov_details":[
         {
            "issue_date":"UNIT OFFICE,TRICHY",
            "cov":"NCWG"
         }
      ],
      "img":"N/A",
      "dl_number":"TN0290000784",
      "address":"PERIYA COLONY  KO PAVAZHANGUDI  VIRUDHACHALAM TK",
      "issue_date":"20-02-2011",
      "dob":"11-03-1981",
      "name":"Variyar",
      "blood_group":"",
      "validity":{
         "transport":"",
         "non-transport":"24-03-2010 to 23-02-2030"
      },
      "father/husband":"Chopra"
   },
   "status-code":"101",
   "request_id":"a2642ae9-2f10-4e9a-9f7e-c3ee1a9a2dbe"
}

【讨论】：

org.json JSONObject 与 jackson ObjectMapper 的性能如何？
overops.com/blog/…

【解决方案4】：

我建议使用字符串替换“img”对象如下（不管你有什么“img”值或长度）：

首先获取“img”对象值作为字符串：

String imgObject = "\"img\": \"" + json.getJSONObject("result").getString("img") + "\",";

输出将是：

"img": "/9j/4AAQSkZJRgABAQAABAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKS",

然后只提取“img”值：

imgObject = imgObject.substring(8,imgObject.length()-2);
imgObject = imgObject.replace("\",","");

输出将是：

/9j/4AAQSkZJRgABAQAABAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKS

将原来的Json转成字符串：

String convertedJson = json.toString();

将“img”替换为“N/A”：

convertedJson = convertedJson.replace(imgObject,"N/A");

转换回 JSONObject：
```
json = new JSONObject(convertedJson);
```

就是这样。

完整代码：

        JSONObject json = new JSONObject("{\n" +
            "   \"result\":{\n" +
            "      \"issue_date\":\"20-02-2011\",\n" +
            "      \"father/husband\":\"Chopra\",\n" +
            "      \"name\":\"Variyar\",\n" +
            "      \n" +
            " \"img\":\"/9j/4AAQSkZJRgABAQAABAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKS\",\n" +
            "      \"blood_group\":\"\",\n" +
            "      \"dob\":\"11-03-1981\",\n" +
            "      \"validity\":{\n" +
            "         \"non-transport\":\"24-03-2010 to 23-02-2030\",\n" +
            "         \"transport\":\"\"\n" +
            "      },\n" +
            "      \"cov_details\":[\n" +
            "         {\n" +
            "            \"issue_date\":\"UNIT OFFICE,TRICHY\",\n" +
            "            \"cov\":\"NCWG\"\n" +
            "         }\n" +
            "      ],\n" +
            "      \"dl_number\":\"TN0290000784\",\n" +
            "      \"address\":\"PERIYA COLONY  KO PAVAZHANGUDI  VIRUDHACHALAM TK\"\n" +
            "   },\n" +
            "   \"request_id\":\"a2642ae9-2f10-4e9a-9f7e-c3ee1a9a2dbe\",\n" +
            "   \"status-code\":\"101\"\n" +
            "}");

    System.out.println("Original img value: "+ json.getJSONObject("result").getString("img"));

    //SubString the img object:
    String imgObject = "\"img\": \"" + json.getJSONObject("result").getString("img") + "\",";
    System.out.println("img object key and value: "+imgObject);

    imgObject = imgObject.substring(8,imgObject.length()-2);
    imgObject = imgObject.replace("\",","");

    System.out.println("img object only value: "+imgObject);

    //convert json to string:
    String convertedJson = json.toString();

    //replace img
    convertedJson = convertedJson.replace(imgObject,"N/A");


    //convert back to JSONObject
    json = new JSONObject(convertedJson);

    System.out.println("Converted Json with new img value: "+ json.getJSONObject("result").getString("img"));

【讨论】：

它在此代码本身的第一行抛出错误不兼容的类型：字符串无法转换为映射
我已经导入了 import org.json.simple.JSONObject;导入 org.json.simple.parser.JSONParser；还有什么需要吗？
这是因为需要导入org.json.JSONObject;

【解决方案5】：

try {
        com.fasterxml.jackson.databind.ObjectMapper mapper = new com.fasterxml.jackson.databind.ObjectMapper();
        java.util.LinkedHashMap obj = (java.util.LinkedHashMap) mapper.readValue(jsonString, Object.class);
        java.util.LinkedHashMap result = (java.util.LinkedHashMap) obj.get("result");
        result.put("img", "YOUR_VALUE");
        java.io.ByteArrayOutputStream bout = new java.io.ByteArrayOutputStream();
        mapper.writeValue(bout, obj);
        byte[] objectBytes = bout.toByteArray();
        jsonString = new String(objectBytes);
    } catch (java.io.IOException e) {
        e.printStackTrace();
    }

【讨论】：