java 在java中检索嵌套json中的所有键
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时间：2020-10-31 16:51:11 来源:igfitidea点击:
Retrieving all the keys in a nested json in java
提问by Aayush
This is the program i wrote:
这是我写的程序：
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package javaapplication1;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.StringTokenizer;
import net.sf.json.JSONException;
import net.sf.json.JSONObject;
/**
*
* @author 311001
*/
public class NewClass {
public static void main(String args[]) {
JSONObject parentData = new JSONObject();
JSONObject childData = new JSONObject();
try {
parentData.put("command", "login");
parentData.put("uid", "123123123");
childData.put("uid", "007");
childData.put("username", "sup");
childData.put("password", "bros");
parentData.put("params", childData);
System.out.println(parentData);
Map<String, String> map = new HashMap<>();
Iterator<?> iter = parentData.keys();
while (iter.hasNext()) {
String key = (String) iter.next();
String value = parentData.getString(key);
map.put(key, value);
}
for (Entry<String, String> entry : map.entrySet()) {
System.out.println("key > " + entry.getKey() + " : value = " + entry.getValue());
}
String testData = map.get("params.uid");
System.out.println(testData);
System.out.println("Tokenizing json");
String resultStr = parentData.toString();
System.out.println("String tokens ");
StringTokenizer st = new StringTokenizer(resultStr);
System.out.println(st.countTokens());
while (st.hasMoreTokens()) {
System.out.println(st.nextToken());
}
String testDat="abc :: result";
StringTokenizer simpleString = new StringTokenizer(testDat);
System.out.println("Tokenizing simple string");
System.out.println(simpleString.countTokens());
while (simpleString.hasMoreTokens()) {
System.out.println(simpleString.nextToken());
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
the output i got:
我得到的输出：
run:
{"command":"login","uid":"123123123","params":{"uid":"007","username":"sup","password":"bros"}}
key > uid : value = 123123123
key > command : value = login
key > params : value = {"uid":"007","username":"sup","password":"bros"}
null
Tokenizing json
String tokens
1
{"command":"login","uid":"123123123","params":{"uid":"007","username":"sup","password":"bros"}}
Tokenizing simple string
3
abc
::
result
BUILD SUCCESSFUL (total time: 0 seconds)
How can I recieve all the keys in my json object. In case I tokenize why do i get only one string token while for a simple string am getting the correct output 3 tokens.
我怎样才能收到我的 json 对象中的所有键。如果我标记化为什么我只得到一个字符串标记，而对于一个简单的字符串，我会得到正确的输出 3 个标记。
回答by faizan
You can recursively traverse your JsonObject to get all keys. heres the pseudocode
您可以递归遍历 JsonObject 以获取所有键。这是伪代码
findKeys(JsonObject obj,List keys){
List<String>keysFromObj=obj.keys();
keys.addAll(keysFromObj);
for(String key:keysFromObj){
if(obj.get(key).getClass()==JSONObject.class){
findKeys(obj.get(key),keys);
}
}
}
So suppose if your object is {"a":1,"b":{"c":"hello","d":4.0}} the above function should give you ["a","b","c","d"]
所以假设你的对象是 {"a":1,"b":{"c":"hello","d":4.0}} 上面的函数应该给你 ["a","b","c ","d"]
But if you want only ["a","c","d"] as your output,you can write-
但是如果你只想要 ["a","c","d"] 作为你的输出，你可以写 -
findKeys(JsonObject obj,List keys){
List<String>keysFromObj=obj.keys();
for(String key:keysFromObj){
if(obj.get(key).getClass()==JSONObject.class){
findKeys(obj.get(key),keys);
}else{
keys.add(key);
}
}
}
回答by mattyman
Here is one implementation using org.jsonnot org.json.simple
这是使用org.json而不是 org.json.simple 的一种实现
It finds all unique values of a json with the Key:value combination using java.
它使用 Java 查找具有 Key:value 组合的 json 的所有唯一值。
Input json:
输入json：
{
d: {
results: [{
__metadata: {
uri:https://google.com,
type: User
},
userId: jmarthens1,
businessPhone: null,
salaryProrating: null,
empId: 2023,
lastModifiedDateTime: Date(1458308558000 + 0000),
finalJobRole: null,
username: jmarthens,
married: false,
futureLeader: null,
salary: 79000.0,
jobRole: Program Manager,
Professional Services,
nickname: null,
salaryLocal: null
}]
}
}
Result:
结果：
empId-2023
lastModifiedDateTime-Date(1458308558000+0000)
salary-79000.0
userId-jmarthens1
jobRole-Program Manager, Professional Services
type-User
uri-https://google.com
username-jmarthens
Code:
代码：
package test;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class TestClass {
private static StringBuilder strOut = new StringBuilder();
public static void main(String[] args) {
try {
String json = "{\"d\" : {\"results\" : [{\"__metadata\" : {\"uri\" : \"https://apisalesdemo8.successfactors.com:443/odata/v2/User('jmarthens1')\","
+ " \"type\" : \"SFOData.User\"}, \"userId\" : \"jmarthens1\", \"businessPhone\" : null, \"salaryProrating\" : null, \"empId\" : \"2023\", "
+ "\"lastModifiedDateTime\" : \"Date(1458308558000+0000)\", \"finalJobRole\" : null, \"username\" : \"jmarthens\", \"married\" : false, "
+ "\"futureLeader\" : null, \"salary\" : \"79000.0\", \"jobRole\" : \"Program Manager, Professional Services\", \"nickname\" : null, \"salaryLocal\" : null}]}}";
JSONObject inputJson = new JSONObject(json);
List<String> lst = new ArrayList<String>();
lst = findKeysOfJsonObject(inputJson, lst);
try (BufferedWriter writer = new BufferedWriter(new FileWriter("C:\temp\temp.txt"))) {
writer.write(strOut.toString());
}
} catch (JSONException | IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static List<String> findKeysOfJsonArray(JSONArray jsonIn, List<String> keys) {
List<String> keysFromArr = new ArrayList<>();
if (jsonIn != null && jsonIn.length() != 0) {
for (int i = 0; i < jsonIn.length(); i++) {
JSONObject jsonObjIn = jsonIn.getJSONObject(i);
keysFromArr = findKeysOfJsonObject(jsonObjIn, keys);
}
}
return keysFromArr;
}
private static List<String> findKeysOfJsonObject(JSONObject jsonIn, List<String> keys) {
Iterator<String> itr = jsonIn.keys();
List<String> keysFromObj = makeList(itr);
keys.addAll(keysFromObj);
itr = jsonIn.keys();
while (itr.hasNext()) {
String itrStr = itr.next();
// System.out.println("out " + itrStr);
JSONObject jsout = null;
JSONArray jsArr = null;
if (jsonIn.get(itrStr).getClass() == JSONObject.class) {
jsout = jsonIn.getJSONObject(itrStr);
findKeysOfJsonObject(jsout, keys);
} else if (jsonIn.get(itrStr).getClass() == JSONArray.class) {
jsArr = jsonIn.getJSONArray(itrStr);
keys.addAll(findKeysOfJsonArray(jsArr, keys));
} else if (jsonIn.get(itrStr).getClass() == String.class) {
System.out.println(itrStr + "-" + jsonIn.get(itrStr));
strOut.append(itrStr + "," + jsonIn.get(itrStr));
strOut.append(System.lineSeparator());
}
}
return keys;
}
public static List<String> makeList(Iterator<String> iter) {
List<String> list = new ArrayList<String>();
while (iter.hasNext()) {
list.add(iter.next());
}
return list;
}
}
回答by Saptarshi Mitra
static Set<String> finalListOfKeys = new LinkedHashSet<String>();
public static void main(String[] args) {
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("Absolute path of json file"));
JSONObject jsonObject = (JSONObject) obj;
Set<String> jsonKeys = jsonObject.keySet();
for (String key : jsonKeys) {
Object val = jsonObject.get(key);
if (val instanceof JSONArray) {
JSONArray array = (JSONArray) val;
jsonArray(array, key);
} else if (val instanceof JSONObject) {
JSONObject jsonOb = (JSONObject) val;
jsonObj(jsonOb, key);
} else {
finalListOfKeys.add(key);
System.out.println("Key is : " + key);
}
}
System.out.println("Final List : " + finalListOfKeys);
} catch (Exception e) {
e.printStackTrace();
}
}
public static void jsonObj(JSONObject object, String key2) {
Set<String> innerKeys = object.keySet();
System.out.println("Inner Keys : " + innerKeys);
for (String key : innerKeys) {
System.out.println("Key : " + key);
Object val = object.get(key);
if (val instanceof JSONArray) {
JSONArray array = (JSONArray) val;
jsonArray(array, key2 + "->" + key);
} else if (val instanceof JSONObject) {
JSONObject jsonOb = (JSONObject) val;
jsonObj(jsonOb, key2 + "->" + key);
} else {
finalListOfKeys.add(key2 + "->" + key);
System.out.println("Key is : " + key2 + "->" + key);
}
}
}
public static void jsonArray(JSONArray array, String key) {
if (array.size() == 0) {
finalListOfKeys.add(key);
} else {
for (int i = 0; i < array.size(); i++) {
Object jObject = array.get(i);
if (jObject instanceof JSONObject) {
JSONObject job = (JSONObject) jObject;
System.out.println(job);
jsonObj(job, key);
}
}
}
}
