Java 中将 JSON 字符串转换为 HashMap

我使用 Java，我有一个 JSON 字符串:

{
"name" : "abc" ,
"email id " : ["abc@gmail.com","def@gmail.com","ghi@gmail.com"]
}

然后是我的Java地图:

Map retMap = new HashMap();

我想把所有来自JSONObject的数据存储在那个HashMap中。

有人能为此提供代码吗?我想使用org.json库。

492330 次浏览
小开

您可以使用谷歌gson库转换json对象。

https://code.google.com/p/google-gson/‎

其他图书馆如Jackson也可以使用。

这不会将其转换为映射。但是你可以做任何你想做的事情。

小开

使用Gson，你可以做以下事情:

Map<String, Object> retMap = new Gson().fromJson(
jsonString, new TypeToken<HashMap<String, Object>>() {}.getType()
);
小开
最佳答案

递归方式:

public static Map<String, Object> jsonToMap(JSONObject json) throws JSONException {
Map<String, Object> retMap = new HashMap<String, Object>();
    

if(json != JSONObject.NULL) {
retMap = toMap(json);
}
return retMap;
}


public static Map<String, Object> toMap(JSONObject object) throws JSONException {
Map<String, Object> map = new HashMap<String, Object>();


Iterator<String> keysItr = object.keys();
while(keysItr.hasNext()) {
String key = keysItr.next();
Object value = object.get(key);
        

if(value instanceof JSONArray) {
value = toList((JSONArray) value);
}
        

else if(value instanceof JSONObject) {
value = toMap((JSONObject) value);
}
map.put(key, value);
}
return map;
}


public static List<Object> toList(JSONArray array) throws JSONException {
List<Object> list = new ArrayList<Object>();
for(int i = 0; i < array.length(); i++) {
Object value = array.get(i);
if(value instanceof JSONArray) {
value = toList((JSONArray) value);
}


else if(value instanceof JSONObject) {
value = toMap((JSONObject) value);
}
list.add(value);
}
return list;
}

使用Jackson库:

import com.fasterxml.jackson.databind.ObjectMapper;


Map<String, Object> mapping = new ObjectMapper().readValue(jsonStr, HashMap.class);
小开

以下是移植到JSR 353的Vikas代码:

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;


import javax.json.JsonArray;
import javax.json.JsonException;
import javax.json.JsonObject;


public class JsonUtils {
public static Map<String, Object> jsonToMap(JsonObject json) {
Map<String, Object> retMap = new HashMap<String, Object>();


if(json != JsonObject.NULL) {
retMap = toMap(json);
}
return retMap;
}


public static Map<String, Object> toMap(JsonObject object) throws JsonException {
Map<String, Object> map = new HashMap<String, Object>();


Iterator<String> keysItr = object.keySet().iterator();
while(keysItr.hasNext()) {
String key = keysItr.next();
Object value = object.get(key);


if(value instanceof JsonArray) {
value = toList((JsonArray) value);
}


else if(value instanceof JsonObject) {
value = toMap((JsonObject) value);
}
map.put(key, value);
}
return map;
}


public static List<Object> toList(JsonArray array) {
List<Object> list = new ArrayList<Object>();
for(int i = 0; i < array.size(); i++) {
Object value = array.get(i);
if(value instanceof JsonArray) {
value = toList((JsonArray) value);
}


else if(value instanceof JsonObject) {
value = toMap((JsonObject) value);
}
list.add(value);
}
return list;
}
}
小开

最新更新:我已经使用FasterXML Jackson Databind2.12.3转换JSON字符串映射，映射到JSON字符串。

// javax.ws.rs.core.Response clientresponse = null; // Read JSON with Jersey 2.0 (JAX-RS 2.0)
// String json_string = clientresponse.readEntity(String.class);
String json_string = "[\r\n"
+ "{\"domain\":\"stackoverflow.com\", \"userId\":5081877, \"userName\":\"Yash\"},\r\n"
+ "{\"domain\":\"stackoverflow.com\", \"userId\":6575754, \"userName\":\"Yash\"}\r\n"
+ "]";
System.out.println("Input/Response JSON string:"+json_string);
ObjectMapper mapper = new com.fasterxml.jackson.databind.ObjectMapper();
//java.util.Map<String, String> map = mapper.readValue(json_string, java.util.Map.class);
List<Map<String, Object>> listOfMaps = mapper.readValue(json_string, new com.fasterxml.jackson.core.type.TypeReference< List<Map<String, Object>>>() {});


System.out.println("fasterxml JSON string to List of Map:"+listOfMaps);


String json = mapper.writeValueAsString(listOfMaps);
System.out.println("fasterxml List of Map to JSON string:[compact-print]"+json);


json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(listOfMaps);
System.out.println("fasterxml List of Map to JSON string:[pretty-print]"+json);

输出:

Input/Response JSON string:[
{"domain":"stackoverflow.com", "userId":5081877, "userName":"Yash"},
{"domain":"stackoverflow.com", "userId":6575754, "userName":"Yash"}
]
fasterxml JSON string to List of Map:[{domain=stackoverflow.com, userId=5081877, userName=Yash}, {domain=stackoverflow.com, userId=6575754, userName=Yash}]
fasterxml List of Map to JSON string:[compact-print][{"domain":"stackoverflow.com","userId":5081877,"userName":"Yash"},{"domain":"stackoverflow.com","userId":6575754,"userName":"Yash"}]
fasterxml List of Map to JSON string:[pretty-print][ {
"domain" : "stackoverflow.com",
"userId" : 5081877,
"userName" : "Yash"
}, {
"domain" : "stackoverflow.com",
"userId" : 6575754,
"userName" : "Yash"
} ]

将JSON字符串转换为Map

public static java.util.Map<String, Object> jsonString2Map( String jsonString ) throws org.json.JSONException {
Map<String, Object> keys = new HashMap<String, Object>();
    

org.json.JSONObject jsonObject = new org.json.JSONObject( jsonString ); // HashMap
java.util.Iterator<?> keyset = jsonObject.keys(); // HM
    

while (keyset.hasNext()) {
String key =  (String) keyset.next();
Object value = jsonObject.get(key);
System.out.print("\n Key : "+key);
if ( value instanceof org.json.JSONObject ) {
System.out.println("Incomin value is of JSONObject : ");
keys.put( key, jsonString2Map( value.toString() ));
} else if ( value instanceof org.json.JSONArray) {
org.json.JSONArray jsonArray = jsonObject.getJSONArray(key);
//JSONArray jsonArray = new JSONArray(value.toString());
keys.put( key, jsonArray2List( jsonArray ));
} else {
keyNode( value);
keys.put( key, value );
}
}
return keys;
}

将JSON数组转换为列表

public static java.util.List<Object> jsonArray2List( org.json.JSONArray arrayOFKeys ) throws org.json.JSONException {
System.out.println("Incoming value is of JSONArray : =========");
java.util.List<Object> array2List = new java.util.ArrayList<Object>();
for ( int i = 0; i < arrayOFKeys.length(); i++ )  {
if ( arrayOFKeys.opt(i) instanceof org.json.JSONObject ) {
Map<String, Object> subObj2Map = jsonString2Map(arrayOFKeys.opt(i).toString());
array2List.add(subObj2Map);
} else if ( arrayOFKeys.opt(i) instanceof org.json.JSONArray ) {
java.util.List<Object> subarray2List = jsonArray2List((org.json.JSONArray) arrayOFKeys.opt(i));
array2List.add(subarray2List);
} else {
keyNode( arrayOFKeys.opt(i) );
array2List.add( arrayOFKeys.opt(i) );
}
}
return array2List;
}
public static Object keyNode(Object o) {
if (o instanceof String || o instanceof Character) return (String) o;
else if (o instanceof Number) return (Number) o;
else return o;
}

显示任意格式的JSON

public static void displayJSONMAP( Map<String, Object> allKeys ) throws Exception{
Set<String> keyset = allKeys.keySet(); // HM$keyset
if (! keyset.isEmpty()) {
Iterator<String> keys = keyset.iterator(); // HM$keysIterator
while (keys.hasNext()) {
String key = keys.next();
Object value = allKeys.get( key );
if ( value instanceof Map ) {
System.out.println("\n Object Key : "+key);
displayJSONMAP(jsonString2Map(value.toString()));
}else if ( value instanceof List ) {
System.out.println("\n Array Key : "+key);
JSONArray jsonArray = new JSONArray(value.toString());
jsonArray2List(jsonArray);
}else {
System.out.println("key : "+key+" value : "+value);
}
}
}
    

}

Google.gson到HashMap。

小开

下面的解析器读取一个文件，使用谷歌的JsonParser.parse方法将其解析为通用的JsonElement，然后将生成的JSON中的所有项转换为本机Java List<object>或Map<String, Object>。

< em >注意:下面的代码基于Vikas Gupta的回答.

GsonParser.java

import java.io.FileNotFoundException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;


import com.google.gson.GsonBuilder;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.JsonPrimitive;


public class GsonParser {
public static void main(String[] args) {
try {
print(loadJsonArray("data_array.json", true));
print(loadJsonObject("data_object.json", true));
} catch (Exception e) {
e.printStackTrace();
}
}


public static void print(Object object) {
System.out.println(new GsonBuilder().setPrettyPrinting().create().toJson(object).toString());
}


public static Map<String, Object> loadJsonObject(String filename, boolean isResource)
throws UnsupportedEncodingException, FileNotFoundException, JsonIOException, JsonSyntaxException, MalformedURLException {
return jsonToMap(loadJson(filename, isResource).getAsJsonObject());
}


public static List<Object> loadJsonArray(String filename, boolean isResource)
throws UnsupportedEncodingException, FileNotFoundException, JsonIOException, JsonSyntaxException, MalformedURLException {
return jsonToList(loadJson(filename, isResource).getAsJsonArray());
}


private static JsonElement loadJson(String filename, boolean isResource) throws UnsupportedEncodingException, FileNotFoundException, JsonIOException, JsonSyntaxException, MalformedURLException {
return new JsonParser().parse(new InputStreamReader(FileLoader.openInputStream(filename, isResource), "UTF-8"));
}


public static Object parse(JsonElement json) {
if (json.isJsonObject()) {
return jsonToMap((JsonObject) json);
} else if (json.isJsonArray()) {
return jsonToList((JsonArray) json);
}


return null;
}


public static Map<String, Object> jsonToMap(JsonObject jsonObject) {
if (jsonObject.isJsonNull()) {
return new HashMap<String, Object>();
}


return toMap(jsonObject);
}


public static List<Object> jsonToList(JsonArray jsonArray) {
if (jsonArray.isJsonNull()) {
return new ArrayList<Object>();
}


return toList(jsonArray);
}


private static final Map<String, Object> toMap(JsonObject object) {
Map<String, Object> map = new HashMap<String, Object>();


for (Entry<String, JsonElement> pair : object.entrySet()) {
map.put(pair.getKey(), toValue(pair.getValue()));
}


return map;
}


private static final List<Object> toList(JsonArray array) {
List<Object> list = new ArrayList<Object>();


for (JsonElement element : array) {
list.add(toValue(element));
}


return list;
}


private static final Object toPrimitive(JsonPrimitive value) {
if (value.isBoolean()) {
return value.getAsBoolean();
} else if (value.isString()) {
return value.getAsString();
} else if (value.isNumber()){
return value.getAsNumber();
}


return null;
}


private static final Object toValue(JsonElement value) {
if (value.isJsonNull()) {
return null;
} else if (value.isJsonArray()) {
return toList((JsonArray) value);
} else if (value.isJsonObject()) {
return toMap((JsonObject) value);
} else if (value.isJsonPrimitive()) {
return toPrimitive((JsonPrimitive) value);
}


return null;
}
}

FileLoader.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.Scanner;


public class FileLoader {
public static Reader openReader(String filename, boolean isResource) throws UnsupportedEncodingException, FileNotFoundException, MalformedURLException {
return openReader(filename, isResource, "UTF-8");
}


public static Reader openReader(String filename, boolean isResource, String charset) throws UnsupportedEncodingException, FileNotFoundException, MalformedURLException {
return new InputStreamReader(openInputStream(filename, isResource), charset);
}


public static InputStream openInputStream(String filename, boolean isResource) throws FileNotFoundException, MalformedURLException {
if (isResource) {
return FileLoader.class.getClassLoader().getResourceAsStream(filename);
}


return new FileInputStream(load(filename, isResource));
}


public static String read(String path, boolean isResource) throws IOException {
return read(path, isResource, "UTF-8");
}


public static String read(String path, boolean isResource, String charset) throws IOException {
return read(pathToUrl(path, isResource), charset);
}


@SuppressWarnings("resource")
protected static String read(URL url, String charset) throws IOException {
return new Scanner(url.openStream(), charset).useDelimiter("\\A").next();
}


protected static File load(String path, boolean isResource) throws MalformedURLException {
return load(pathToUrl(path, isResource));
}


protected static File load(URL url) {
try {
return new File(url.toURI());
} catch (URISyntaxException e) {
return new File(url.getPath());
}
}


private static final URL pathToUrl(String path, boolean isResource) throws MalformedURLException {
if (isResource) {
return FileLoader.class.getClassLoader().getResource(path);
}


return new URL("file:/" + path);
}
}
小开 
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;


import org.json.simple.JSONArray;
import org.json.simple.JSONObject;




public class JsonUtils {


public static Map<String, Object> jsonToMap(JSONObject json) {
Map<String, Object> retMap = new HashMap<String, Object>();


if(json != null) {
retMap = toMap(json);
}
return retMap;
}


public static Map<String, Object> toMap(JSONObject object) {
Map<String, Object> map = new HashMap<String, Object>();


Iterator<String> keysItr = object.keySet().iterator();
while(keysItr.hasNext()) {
String key = keysItr.next();
Object value = object.get(key);


if(value instanceof JSONArray) {
value = toList((JSONArray) value);
}


else if(value instanceof JSONObject) {
value = toMap((JSONObject) value);
}
map.put(key, value);
}
return map;
}


public static List<Object> toList(JSONArray array) {
List<Object> list = new ArrayList<Object>();
for(int i = 0; i < array.size(); i++) {
Object value = array.get(i);
if(value instanceof JSONArray) {
value = toList((JSONArray) value);
}


else if(value instanceof JSONObject) {
value = toMap((JSONObject) value);
}
list.add(value);
}
return list;
}
}
小开

你也可以使用Jackson API:

    final String json = "....your json...";
final ObjectMapper mapper = new ObjectMapper();
final MapType type = mapper.getTypeFactory().constructMapType(
Map.class, String.class, Object.class);
final Map<String, Object> data = mapper.readValue(json, type);
小开

你可以使用杰克逊库将任意JSON转换为map，如下所示:

String json = "{\r\n\"name\" : \"abc\" ,\r\n\"email id \" : [\"abc@gmail.com\",\"def@gmail.com\",\"ghi@gmail.com\"]\r\n}";
ObjectMapper mapper = new ObjectMapper();
Map<String, Object> map = new HashMap<String, Object>();
// convert JSON string to Map
map = mapper.readValue(json, new TypeReference<Map<String, Object>>() {});
System.out.println(map);

杰克逊的Maven依赖项:

<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.5.3</version>
<scope>compile</scope>
</dependency>


<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.5.3</version>
<scope>compile</scope>
</dependency>

希望这对你有所帮助。快乐编码:)

小开

试试下面的代码:

 Map<String, String> params = new HashMap<String, String>();
try
{


Iterator<?> keys = jsonObject.keys();


while (keys.hasNext())
{
String key = (String) keys.next();
String value = jsonObject.getString(key);
params.put(key, value);


}




}
catch (Exception xx)
{
xx.toString();
}
小开

希望这能起作用，试试这个:

import com.fasterxml.jackson.databind.ObjectMapper;
Map<String, Object> response = new ObjectMapper().readValue(str, HashMap.class);

str，你的JSON字符串

就这么简单，如果你想要电子邮件，

String emailIds = response.get("email id").toString();
小开

想象一下你有如下的邮件列表。不受任何编程语言的限制，

emailsList = ["abc@gmail.com","def@gmail.com","ghi@gmail.com"]

下面是JAVA代码-用于将json转换为map

JSONObject jsonObj = new JSONObject().put("name","abc").put("email id",emailsList);
Map<String, Object> s = jsonObj.getMap();
小开

简单实用:

/**
* @param jsonThing can be a <code>JsonObject</code>, a <code>JsonArray</code>,
*                     a <code>Boolean</code>, a <code>Number</code>,
*                     a <code>null</code> or a <code>JSONObject.NULL</code>.
* @return <i>Appropriate Java Object</i>, that may be a <code>Map</code>, a <code>List</code>,
* a <code>Boolean</code>, a <code>Number</code> or a <code>null</code>.
*/
public static Object jsonThingToAppropriateJavaObject(Object jsonThing) throws JSONException {
if (jsonThing instanceof JSONArray) {
final ArrayList<Object> list = new ArrayList<>();


final JSONArray jsonArray = (JSONArray) jsonThing;
final int l = jsonArray.length();
for (int i = 0; i < l; ++i) list.add(jsonThingToAppropriateJavaObject(jsonArray.get(i)));
return list;
}


if (jsonThing instanceof JSONObject) {
final HashMap<String, Object> map = new HashMap<>();


final Iterator<String> keysItr = ((JSONObject) jsonThing).keys();
while (keysItr.hasNext()) {
final String key = keysItr.next();
map.put(key, jsonThingToAppropriateJavaObject(((JSONObject) jsonThing).get(key)));
}
return map;
}


if (JSONObject.NULL.equals(jsonThing)) return null;


return jsonThing;
}

谢谢@Vikas古普塔。

小开

使用json-simple你可以将数据JSON转换为Map和Map转换为JSON。

try
{
JSONObject obj11 = new JSONObject();
obj11.put(1, "Kishan");
obj11.put(2, "Radhesh");
obj11.put(3, "Sonal");
obj11.put(4, "Madhu");


Map map = new  HashMap();


obj11.toJSONString();


map = obj11;


System.out.println(map.get(1));




JSONObject obj12 = new JSONObject();


obj12 = (JSONObject) map;


System.out.println(obj12.get(1));
}
catch(Exception e)
{
System.err.println("EROR : 01 :"+e);
}
小开

如果你讨厌递归-使用Stack和javax。将一个json字符串转换成一个地图列表:

import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Stack;
import javax.json.Json;
import javax.json.stream.JsonParser;


public class TestCreateObjFromJson {
public static List<Map<String,Object>> extract(InputStream is) {
List extracted = new ArrayList<>();
JsonParser parser = Json.createParser(is);


String nextKey = "";
Object nextval = "";
Stack s = new Stack<>();
while(parser.hasNext()) {
JsonParser.Event event = parser.next();
switch(event) {
case START_ARRAY :  List nextList = new ArrayList<>();
if(!s.empty()) {
// If this is not the root object, add it to tbe parent object
setValue(s,nextKey,nextList);
}
s.push(nextList);
break;
case START_OBJECT : Map<String,Object> nextMap = new HashMap<>();
if(!s.empty()) {
// If this is not the root object, add it to tbe parent object
setValue(s,nextKey,nextMap);
}
s.push(nextMap);
break;
case KEY_NAME : nextKey = parser.getString();
break;
case VALUE_STRING : setValue(s,nextKey,parser.getString());
break;
case VALUE_NUMBER : setValue(s,nextKey,parser.getLong());
break;
case VALUE_TRUE :   setValue(s,nextKey,true);
break;
case VALUE_FALSE :  setValue(s,nextKey,false);
break;
case VALUE_NULL :   setValue(s,nextKey,"");
break;
case END_OBJECT :
case END_ARRAY  :   if(s.size() > 1) {
// If this is not a root object, move up
s.pop();
} else {
// If this is a root object, add ir ro rhw final
extracted.add(s.pop());
}
default         :   break;
}
}


return extracted;
}


private static void setValue(Stack s, String nextKey, Object v) {
if(Map.class.isAssignableFrom(s.peek().getClass()) ) ((Map)s.peek()).put(nextKey, v);
else ((List)s.peek()).add(v);
}
}
小开
这是一个老问题，但可能仍然与某些人有关 假设你有字符串HashMap hash和JsonObject jsonObject.

1)定义key-list 例子:< / p > 

ArrayList<String> keyArrayList = new ArrayList<>();
keyArrayList.add("key0");
keyArrayList.add("key1");

2)创建foreach循环，从jsonObject中添加hash:

for(String key : keyArrayList){
hash.put(key, jsonObject.getString(key));
}

这就是我的方法，希望它能回答问题。

小开

使用Jackson转换:

JSONObject obj = new JSONObject().put("abc", "pqr").put("xyz", 5);


Map<String, Object> map = new ObjectMapper().readValue(obj.toString(), new TypeReference<Map<String, Object>>() {});
小开

我只用了Gson

HashMap<String, Object> map = new Gson().fromJson(json.toString(), HashMap.class);
小开

有一个使用javax.json发布的在这里的旧答案，但它只转换JsonArray和JsonObject，但输出中仍然有JsonString、JsonNumber和JsonValue包装器类。如果你想摆脱这些，这是我的解决方案，它会打开所有东西。

除此之外，它还使用Java 8流，并包含在单个方法中。

/**
* Convert a JsonValue into a “plain” Java structure (using Map and List).
*
* @param value The JsonValue, not <code>null</code>.
* @return Map, List, String, Number, Boolean, or <code>null</code>.
*/
public static Object toObject(JsonValue value) {
Objects.requireNonNull(value, "value was null");
switch (value.getValueType()) {
case ARRAY:
return ((JsonArray) value)
.stream()
.map(JsonUtils::toObject)
.collect(Collectors.toList());
case OBJECT:
return ((JsonObject) value)
.entrySet()
.stream()
.collect(Collectors.toMap(
Entry::getKey,
e -> toObject(e.getValue())));
case STRING:
return ((JsonString) value).getString();
case NUMBER:
return ((JsonNumber) value).numberValue();
case TRUE:
return Boolean.TRUE;
case FALSE:
return Boolean.FALSE;
case NULL:
return null;
default:
throw new IllegalArgumentException("Unexpected type: " + value.getValueType());
}
}

提交答案