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<String, Object> retMap = new HashMap<String, Object>();
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?我想用org。json库。
当前回答
我只用了Gson
HashMap<String, Object> map = new Gson().fromJson(json.toString(), HashMap.class);
其他回答
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;
}
}
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();
最新更新:我已经使用fastxmljackson Databind2.12.3转换JSON字符串到映射，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);
}
}
}
}
谷歌。gson到HashMap。
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>>() {});
下面的解析器读取一个文件，使用谷歌的JsonParser将其解析为通用的JsonElement。解析方法，然后将生成JSON中的所有项转换为原生Java List<object>或Map<String, object>。
注意:下面的代码是基于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);
}
}
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