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
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);
}
}
其他回答
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。
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;
}
}
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);
}
}
我只用了Gson
HashMap<String, Object> map = new Gson().fromJson(json.toString(), HashMap.class);
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();
}
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