blocks|key|273345|text|Gson还可以用于序列化任意复杂的对象。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|273346|下面是你如何使用它：|273347|Gson+gson+=+new+Gson();+
String+json+=+gson.toJson(myObject);+|code-block|syntax|javascript|273348|Gson会自动将集合转换为JSON数组。Gson可以序列化私有字段，并自动忽略瞬态字段。|style|CODE|273349|entityMap|0|LINK|mutability|MUTABLE|url|https://code.google.com/p/google-gson/^0|0|4|0|0|0|0|0|4|D|4|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|12|8|@$A|13|B|14|M|N]|$A|15|B|16|M|N]]|9|@]|C|$]]|$1|O|3|-4|5|6|7|17|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

<a href="https://code.google.com/p/google-gson/" rel="noreferrer">Gson</a> can also be used to serialize arbitrarily complex objects. 

Here is how you use it: 

<pre><code>Gson gson = new Gson(); 
String json = gson.toJson(myObject); 
</code></pre>

<code>Gson</code> will automatically convert collections to <code>JSON</code> arrays. Gson can serialize private fields and automatically ignores transient fields.

blocks|key|490365|text|使用json的示例|type|unstyled|depth|inlineStyleRanges|entityRanges|data|490366|Map<String,+Object>+data+=+new+HashMap<String,+Object>();
++++data.put(+"name",+"Mars"+);
++++data.put(+"age",+32+);
++++data.put(+"city",+"NY"+);
++++JSONObject+json+=+new+JSONObject();
++++json.putAll(+data+);
++++System.out.printf(+"JSON:+%25s",+json.toString(2)+);|code-block|syntax|javascript|490367|输出：|490368|JSON:+{
++"age":+32,
++"name":+"Mars",
++"city":+"NY"
}|490369|您也可以尝试使用Google的GSON。Google的GSON是将Java对象转换为JSON表示的最佳库。|490370|http://code.google.com/p/google-gson/|offset|length|490371|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|0|0|0|11|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Z|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|11|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|12|8|@]|9|@$O|13|P|14|1|15]]|A|$]]|$1|Q|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|N]]]]

Example using json 

<pre><code>Map&lt;String, Object&gt; data = new HashMap&lt;String, Object&gt;();
 data.put( "name", "Mars" );
 data.put( "age", 32 );
 data.put( "city", "NY" );
 JSONObject json = new JSONObject();
 json.putAll( data );
 System.out.printf( "JSON: %s", json.toString(2) );
</code></pre>

output::

<pre><code>JSON: {
 "age": 32,
 "name": "Mars",
 "city": "NY"
}
</code></pre>

You can also try to use Google's GSON.Google's GSON is the best library available to convert Java Objects into their JSON representation.

<a href="http://code.google.com/p/google-gson/" rel="noreferrer">http://code.google.com/p/google-gson/</a>

blocks|key|490686|text|在我的例子中，我不想要任何依赖。使用Java+8，您可以将JSON作为字符串获取，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|490687|Map<String,+Object>+map+=+new+HashMap<>();
map.put("key",+"value");
map.put("key2",+"value2");
String+json+=+"{"%2Bmap.entrySet().stream()
++++.map(e+->+"\""%2B+e.getKey()+%2B+"\":\""+%2B+String.valueOf(e.getValue())+%2B+"\"")
++++.collect(Collectors.joining(",+"))%2B"}";|code-block|syntax|javascript|490688|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In my case I didn't want any dependancies. Using Java 8 you can get JSON as a string this simple:
<pre><code>Map&lt;String, Object&gt; map = new HashMap&lt;&gt;();
map.put(&quot;key&quot;, &quot;value&quot;);
map.put(&quot;key2&quot;, &quot;value2&quot;);
String json = &quot;{&quot;+map.entrySet().stream()
 .map(e -&gt; &quot;\&quot;&quot;+ e.getKey() + &quot;\&quot;:\&quot;&quot; + String.valueOf(e.getValue()) + &quot;\&quot;&quot;)
 .collect(Collectors.joining(&quot;, &quot;))+&quot;}&quot;;
</code></pre>

blocks|key|273719|text|您可以只枚举映射并将键-值对添加到JSONObject|type|unstyled|depth|inlineStyleRanges|entityRanges|data|273720|方法：|273721|private+JSONObject+getJsonFromMap(Map<String,+Object>+map)+throws+JSONException+{
++++JSONObject+jsonData+=+new+JSONObject();
++++for+(String+key+:+map.keySet())+{
++++++++Object+value+=+map.get(key);
++++++++if+(value+instanceof+Map<?,+?>)+{
++++++++++++value+=+getJsonFromMap((Map<String,+Object>)+value);
++++++++}
++++++++jsonData.put(key,+value);
++++}
++++return+jsonData;
}|code-block|syntax|javascript|273722|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can just enumerate the map and add the key-value pairs to the JSONObject

Method : 

<pre><code>private JSONObject getJsonFromMap(Map&lt;String, Object&gt; map) throws JSONException {
 JSONObject jsonData = new JSONObject();
 for (String key : map.keySet()) {
 Object value = map.get(key);
 if (value instanceof Map&lt;?, ?&gt;) {
 value = getJsonFromMap((Map&lt;String, Object&gt;) value);
 }
 jsonData.put(key, value);
 }
 return jsonData;
}
</code></pre>

blocks|key|490592|text|Underscore-java库可以将散列映射或数组列表转换为json，反之亦然。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|490593|import+com.github.underscore.lodash.U;
import+java.util.*;

public+class+Main+{

++++public+static+void+main(String[]+args)+{

++++++++Map<String,+Object>+map+=+new+LinkedHashMap<>();
++++++++map.put("1",+"a");
++++++++map.put("2",+"b");

++++++++System.out.println(U.toJson(map));
++++++++//+{
++++++++//++++"1":+"a",
++++++++//++++"2":+"b"
++++++++//+}
++++}
}|code-block|syntax|javascript|490594|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/javadev/underscore-java^0|0|F|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

<a href="https://github.com/javadev/underscore-java" rel="nofollow noreferrer">Underscore-java</a> library can convert hash map or array list to json and vice verse.

<pre><code>import com.github.underscore.lodash.U;
import java.util.*;

public class Main {

 public static void main(String[] args) {

 Map&lt;String, Object&gt; map = new LinkedHashMap&lt;&gt;();
 map.put("1", "a");
 map.put("2", "b");

 System.out.println(U.toJson(map));
 // {
 // "1": "a",
 // "2": "b"
 // }
 }
}
</code></pre>

blocks|key|273447|text|来晚了，但这里是我的GSON临时编写器，用于序列化哈希图。我不得不把键值对的映射写成json字符串属性，希望有一个特定的是整型的。我不想为这个简单的用例创建定制的JavaBean包装器。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|273448|GSON+JsonWriter类是一个包含少量强类型writer.value()函数的易于使用的序列化程序类。|273449|//+write+Map+as+JSON+document+to+http+servlet+response
Map<String,String>+sd+=+DAO.getSD(123);
res.setContentType("application/json;+charset=UTF-8");
res.setCharacterEncoding("UTF-8");
JsonWriter+writer+=+new+JsonWriter(new+OutputStreamWriter(res.getOutputStream(),+"UTF-8"));
writer.beginObject();
for(String+key+:+sd.keySet())+{
++++String+val+=+sd.get(key);
++++writer.name(key);
++++if+(key.equals("UniqueID")+&&+val!=null)
++++++++writer.value(Long.parseLong(val));
++++else
++++++++writer.value(val);
}
writer.endObject();
writer.close();|code-block|syntax|javascript|273450|如果不需要任何自定义类型，我可以只使用toJson()函数。gson-2.2.4.jar库不到190KB，没有任何严重的依赖关系。易于在任何自定义servlet应用程序或独立应用程序上使用，无需大型框架集成。|273451|Gson+gson+=+new+Gson();+
String+json+=+gson.toJson(myMap);+|273452|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/google-gson/^0|A|4|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|13|8|@]|9|@]|C|$I|J]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

Late to the party but here is my <a href="http://code.google.com/p/google-gson/" rel="noreferrer">GSON</a> adhoc writer for serializing hashmap. I had to write map of key-value pairs as json string attributes, expect one specific to be integer type. I did not want to create custom JavaBean wrapper for this simple usecase. 

GSON JsonWriter class is easy to use serializer class containing few strongly typed writer.value() functions.

<pre><code>// write Map as JSON document to http servlet response
Map&lt;String,String&gt; sd = DAO.getSD(123);
res.setContentType("application/json; charset=UTF-8");
res.setCharacterEncoding("UTF-8");
JsonWriter writer = new JsonWriter(new OutputStreamWriter(res.getOutputStream(), "UTF-8"));
writer.beginObject();
for(String key : sd.keySet()) {
 String val = sd.get(key);
 writer.name(key);
 if (key.equals("UniqueID") &amp;&amp; val!=null)
 writer.value(Long.parseLong(val));
 else
 writer.value(val);
}
writer.endObject();
writer.close();
</code></pre>

If none of the custom types be needed I could have just use toJson() function. gson-2.2.4.jar library is just under 190KB without any brutal dependencies. Easy to use on any custom servlet app or standalone application without big framework integrations.

<pre><code>Gson gson = new Gson(); 
String json = gson.toJson(myMap); 
</code></pre>

blocks|key|273179|text|这通常是Json库的工作，你不应该自己去做。所有json库都应该实现您所要求的内容，您可以在页面底部的json.org上找到Java+Json库的列表。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|273180|entityMap|0|LINK|mutability|MUTABLE|url|http://www.json.org/^0|1F|8|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

This is typically the work of a Json library, you should not try to do it yourself. All json libraries should implement what you are asking for, and you can
find a list of Java Json libraries on <a href="http://www.json.org/" rel="nofollow noreferrer">json.org</a>, at the bottom of the page.

blocks|key|490625|text|如果您需要在代码中使用它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|490626|Gson+gsone+=+new+Gson();
JsonObject+res+=+gsone.toJsonTree(sqlParams).getAsJsonObject();|code-block|syntax|javascript|490627|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you need use it in the code.

<pre><code>Gson gsone = new Gson();
JsonObject res = gsone.toJsonTree(sqlParams).getAsJsonObject();
</code></pre>

blocks|key|491017|text|此解决方案适用于复杂的JSON：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|491018|public+Object+toJSON(Object+object)+throws+JSONException+{
++++if+(object+instanceof+HashMap)+{
++++++++JSONObject+json+=+new+JSONObject();
++++++++HashMap+map+=+(HashMap)+object;
++++++++for+(Object+key+:+map.keySet())+{
++++++++++++json.put(key.toString(),+toJSON(map.get(key)));
++++++++}
++++++++return+json;
++++}+else+if+(object+instanceof+Iterable)+{
++++++++JSONArray+json+=+new+JSONArray();
++++++++for+(Object+value+:+((Iterable)+object))+{
++++++++++++json.put(toJSON(value));
++++++++}
++++++++return+json;
++++}
++++else+{
++++++++return+object;
++++}
}|code-block|syntax|javascript|491019|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This solution works with complex JSONs:

<pre><code>public Object toJSON(Object object) throws JSONException {
 if (object instanceof HashMap) {
 JSONObject json = new JSONObject();
 HashMap map = (HashMap) object;
 for (Object key : map.keySet()) {
 json.put(key.toString(), toJSON(map.get(key)));
 }
 return json;
 } else if (object instanceof Iterable) {
 JSONArray json = new JSONArray();
 for (Object value : ((Iterable) object)) {
 json.put(toJSON(value));
 }
 return json;
 }
 else {
 return object;
 }
}
</code></pre>

blocks|key|490835|text|下面是我使用GSON的单行解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|490836|myObject+=+new+Gson().fromJson(new+Gson().toJson(myHashMap),+MyClass.class);|code-block|syntax|javascript|490837|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here my single-line solution with GSON:

<pre><code>myObject = new Gson().fromJson(new Gson().toJson(myHashMap), MyClass.class);
</code></pre>

blocks|key|490871|text|对于那些使用org.json.simple.JSONObject的用户，您可以将映射转换为Json字符串，并对其进行解析以获得JSONObject。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|490872|JSONObject+object+=+(JSONObject)+new+JSONParser().parse(JSONObject.toJSONString(map));|code-block|syntax|javascript|490873|entityMap^0|6|Q|1R|A|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

For those using <code>org.json.simple.JSONObject</code>, you could convert the map to Json String and parse it to get the <code>JSONObject</code>.

<pre><code>JSONObject object = (JSONObject) new JSONParser().parse(JSONObject.toJSONString(map));
</code></pre>

blocks|key|490917|text|我找到了另一种方法来处理它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|490918|Map+obj=new+HashMap();++++
obj.put("name","sonoo");++++
obj.put("age",new+Integer(27));++++
obj.put("salary",new+Double(600000));+++
String+jsonText+=+JSONValue.toJSONString(obj);++
System.out.print(jsonText);|code-block|syntax|javascript|490919|希望这能有所帮助。|490920|谢谢。|490921|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I found another way to handle it.

<pre><code>Map obj=new HashMap(); 
obj.put("name","sonoo"); 
obj.put("age",new Integer(27)); 
obj.put("salary",new Double(600000)); 
String jsonText = JSONValue.toJSONString(obj); 
System.out.print(jsonText);
</code></pre>

Hope this helps.

Thanks.

blocks|key|273836|text|如果你并不真正需要HashMap，那么你可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|273837|String+jsonString+=+new+JSONObject()+{{
++put("firstName",+user.firstName);
++put("lastName",+user.lastName);
}}.toString();|code-block|syntax|javascript|273838|输出：|273839|{
++"firstName":+"John",
++"lastName":+"Doe"
}|273840|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

If you don't really need HashMap then you can do something like that:

<pre><code>String jsonString = new JSONObject() {{
 put("firstName", user.firstName);
 put("lastName", user.lastName);
}}.toString();
</code></pre>

Output:

<pre><code>{
 "firstName": "John",
 "lastName": "Doe"
}
</code></pre>

blocks|key|491089|text|我们使用Gson。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|491090|Gson+gson+=+new+Gson();
Type+gsonType+=+new+TypeToken<HashMap>(){}.getType();
String+gsonString+=+gson.toJson(elements,gsonType);|code-block|syntax|javascript|491091|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

we use Gson.

<pre><code>Gson gson = new Gson();
Type gsonType = new TypeToken&lt;HashMap&gt;(){}.getType();
String gsonString = gson.toJson(elements,gsonType);
</code></pre>

blocks|key|273898|text|我使用的是阿里巴巴的fastjson，简单易懂：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|273899|<dependency>
++++<groupId>com.alibaba</groupId>
++++<artifactId>fastjson</artifactId>
++++<version>VERSION_CODE</version>
</dependency>|code-block|syntax|javascript|273900|和导入：|273901|import+com.alibaba.fastjson.JSON;|273902|然后：|273903|String+text+=+JSON.toJSONString(obj);+//+serialize
VO+vo+=+JSON.parseObject("{...}",+VO.class);+//unserialize|273904|一切都很好。|273905|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I'm using Alibaba fastjson, easy and simple:

<pre><code>&lt;dependency&gt;
 &lt;groupId&gt;com.alibaba&lt;/groupId&gt;
 &lt;artifactId&gt;fastjson&lt;/artifactId&gt;
 &lt;version&gt;VERSION_CODE&lt;/version&gt;
&lt;/dependency&gt;
</code></pre>

and import:

<pre><code>import com.alibaba.fastjson.JSON;
</code></pre>

Then:

<pre><code>String text = JSON.toJSONString(obj); // serialize
VO vo = JSON.parseObject("{...}", VO.class); //unserialize
</code></pre>

Everything is ok.

blocks|key|274014|text|如果您正在使用JSR+374:+Java+API+for+JSON+Processing+(+javax+json+)，这似乎可以做到这一点：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|274015|++++JsonObjectBuilder+job+=+Json.createObjectBuilder((Map<String,+Object>)+obj);
++++JsonObject+jsonObject+=+job.build();|code-block|syntax|javascript|274016|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are using JSR 374: Java API for JSON Processing ( javax json )
This seems to do the trick:

<pre><code> JsonObjectBuilder job = Json.createObjectBuilder((Map&lt;String, Object&gt;) obj);
 JsonObject jsonObject = job.build();
</code></pre>

blocks|key|273287|text|你可以使用XStream+-它真的很方便。请参阅示例here|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|273288|package+com.thoughtworks.xstream.json.test;

import+com.thoughtworks.xstream.XStream;
import+com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;

public+class+WriteTest+{

++++public+static+void+main(String[]+args)+{

++++++HashMap<String,String>+map+=+new+HashMap<String,String>();
++++++map.add("1",+"a");
++++++map.add("2",+"b");
++++++XStream+xstream+=+new+XStream(new+JettisonMappedXmlDriver());

++++++System.out.println(xstream.toXML(map));+++++++

++++}

}|code-block|syntax|javascript|273289|entityMap|0|LINK|mutability|MUTABLE|url|http://xstream.codehaus.org/json-tutorial.html^0|Q|4|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

You can use XStream - it is really handy. See the examples <a href="http://xstream.codehaus.org/json-tutorial.html" rel="nofollow">here</a>

<pre><code>package com.thoughtworks.xstream.json.test;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;

public class WriteTest {

 public static void main(String[] args) {

 HashMap&lt;String,String&gt; map = new HashMap&lt;String,String&gt;();
 map.add("1", "a");
 map.add("2", "b");
 XStream xstream = new XStream(new JettisonMappedXmlDriver());

 System.out.println(xstream.toXML(map)); 

 }

}
</code></pre>

blocks|key|273491|text|如果您使用的是net.sf.json.JSONObject，那么您不会在其中找到JSONObject(map)构造函数。您必须使用public+static+JSONObject+fromObject(+Object+object+)方法。这个方法接受JSON格式的字符串、Maps、DynaBeans和JavaBeans。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|273492|JSONObject+jsonObject+=+JSONObject.fromObject(myMap);|273493|entityMap^0|7|M|14|F|1T|1G|0|0|1H|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|I|$]]

If you are using <code>net.sf.json.JSONObject</code> then you won't find a <code>JSONObject(map)</code> constructor in it. You have to use the <code>public static JSONObject fromObject( Object object )</code> method. This method accepts JSON formatted strings, Maps, DynaBeans and JavaBeans.

<code>JSONObject jsonObject = JSONObject.fromObject(myMap);</code>

blocks|key|273777|text|++++import+org.json.JSONObject;

++++HashMap<Object,+Object>+map+=+new+HashMap<>();
++++String[]+list={"Grader","Participant"};
++++String[]+list1={"Assistant","intern"};
++++map.put("TeachingAssistant",list);
++++map.put("Writer",list1);
++++JSONObject+jsonObject+=+new+JSONObject(map);
++++System.out.printf(jsonObject.toString());

++++//+Result:+{"TeachingAssistant":["Grader","Participant"],"Writer":["Assistant","intern"]}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|273778|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code> import org.json.JSONObject;

 HashMap&lt;Object, Object&gt; map = new HashMap&lt;&gt;();
 String[] list={"Grader","Participant"};
 String[] list1={"Assistant","intern"};
 map.put("TeachingAssistant",list);
 map.put("Writer",list1);
 JSONObject jsonObject = new JSONObject(map);
 System.out.printf(jsonObject.toString());

 // Result: {"TeachingAssistant":["Grader","Participant"],"Writer":["Assistant","intern"]}
</code></pre>

blocks|key|273854|text|这对我来说很有效：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|273855|import+groovy.json.JsonBuilder
properties+=+new+Properties()
properties.put("name",+"zhangsan")

println+new+JsonBuilder(properties).toPrettyString()|code-block|syntax|javascript|273856|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

this works for me :

<pre><code>import groovy.json.JsonBuilder
properties = new Properties()
properties.put("name", "zhangsan")

println new JsonBuilder(properties).toPrettyString()
</code></pre>

blocks|key|490760|text|在selenium中反序列化来自自定义命令的响应时，我遇到了类似的问题。响应是json，但selenium会在内部将其转换为java.util.HashMapString对象|type|unstyled|depth|inlineStyleRanges|entityRanges|data|490761|如果您熟悉scala并使用JSON的play-API，您可能会从中受益：|490762|import+play.api.libs.json.{JsValue,+Json}
import+scala.collection.JavaConversions.mapAsScalaMap


object+JsonParser+{

++def+parse(map:+Map[String,+Any]):+JsValue+=+{
++++val+values+=+for((key,+value)+<-+map)+yield+{
++++++value+match+{
++++++++case+m:+java.util.Map[String,+_]+@unchecked+=>+Json.obj(key+->+parse(m.toMap))
++++++++case+m:+Map[String,+_]+@unchecked+=>+Json.obj(key+->+parse(m))
++++++++case+int:+Int+=>+Json.obj(key+->+int)
++++++++case+str:+String+=>+Json.obj(key+->+str)
++++++++case+bool:+Boolean+=>+Json.obj(key+->+bool)
++++++}
++++}

++++values.foldLeft(Json.obj())((temp,+obj)+=>+{
++++++temp.deepMerge(obj)
++++})
++}
}|code-block|syntax|javascript|490763|小代码描述：|490764|代码递归地遍历HashMap，直到找到基本类型(字符串、整数、布尔值)。这些基本类型可以直接包装到JsObject中。当递归展开时，深度合并将连接所创建的对象。|490765|'@unchecked‘处理类型擦除警告。|490766|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I faced a similar problem when deserializing the Response from custom commands in selenium. The response was json, but selenium internally translates that into a java.util.HashMap[String, Object]

If you are familiar with scala and use the play-API for JSON, you might benefit from this:

<pre><code>import play.api.libs.json.{JsValue, Json}
import scala.collection.JavaConversions.mapAsScalaMap


object JsonParser {

 def parse(map: Map[String, Any]): JsValue = {
 val values = for((key, value) &lt;- map) yield {
 value match {
 case m: java.util.Map[String, _] @unchecked =&gt; Json.obj(key -&gt; parse(m.toMap))
 case m: Map[String, _] @unchecked =&gt; Json.obj(key -&gt; parse(m))
 case int: Int =&gt; Json.obj(key -&gt; int)
 case str: String =&gt; Json.obj(key -&gt; str)
 case bool: Boolean =&gt; Json.obj(key -&gt; bool)
 }
 }

 values.foldLeft(Json.obj())((temp, obj) =&gt; {
 temp.deepMerge(obj)
 })
 }
}
</code></pre>

Small code description:

The code recursively traverses through the HashMap until basic types (String, Integer, Boolean) are found. These basic types can be directly wrapped into a JsObject. When the recursion is unfolded, the deepmerge concatenates the created objects.

'@unchecked' takes care of type erasure warnings.

blocks|key|491035|text|首先将所有对象转换为有效的字符串|type|unstyled|depth|inlineStyleRanges|entityRanges|data|491036|HashMap<String,+String>+params+=+new+HashMap<>();
params.put("arg1",+"some+text");
params.put("arg2",+someObject.toString());|code-block|syntax|javascript|491037|然后将整个地图插入到org.json.JSONObject中|491038|JSONObject+postData+=+new+JSONObject(params);|491039|现在，只需调用对象的toString即可获得JSON|491040|postData.toString()
//{"arg1":"some+text<\/b>"+"arg2":"object+output"}|491041|创建新的JSONObject|491042|JSONObject+o+=+new+JSONObject(postData.toString());|491043|或作为用于通过HTTP发送的字节数组|491044|postData.toString().getBytes("UTF-8");|491045|entityMap^0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|14|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|16|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|W|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|X|$]]

First convert all your objects into valid Strings

<pre><code>HashMap&lt;String, String&gt; params = new HashMap&lt;&gt;();
params.put("arg1", "&lt;b&gt;some text&lt;/b&gt;");
params.put("arg2", someObject.toString());
</code></pre>

Then insert the entire map into a org.json.JSONObject

<pre><code>JSONObject postData = new JSONObject(params);
</code></pre>

Now you can get the JSON by simply calling the object's toString

<pre><code>postData.toString()
//{"arg1":"&lt;b&gt;some text&lt;\/b&gt;" "arg2":"object output"}
</code></pre>

Create a new JSONObject

<pre><code>JSONObject o = new JSONObject(postData.toString());
</code></pre>

Or as a byte array for sending over HTTP

<pre><code>postData.toString().getBytes("UTF-8");
</code></pre>

How to convert or cast hashmap to JSON object in Java, and again convert JSON object to JSON string?

How to convert hashmap to JSON object in Java

JSON

Java

如何在Java中将hashmap转换或转换为JSON对象，并再次将JSON对象转换为JSON字符串？

问如何在Java中将hashmap转换为JSON对象
EN

回答 22

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何在Java中将hashmap转换为JSON对象EN

回答 22

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何在Java中将hashmap转换为JSON对象
EN