json

org.json包

生成JSON

使用JSONObject 或JSONArray，然后调用toString()

解析JSON

 String json = "{"
         + "  \"query\": \"Pizza\", "
         + "  \"locations\": [ 94043, 90210 ] "
         + "}";
 JSONObject object = (JSONObject) new JSONTokener(json).nextValue();
 String query = object.getString("query");
 JSONArray locations = object.getJSONArray("locations");

JSONWriter & JSONReader (API Level 11)

输出和读取类似的JSON

 [
   {
     "id": 912345678901,
     "text": "How do I write JSON on Android?",
     "geo": null,
     "user": {
       "name": "android_newb",
       "followers_count": 41

   },
   {
     "id": 912345678902,
     "text": "@android_newb just use android.util.JsonWriter!",
     "geo": [50.454722, -104.606667],
     "user": {
       "name": "jesse",
       "followers_count": 2
     }
   }
 ]}

读取JSON

 public List readJsonStream(InputStream in) throws IOException {
     JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8"));
     try {
       return readMessagesArray(reader);
      finally {
       reader.close();
     }
   }
   public List readMessagesArray(JsonReader reader) throws IOException {
     List messages = new ArrayList();
     reader.beginArray();
     while (reader.hasNext()) {
       messages.add(readMessage(reader));
     }
     reader.endArray();
     return messages;
   }
   public Message readMessage(JsonReader reader) throws IOException {
     long id = -1;
     String text = null;
     User user = null;
     List geo = null;
     reader.beginObject();
     while (reader.hasNext()) {
       String name = reader.nextName();
       if (name.equals("id")) {
         id = reader.nextLong();
       } else if (name.equals("text")) {
         text = reader.nextString();
       } else if (name.equals("geo") && reader.peek() != JsonToken.NULL) {
         geo = readDoublesArray(reader);
       } else if (name.equals("user")) {
         user = readUser(reader);
       } else {
         reader.skipValue();
       }
     }
     reader.endObject();
     return new Message(id, text, user, geo);
   }
   public List readDoublesArray(JsonReader reader) throws IOException {
     List doubles = new ArrayList();
     reader.beginArray();
     while (reader.hasNext()) {
       doubles.add(reader.nextDouble());
     }
     reader.endArray();
     return doubles;
   }
   public User readUser(JsonReader reader) throws IOException {
     String username = null;
     int followersCount = -1;
     reader.beginObject();
     while (reader.hasNext()) {
       String name = reader.nextName();
       if (name.equals("name")) {
         username = reader.nextString();
       } else if (name.equals("followers_count")) {
         followersCount = reader.nextInt();
       } else {
         reader.skipValue();
       }
     }
     reader.endObject();
     return new User(username, followersCount);
   }}

输出JSON

使用下面代码：

public void writeJsonStream(OutputStream out, List messages) throws IOException {
     JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8"));
     writer.setIndent("  ");
     writeMessagesArray(writer, messages);
     writer.close();

   public void writeMessagesArray(JsonWriter writer, List messages) throws IOException {
     writer.beginArray();
     for (Message message : messages) {
       writeMessage(writer, message);
     }
     writer.endArray();
   }
   public void writeMessage(JsonWriter writer, Message message) throws IOException {
     writer.beginObject();
     writer.name("id").value(message.getId());
     writer.name("text").value(message.getText());
     if (message.getGeo() != null) {
       writer.name("geo");
       writeDoublesArray(writer, message.getGeo());
     } else {
       writer.name("geo").nullValue();
     }
     writer.name("user");
     writeUser(writer, message.getUser());
     writer.endObject();
   }
   public void writeUser(JsonWriter writer, User user) throws IOException {
     writer.beginObject();
     writer.name("name").value(user.getName());
     writer.name("followers_count").value(user.getFollowersCount());
     writer.endObject();
   }
   public void writeDoublesArray(JsonWriter writer, List doubles) throws IOException {
     writer.beginArray();
     for (Double value : doubles) {
       writer.value(value);
     }
     writer.endArray();
   }}