(Node.js, socket.io) JSONObject 无法转换为 int

Question

我正在尝试创建一个多人游戏，如果大厅未满，主机有 AI 飞船，它们将动作发送到服务器，服务器将他们的“动作”广播到客户端游戏中的空白飞船。广播伴随着一个“i”，它是 AIShips 标识符，因此正确的船被告知在客户端游戏中移动。

以下是使用顺序的代码：

初始发射：(AIShip.java)

JSONObject data = new JSONObject();
try {
    data.put("i", identifier); //Identifier is an int set once in the constructor
    gameScreen.spaceSoccer.socket.emit("moveAIShipForward", data);
} catch (JSONException e){
    e.printStackTrace();
}

我的服务器：(index.js)

socket.on("moveAIShipForward", function(i) {
            socket.broadcast.emit("moveAIShipForward", {id: socket.id, i: i})
});

对广播的响应：(SpaceSoccer.java)

.on("moveAIShipForward", new Emitter.Listener() {
            @Override
            public void call(Object... args) {
                JSONObject data = (JSONObject) args[0];
                try {
                    int i = data.getInt("i"); //error
                    gameScreen.AIShip[i].moveBodyForward();
                } catch (JSONException e) {
                    e.printStackTrace();
                }
});

错误：W/System.err: org.json.JSONException: Value {"i":0} at i of type org.json.JSONObject cannot be convert to int W/System.err：在 org.json.JSON.typeMismatch(JSON.java:100)

Answer 1

这是因为您嵌套了{ "i": identifier } 对象。看看（在下面的注释代码中解释）：

初始发射：(AIShip.java)

JSONObject data = new JSONObject();
...
    data.put("i", identifier);

    // here the `data` is like `{ "i": 0 }` and it's emmited
    gameScreen.spaceSoccer.socket.emit("moveAIShipForward", data);
...

我的服务器：(index.js)

// here, the `i` is what you have sent earlier: `{ "i": 0 }`
socket.on("moveAIShipForward", function(i) {
    // here, you are passing the `{ "i": 0 }` object to the new object, under `i` key, the resulting object looks like this:
    // `{ id: 0, i: { i: 0 } }`
    // and it's emitted
    socket.broadcast.emit("moveAIShipForward", {id: socket.id, i: i})
});

对广播的响应：(SpaceSoccer.java)

.on("moveAIShipForward", new Emitter.Listener() {
...
            JSONObject data = (JSONObject) args[0];
            try {
                // now here, the object looks like above (in the .js file), so `.get("i")` would return a `{ "i": 0 }` obejct, which obviously cannot be converted to int.
                int i = data.getInt("i"); // { "i": 0 } is not an integer!
....
});

解决方案（不是唯一的，一旦你知道原因，tho）：
在您的 index.js 中，将您发送的有效负载更改为这样的内容，例如：

socket.on("moveAIShipForward", function(data) {
    socket.broadcast.emit("moveAIShipForward", {id: socket.id, i: data.i})
});