2017-02-21

json-lib-2.4-jdk15 的疑似 bug

使用 json-lib 时发现了比较诡异的现象，分析半天没有找到原因。最后因时间关系，直接替换成 org.json 解决了。疑似json-lib 有 bug，Mark 一个，以后再看。

最近尝试封装某网络 API ，提供接口给上层调用。该 API 使用 json 发送数据。一开始图方便，本想直接用 String 拼接了事，后来实际一写，发现 json 结构有三层，比较复杂，而且有动态增删改字段的需求，改为老老实实构建 JSONObject ，发送前转成 String 。

不像 JavaScript 和 Python 那样有官方的 json 实现，Java 的 json 实现山头林立。我粗略数了一下 json.org 官网上都有25个之多！我也不要什么复杂的功能，只要

根据需要建立标准 json 对象结构
方便在对象和字符串之间互相转换

够了。

大概扫一眼，net.sf.json-lib 和 org.json 都够用，刚好这两个包接口极为接近。项目别的地方已经引用了 json-lib，干脆就它。

注：代码是对某网络 API的封装，它的API都是公开信息。敏感信息我已经消去。

@Override
public boolean setPredefinedKeyValue(String key, Object value)
        throws Exception {
    System.out.println("key:" + key + ", value:" + value);
    if (ROOT_KEYS.contains(key)) {
        rootJson.put(key, value);
    } else if (PAYLOAD_KEYS.contains(key)) {
        JSONObject payloadJson = null;
        if (rootJson.has("payload")) {
            payloadJson = rootJson.getJSONObject("payload");
            System.out.println("payload exists: " + payloadJson.toString());
        } else {
            payloadJson = new JSONObject();
            rootJson.put("payload", payloadJson);
            System.out.println("new payload.");
        }
        payloadJson.put(key, value);
    } else if (BODY_KEYS.contains(key)) {
        System.out.println("Enter body ==========");
        JSONObject bodyJson = null;
        JSONObject payloadJson = null;
        if (rootJson.has("payload")) {
            payloadJson = rootJson.getJSONObject("payload");
            System.out.println("payload exists: " + payloadJson.toString());
        } else {
            payloadJson = new JSONObject();
            rootJson.put("payload", payloadJson);
            System.out.println("new payload and add. root: " + rootJson.toString());
        }
        System.out.println("payload before has(body) : " + payloadJson.toString());
        if (payloadJson.has("body")) {
            bodyJson = payloadJson.getJSONObject("body");
            System.out.println("body exists: " + bodyJson.toString());
        } else {
            bodyJson = new JSONObject();
            payloadJson.put("body", bodyJson);
            System.out.println("new body and add. payload: " + payloadJson.toString());
        }
        System.out.println("body before put: " + bodyJson.toString());
        bodyJson.put(key, value);
        System.out.println("body after put: " + bodyJson.toString());
        System.out.println("Exit body ==========");
    } else if (POLICY_KEYS.contains(key)) {
        // ......
    } else {
        // ......
    }
    return true;
}

以下是 json-lib 的log

key:appkey, value:********************************
key:type, value:customizedcast
key:alias, value:***********
key:alias_type, value:phone
key:ticker, value:测试
Enter body ==========
new payload and add. root: {"alias_type":"phone","payload":{},"alias":"***********","appkey":"********************************","type":"customizedcast"}
payload before has(body) : {}
new body and add. payload: {"body":{}}
body before put: {}
body after put: {"ticker":"测试"}
Exit body ==========
key:title, value:测试标题
Enter body ==========
payload exists: {}
payload before has(body) : {}
new body and add. payload: {"body":{}}
body before put: {}
body after put: {"title":"测试标题"}
Exit body ==========
key:text, value:测试内容
Enter body ==========
payload exists: {}
payload before has(body) : {}
new body and add. payload: {"body":{}}
body before put: {}
body after put: {"text":"测试内容"}
Exit body ==========
key:after_open, value:go_app
Enter body ==========
payload exists: {"body":{"text":"测试内容"}}
payload before has(body) : {"body":{"text":"测试内容"}}
body exists: {"text":"测试内容"}
body before put: {"text":"测试内容"}
body after put: {"text":"测试内容","after_open":"go_app"}
Exit body ==========
key:display_type, value:notification
payload exists: {"body":{"text":"测试内容","after_open":"go_app"}}
key:production_mode, value:true
key:timestamp, value:**********
body: {"appkey":"********************************","type":"customizedcast","alias":"***********","alias_type":"phone","payload":{"display_type":"notification","body":{"text":"测试内容","after_open":"go_app"}},"production_mode":"true","timestamp":"**********"}

问题在第 15 行开始出现，明明前面刚添加完 body ，马上就不见了；然而最后添加 after_open 时，包含 text 的 body 却保留下来了！而且每次运行结果都一样，并不随机。

改为 org.json 后的 log （因两个包接口基本兼容，只是修改 import 的包，还有把初始化 JSONObject.fromObject(str) 改为 new JSONObject(str) 而已，上面代码一点没动，就不重新贴了）

key:appkey, value:********************************
key:type, value:customizedcast
key:alias, value:***********
key:alias_type, value:phone
key:ticker, value:测试
Enter body ==========
new payload and add. root: {"alias_type":"phone","payload":{},"alias":"***********","appkey":"********************************","type":"customizedcast"}
payload before has(body) : {}
new body and add. payload: {"body":{}}
body before put: {}
body after put: {"ticker":"测试"}
Exit body ==========
key:title, value:测试标题
Enter body ==========
payload exists: {"body":{"ticker":"测试"}}
payload before has(body) : {"body":{"ticker":"测试"}}
body exists: {"ticker":"测试"}
body before put: {"ticker":"测试"}
body after put: {"ticker":"测试","title":"测试标题"}
Exit body ==========
key:text, value:测试内容
Enter body ==========
payload exists: {"body":{"ticker":"测试","title":"测试标题"}}
payload before has(body) : {"body":{"ticker":"测试","title":"测试标题"}}
body exists: {"ticker":"测试","title":"测试标题"}
body before put: {"ticker":"测试","title":"测试标题"}
body after put: {"ticker":"测试","text":"测试内容","title":"测试标题"}
Exit body ==========
key:after_open, value:go_app
Enter body ==========
payload exists: {"body":{"ticker":"测试","text":"测试内容","title":"测试标题"}}
payload before has(body) : {"body":{"ticker":"测试","text":"测试内容","title":"测试标题"}}
body exists: {"ticker":"测试","text":"测试内容","title":"测试标题"}
body before put: {"ticker":"测试","text":"测试内容","title":"测试标题"}
body after put: {"after_open":"go_app","ticker":"测试","text":"测试内容","title":"测试标题"}
Exit body ==========
key:display_type, value:notification
payload exists: {"body":{"after_open":"go_app","ticker":"测试","text":"测试内容","title":"测试标题"}}
key:production_mode, value:true
key:timestamp, value:**********
body: {"alias_type":"phone","payload":{"display_type":"notification","body":{"after_open":"go_app","ticker":"测试","text":"测试内容","title":"测试标题"}},"alias":"***********","appkey":"********************************","type":"customizedcast","production_mode":"true","timestamp":"**********"}

一个可以明显发现的细节是，json-lib 保持了添加顺序，而 org.json 没有。我看过 json-lib 源码是用 ListOrderedMap（看的最新代码，没找我引用的版本，不过估计差别不会太大）。

然而这并没有什么用，内容都丢了，保持顺序有毛线用。

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json-lib-2.4-jdk15 的疑似 bug