java - 使用 Gson 创建 JSON 时 POJO 中黑色字段的影响

Question

我正在尝试将 JSON 字符串转换为 POJO 和从 POJO 转换。我想知道对于不同类型的 json 是否最好有一个新的类定义。正如我认为让 google gson 必须解析空字段会减慢它的速度。（不是很明显，但仍然。我认为值得进行实验并在此处发布。）例如登录客户端可能是。

public class CustomJSON {
    private String name;

    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
}

但我可以从客户那里收到其他东西，例如。最喜欢的颜色，食物等。

public class CommonJSON {
    private String name;
    private String food;
    private String music;

    //getters and setters.
}

所以我进行了测试。

CustomJson 与上面相同，并且使用 CommonJSON 我添加了 50 个其他空字段，这些字段将不使用 a 到 ax。

public class CommonJSON {
    private String name;
    private String a;
          ...
    private String ax;

    //getters and setters.
}

我运行测试的主要方法如下。

public static void main(String[] args) {
        // TODO Auto-generated method stub


        String theJSON = "";

        int passes = 100;
        long start;
        long finish;
        long exeTime;

        Gson gson = new Gson();

        //custom JSON
        start = System.nanoTime();
        for(int i=0;i<passes;i++)
        {
            CustomJSON custom = new CustomJSON();
            custom.setName("StackOverFlow");            
            theJSON = gson.toJson(custom);
        }
        finish = System.nanoTime();
        System.out.println(theJSON);
        exeTime = finish-start;
        System.out.println("Custom JSON \n\t>\t "+(exeTime)+" Nano seconds");
        System.out.println(" \t>\t "+Math.round((exeTime)/1000000.0)+" Micro seconds\n");

    //common JSON
    start= System.nanoTime();
    for(int i=0;i<passes;i++)
    {
        CommonJSON toClientJSONd = new CommonJSON();
        toClientJSONd.setName("StackOverFlow");
        theJSON = gson.toJson(toClientJSONd);
    }
    finish = System.nanoTime();
    System.out.println(theJSON);
    exeTime = finish-start;
    System.out.println("Common JSON \n\t>\t "+(exeTime)+" Nano seconds");
    System.out.println(" \t>\t "+Math.round((exeTime)/1000000.0)+" Micro seconds");

}

The results are not as I expected. With 100 passes the common class finishes 10ms faster on my machine. If I increase the number of passes the common class eventually starts to lag behind.

What makes the common class faster to start of with? Should I worry about this in my code or just use one class for a common class for all jsons?

I can provide full source and an eclipse project if anyone would like to run it.

Answer 1

You seem to be experiencing the effects of the JVM warming up. See this SO post for more info.

Answer 2

To answer the other part of my question. For Simple JSON objects its neater to use the JsonObject from the GSON lib and add properties.

JsonObject json = new JsonObject();
json.addProperty("myBool", false);