java - 如何正确选择json结构

Question

嗨，我有一个 php 脚本，它将用户数据输入到 mysql 中，从 mysql 中我得到一个数组中的结果，最后通过 PHP 的 json_encode 函数得到 json 格式。下面提供了该文件的内容。

[{"priority":"1","rule_body":"person(?x),pid(?y),haspid(?x,?y)","cons":"patient(?x)","boolean":"1"},
{"priority":"1","rule_body":"patient(?x),hasbp(high)","cons":"situation(emergency)","boolean":"1"},
{"priority":"1","rule_body":"patient(?x),hasbp(high)","cons":"situation(emergency)","boolean":"1"},
{"priority":"1","rule_body":"patient(?x),hasbp(high)","cons":"situation(emergency)","boolean":"1"},
{"priority":"1","rule_body":"aaa(bbb)","cons":"z(x)","boolean":"1"},
{"priority":"1","rule_body":"aaa(bbb)","cons":"z(x)","boolean":"1"},
{"priority":"1","rule_body":"aaa(bbb)","cons":"z(x)","boolean":"1"}]

但是现在我需要在 JAVA 中读取 json，为了方便起见，我将 json 文件的内容复制并粘贴到字符串中。我能够阅读内容，但位置已更改为以下顺序

这是输出

    LENGTH IS____7
{"priority":"1","boolean":"1","rule_body":"person(?x),pid(?y),haspid(?x,?y)","cons":"patient(?x)"}
{"priority":"1","boolean":"1","rule_body":"patient(?x),hasbp(high)","cons":"situation(emergency)"}
{"priority":"1","boolean":"1","rule_body":"patient(?x),hasbp(high)","cons":"situation(emergency)"}
{"priority":"1","boolean":"1","rule_body":"patient(?x),hasbp(high)","cons":"situation(emergency)"}
{"priority":"1","boolean":"1","rule_body":"aaa(bbb)","cons":"z(x)"}
{"priority":"1","boolean":"1","rule_body":"aaa(bbb)","cons":"z(x)"}
{"priority":"1","boolean":"1","rule_body":"aaa(bbb)","cons":"z(x)"}

正如您所看到的， boolean 值必须位于最后，但它会弹出在第二个数字上。我尝试了与教程不同的代码，并做了一些自己的代码，如下所示，但结果是相同的:在这件事上需要帮助。

jsonInput=[....as shown above the json contents....]
JSONArray ja = new JSONArray(jsonInput);
System.out.println("LENGTH IS____"+ja.length());
  for(int x=0;x<ja.length();x++)
  {
      JSONObject jb = ja.getJSONObject(x);
      System.out.println(jb);
  }
  System.out.println("KKKKKKKKKKKKKKKKKKKKKKKKKKKKKK");

Answer 1

JSON 未指定键的顺序 As Adrian Smith said :

JSON libraries are free to rearrange the order of the elements as they see fit. This is not a bug.

您可能使用 org.json。您可以使用 getString("myKey") 访问 JSONObject 中的值，而无需知道其位置。

另一种解决方案是创建一个代表您的数据的类:

public class myClass{
    private int priority;
    private String rule_body;
    private String cons;
    private String boolean; //STRING ! 1 is not a valid boolean value.
}

然后创建您的类的 ArrayList 并使用 Gson 反序列化其中的 JSON。

Gson myGsonTool = new Gson();
ArrayList<myClass> myData = gson.fromJson(myJsonString, ArrayList<myClass>.class);

然后，您就有了一个包含所有数据的 POJO。您现在可以轻松访问您的数据:

//If i want the value of rule body:
myData.get(0).getRule_Body();

我不知道你的程序的目的，所以这可能不是最好的解决方案。

编辑:Gson 维护记录的顺序。