从 Apache Camel 中的 JSON 正文访问数据

2022-01-19 00:00:00 json java apache-camel

我正在使用一个基本上允许文件系统导航的 API.我正在尝试从 API 返回的 JSON 中访问数据，以便对其执行功能.

I am working with an API which basically allows for the navigation of a file-system. I am trying to access data from within the returned JSON by the API in order to perform a function on it.

下面是我使用访问 API 的代码.我曾尝试使用 unmarshal 来将返回的 JSON 转换为 Map.

Below is the code I am using the access the API. I have tried to use unmarshal to convert the JSON returned to a Map. 

from("timer://foo?fixedRate=true&period=120000")
    .log("Checking for files")
    .setHeader("Authorization", simple(myHttp.getAuth()))
    .setHeader("CamelHttpMethod", constant("GET"))
    .to(myHttp.getFullRequest())
    .unmarshal(new JacksonDataFormat(Map.class)).log("${body}");

这会将这些数据返回给我:

Which returns this data to me: 

{
    objects=[
    {
        name=file1.csv,
        type=file
    },
    {
        name=dir1,
        type=directory,
    },
    {
        name=dir2,
        type=directory
    },
    {
        name=dir3,
        type=directory
    },
    {
        name=dir4,
        type=directory
    }]
}

我想访问对象"下的数组，以检查此目录中是否存在任何文件.到目前为止，我只尝试在对象下记录数据，因此我使用了以下代码:

I want to access the array under "objects" in order to check whether any files exist inside this directory. So far, I only tried to log the data under objects and therefore I have used this code:

   .unmarshal(new JacksonDataFormat(Map.class)).log("${body.objects}");

使用 ${body.objects}，我仍然无法访问 MAP 内的数据.我希望这样的东西会被退回:

Using ${body.objects}, I'm still unable to access the data inside the MAP. I expected something like this to be returned: 

        [{
            name=file1.csv,
            type=file
        },
        {
            name=dir1,
            type=directory,
        },
        {
            name=dir2,
            type=directory
        },
        {
            name=dir3,
            type=directory
        },
        {
            name=dir4,
            type=directory
        }]

但是我得到了这个错误:

but instead I get this error:

方法名称:在 bean 上找不到对象:{objects=[{name=file1.csv,type=file},{name=dir1,type=directory,},{name=dir2,type=directory},{name=dir3,type=directory},{name=dir4,type=directory}]} 类型:java.util.LinkedHashMap.交换[ID-IT1289-1529914067957-0-1]

Method with name: objects not found on bean: {objects=[{name=file1.csv,type=file},{name=dir1,type=directory,},{name=dir2,type=directory},{name=dir3,type=directory},{name=dir4,type=directory}]} of type: java.util.LinkedHashMap. Exchange[ID-IT1289-1529914067957-0-1]

我是否在错误地使用 unmarshall 后访问了返回的 MAP?如果是这样，我必须使用什么正确的语法?

Am I accessing the returned MAP after using unmarshall incorrectly? What is the correct syntax I must I use if so?

我见过其他解组的例子……但我不能完全理解.我注意到许多示例使用具有 JSON 结构的类.这是必要的吗?如果我的 body 当前是 java.util.LinkedHashMap 类型，我希望访问它应该不是问题，但我似乎找不到路.

I have seen other examples of unmarshalling... but I cannot understand completely. I've noticed many examples use a class with the structure of the JSON. Is this necessary? If my body is currently of type: java.util.LinkedHashMap, I expect it shouldn't be a problem to access but I cannot seem to find the way.

提前致谢

推荐答案

最好的方法是创建一个与你的 Json 结构匹配的类.

The best way to do this is to create a class matching your Json Structure. 

class RestResponse {
   List<FileNameType> objects;
   //Getters and Setters
}

class FileNameType {
  String name;
  String type;
  //Getters and setters.
}

然后像这样改变你的路线

Then change your route like this 

from("timer://foo?fixedRate=true&period=120000")
    .log("Checking for files")
    .setHeader("Authorization", simple(myHttp.getAuth()))
    .setHeader("CamelHttpMethod", constant("GET"))
    .to(myHttp.getFullRequest())
    .unmarshal().json(JsonLibrary.Jackson, RestResponse.class)
    .to(....);

最后一部分我留空了，在这里你可以添加一个处理器来验证你的逻辑.您可以从 exchange.getIn().getBody() 中获取 RestResponse 对象.像这样的事情会做

The last part I have left it blank, here you can add a processor to verify your logic. You can get the RestResponse object from exchange.getIn().getBody(). Some thing like this will do 

........
.unmarshal().json(JsonLibrary.Jackson, RestResponse.class)
.process(exchange -> {

              RestResponse response = exchange.getIn().getBody(RestResponse.class);
               // Do your logic here.

  })

您可能需要添加此依赖项

You might need to add this dependency

<dependency>
       <groupId>org.apache.camel</groupId>
       <artifactId>camel-jackson</artifactId>
       <version>yourcamelversion</version>
 </dependency>

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