Parsing JSON in Jersey | 易学教程

问题

I have a JSON string with multiple key-value pairs and few single objects as under.

I am using Jersey to write a resource class that will read this JSON and convert it to a Java object but I am unable to do so.

Can anyone help me to write the corresponsing Java object and how to parse the JSON to populate this Java object?

{
  "Name": "TestName",
  "MyMap": [
    {
      "key": "Color",
      "value": "red"
    },
    {
      "key": "distance",
      "value": "long"
    },
    {
      "key": "Size",
      "value": "large"
    }
  ]
}

My resource class:

@POST
@Path("/somePath")
@Consumes(MediaType.APPLICATION_JSON)
public Response generateDetails(MyObject myObject) {
    myObject.getName();
    System.out.println("Name " + myObject.getName());
}

回答1:

Designing your POJO to work with Jackson

If you are open to use Jackson as a JSON parser, you can have the following:

public class RequestContent {

    @JsonProperty("Name")
    private String name;

    @JsonProperty("MyMap")
    private List<KeyValuePair> map;

    // Getters and setters ommited
}

public class KeyValuePair {

    private String key;

    private String value;

    // Getters and setters ommited
}

Parsing the JSON with Jackson

With Jersey and Jackson, you won't need to parse your JSON string with ObjectMapper, as shown below:

String json = "{\"Name\":\"TestName\",\"MyMap\":[{\"key\":\"Color\",\"value\":\"red\"},{\"key\":\"distance\",\"value\":\"long\"},{\"key\":\"Size\",\"value\":\"large\"}]}";";

ObjectMapper mapper = new ObjectMapper();
RequestContent requestContent = mapper.readValue(json, RequestContent.class);

Just ensure your resource method look as following and let Jackson's MessageBodyReader do the job for you:

@POST 
@Path("/somePath") 
@Consumes(MediaType.APPLICATION_JSON) 
public Response generateDetails(RequestContent requestContent) {
    ...
}

JSON parsing will the automatically handled by the JacksonJsonProvider class, which implements MessageBodyReader.

Jackson dependencies

To use Jackson 2.x as your JSON provider you need to add jersey-media-json-jackson module to your pom.xml file:

<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson</artifactId>
    <version>2.23.1</version>
</dependency>

To use Jackson 1.x it'll look like:

<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson1</artifactId>
    <version>2.23.1</version>
</dependency>

If you're not using Maven make sure to have all needed dependencies (see jersey-media-json-jackson or jersey-media-json-jackson1) on the classpath.

In order to use Jackson as your JSON provider you need to register JacksonFeature (or Jackson1Feature for Jackson 1.x) in your Application/ResourceConfig sub-class.

For more details, check the Jersey documentation about support for common media type representations.

Update based in your requirement change

Change the RequestContent class to be like:

public class RequestContent {

    @JsonProperty("Name")
    private String name;

    @JsonProperty("MyMap")
    private List<List<KeyValuePair>> map;

    // Getters and setters ommited
}

Then parse the JSON with one of the approaches shown above.

回答2:

1. Create a Pojo class having same keys like your json string contains:
     eg: name , arraylist for your array

 2. Read the above json string and then convert to your pojo.

eg:

ObjectMapper mapper = new ObjectMapper();
String jsonInString = "{'name' : 'gokul'}";
Staff obj = mapper.readValue(jsonInString, Staff.class);

来源：https://stackoverflow.com/questions/38779319/parsing-json-in-jersey

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