如何在请求和响应rest API的HTTP方法中应用Json序列化或反序列化

Question

我在java中很新的Rest api。我的问题是如何在post或get函数之前直接将json字符串请求转换为java类对象，如

json string : '{"id":3,"name":name}'

休息api post方法：

@Post
 public Something postData(Something obj) throws Exception {
} 

那么如何在请求之前对这个方法应用json序列化。 现在我在postData方法中转换它。

Answer 1

您可以使用Jackson API来使用JSON。 对于以下JSON数据，Java对象映射可以如下完成。

    {
  "id": 123,
  "name": "Pankaj",
  "permanent": true,
  "address": {
    "street": "Albany Dr",
    "city": "San Jose",
    "zipcode": 95129
  },
  "phoneNumbers": [
    123456,
    987654
  ],
  "role": "Manager",
  "cities": [
    "Los Angeles",
    "New York"
  ],
  "properties": {
    "age": "29 years",
    "salary": "1000 USD"
  }
}

import java.io.File;
import java.io.IOException;
import java.io.StringWriter;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.journaldev.jackson.model.Address;
import com.journaldev.jackson.model.Employee;


public class JacksonObjectMapperExample {

    public static void main(String[] args) throws IOException {

        //read json file data to String
        byte[] jsonData = Files.readAllBytes(Paths.get("employee.txt"));

        //create ObjectMapper instance
        ObjectMapper objectMapper = new ObjectMapper();

        //convert json string to object
        Employee emp = objectMapper.readValue(jsonData, Employee.class);

        System.out.println("Employee Object\n"+emp);

        //convert Object to json string
        Employee emp1 = createEmployee();
        //configure Object mapper for pretty print
        objectMapper.configure(SerializationFeature.INDENT_OUTPUT, true);

        //writing to console, can write to any output stream such as file
        StringWriter stringEmp = new StringWriter();
        objectMapper.writeValue(stringEmp, emp1);
        System.out.println("Employee JSON is\n"+stringEmp);
    }

    public static Employee createEmployee() {

        Employee emp = new Employee();
        emp.setId(100);
        emp.setName("David");
        emp.setPermanent(false);
        emp.setPhoneNumbers(new long[] { 123456, 987654 });
        emp.setRole("Manager");

        Address add = new Address();
        add.setCity("Bangalore");
        add.setStreet("BTM 1st Stage");
        add.setZipcode(560100);
        emp.setAddress(add);

        List<String> cities = new ArrayList<String>();
        cities.add("Los Angeles");
        cities.add("New York");
        emp.setCities(cities);

        Map<String, String> props = new HashMap<String, String>();
        props.put("salary", "1000 Rs");
        props.put("age", "28 years");
        emp.setProperties(props);

        return emp;
    }

}

资料来源： http ： //www.journaldev.com/2324/jackson-json-processing-api-in-java-example-tutorial

Answer 2

您可以使用Gson或使用JSONObject / JSONArray类进行手动序列化/反序列化（ 此处示例 ）。 还有很多其他方法/库可以做到这一点。