How to parse complex JSON data using Fastjson?

To parse complex JSON data using Fastjson, you can follow the steps below:

1. Introduce the Fastjson library: Add the Fastjson library to the project dependencies.
2. Create Java objects: based on the structure of JSON data, create corresponding Java objects, define the appropriate properties and methods.
3. Parse JSON data: Use Fastjson’s JSONObject.parseObject() or JSONArray.parseArray() method to convert JSON string into Java object.
4. Access data: Retrieve the necessary information through the properties and methods of Java objects.

Below is an example code demonstrating how to use Fastjson to parse complex JSON data.

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class Main {
    public static void main(String[] args) {
        // 复杂的JSON数据
        String jsonData = "{\"name\": \"John\", \"age\": 30, \"address\": {\"city\": \"New York\", \"state\": \"NY\"}, \"hobbies\": [\"reading\", \"traveling\"]}";

        // 解析JSON数据
        JSONObject jsonObject = JSON.parseObject(jsonData);

        // 获取基本数据
        String name = jsonObject.getString("name");
        int age = jsonObject.getIntValue("age");

        // 获取嵌套对象
        JSONObject address = jsonObject.getJSONObject("address");
        String city = address.getString("city");
        String state = address.getString("state");

        // 获取数组数据
        JSONArray hobbies = jsonObject.getJSONArray("hobbies");
        for (int i = 0; i < hobbies.size(); i++) {
            String hobby = hobbies.getString(i);
            System.out.println(hobby);
        }
    }
}

In the example above, we started by creating a complex JSON string and then converted it to a JSONObject object using the JSON.parseObject() method. Next, we retrieved the required data using methods such as getString(), getIntValue(), and getJSONObject().

It should be noted that Fastjson also provides additional features such as automatic type conversion, serialization, deserialization, and more. For detailed usage, please refer to Fastjson’s official documentation.