java map转为json字符串

可以使用Jackson库将Java Map转换为JSON字符串。示例代码如下：

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.HashMap;
import java.util.Map;

public class MapToJsonExample {
    public static void main(String[] args) throws JsonProcessingException {
        Map<String, Object> map = new HashMap<>();
        map.put("name", "John");
        map.put("age", 30);
        map.put("city", "New York");

        ObjectMapper objectMapper = new ObjectMapper();
        String json = objectMapper.writeValueAsString(map);

        System.out.println(json);
    }
}

输出结果为：

{"city":"New York","name":"John","age":30}