先在專案內引入包。

gradle:

dependencies {
    compile(
            "com.fasterxml.jackson.core:jackson-databind:2.9.6"
    )
}

maven:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.6</version
 
>
</dependency>

建立類JsonUtil，將轉換方法寫成靜態，然後就可以在專案的任意地方都可以引用了。

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

public class JsonUtil {
    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();

    public static String parseJson
 
(Object o) {
        if (o == null) {
            return "null";
        }
        try {
            return OBJECT_MAPPER.writeValueAsString(o);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return "null";
    }

}