在java專案中，通常會用到json型別的轉換，常常需要對 json字串和物件進行相互轉換。

在製作自定義的json轉換類之前，先引入以下依賴

<!--json解析工具-->
<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-guava</artifactId>
  <version>2.5.3</version>
</dependency>
<dependency>
  <groupId>org.codehaus.jackson</groupId>
  <artifactId>jackson-core-asl</artifactId>
  <version>1.9.13</version>
</dependency>
<dependency>
  <groupId>org.codehaus.jackson</groupId>
  <artifactId>jackson-mapper-asl</artifactId>
  <version>1.9.13</version>
</dependency>

自定義json工具類的實現:

import lombok.extern.slf4j.Slf4j;
import org.codehaus.jackson.map.DeserializationConfig;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.annotate.JsonSerialize;
import org.codehaus.jackson.map.ser.impl.SimpleFilterProvider;
import org.codehaus.jackson.type.TypeReference;
/**
 * json轉換
 */
@Slf4j
public class JsonMapper {

    private static ObjectMapper objectMapper = new ObjectMapper();
    static {
        // config
        objectMapper.disable(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES);
        objectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS,false);
        objectMapper.setFilters(new SimpleFilterProvider().setFailOnUnknownId(false));
        objectMapper.setSerializationInclusion(JsonSerialize.Inclusion.NON_EMPTY);
    }

    /**
     * 物件轉為json字串
     * @param src
     * @param <T>
     * @return
     */
    public static <T> String obj2String(T src){
        if(src == null){
            return null;
        }
        try{
            return src instanceof String ? (String) src : objectMapper.writeValueAsString(src);
        } catch (Exception e) {
            log.warn("parse object to String exception",e);
            return null;
        }
    }

    /**
     * json字串轉為物件
     * @param src
     * @param typeReference
     * @param <T>
     * @return
     */
    public static <T> T string2Obj(String src, TypeReference<T> typeReference) {
        if (src == null || typeReference == null) {
            return null;
        }
        try {
            return (T) (typeReference.getType().equals(String.class) ? src : objectMapper.readValue(src, typeReference));
        } catch (Exception e) {
            log.warn("parse String to Object exception, String:{}, TypeReference<T>:{}, error:{}", src, typeReference.getType(), e);
            return null;
        }
    }

}