JSON 的几种转换

 package com.qbskj.project.util;

 import java.io.IOException;
 import java.io.Writer;

 import org.springframework.util.Assert;

 import com.fasterxml.jackson.core.JsonGenerationException;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.ObjectMapper;

 /**
  * Utils - JSON
  */
 public final class JsonUtils {

     /** ObjectMapper */
     private static ObjectMapper mapper = new ObjectMapper();

     /**
      * 不可实例化
      */
     private JsonUtils() {
     }

     /**
      * 将对象转换为JSON字符串
      *
      * @param value
      *            对象
      * @return JSOn字符串
      */
     public static String toJson(Object value) {
         try {
             return mapper.writeValueAsString(value);
         } catch (Exception e) {
             e.printStackTrace();
         }
         return null;
     }

     /**
      * 将JSON字符串转换为对象
      *
      * @param json
      *            JSON字符串
      * @param valueType
      *            对象类型
      * @return 对象
      */
     public static <T> T toObject(String json, Class<T> valueType) {
         Assert.hasText(json, "");
         Assert.notNull(valueType, "");
         try {
             return mapper.readValue(json, valueType);
         } catch (Exception e) {
             e.printStackTrace();
         }
         return null;
     }

     /**
      * 将JSON字符串转换为对象
      *
      * @param json
      *            JSON字符串
      * @param typeReference
      *            对象类型
      * @return 对象
      */
     public static <T> T toObject(String json, TypeReference<?> typeReference) {
         Assert.hasText(json, "");
         Assert.notNull(typeReference, "");
         try {
             return mapper.readValue(json, typeReference);
         } catch (Exception e) {
             e.printStackTrace();
         }
         return null;
     }

     /**
      * 将JSON字符串转换为对象
      *
      * @param json
      *            JSON字符串
      * @param javaType
      *            对象类型
      * @return 对象
      */
     public static <T> T toObject(String json, JavaType javaType) {
         Assert.hasText(json, "");
         Assert.notNull(javaType, "");
         try {
             return mapper.readValue(json, javaType);
         } catch (Exception e) {
             e.printStackTrace();
         }
         return null;
     }

     /**
      * 将对象转换为JSON流
      *
      * @param writer
      *            writer
      * @param value
      *            对象
      */
     public static void writeValue(Writer writer, Object value) {
         try {
             mapper.writeValue(writer, value);
         } catch (JsonGenerationException e) {
             e.printStackTrace();
         } catch (JsonMappingException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }
     }

 }