java对象与json互转

 package com.liveyc;

 import java.io.StringWriter;

 import org.junit.Test;

 import com.fasterxml.jackson.annotation.JsonInclude.Include;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.liveyc.core.bean.user.Buyer;

 /**
  * 测试类  junit + Spring
  * @author lx
  *
  */
 public class TestJson {

     @Test
     public void testJSON() throws Exception {
         //Springmvc 课程时   @RequestBody   @ResponseBody   JSON与对象转换
         // OOM out of memery
         Buyer buyer = new Buyer();
         buyer.setUsername("范冰冰");
         ObjectMapper om = new ObjectMapper();
         //不要NULL 不要转了
         om.setSerializationInclusion(Include.NON_NULL);
         StringWriter w   = new StringWriter();
         om.writeValue(w, buyer);
         System.out.println(w.toString());
         //转回对象
         Buyer r = om.readValue(w.toString(), Buyer.class);
         System.out.println(r);
     }
 }

输出：

 {"username":"范冰冰"}
 Buyer [Hash = 452805835, id=null, username=范冰冰, password=null, gender=null, email=null, realName=null, registerTime=null, province=null, city=null, town=null, addr=null, isDel=null, serialVersionUID=1]

如果对象中有 非常规属性 可以加 @JsonIgnore 注解给屏蔽掉

     @JsonIgnore
     public Integer getProductAmount(){
         Integer result = 0;
         //计算过程
         for (BuyerItem buyerItem : items) {
             result += buyerItem.getAmount();
         }
         return result;
     }