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;
    }