json 实体互转, list json互转 ,List<实体> 转List<Object> , List<Objcet> 转List<Map> map 转实体 ， map转json

//    json 实体互转, list json互转 ,List<实体> 转List<Object> , List<Objcet> 转List<Map>          使用alibaba的json工具包
     

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.dao.model.Brand;

import java.util.ArrayList;
import java.util.List;

    /**
     * Created by chengda on 2017/2/23.
     */
    public class JsonTest {

        public static void main(String[] args) {
            List<Brand> brandList = new ArrayList<Brand>();
            Brand b = new Brand();
            b.setBrandId(1);
            b.setBrandName("测试");
            b.setStatus(false);
            Brand b1 = new Brand();
            b1.setBrandId(2);
            b1.setBrandName("测试2");
            b1.setStatus(false);
            Brand b2 = new Brand();
            b2.setBrandId(3);
            b2.setBrandName("测试3");
            b2.setStatus(false);

            brandList.add(b1);
            brandList.add(b2);
            brandList.add(b);

            /**
             *
             *实体转为json
             */
            String s = JSONObject.toJSONString(b);
            System.out.println(s);

            /**
             *
             *json转为实体
             */
            Brand brand = JSONObject.parseObject(s, Brand.class);
            System.out.println(brand + "==============");


            /**
             *
             *list集合转json
             */
            String s1 = JSON.toJSONString(brandList);
            System.out.println(s1 + "999999");
            //json 转list
            List<Brand> brands = JSONObject.parseArray(s1, Brand.class);
            System.out.println(brands);


        }


        /**
         * List<实体>转为list<Object>
         *
         * @param t
         * @return
         */
        public List<Object> beanToObject(List<?> t) {
            List<Object> o = new ArrayList<Object>();
            Iterator<?> it = t.iterator();
            while (it.hasNext()) {
                o.add(it.next());
            }

            return o;
        }


        /**
         * List<objcet> 转为List<Map>
         *
         * @param object
         * @return
         * @throws Exception
         */
        public List<Map> beanToMap(List<Object> object) throws Exception {
            List<Map> maps = new ArrayList<Map>();
            for (Object o : object) {
                String s = JSON.toJSONString(o);
                Map map = JSONObject.parseObject(s, Map.class);

                maps.add(map);
            }
            return maps;
        }

        /**
         *   map  转  json
	 *	导  import net.sf.json.JSONObject;
         */
        public String mapToJson(){
            Map<String,String> map = new HashMap<String,String>();
            map.put("huahua1","huahua1");
            map.put("huahua2","huahua2");
            map.put("huahua3","huahua3");
            JSONObject smsparam = JSONObject.fromObject(smsParam);
            return smsparam.toJSONString();
            
        }


        另外一种map 转json 	导  com.alibaba.druid.support.json;	

	String s = JSONUtils.toJSONString(map)




        /**
         * map   转   实体
         */
        public static <T> T toBean(Class<T> clazz, Map map) {
            T obj = null;
            try {
                BeanInfo beanInfo = Introspector.getBeanInfo(clazz);
                obj = clazz.newInstance(); // 创建 JavaBean 对象

                // 给 JavaBean 对象的属性赋值
                PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
                for (int i = 0; i < propertyDescriptors.length; i++) {
                    PropertyDescriptor descriptor = propertyDescriptors[i];
                    String propertyName = descriptor.getName();
                    if (map.containsKey(propertyName)) {
                        // 下面一句可以 try 起来，这样当一个属性赋值失败的时候就不会影响其他属性赋值。
                        Object value = map.get(propertyName);
                        if ("".equals(value)) {
                            value = null;
                        }
                        Object[] args = new Object[1];
                        args[0] = value;
                        try {
                            descriptor.getWriteMethod().invoke(obj, args);
                        } catch (InvocationTargetException e) {
                            System.out.println("字段映射失败");
                        }
                    }
                }
            } catch (IllegalAccessException e) {
                System.out.println("实例化 JavaBean 失败");
            } catch (IntrospectionException e) {
                System.out.println("分析类属性失败");
            } catch (IllegalArgumentException e) {
                System.out.println("映射错误");
            } catch (InstantiationException e) {
                System.out.println("实例化 JavaBean 失败");
            }
            return (T) obj;
        }
    }