import java.util.HashMap;

 import java.util.Iterator;

 import java.util.Map;

 import java.util.Map.Entry;

 import java.util.Set;  

 import com.alibaba.fastjson.JSON;

 import com.alibaba.fastjson.TypeReference;  

public class Demo {

    public static void main(String[] args) {

        Map<String, Student> map = new HashMap<String, Student>();

        Student stu1 = new Student("1", "莎拉波娃");

        Student stu2 = new Student("2", "布沙尔");

        Student stu3 = new Student("3", "哈勒普");  

        map.put("00011", stu1);

        map.put("00012", stu2);

        map.put("00013", stu3);  

        objectToStr(map);

        String str = "{'00011':{'id':'1','name':'silei'},'00012':{'id':'2','name':'布沙尔'},'00013':{'id':'3','name':'哈勒普'}}";

        strToObject(str);

    }  

    public static void strToObject(String str) {

        Map<String, Student> map = (Map<String, Student>) JSON.parseObject(str, new TypeReference<Map<String, Student>>() {

        });

        Set<Entry<String, Student>> m = map.entrySet();

        Iterator<Entry<String, Student>> it = m.iterator();

        while (it.hasNext()) {

            Entry<String, Student> en = it.next();

            String id = en.getKey();

            Student stu = en.getValue();

            System.out.println(stu.getId() + "===" + stu.getName());

        }

        System.out.println(map.size());

    }  

    // 把对象转换成JSON字符串

    public static void objectToStr(Map map) {

        String str = JSON.toJSONString(map);

        System.out.println(str);

    }

}