将pojo转换成Map，直接构造mongodb bsonobject

package com.skmbw.yinlei.mongo;  
  
import java.util.Date;  
import java.util.HashMap;  
import java.util.Map;  
import java.util.Map.Entry;  
import java.util.concurrent.ConcurrentHashMap;  
import java.util.concurrent.ConcurrentMap;  
  
import org.apache.commons.lang3.StringUtils;  
import org.springframework.cglib.beans.BeanMap;  
  
import com.alibaba.fastjson.JSON;  
import com.alibaba.fastjson.JSONObject;  
import com.esotericsoftware.reflectasm.MethodAccess;  
  
public class JSONUtils {  
    public static ConcurrentMap<String, BeanMap> beanMapCache = new ConcurrentHashMap<String, BeanMap>();  
      
    //JSONObject就是个Map，它实现了Map接口  
    public static Map<String, ?> toMap(Object object) {  
        JSONObject jsonObject = (JSONObject)JSON.toJSON(object);  
        return jsonObject;  
    }  
      
    //去掉null  
    public static Map<String, ?> toMaps(Object object) {  
        Map<String, Object> map = new HashMap<String, Object>();  
        JSONObject jsonObject = (JSONObject) JSON.toJSON(object);  
        for (Entry<String, Object> entry : jsonObject.entrySet()) {  
            if (entry.getValue() != null) {  
                map.put(entry.getKey(), entry.getValue());  
            }  
        }  
        return map;  
    }  
      
    public static void main(String[] aa) {  
        User user = new User();  
        user.setAccount("asdf");  
        user.setAge(22);  
        user.setDate(new Date());  
        Map<String, Object> result = new HashMap<String, Object>();  
        Map<String, Object> result2 = new HashMap<String, Object>();  
          
        long d2 = System.nanoTime();  
        JSONObject jsonObject = (JSONObject)JSON.toJSON(user);  
        String json = jsonObject.toJSONString();  
        Map<String, Object> jsonMap = JSON.parseObject(json);  
        System.out.println(System.nanoTime() - d2);  
          
          
        long dd = System.nanoTime();  
        Map<String, Object> map = (Map<String, Object>)jsonObject;  
        result.putAll(map);  
        System.out.println(System.nanoTime() - dd);  
        long d = System.nanoTime();  
        for (Entry<String, Object> entry : jsonObject.entrySet()) {  
            if (entry.getValue() != null) {  
                result2.put(entry.getKey(), entry.getValue());  
            }  
        }  
        System.out.println(System.nanoTime() - d);  
          
        Map<String, Object> toMap = new HashMap<String, Object>();  
        beanToMap(user, toMap);  
          
        Map<String, Object> toMap2 = beanToMap(user);  
          
        System.out.println(toMap2);  
    }  
      
    public static void beanToMap(Object fromBean, Map<String, Object> toMap) {  
        //MethodAccess要缓存  
        MethodAccess methodAccess = MethodAccess.get(fromBean.getClass());  
        String[] methodNames = methodAccess.getMethodNames();   
        for (String methodName : methodNames){   
            if (methodName.startsWith("get")){   
                Object value = methodAccess.invoke(fromBean, methodName, (Object[])null);   
                toMap.put(StringUtils.uncapitalize(methodName.substring(3)), value);   
            }   
        }  
    }  
      
    public static BeanMap getBeanMap(Object object) {  
        BeanMap beanMap = beanMapCache.get(object.getClass().getName());  
        if (beanMap == null) {  
            beanMap = BeanMap.create(object);  
            beanMapCache.put(object.getClass().getName(), beanMap);  
        }  
        return beanMap;  
    }  
      
    //如果使用BeanMap缓存，这个性能最好。  
    public static Map<String, Object> beanToMap(Object object) {  
          
        BeanMap beanMap = getBeanMap(object);  
        beanMap.setBean(object);  
        @SuppressWarnings("unchecked")  
        Map<String, Object> toMap = beanMap;  
          
        for (Entry<String, Object> entry : toMap.entrySet()) {  
            if (entry.getValue() != null) {  
                toMap.put(entry.getKey(), entry.getValue());  
            }  
        }  
        return toMap;  
    }  
}