使用字节码asm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，最差
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);
}
//性能次之
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;
}
}