Java反射三种方式的效率对比

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我是靠谱客的博主友好金鱼，这篇文章主要介绍Java反射三种方式的效率对比，现在分享给大家，希望可以做个参考。

0 先放结论
org.apache.commons.beanutils.BeanUtils的性能比较差
spring自带的BeanUtils性能还可以（看了源码，也是通过反射来实现的）
1 使用field

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long start = System.nanoTime();
Field[] fields = CallCount.class.getDeclaredFields();
for (String str : dateList) {
boolean exist = false;
for (Field field : fields){
field.setAccessible(true);
if (field.getName().endsWith(str)) {
int value = 0;
for (CallCount callCount : callCountList) {
value += (Integer)field.get(callCount);
}
resultList.add(value);
exist = true;
break;
}
}
if (!exist) {
resultList.add(0);
}
}
long end = System.nanoTime();
log.info("old call cost :" + (end-start));

2 使用 org.apache.commons.beanutils.BeanUtils来获取属性

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long start = System.nanoTime();
for (String str : dateList) {
Integer value = getMinuteAccessCount(str, callCountList);
resultList.add(value);
}
long end = System.nanoTime();
log.info("new call cost :" + (end-start));
private Integer getMinuteAccessCount(String minute, List<CallCount> callCountList) {
Integer result = 0;
String propertyName = "logMinute" + minute;
for (CallCount callCount : callCountList) {
int value = 0;
try {
value = Integer.valueOf(BeanUtils.getProperty(callCount, propertyName));
} catch (NumberFormatException | IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
e.printStackTrace();
}
result += value;
}
return result;
}

3 使用java.lang.reflect.Method获取值

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long start = System.nanoTime();
for (String str : dateList) {
Integer value = getMinuteAccessCount(str, callCountList);
resultList.add(value);
}
long end = System.nanoTime();
log.info("new call cost :" + (end-start));
private Integer getMinuteAccessCount(String minute, List<CallCount> callCountList) {
Integer result = 0;
for (CallCount callCount : callCountList) {
int value = 0;
try {
Method method = callCount.getClass().getDeclaredMethod("getLogMinute"+minute);
Object obj = method.invoke(callCount);
value = (Integer)obj;
} catch (NumberFormatException | IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
e.printStackTrace();
}
result += value;
}
return result;
}

4 耗时对比，在使用相同的查询条件，相同的数据的情况下。通过实验得到以下两组数据（耗时/纳秒）

1 old call cost :517599
1 old call cost :347916
1 old call cost :337312
1 old call cost :177893
1 old call cost :131709
1 old call cost :82789
1 old call cost :63973

3 new call cost :925383
3 new call cost :794016
3 new call cost :912382

1 old call cost :755016
1 old call cost :365364
1 old call cost :231944
1 old call cost :123498
1 old call cost :103315
1 old call cost :92025
1 old call cost :81762

2 new call cost :139741338
2 new call cost :3387140
2 new call cost :2230497
2 new call cost :9215854
2 new call cost :2313970
2 new call cost :1549374
2 new call cost :1884291
2 new call cost :1100880
2 new call cost :1488138

每组数据前的数字代表之前取值的方式。
由数据对比可以看出，耗时最小的，始终是方式1，并且方式1在多次调用时，耗时是逐步减少的，可能是有缓存机制。
耗时第二少的是方式3，耗时最多的是方式2.