1 使用field

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

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 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

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 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.

5 解析

方式1，采用了最基本的java反射方式，使用Filed，循环bean的Field，得到Object，再转换为Integer类型。 方式2，采用了看似最简洁的BeanUitls，根据属性名，获取属性值。这样最耗时。 方式3，采用了获取bean的Method，然后invoke的方式来获取值。