幾個代碼瘦身優(yōu)化的案例

史蒂夫.喬布斯說，”復雜的終極境界是簡單“，同樣的優(yōu)雅的代碼一定是精簡明了，可讀性好。

使用LocalDate和LocalDateTime

LocalDate精確到日期，LocalDateTime精確到時分秒。優(yōu)化前14行代碼

try {
    SimpleDateFormat sdfDay = new SimpleDateFormat("yyyy-MM-dd");
    SimpleDateFormat sdfMins = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    Date now = new Date();
    String today = sdfDay.format(now);
    String waterStart = today + " 03:00:00";
    String waterEnd = today + " 04:00:00";
    Date waterStartTime = sdfMins.parse(waterStart);
    Date waterEndTime = sdfMins.parse(waterEnd);
} catch (ParseException pe) {
    return XX;
}

優(yōu)化后3行代碼

LocalDateTime now = LocalDateTime.now();
LocalDateTime waterStart = LocalDateTime.of(now.getYear(), now.getMonth(),now.getDayOfMonth(),3,0);
LocalDateTime waterEndTime =LocalDateTime.of(now.getYear(), now.getMonth(),now.getDayOfMonth(),4,0);

默認值使用Optional

優(yōu)化前五行

if (null == status) {
    param.put("status", new ArrayList<String>());
} else {
    param.put("status", status);
}

優(yōu)化后一行，使用JDK8的Optional

Optional.ofNullable(status).orElse(new ArrayList<String>());

如果是字符串可以用

StringUtils.defaultIfEmpty(status,"")

字符串累加

字符串只要不在for循環(huán)里累加，可以直接用+號，因為編譯成字節(jié)碼后會變成StringBuilder，如果在for循環(huán)里面用+號會生成多個StringBuilder，所以在for循環(huán)里累加最好在循環(huán)外創(chuàng)建StringBuilder。優(yōu)化前五行

StringBuffer sblog = new StringBuffer();
sblog.append("waterDriven|sellerId=");
sblog.append(request.getSellerTaobaoId());
sblog.append("|result=");
sblog.append(isSuccess);

優(yōu)化后一行

String sblog="waterDriven|sellerId="+request.getSellerTaobaoId()+"|result="+isSuccess;

以上場景用逗號和等號連接數(shù)據(jù)，使用GUAVA的Joiner更精簡，可讀性更好

String sblog=Joiner.on("|").withKeyValueSeparator("=").join(ImmutableMap.of("sellerId", request.getSellerTaobaoId(), "result", isSuccess))

LIST TO MAP

優(yōu)化前4行

Map<String, String> AssetsMetaIdMap = Maps.newHashMap();
for (AssetsInfoBO assetsInfoBO : request.getAssetsCollectionList()) {
    AssetsMetaIdMap.put(assetsInfoBO.getAssetMetadataId(), assetsInfoBO.getAssetMetadataId());
}

優(yōu)化后1行

Map<String, String> AssetsMetaIdMap = request.getAssetsCollectionList().stream().collect(Collectors.toMap(Hosting::getAssetMetadataId, Hosting::getAssetMetadataId));

如果key重復會拋出異常

Exception in thread "main" java.lang.IllegalStateException: Duplicate key 80000

減少不需要的判斷

優(yōu)化前5行

String requestId = null;
if (null != request.getExtData()) {
    requestId = request.getExtDataValue(REQUEST_ID_KEY);
}
return requestId;

優(yōu)化后1行

return request.getExtDataValue(REQUEST_ID_KEY);

去掉else

優(yōu)化前5行

if (null != result && StringUtils.isNotBlank(no)) {
     return no;
 } else {
     throw new RuntimeException("XX");
 }

優(yōu)化后4行

if (null != result && StringUtils.isNotBlank(no)) {
     return no;
 }
 throw new RuntimeException("XX");

不要返回布爾

優(yōu)化前5行

if ("true".equalsIgnoreCase(value.toString())) {
    invoke = true;
 } else {
    invoke = false;
 }

優(yōu)化后一行

invoke = "true".equalsIgnoreCase(value.toString());

使用級聯(lián)

優(yōu)化前5行

ParamBO paramBO = new ParamBO();
paramBO.setId(1);
paramBO.setName(”ifeve“);
paramBO.setOld(7);

優(yōu)化后1行

new ParamBO().withId(1).withName("ifeve").withOld(7);