我有一种情况，必须检查数据库中是否已经存在模板。如果存在，我必须根据现有模板返回一条消息。
我有几个模板：电子邮件，信函，短信。如果它们全部都存在，我必须返回“所有模板已经存在”。
如果仅存在电子邮件模板，那么我必须返回，仅电子邮件模板存在，对于Letter和Sms模板也是如此。
代码：
for (EventVO eventVO: eventModuleList) {
List <EmailTemplateMaster> emailTemplateList = communicationDAO
.checkEmailTemplateExist(eventVO.getEventCode());
if (CollectionUtils.isNotEmpty(emailTemplateList)) {
emailTemplateExist = true;
}
List <LetterTemplateMaster> letterTemplateList = communicationDAO
.checkLetterTemplateExist(eventVO.getEventCode());
if (CollectionUtils.isNotEmpty(letterTemplateList)) {
letterTemplateExist = true;
}
List <SmsTemplateMaster> smsTemplateList = communicationDAO
.checkSmsTemplateExist(eventVO.getEventCode());
if (CollectionUtils.isNotEmpty(smsTemplateList)) {
smsTemplateExist = true;
}
if (emailTemplateExist && letterTemplateExist && smsTemplateExist) {
templateExist = CommunicationConstants.ALL_TEMPLATE_EXIST;
}
if (emailTemplateExist || !letterTemplateExist && !smsTemplateExist) {
templateExist = CommunicationConstants.EMAIL_TEMPLATE_EXIST;
}
if (!emailTemplateExist && letterTemplateExist && !smsTemplateExist) {
templateExist = CommunicationConstants.LETTER_TEMPLATE_EXIST;
}
if (!emailTemplateExist && !letterTemplateExist && smsTemplateExist) {
templateExist = CommunicationConstants.SMS_TEMPLATE_EXIST;
}
}
我能知道检查退出模板的布尔值是否存在的最简单方法。
基于退出，我必须发送相应的消息。
public static final String ALL_TEMPLATE_EXIST = "Email, Letter and Sms Template already exist for the selected event.";
public static final String EMAIL_TEMPLATE_EXIST = "Email Template already exist for the selected event.";
public static final String SMS_TEMPLATE_EXIST = "Sms Template already exist for the selected event.";
public static final String LETTER_TEMPLATE_EXIST = "Email Letter Template already exist for the selected event.";
public static final String EMAIL_SMS_TEMPLATE_EXIST = "Email and Sms Template already exist for the selected event.";
public static final String EMAIL_LETTER_TEMPLATE_EXIST = "Email and Letter Template already exist for the selected event.";
public static final String SMS_LETTER_TEMPLATE_EXIST = "Sms and Letter Template already exist for the selected event.";
答案 0 :(得分：2)
您可以“准备”布尔值与CommunicationConstants类中的消息之间的映射：
public class CommunicationConstants
{
private static final Map<List<Boolean>, String> CONSTANTS = new HashMap<>();
static
{
CONSTANTS.put(Arrays.asList(true, true, true), "Email, Letter and Sms Template already exist for the selected event.");
CONSTANTS.put(Arrays.asList(true, true, false), "Email and Sms Template already exist for the selected event.");
CONSTANTS.put(Arrays.asList(true, false, true), "Email and Letter Template already exist for the selected event.");
CONSTANTS.put(Arrays.asList(false, true, true), "Sms and Letter Template already exist for the selected event.");
CONSTANTS.put(Arrays.asList(true, false, false), "Email Template already exist for the selected event.");
CONSTANTS.put(Arrays.asList(false, true, false), "Sms Template already exist for the selected event.");
CONSTANTS.put(Arrays.asList(false, false, true), "Letter Template already exist for the selected event.");
}
public static String getMessage(boolean emailExists, boolean smsExists, boolean letterExists)
{
return CONSTANTS.get(Arrays.asList(emailExists, smsExists, letterExists));
}
}
然后检索它的代码将是单行代码：
System.out.println(CommunicationConstants.getMessage(true, false, true));
答案 1 :(得分：0)
如果可以更改数据库模型，请进行以下更改：
1-将所有布尔值更改为具有以下允许值的VARCHAR（）模板类型=> ALL_TEMPLATE_EXIST，EMAIL_TEMPLATE_EXIST，LETTER_TEMPLATE_EXIST，SMS_TEMPLATE_EXIST
2-从数据库中读取值后，仅使用一个行代码来设置您的值：
templateExist = CommunicationConstants.valueOf(thePropertyValueYouReadFromDataBase);
编辑
通过此更改，决定哪个模板已经存在将取决于插入模板的业务代码，仅读取部分实际读取的内容的值
答案 2 :(得分：0)
我会这样做。我发现它更清晰，但显然每个人的思想都不同。
if (emailTemplateExist) {
templateExist = letterTemplateExist && smsTemplateExist ? CommunicationConstants.ALL_TEMPLATE_EXIST: CommunicationConstants.EMAIL_TEMPLATE_EXIST;
}
else{
if (letterTemplateExist && !smsTemplateExist)
templateExist = CommunicationConstants.LETTER_TEMPLATE_EXIST;
else if (!letterTemplateExist && smsTemplateExist)
templateExist = CommunicationConstants.SMS_TEMPLATE_EXIST;
}
// There is a possiblity that you will end up with a null value in templateExist so you should initialize it with some default.
答案 3 :(得分：0)
我认为您遗漏了几种情况……但是，可以通过嵌套if语句来做到这一点。请注意，我在enum中添加了一个值，该值表示数据库中不存在模板的情况。使用这种方法，您将需要电子邮件和短信，电子邮件和信件以及字母和短信的其他enum值。如果您确定这些情况永远不会发生，那么这种方法涵盖了太多。
public static void main(String[] args) {
boolean emailTemplateExist = true;
boolean letterTemplateExist = true;
boolean smsTemplateExist = true;
CommunicationConstants templateExist = CommunicationConstants.NO_TEMPLATE_EXIST;
if (emailTemplateExist) {
if (letterTemplateExist) {
if (smsTemplateExist) {
// email exists, letter exists, sms exists ==> 3/3
templateExist = CommunicationConstants.ALL_TEMPLATE_EXIST;
} else {
// email exists, letter exists, sms does not exist ==> 2/3
// what to do here?
/*
* what to do in this case? The enum has no value for that...
*/
}
} else {
if (smsTemplateExist) {
// email exists, letter does not exist, sms exists ==> 2/3
/*
* what to do in this case? The enum has no value for that...
*/
} else {
// email exists, letter does not exist, sms does not exist ==> 1/3
}
}
} else {
if (letterTemplateExist) {
if (smsTemplateExist) {
// email does not exist, letter exists, sms exists ==> 2/3
/*
* what to do in this case? The enum has no value for that...
*/
} else {
// email does not exist, letter exists, sms does not exist ==> 1/3
templateExist = CommunicationConstants.LETTER_TEMPLATE_EXIST;
}
} else {
if (smsTemplateExist) {
// email does not exist, letter does not exist, sms exists ==> 1/3
templateExist = CommunicationConstants.SMS_TEMPLATE_EXIST;
} else {
// email does not exist, letter does not exist, sms does not exist ==> 0/3
/*
* by initializing the return value with something like "NO_TEMPLATE_EXIST",
* you can omit this else block entirely
*/
templateExist = CommunicationConstants.NO_TEMPLATE_EXIST;
}
}
}
System.out.println(templateExist.toString());
}
enum CommunicationConstants {
ALL_TEMPLATE_EXIST,
EMAIL_TEMPLATE_EXIST,
LETTER_TEMPLATE_EXIST,
SMS_TEMPLATE_EXIST,
NO_TEMPLATE_EXIST
}
只需处理初始值（当前均为true）。
答案 4 :(得分：0)
以下代码使用单个模板生成所有组合：
firstChild测试输出：
public class Main {
enum TemplateType {
Email, Sms, Letter
}
private static final String MSG_EXISTS = "%s Template%s already exist%s for the selected event.";
private static int testCounter;
public static void main(String[] args) {
// Generates all combinations
for (testCounter = 0; testCounter < 8; testCounter++) {
System.out.println(testCounter + ". " + evaluate());
}
}
private static String evaluate() {
List<String> templateList = Arrays.stream(TemplateType.values())
.filter(Main::checkExistence)
.map(TemplateType::name)
.collect(Collectors.toList());
if (templateList.isEmpty()) {
return null;
}
int size = templateList.size();
String arg1 = prettyPrintListJoiner(templateList);
return String.format(MSG_EXISTS, arg1, size == 1 ? "" : "s", size == 1 ? "s" : "");
}
private static String prettyPrintListJoiner(List<String> templateList) {
int size = templateList.size();
if (size == 1) {
return templateList.get(0);
}
StringJoiner joiner = new StringJoiner(", ");
if (size > 2) {
joiner.add(String.join(", ", templateList.subList(0, size - 2)));
}
return joiner.add(String.join(" and ", templateList.subList(size - 2, size))).toString();
}
// To generate all possibilities with help of testCounter
private static boolean checkExistence(TemplateType type) {
switch (type) {
case Email:
return ((testCounter >> 2) & 1) == 1;
case Sms:
return ((testCounter >> 1) & 1) == 1;
case Letter:
return ((testCounter) & 1) == 1;
}
throw new IllegalArgumentException();
}
}