我有函数式编程中设计模式责任链的代码。我正在尝试将其转换为常规的 OOP 类。以下是设计模式的工作代码：
函数式编程代码
enum class LogLevel {
INFO, DEBUG, WARNING, ERROR, FUNCTIONAL_MESSAGE, FUNCTIONAL_ERROR;
companion object {
public fun all(): Array<LogLevel> {
return values()
}
}
}
/**
* Handler: Contains a method for building a chain of handlers.
* It also declares a method for executing a request.
*/
fun interface Logger {
fun message(message: String, severity: LogLevel)
fun appendNext(nextLogger: Logger): Logger {
return Logger { message, severity ->
message(message, severity)
nextLogger.message(message, severity)
}
}
}
/**
* Base Handler: Base handler is an optional class where you can put the boilerplate
* code that’s common to all handler classes.
*
* @param writeMessage is the container that acts as the next link in the chain of handlers.
*/
fun writeLogger(vararg levels: LogLevel,
writeMessage: (String) -> Unit
): Logger {
val specifiedLevelsSet = EnumSet.copyOf(listOf(*levels))
return Logger { message, requestedLogLevel ->
if (specifiedLevelsSet.contains(requestedLogLevel)) {
writeMessage(message)
}
}
}
/**
* Concrete Handlers: Concrete handlers contain the actual code for processing requests.
*/
fun consoleLogger(vararg levels: LogLevel) =
writeLogger(*levels) { message -> System.err.println("Writing to console: $message") }
fun emailLogger(vararg levels: LogLevel) =
writeLogger(*levels) { message -> System.err.println("Sending via email: $message") }
fun fileLogger(vararg levels: LogLevel) =
writeLogger(*levels) { message -> System.err.println("Writing to Log File: $message") }
/**
* Client:
*/
fun main() {
// Build an immutable chain of responsibility
val logger = consoleLogger(*LogLevel.all())
.appendNext(emailLogger(LogLevel.FUNCTIONAL_MESSAGE, LogLevel.FUNCTIONAL_ERROR))
.appendNext(fileLogger(LogLevel.WARNING, LogLevel.ERROR))
// Handled by consoleLogger since it has been set to log all levels
logger.message("Entering function ProcessOrder().", LogLevel.DEBUG)
logger.message("Order record retrieved.", LogLevel.INFO)
// Handled by consoleLogger and emailLogger since the emailLogger
// implements FUNCTIONAL_ERROR & FUNCTIONAL_MESSAGE
logger.message(
"Unable to Process Order ORD1 Dated D1 For Customer C1.",
LogLevel.FUNCTIONAL_ERROR
)
logger.message("Order Dispatched.", LogLevel.FUNCTIONAL_MESSAGE)
// Handled by consoleLogger and fileLogger since fileLogger implements WARNING & ERROR
logger.message("Customer Address details missing in Branch DataBase.", LogLevel.WARNING)
logger.message("Customer Address details missing in Organization DataBase.", LogLevel.ERROR)
}
出于学习目的，我将函数式编程代码转换为常规类。我fun interface转换为常规interface，将函数writeLogger()转换为抽象类/常规类BaseLogger，consoleLogger()转换为类ConsoleLogger，emailLogger()转换为EmailLogger等等。
问题
以下是我到目前为止管理的 OOP 代码，但上面写的同一个 main() 函数没有调用EmailLogger代码：
OOP 类
abstract class Logger(vararg levels: LogLevel) {
private var nextLogger: Logger? = null
private val specifiedLevelsSet = EnumSet.copyOf(listOf(*levels))
fun appendNext(nextLogger: Logger): Logger {
this.nextLogger = nextLogger
return this
}
fun message(message: String, severity: LogLevel) {
if (specifiedLevelsSet.contains(severity)) {
log(message)
}
nextLogger?.message(message, severity)
}
abstract fun log(message: String)
}
class ConsoleLogger(vararg level: LogLevel) : Logger(*level) {
override fun log(message: String) {
System.err.println("Writing to console: $message")
}
}
class EmailLogger(vararg level: LogLevel) : Logger(*level) {
override fun log(message: String) {
System.err.println("Sending via email: $message")
}
}
class FileLogger(vararg level: LogLevel) : Logger(*level) {
override fun log(message: String) {
System.err.println("Writing to Log File: $message")
}
}
任何意见将不胜感激。
基本处理程序
我用具有链条制造能力的abstract class替换了fun interface：
abstract class Logger(vararg levels: LogLevel) {
private var nextLogger: Logger? = null
private val specifiedLevelsSet = EnumSet.copyOf(listOf(*levels))
fun appendNext(nextLogger: Logger) {
this.nextLogger = nextLogger
}
fun message(message: String, severity: LogLevel) {
if (specifiedLevelsSet.contains(severity)) {
log(message)
}
nextLogger?.message(message, severity)
}
abstract fun log(message: String)
}
混凝土搬运机
将实现函数转换为各种类：
class ConsoleLogger(vararg level: LogLevel) : Logger(*level) {
override fun log(message: String) {
System.err.println("Writing to console: $message")
}
}
class EmailLogger(vararg level: LogLevel) : Logger(*level) {
override fun log(message: String) {
System.err.println("Sending via email: $message")
}
}
class FileLogger(vararg level: LogLevel) : Logger(*level) {
override fun log(message: String) {
System.err.println("Writing to Log File: $message")
}
}
客户端
fun main() {
// Build an immutable chain of responsibility
val logger = ConsoleLogger(*LogLevel.all())
val emailLogger = EmailLogger(LogLevel.FUNCTIONAL_MESSAGE, LogLevel.FUNCTIONAL_ERROR)
val fileLogger = FileLogger(LogLevel.WARNING, LogLevel.ERROR)
logger.appendNext(emailLogger)
emailLogger.appendNext(fileLogger)
// Handled by consoleLogger since it has been set to log all levels
logger.message("Entering function ProcessOrder().", LogLevel.DEBUG)
logger.message("Order record retrieved.", LogLevel.INFO)
// Handled by consoleLogger and emailLogger since the emailLogger
// implements FUNCTIONAL_ERROR & FUNCTIONAL_MESSAGE
logger.message(
"Unable to Process Order ORD1 Dated D1 For Customer C1.",
LogLevel.FUNCTIONAL_ERROR
)
logger.message("Order Dispatched.", LogLevel.FUNCTIONAL_MESSAGE)
// Handled by consoleLogger and fileLogger since fileLogger implements WARNING & ERROR
logger.message("Customer Address details missing in Branch DataBase.", LogLevel.WARNING)
logger.message("Customer Address details missing in Organization DataBase.", LogLevel.ERROR)
}