私の同僚のこのエレガントな解決策がこの長い投稿にも見られることを期待して、インターフェースアプローチ以降のサブクラス化のためのこのアプローチを共有したいと思います。
ここではカスタムの例外を使用しており、例外に置き換えない限り、このコードはコンパイルされないことに注意してください。
ドキュメントは広範囲にわたっており、ほとんどの人が理解できることを願っています。
すべてのサブクラス化された列挙型が実装する必要のあるインターフェース。
public interface Parameter {
/**
* Retrieve the parameters name.
*
* @return the name of the parameter
*/
String getName();
/**
* Retrieve the parameters type.
*
* @return the {@link Class} according to the type of the parameter
*/
Class<?> getType();
/**
* Matches the given string with this parameters value pattern (if applicable). This helps to find
* out if the given string is a syntactically valid candidate for this parameters value.
*
* @param valueStr <i>optional</i> - the string to check for
* @return <code>true</code> in case this parameter has no pattern defined or the given string
* matches the defined one, <code>false</code> in case <code>valueStr</code> is
* <code>null</code> or an existing pattern is not matched
*/
boolean match(final String valueStr);
/**
* This method works as {@link #match(String)} but throws an exception if not matched.
*
* @param valueStr <i>optional</i> - the string to check for
* @throws ArgumentException with code
* <dl>
* <dt>PARAM_MISSED</dt>
* <dd>if <code>valueStr</code> is <code>null</code></dd>
* <dt>PARAM_BAD</dt>
* <dd>if pattern is not matched</dd>
* </dl>
*/
void matchEx(final String valueStr) throws ArgumentException;
/**
* Parses a value for this parameter from the given string. This method honors the parameters data
* type and potentially other criteria defining a valid value (e.g. a pattern).
*
* @param valueStr <i>optional</i> - the string to parse the parameter value from
* @return the parameter value according to the parameters type (see {@link #getType()}) or
* <code>null</code> in case <code>valueStr</code> was <code>null</code>.
* @throws ArgumentException in case <code>valueStr</code> is not parsable as a value for this
* parameter.
*/
Object parse(final String valueStr) throws ArgumentException;
/**
* Converts the given value to its external form as it is accepted by {@link #parse(String)}. For
* most (ordinary) parameters this is simply a call to {@link String#valueOf(Object)}. In case the
* parameter types {@link Object#toString()} method does not return the external form (e.g. for
* enumerations), this method has to be implemented accordingly.
*
* @param value <i>mandatory</i> - the parameters value
* @return the external form of the parameters value, never <code>null</code>
* @throws InternalServiceException in case the given <code>value</code> does not match
* {@link #getType()}
*/
String toString(final Object value) throws InternalServiceException;
}
ENUM基本クラスの実装。
public enum Parameters implements Parameter {
/**
* ANY ENUM VALUE
*/
VALUE(new ParameterImpl<String>("VALUE", String.class, "[A-Za-z]{3,10}"));
/**
* The parameter wrapped by this enum constant.
*/
private Parameter param;
/**
* Constructor.
*
* @param param <i>mandatory</i> - the value for {@link #param}
*/
private Parameters(final Parameter param) {
this.param = param;
}
/**
* {@inheritDoc}
*/
@Override
public String getName() {
return this.param.getName();
}
/**
* {@inheritDoc}
*/
@Override
public Class<?> getType() {
return this.param.getType();
}
/**
* {@inheritDoc}
*/
@Override
public boolean match(final String valueStr) {
return this.param.match(valueStr);
}
/**
* {@inheritDoc}
*/
@Override
public void matchEx(final String valueStr) {
this.param.matchEx(valueStr);
}
/**
* {@inheritDoc}
*/
@Override
public Object parse(final String valueStr) throws ArgumentException {
return this.param.parse(valueStr);
}
/**
* {@inheritDoc}
*/
@Override
public String toString(final Object value) throws InternalServiceException {
return this.param.toString(value);
}
}
基本クラスから「継承」するサブクラス化されたENUM。
public enum ExtendedParameters implements Parameter {
/**
* ANY ENUM VALUE
*/
VALUE(my.package.name.VALUE);
/**
* EXTENDED ENUM VALUE
*/
EXTENDED_VALUE(new ParameterImpl<String>("EXTENDED_VALUE", String.class, "[0-9A-Za-z_.-]{1,20}"));
/**
* The parameter wrapped by this enum constant.
*/
private Parameter param;
/**
* Constructor.
*
* @param param <i>mandatory</i> - the value for {@link #param}
*/
private Parameters(final Parameter param) {
this.param = param;
}
/**
* {@inheritDoc}
*/
@Override
public String getName() {
return this.param.getName();
}
/**
* {@inheritDoc}
*/
@Override
public Class<?> getType() {
return this.param.getType();
}
/**
* {@inheritDoc}
*/
@Override
public boolean match(final String valueStr) {
return this.param.match(valueStr);
}
/**
* {@inheritDoc}
*/
@Override
public void matchEx(final String valueStr) {
this.param.matchEx(valueStr);
}
/**
* {@inheritDoc}
*/
@Override
public Object parse(final String valueStr) throws ArgumentException {
return this.param.parse(valueStr);
}
/**
* {@inheritDoc}
*/
@Override
public String toString(final Object value) throws InternalServiceException {
return this.param.toString(value);
}
}
最後に、いくつかのユーティリティを追加するための汎用ParameterImpl。
public class ParameterImpl<T> implements Parameter {
/**
* The default pattern for numeric (integer, long) parameters.
*/
private static final Pattern NUMBER_PATTERN = Pattern.compile("[0-9]+");
/**
* The default pattern for parameters of type boolean.
*/
private static final Pattern BOOLEAN_PATTERN = Pattern.compile("0|1|true|false");
/**
* The name of the parameter, never <code>null</code>.
*/
private final String name;
/**
* The data type of the parameter.
*/
private final Class<T> type;
/**
* The validation pattern for the parameters values. This may be <code>null</code>.
*/
private final Pattern validator;
/**
* Shortcut constructor without <code>validatorPattern</code>.
*
* @param name <i>mandatory</i> - the value for {@link #name}
* @param type <i>mandatory</i> - the value for {@link #type}
*/
public ParameterImpl(final String name, final Class<T> type) {
this(name, type, null);
}
/**
* Constructor.
*
* @param name <i>mandatory</i> - the value for {@link #name}
* @param type <i>mandatory</i> - the value for {@link #type}
* @param validatorPattern - <i>optional</i> - the pattern for {@link #validator}
* <dl>
* <dt style="margin-top:0.25cm;"><i>Note:</i>
* <dd>The default validation patterns {@link #NUMBER_PATTERN} or
* {@link #BOOLEAN_PATTERN} are applied accordingly.
* </dl>
*/
public ParameterImpl(final String name, final Class<T> type, final String validatorPattern) {
this.name = name;
this.type = type;
if (null != validatorPattern) {
this.validator = Pattern.compile(validatorPattern);
} else if (Integer.class == this.type || Long.class == this.type) {
this.validator = NUMBER_PATTERN;
} else if (Boolean.class == this.type) {
this.validator = BOOLEAN_PATTERN;
} else {
this.validator = null;
}
}
/**
* {@inheritDoc}
*/
@Override
public boolean match(final String valueStr) {
if (null == valueStr) {
return false;
}
if (null != this.validator) {
final Matcher matcher = this.validator.matcher(valueStr);
return matcher.matches();
}
return true;
}
/**
* {@inheritDoc}
*/
@Override
public void matchEx(final String valueStr) throws ArgumentException {
if (false == this.match(valueStr)) {
if (null == valueStr) {
throw ArgumentException.createEx(ErrorCode.PARAM_MISSED, "The value must not be null",
this.name);
}
throw ArgumentException.createEx(ErrorCode.PARAM_BAD, "The value must match the pattern: "
+ this.validator.pattern(), this.name);
}
}
/**
* Parse the parameters value from the given string value according to {@link #type}. Additional
* the value is checked by {@link #matchEx(String)}.
*
* @param valueStr <i>optional</i> - the string value to parse the value from
* @return the parsed value, may be <code>null</code>
* @throws ArgumentException in case the parameter:
* <ul>
* <li>does not {@link #matchEx(String)} the {@link #validator}</li>
* <li>cannot be parsed according to {@link #type}</li>
* </ul>
* @throws InternalServiceException in case the type {@link #type} cannot be handled. This is a
* programming error.
*/
@Override
public T parse(final String valueStr) throws ArgumentException, InternalServiceException {
if (null == valueStr) {
return null;
}
this.matchEx(valueStr);
if (String.class == this.type) {
return this.type.cast(valueStr);
}
if (Boolean.class == this.type) {
return this.type.cast(Boolean.valueOf(("1".equals(valueStr)) || Boolean.valueOf(valueStr)));
}
try {
if (Integer.class == this.type) {
return this.type.cast(Integer.valueOf(valueStr));
}
if (Long.class == this.type) {
return this.type.cast(Long.valueOf(valueStr));
}
} catch (final NumberFormatException e) {
throw ArgumentException.createEx(ErrorCode.PARAM_BAD, "The value cannot be parsed as "
+ this.type.getSimpleName().toLowerCase() + ".", this.name);
}
return this.parseOther(valueStr);
}
/**
* Field access for {@link #name}.
*
* @return the value of {@link #name}.
*/
@Override
public String getName() {
return this.name;
}
/**
* Field access for {@link #type}.
*
* @return the value of {@link #type}.
*/
@Override
public Class<T> getType() {
return this.type;
}
/**
* {@inheritDoc}
*/
@Override
public final String toString(final Object value) throws InternalServiceException {
if (false == this.type.isAssignableFrom(value.getClass())) {
throw new InternalServiceException(ErrorCode.PANIC,
"Parameter.toString(): Bad type of value. Expected {0} but is {1}.", this.type.getName(),
value.getClass().getName());
}
if (String.class == this.type || Integer.class == this.type || Long.class == this.type) {
return String.valueOf(value);
}
if (Boolean.class == this.type) {
return Boolean.TRUE.equals(value) ? "1" : "0";
}
return this.toStringOther(value);
}
/**
* Parse parameter values of other (non standard types). This method is called by
* {@link #parse(String)} in case {@link #type} is none of the supported standard types (currently
* String, Boolean, Integer and Long). It is intended for extensions.
* <dl>
* <dt style="margin-top:0.25cm;"><i>Note:</i>
* <dd>This default implementation always throws an InternalServiceException.
* </dl>
*
* @param valueStr <i>mandatory</i> - the string value to parse the value from
* @return the parsed value, may be <code>null</code>
* @throws ArgumentException in case the parameter cannot be parsed according to {@link #type}
* @throws InternalServiceException in case the type {@link #type} cannot be handled. This is a
* programming error.
*/
protected T parseOther(final String valueStr) throws ArgumentException, InternalServiceException {
throw new InternalServiceException(ErrorCode.PANIC,
"ParameterImpl.parseOther(): Unsupported parameter type: " + this.type.getName());
}
/**
* Convert the values of other (non standard types) to their external form. This method is called
* by {@link #toString(Object)} in case {@link #type} is none of the supported standard types
* (currently String, Boolean, Integer and Long). It is intended for extensions.
* <dl>
* <dt style="margin-top:0.25cm;"><i>Note:</i>
* <dd>This default implementation always throws an InternalServiceException.
* </dl>
*
* @param value <i>mandatory</i> - the parameters value
* @return the external form of the parameters value, never <code>null</code>
* @throws InternalServiceException in case the given <code>value</code> does not match
* {@link #getClass()}
*/
protected String toStringOther(final Object value) throws InternalServiceException {
throw new InternalServiceException(ErrorCode.PANIC,
"ParameterImpl.toStringOther(): Unsupported parameter type: " + this.type.getName());
}
}