infra.beans.propertyeditors.CharacterEditor Maven / Gradle / Ivy
/*
* Copyright 2017 - 2024 the original author or authors.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [https://www.gnu.org/licenses/]
*/
package infra.beans.propertyeditors;
import java.beans.PropertyEditorSupport;
import infra.beans.BeanWrapperImpl;
import infra.lang.Nullable;
import infra.util.StringUtils;
/**
* Editor for a {@link Character}, to populate a property
* of type {@code Character} or {@code char} from a String value.
*
* Note that the JDK does not contain a default
* {@link java.beans.PropertyEditor property editor} for {@code char}!
* {@link BeanWrapperImpl} will register this
* editor by default.
*
*
Also supports conversion from a Unicode character sequence; e.g.
* {@code u0041} ('A').
*
* @author Juergen Hoeller
* @author Rob Harrop
* @author Rick Evans
* @see Character
* @see BeanWrapperImpl
* @since 4.0
*/
public class CharacterEditor extends PropertyEditorSupport {
/**
* The prefix that identifies a string as being a Unicode character sequence.
*/
private static final String UNICODE_PREFIX = "\\u";
/**
* The length of a Unicode character sequence.
*/
private static final int UNICODE_LENGTH = 6;
private final boolean allowEmpty;
/**
* Create a new CharacterEditor instance.
*
The "allowEmpty" parameter controls whether an empty String is to be
* allowed in parsing, i.e. be interpreted as the {@code null} value when
* {@link #setAsText(String) text is being converted}. If {@code false},
* an {@link IllegalArgumentException} will be thrown at that time.
*
* @param allowEmpty if empty strings are to be allowed
*/
public CharacterEditor(boolean allowEmpty) {
this.allowEmpty = allowEmpty;
}
@Override
public void setAsText(@Nullable String text) throws IllegalArgumentException {
if (this.allowEmpty && StringUtils.isEmpty(text)) {
// Treat empty String as null value.
setValue(null);
}
else if (text == null) {
throw new IllegalArgumentException("null String cannot be converted to char type");
}
else if (isUnicodeCharacterSequence(text)) {
setAsUnicode(text);
}
else if (text.length() == 1) {
setValue(text.charAt(0));
}
else {
throw new IllegalArgumentException("String [" + text + "] with length " +
text.length() + " cannot be converted to char type: neither Unicode nor single character");
}
}
@Override
public String getAsText() {
Object value = getValue();
return (value != null ? value.toString() : "");
}
private boolean isUnicodeCharacterSequence(String sequence) {
return (sequence.startsWith(UNICODE_PREFIX) && sequence.length() == UNICODE_LENGTH);
}
private void setAsUnicode(String text) {
int code = Integer.parseInt(text.substring(UNICODE_PREFIX.length()), 16);
setValue((char) code);
}
}