在js中, replace函数的功能很强大,其原型是stringObj.replace(rgExp, replaceText), 而replaceText也可以是返回替换文本的函数。这个功能还是比较好的：
function f2c(s) {
var test = /(\d+(\.\d*)?)℉/g;
return(s.replace(test,function($0,$1,$2) {
return((($1-32) * 5/9) + "℃");
}
)
);
}
alert(f2c("Water freezes at 32℉ and boils at 212℉.")); 如果在java中怎么写呢?
java中的replace方法也很强大,只是不支持回调函数，所以就动手写了个简单的替换工具类：
/**
* @author yeyong
*/
public class StringUtils { // 就把它们放在StringUtils工具类中了
/**
* 将String中的所有regex匹配的字串全部替换掉
* @param string 代替换的字符串
* @param regex 替换查找的正则表达式
* @param replacement 替换函数
* @return
*/
public static String replaceAll(String string, String regex, ReplaceCallBack replacement) {
return replaceAll(string, pile(regex), replacement);
}
/**
* 将String中的所有pattern匹配的字串替换掉
* @param string 代替换的字符串
* @param pattern 替换查找的正则表达式对象
* @param replacement 替换函数
* @return
*/
public static String replaceAll(String string, Pattern pattern, ReplaceCallBack replacement) {
if (string == null) {
return null;
}
Matcher m = pattern.matcher(string);
if (m.find()) {
StringBuffer sb = new StringBuffer();
int index = 0;
while (true) {
m.appendReplacement(sb, replacement.replace(m.group(0), index++, m));
if (!m.find()) {
break;
}
}
m.appendTail(sb);
return sb.toString();
}
return string;
}
/**
* 将String中的regex第一次匹配的字串替换掉
* @param string 代替换的字符串
* @param regex 替换查找的正则表达式
* @param replacement 替换函数
* @return
*/
public static String replaceFirst(String string, String regex, ReplaceCallBack replacement) {
return replaceFirst(string, pile(regex), replacement);
}
/**
* 将String中的pattern第一次匹配的字串替换掉
* @param string 代替换的字符串
* @param pattern 替换查找的正则表达式对象
* @param replacement 替换函数
* @return
*/
public static String replaceFirst(String string, Pattern pattern, ReplaceCallBack replacement) {
if (string == null) {
return null;
}
Matcher m = pattern.matcher(string);
StringBuffer sb = new StringBuffer();
if (m.find()) {
m.appendReplacement(sb, replacement.replace(m.group(0), 0, m));
}
m.appendTail(sb);
return sb.toString();
}
}
回调类及其一个抽象类：
/**
* 字符串替换的回调接口
*
* @author yeyong
*
*/
public interface ReplaceCallBack {
/**
* 将text转化为特定的字串返回
* @param text 指定的字符串
* @param index 替换的次序
* @param matcher Matcher对象
* @return
*/
public String replace(String text, int index, Matcher matcher);
}
/**
* 抽象的字符串替换接口
*
主要是添加了$(group)方法来替代matcher.group(group)
* @author yeyong
*
*/
public abstract class AbstractReplaceCallBack implements ReplaceCallBack {
protected Matcher matcher;
/*
* (non-Javadoc)
* @see utils.ReplaceCallBack#replace(java.lang.String, int, java.util.regex.Matcher)
*/
final public String replace(String text, int index, Matcher matcher) {
this.matcher = matcher;
try {
return doReplace(text, index, matcher);
} finally {
this.matcher = null;
}
}
/**
* 将text转化为特定的字串返回
* @param text 指定的字符串
* @param index 替换的次序
* @param matcher Matcher对象
* @return
*/
public abstract String doReplace(String text, int index, Matcher matcher);
/**
* 获得matcher中的组数据
*
等同于matcher.group(group)
*
该函数只能在{@link #doReplace(String, int, Matcher)} 中调用
* @param group
* @return
*/
protected String $(int group) {
String data = matcher.group(group);
return data == null ? "" : data;
}
}
测试一下：
String string = "the quick-brown fox jumps over the lazy-dog.";
String pattern = "\\b(\\w)(\\w*?)\\b";
// 将每个单词改为首字大写其他字母小写
System.out.println(StringUtils.replaceAll(string, pattern,
new AbstractReplaceCallBack() {
public String doReplace(String text, int index, Matcher matcher) {
return $(1).toUpperCase() + $(2).toLowerCase();
}
}));
//输出:The Quick-Brown Fox Jumps Over The Lazy-Dog.
// 将文本中类似aaa-bbb-ccc的替换为AaaBbbCcc
string = "the quick-brown fox jumps over the lazy-dog. aaa-bbbb-cccc-ddd";
pattern = "\\b\\w+(?:-\\w+)+\\b";
System.out.println(StringUtils.replaceAll(string, pattern,
new AbstractReplaceCallBack() {
private ReplaceCallBack callBack = new AbstractReplaceCallBack() {
public String doReplace(String text, int index, Matcher matcher) {
return $(1).toUpperCase() + $(2).toLowerCase();
}
};
public String doReplace(String text, int index, Matcher matcher) {
return StringUtils.replaceAll(text, "(?:\\b|-)(\\w)(\\w*?)\\b", callBack);
}
}));
// 输出: the QuickBrown fox jumps over the LazyDog. AaaBbbbCcccDdd
//过滤安全字符... TODO 应提取为一个方法
final Map map = new HashMap() {
private static final long serialVersionUID = 1L;
{
put("
put(">", ">");
put("\"", """);
put("'", "'");
}
};
ReplaceCallBack callBack = new ReplaceCallBack() {
public String replace(String text, int index, Matcher matcher) {
return map.get(text);
}
};
string = "
xxxxx 1<4 & 7>5";
System.out.println(StringUtils.replaceAll(string.replace("&", "&"),
"[<>\"\']", callBack));
// 输出: <html><body>xxxxx 1<4 & 7>5</body></html>
实现上面js例子的替换：
// 实现上面js例子的替换
string = "Water freezes at 32℉ and boils at 212℉.";
System.out.println(StringUtils.replaceAll(string, "(\\d+(\\.\\d*)?)℉",
new AbstractReplaceCallBack() {
public String doReplace(String text, int index, Matcher matcher) {
return (((Double.parseDouble($(1)) - 32) * 5 / 9) + "℃");
}
}));
// 输出: Water freezes at 0.0℃ and boils at 100.0℃.
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