正则表达式举例
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- 2017-05-09
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最近工作中碰到了正则表达式，就稍微研究了下。真是处理复杂字符串问题的利器！
在此记录几个例子，方便日后查阅。
1、查找匹配的子串
import java.util.regex.Pattern;
import java.util.regex.Matcher;
// 查找在${}中，以$开头的字母串
public class MatchTest {
public static void main(String[] args) {
String inputLine = "<span style=\"color:rgb(255,153,0);font-size:13px;font-family:AdobeArabic-Regular;\">${=$a}</span><span style=\"color:rgb(255,153,0);font-size:13px;font-family:AdobeArabic-Regular;\">${=dj($abc)}</span>";
Pattern r = Pattern.compile("\\$\\{=.*?(\\$\\w+)[\\W]");
Matcher m = r.matcher(inputLine);
while(m.find()) {
System.out.println(m.group(1));
}
}
}
输出：
$a $abc
2、匹配两个字段
import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class REmatchTwoFields {
public static void main(String[] args) {
String inputLine = "Adams, Jonh Quincy";
Pattern r = Pattern.compile("(.*), (.*)");
Matcher m = r.matcher(inputLine);
if (!m.matches())
throw new IllegalArgumentException("Bad input");
System.out.println(m.group(2) + ' ' + m.group(1));
}
}
输出：
Jonh Quincy Adams
3、字符串分割
Java 中，String.split 方法是直接支持正则表达式的。下面的例子中，用被 <br> 包围的，3个及以上的"-"分割字符串。（即单独一行的，3个及以上的减号，与 markdown 语法中的分割线一致）。
public class SplitTest {
public static void test() {
String[] texts = new String[4];
texts[0] = "aaa<br><span>haha</span><br><span class='dlsn' style='dsljasf' font='sdkb'>------</span><br>bbb<br><span>----</span> <br>----<br>ccc---";
texts[1] = "<span style=\"font-size:13px;font-family:AdobeArabic-Regular;\">${=formletName}</span><span style=\"font-size:13px;font-family:AdobeArabic-Regular;\"><br></span><span style=\"font-size:13px;font-family:AdobeArabic-Regular;\">----<br>729374${=formletName}</span>";
texts[2] = "<span style=\"color:rgb(0,0,255);font-size:13px;font-family:Dialog;\"><strong>2017-04-28</strong></span><span style=\"color:rgb(0,0,255);font-size:13px;font-family:Dialog;\"><strong><br></strong></span><span style=\"color:rgb(0,0,255);font-size:13px;font-family:Dialog;\"><strong>----<br>2017-04-28 09:23:55</strong></span>";
texts[3] = "<span style=\"color:rgb(255,0,0);font-size:15px;font-family:Dialog;\"><strong>${=sql(\"FRDemo\", \"SELECT CUSTOMERNAME FROM CUSTOMER where CUSTOMERID=1\",1)}</strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:Dialog;\"><strong><br></strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:AdobeArabic-Bold;\"><strong>----</strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:Dialog;\"><strong><br></strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:Dialog;\"><strong>${=IF(false,\"first\",\"second\")}</strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:Dialog;\"><strong><br></strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:AdobeArabic-Bold;\"><strong>----</strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:Dialog;\"><strong><br> </strong></span><span style=\"color:rgb(255,0,0);font-size:15px;font-family:Dialog;\"><strong>${=sum(1,1)}</strong></span>";
for (int i = 0; i < texts.length; i++) {
String[] ss = texts[i].split("<br>((\\s*?</?\\w[^>]*?>)*?-{3,}(</?\\w[^>]*?>)*?\\s*?<br>)+");
for (String s: ss) {
System.out.println(s);
}
System.out.println("\n\n");
}
}
public static void main(String[] args) {
test();
}
}
输出：
aaa<br><span>haha</span>
bbb
ccc---
<span style="font-size:13px;font-family:AdobeArabic-Regular;">${=formletName}</span><span style="font-size:13px;font-family
:AdobeArabic-Regular;">
729374${=formletName}</span>
<span style="color:rgb(0,0,255);font-size:13px;font-family:Dialog;"><strong>2017-04-28</strong></span><span style="color:rg
b(0,0,255);font-size:13px;font-family:Dialog;"><strong>
2017-04-28 09:23:55</strong></span>
<span style="color:rgb(255,0,0);font-size:15px;font-family:Dialog;"><strong>${=sql("FRDemo", "SELECT CUSTOMERNAME FROM CUST
OMER where CUSTOMERID=1",1)}</strong></span><span style="color:rgb(255,0,0);font-size:15px;font-family:Dialog;"><strong>
</strong></span><span style="color:rgb(255,0,0);font-size:15px;font-family:Dialog;"><strong>${=IF(false,"first","second")}<
/strong></span><span style="color:rgb(255,0,0);font-size:15px;font-family:Dialog;"><strong>
</strong></span><span style="color:rgb(255,0,0);font-size:15px;font-family:Dialog;"><strong>${=sum(1,1)}</strong></span>
4、JS 字符串分割
js 字符串的 split 方法也支持正则表达式，不过语法有点变化。
> var value = "你好啊，<br>----------<br>李银河";
> value.split(/<br>-{3,}<br>/); // ["你好啊，", "李银河"]