在Java中使用正则表达式

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　　jdk1.4中加入了java.util.regex包提供对正则表达式的支持。而且Java.lang.String类中的replaceAll和split函数也是调用的正则表达式来实现的。　　正则表达式对字符串的操作主要包括：字符串匹配，指定字符串替换，指定字符串查找和字符串分割。下面就用一个例子来说明这些操作是如何实现的： ＜%@ page import="java.util.regex.*"%＞＜%Pattern p=null; //正则表达式Matcher m=null; //操作的字符串boolean b;String s=null;StringBuffer sb=null;int i=0;//字符串匹配，这是不符合的p = Pattern.compile("a*b");m = p.matcher("baaaaab");b = m.matches();out.println(b "＜br＞");//字符串匹配，这是符合的p = Pattern.compile("a*b");m = p.matcher("aaaaab");b = m.matches();out.println(b "＜br＞");//字符串替换p = Pattern.compile("ab");m = p.matcher("aaaaab");s = m.replaceAll("d"); out.println(s "＜br＞");p = Pattern.compile("a*b");m = p.matcher("aaaaab");s = m.replaceAll("d"); out.println(s "＜br＞");p = Pattern.compile("a*b");m = p.matcher("caaaaab");s = m.replaceAll("d"); out.println(s "＜br＞");//字符串查找p = Pattern.compile("cat");m = p.matcher("one cat two cats in the yard");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "dog");i ;}m.appendTail(sb);out.println(sb.toString() "＜br＞");out.println(i "＜br＞");i=0; p = Pattern.compile("cat");m = p.matcher("one cat two ca tsi nthe yard");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "dog");i ;}m.appendTail(sb);out.println(sb.toString() "＜br＞");out.println(i "＜br＞");p = Pattern.compile("cat");m = p.matcher("one cat two cats in the yard");p=m.pattern();m = p.matcher("bacatab");b = m.matches();out.println(b "＜br＞"); s = m.replaceAll("dog"); out.println(s "＜br＞"); i=0;p = Pattern.compile("(fds){2,}");m = p.matcher("dsa da fdsfds aaafdsafds aaf");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "dog");i ;}m.appendTail(sb);out.println(sb.toString() "＜br＞");out.println(i "＜br＞");p = Pattern.compile("cat");m = p.matcher("one cat two cats in the yard");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "＜font color=\"red\"＞cat＜/font＞");}m.appendTail(sb);out.println(sb.toString() "＜br＞");String aa=sb.toString();out.println(aa "＜br＞");//字符串分割p = Pattern.compile("a ");String[] a=p.split("caaaaaat");for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}p = Pattern.compile("a ");a=p.split("c aa aaaa t",0);for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}p = Pattern.compile(" ");a=p.split("c aa aaaa t",0);for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}p = Pattern.compile("\\ ");a=p.split("dsafasdfdsafsda dsagfasdfa sdafds");out.println(a.length "＜br＞");for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}%＞ 　　jdk1.4中加入了java.util.regex包提供对正则表达式的支持。而且Java.lang.String类中的replaceAll和split函数也是调用的正则表达式来实现的。　　正则表达式对字符串的操作主要包括：字符串匹配，指定字符串替换，指定字符串查找和字符串分割。下面就用一个例子来说明这些操作是如何实现的： ＜%@ page import="java.util.regex.*"%＞＜%Pattern p=null; //正则表达式Matcher m=null; //操作的字符串boolean b;String s=null;StringBuffer sb=null;int i=0;//字符串匹配，这是不符合的p = Pattern.compile("a*b");m = p.matcher("baaaaab");b = m.matches();out.println(b "＜br＞");//字符串匹配，这是符合的p = Pattern.compile("a*b");m = p.matcher("aaaaab");b = m.matches();out.println(b "＜br＞");//字符串替换p = Pattern.compile("ab");m = p.matcher("aaaaab");s = m.replaceAll("d"); out.println(s "＜br＞");p = Pattern.compile("a*b");m = p.matcher("aaaaab");s = m.replaceAll("d"); out.println(s "＜br＞");p = Pattern.compile("a*b");m = p.matcher("caaaaab");s = m.replaceAll("d"); out.println(s "＜br＞");//字符串查找p = Pattern.compile("cat");m = p.matcher("one cat two cats in the yard");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "dog");i ;}m.appendTail(sb);out.println(sb.toString() "＜br＞");out.println(i "＜br＞");i=0; p = Pattern.compile("cat");m = p.matcher("one cat two ca tsi nthe yard");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "dog");i ;}m.appendTail(sb);out.println(sb.toString() "＜br＞");out.println(i "＜br＞");p = Pattern.compile("cat");m = p.matcher("one cat two cats in the yard");p=m.pattern();m = p.matcher("bacatab");b = m.matches();out.println(b "＜br＞"); s = m.replaceAll("dog"); out.println(s "＜br＞"); i=0;p = Pattern.compile("(fds){2,}");m = p.matcher("dsa da fdsfds aaafdsafds aaf");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "dog");i ;}m.appendTail(sb);out.println(sb.toString() "＜br＞");out.println(i "＜br＞");p = Pattern.compile("cat");m = p.matcher("one cat two cats in the yard");sb = new StringBuffer();while (m.find()) {m.appendReplacement(sb, "＜font color=\"red\"＞cat＜/font＞");}m.appendTail(sb);out.println(sb.toString() "＜br＞");String aa=sb.toString();out.println(aa "＜br＞");//字符串分割p = Pattern.compile("a ");String[] a=p.split("caaaaaat");for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}p = Pattern.compile("a ");a=p.split("c aa aaaa t",0);for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}p = Pattern.compile(" ");a=p.split("c aa aaaa t",0);for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}p = Pattern.compile("\\ ");a=p.split("dsafasdfdsafsda dsagfasdfa sdafds");out.println(a.length "＜br＞");for(i=0;i＜a.length;i ){out.println(a[i] "＜br＞");}%＞ 下载本文示例代码


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