public static void main(String[] args) {     //被替换关键字的的数据源     Map<String,String> tokens = new HashMap<String,String>();     tokens.put("cat", "Garfield");     tokens.put("beverage", "coffee");     //匹配类似velocity规则的字符串     String template = "${cat} really needs some ${beverage}.";     //生成匹配模式的正则表达式     String patternString = "\$\{(" + StringUtils.join(tokens.keySet(), "|") + ")\}";     Pattern pattern = Pattern.compile(patternString);     Matcher matcher = pattern.matcher(template);     //两个方法：appendReplacement, appendTail     StringBuffer sb = new StringBuffer();     while(matcher.find()) {         matcher.appendReplacement(sb, tokens.get(matcher.group(1)));     }     matcher.appendTail(sb);     //out: Garfield really needs some coffee.     System.out.println(sb.toString());     //对于特殊含义字符"","$"，使用Matcher.quoteReplacement消除特殊意义     matcher.reset();     //out: cat really needs some beverage.     System.out.println(matcher.replaceAll("$1"));     //out: $1 really needs some $1.     System.out.println(matcher.replaceAll(Matcher.quoteReplacement("$1")));     //到得邮箱的前缀名。插一句，其实验证邮箱的正则多种多样，根据自己的需求写对应的正则才是王道     String emailPattern = "^([a-z0-9_\.\-\+]+)@([\da-z\.\-]+)\.([a-z\.]{2,6})$";     pattern = Pattern.compile(emailPattern);     matcher = pattern.matcher("test@qq.com");     //验证是否邮箱     System.out.println(matcher.find());     //得到@符号前的邮箱名  out: test     System.out.println(matcher.replaceAll("$1"));     //获得匹配值     String temp = "<meta-data android:name="appid" android:value="joy"></meta-data>";     pattern = Pattern.compile("android:(name|value)="(.+?)"");     matcher = pattern.matcher(temp);     while(matcher.find()) {         //out: appid, joy         System.out.println(matcher.group(2));     } }