Go语言视频零基础入门到精通

javalearner

徒弟：师傅呀，正则怎么用呀？搞个有条理性的东东给我看看吧！
师傅：也对，没条理的东西，不懂的人，看了更加晕，先讲讲：字符组。

1、基本功能
字符组:
l 正则表达式的最基本结构之一
l 作用：规格某个位置能够出现的字符
l 形式：以[...]给出，在方括号内列出字符

实例：
判断10进制数值，只要能够判断每个数字出现在0-9之间，那就是10进制数值。

1. public class GeneralNumTest {
   
2. public static void main(String[] args) {
   
3. String[] octDigits = new String[] { "0", "1", "2", "3","4","5","6","7","8","9"};
   
4. String[] hexDigits = new String[] { "0", "1", "2", "3","4","5","6","7","8","9",
   
5. "a", "b", "c", "d","e","f"};
   
6. String octDigitRegex = "[0123456789]";
   
7. String hexDigitRegex = "[0123456789abcdef]";
   
8. for (String octDigit : octDigits) {
   
9. if(regexMatch(octDigit,octDigitRegex)){
   
10.    System.out.println("10进制数值:" + octDigit +"能够匹配正则:" + octDigitRegex);
    
11. }else{
    
12.    System.out.println("10进制数值:" + octDigit +"不能够能够匹配正则:" + octDigitRegex);
    
13. }
    
14. }
    
15. for (String hexDigit : hexDigits) {
    
16.   if(regexMatch(hexDigit,hexDigitRegex)){
    
17.     System.out.println("16进制数值:" + hexDigit +"能够匹配正则:" + hexDigitRegex);
    
18.   }else{
    
19.     System.out.println("16进制数值:" + hexDigit +"不能够能够匹配正则:" + hexDigitRegex);
    
20.   }
    
21. }
    
22. }
    
23. private static boolean regexMatch(String s, String regex) {
    
24.    return s.matches(regex);
    
25. }
    
26. }

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运行结果：
10进制数值:0能够匹配正则:[0123456789]
10进制数值:1能够匹配正则:[0123456789]
10进制数值:2能够匹配正则:[0123456789]
10进制数值:3能够匹配正则:[0123456789]
10进制数值:4能够匹配正则:[0123456789]
10进制数值:5能够匹配正则:[0123456789]
10进制数值:6能够匹配正则:[0123456789]
10进制数值:7能够匹配正则:[0123456789]
10进制数值:8能够匹配正则:[0123456789]
10进制数值:9能够匹配正则:[0123456789]
16进制数值:0能够匹配正则:[0123456789abcdef]
16进制数值:1能够匹配正则:[0123456789abcdef]
16进制数值:2能够匹配正则:[0123456789abcdef]
16进制数值:3能够匹配正则:[0123456789abcdef]
16进制数值:4能够匹配正则:[0123456789abcdef]
16进制数值:5能够匹配正则:[0123456789abcdef]
16进制数值:6能够匹配正则:[0123456789abcdef]
16进制数值:7能够匹配正则:[0123456789abcdef]
16进制数值:8能够匹配正则:[0123456789abcdef]
16进制数值:9能够匹配正则:[0123456789abcdef]
16进制数值:a能够匹配正则:[0123456789abcdef]
16进制数值:b能够匹配正则:[0123456789abcdef]
16进制数值:c能够匹配正则:[0123456789abcdef]
16进制数值:d能够匹配正则:[0123456789abcdef]
16进制数值:e能够匹配正则:[0123456789abcdef]
16进制数值:f能够匹配正则:[0123456789abcdef]

以连字符"-"表示范围:
l [0123456789]的表示法过于累赘，可以用范围表示法简要描述
l [0123456789] = [0-9]
l [0-789] = [0-9]
l [0123456789abcdef] = [0-9a-f]

刚刚的例子，可以修改为：
String octDigitRegex = "[0-9]";
String hexDigitRegex = "[0-9a-f]";

关于连字符的注意事项：
l 在字符组内部，只有当连字符出现在两个字符之间时，才能表示字符的范围；
l 如果出现在字符组的开头，则只能表示单个字符"-",就是连字符本身。

例如：

1. public class GeneralNumTwo {
   
2. public static void main(String[] args) {
   
3. String[] characters = new String[] { "a", "b", "c", "d","e","f","g","-"};
   
4. String regex1 = "[a-g]";
   
5. String regex2 = "[-ag]";
   
6. for (String character : characters) {
   
7.   if(regexMatch(character,regex1)){
   
8.    System.out.println("字符:" + character +"能够匹配正则:" + regex1);
   
9.   }else{
   
10.    System.out.println("字符:" + character +"不能够能够匹配正则:" + regex1);
    
11. }
    
12. }
    
13. for (String character : characters) {
    
14. if(regexMatch(character,regex2)){
    
15.    System.out.println("字符:" + character +"能够匹配正则:" + regex2);
    
16. }else{
    
17.    System.out.println("字符:" + character +"不能够能够匹配正则:" + regex2);  
    
18. }
    
19. }
    
20. }
    
21. private static boolean regexMatch(String s, String regex) {
    
22.    return s.matches(regex);
    
23. }
    
24. }

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运行结果：
字符:a能够匹配正则:[a-g]
字符:b能够匹配正则:[a-g]
字符:c能够匹配正则:[a-g]
字符:d能够匹配正则:[a-g]
字符:e能够匹配正则:[a-g]
字符:f能够匹配正则:[a-g]
字符:g能够匹配正则:[a-g]
字符:-不能够匹配正则:[a-g]
字符:a能够匹配正则:[-ag]
字符:b不能够匹配正则:[-ag]
字符:c不能够匹配正则:[-ag]
字符:d不能够匹配正则:[-ag]
字符:e不能够匹配正则:[-ag]
字符:f不能够匹配正则:[-ag]
字符:g能够匹配正则:[-ag]
字符:-能够匹配正则:[-ag] 本文出自 “leolee” 博客，请务必保留此出处http://jooben.blog.51cto.com/253727/317152

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源码下载：http://file.javaxxz.com/2014/10/31/000029843.zip