public class Demo1 {
 public static void main(String[] args) {
 //字符串a(chǎn)bc匹配正則表達(dá)式"...", 其中"."表示一個(gè)字符
 //"..."表示三個(gè)字符
 System.out.println("abc".matches("..."));

 System.out.println("abcd".matches("..."));
 }
}
//輸出結(jié)果
true
false

public class Demo1 {
 public static void main(String[] args) {
 //字符串a(chǎn)bc匹配正則表達(dá)式"...", 其中"."表示一個(gè)字符
 //"..."表示三個(gè)字符
 System.out.println("abc".matches("..."));

 System.out.println("abcd".matches("..."));
 }
}
//輸出結(jié)果
true
false

public class Demo3 {
 /**
 * 為了省略每次寫打印語句, 這里把輸出語句封裝起來
 * @param o
 */
 private static void p(Object o){
 System.out.println(o);
 }

 /**
 * . Any character (may or may not match line terminators), 任意字符
 * X? X, once or not at all 零個(gè)或一個(gè)
 * X* X, zero or more times 零個(gè)或多個(gè)
 * X+ X, one or more times 一個(gè)或多個(gè)
 * X{n} X, exactly n times x出現(xiàn)n次
 * X{n,} X, at least n times x出現(xiàn)至少n次
 * X{n,m} X, at least n but not more than m times 出現(xiàn)n~m次
 * @param args
 */
 public static void main(String[] args) {
 p("a".matches("."));
 p("aa".matches("aa"));
 p("aaaa".matches("a*"));
 p("aaaa".matches("a+"));
 p("".matches("a*"));
 p("a".matches("a?"));

 // \d A digit: [0-9], 表示數(shù)字, 但是在java中對(duì)"\"這個(gè)符號(hào)需要使用\進(jìn)行轉(zhuǎn)義, 所以出現(xiàn)\\d
 p("2345".matches("\\d{2,5}"));
 // \\.用于匹配"."
 p("192.168.0.123".matches("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}"));
 // [0-2]指必須是0~2中的一個(gè)數(shù)字
 p("192".matches("[0-2][0-9][0-9]"));
 }
}
//輸出結(jié)果
//全為true

public class Demo4 {
 private static void p(Object o){
 System.out.println(o);
 }

 public static void main(String[] args) {
 //[abc]指abc中的其中一個(gè)字母
 p("a".matches("[abc]"));
 //[^abc]指除了abc之外的字符
 p("1".matches("[^abc]"));
 //a~z或A~Z的字符, 以下三個(gè)均是或的寫法
 p("A".matches("[a-zA-Z]"));
 p("A".matches("[a-z|A-Z]"));
 p("A".matches("[a-z[A-Z]]"));
 //[A-Z&&[REQ]]指A~Z中并且屬于REQ其中之一的字符
 p("R".matches("[A-Z&&[REQ]]"));
 }
}
//輸出結(jié)果

public class Demo5 {
 private static void p(Object o){
 System.out.println(o);
 }

 public static void main(String[] args) {
 /**
 * \d A digit: [0-9] 數(shù)字
 * \D A non-digit: [^0-9] 非數(shù)字
 * \s A whitespace character: [ \t\n\x0B\f\r] 空格
 * \S A non-whitespace character: [^\s] 非空格
 * \w A word character: [a-zA-Z_0-9] 數(shù)字字母和下劃線
 * \W A non-word character: [^\w] 非數(shù)字字母和下劃線
 */
 // \\s{4}表示4個(gè)空白符
 p(" \n\r\t".matches("\\s{4}"));
 // \\S表示非空白符
 p("a".matches("\\S"));
 // \\w{3}表示數(shù)字字母和下劃線
 p("a_8".matches("\\w{3}"));
 p("abc888&^%".matches("[a-z]{1,3}\\d+[%^&*]+"));
 // 匹配 \
 p("\\".matches("\\\\"));
 }
}
//輸出結(jié)果

public class Demo6 {
 private static void p(Object o){
 System.out.println(o);
 }

 public static void main(String[] args) {
 /**
 * ^ The beginning of a line 一個(gè)字符串的開始
 * $ The end of a line 字符串的結(jié)束
 * \b A word boundary 一個(gè)單詞的邊界, 可以是空格, 換行符等
 */
 p("hello sir".matches("^h.*"));
 p("hello sir".matches(".*r$"));
 p("hello sir".matches("^h[a-z]{1,3}o\\b.*"));
 p("hellosir".matches("^h[a-z]{1,3}o\\b.*"));
 }
}

public class Demo8 {
 private static void p(Object o){
 System.out.println(o);
 }

 public static void main(String[] args) {
 Pattern pattern = Pattern.compile("\\d{3,5}");
 String s = "123-34345-234-00";
 Matcher m = pattern.matcher(s);

 //先演示matches(), 與整個(gè)字符串匹配.
 p(m.matches());
 //結(jié)果為false, 顯然要匹配3~5個(gè)數(shù)字會(huì)在-處匹配失敗

 //然后演示find(), 先使用reset()方法把當(dāng)前位置設(shè)置為字符串的開頭
 m.reset();
 p(m.find());//true 匹配123成功
 p(m.find());//true 匹配34345成功
 p(m.find());//true 匹配234成功
 p(m.find());//false 匹配00失敗

 //下面我們演示不在matches()使用reset(), 看看當(dāng)前位置的變化
 m.reset();//先重置
 p(m.matches());//false 匹配整個(gè)字符串失敗, 當(dāng)前位置來到-
 p(m.find());// true 匹配34345成功
 p(m.find());// true 匹配234成功
 p(m.find());// false 匹配00始邊
 p(m.find());// false 沒有東西匹配, 失敗

 //演示lookingAt(), 從頭開始找
 p(m.lookingAt());//true 找到123, 成功
 }
}

public class Demo9 {
 private static void p(Object o){
 System.out.println(o);
 }

 public static void main(String[] args) {
 Pattern pattern = Pattern.compile("\\d{3,5}");
 String s = "123-34345-234-00";
 Matcher m = pattern.matcher(s);

 p(m.find());//true 匹配123成功
 p("start: " + m.start() + " - end:" + m.end());
 p(m.find());//true 匹配34345成功
 p("start: " + m.start() + " - end:" + m.end());
 p(m.find());//true 匹配234成功
 p("start: " + m.start() + " - end:" + m.end());
 p(m.find());//false 匹配00失敗
 try {
 p("start: " + m.start() + " - end:" + m.end());
 }catch (Exception e){
 System.out.println("報(bào)錯(cuò)了...");
 }
 p(m.lookingAt());
 p("start: " + m.start() + " - end:" + m.end());
 }
}
//輸出結(jié)果
true
start: 0 - end:3
true
start: 4 - end:9
true
start: 10 - end:13
false
報(bào)錯(cuò)了...
true
start: 0 - end:3

public class Demo10 {
 private static void p(Object o){
 System.out.println(o);
 }

 public static void main(String[] args) {
 Pattern p = Pattern.compile("java");
 Matcher m = p.matcher("java Java JAVA JAva I love Java and you");
 p(m.replaceAll("JAVA"));//replaceAll()方法會(huì)替換所有匹配到的字符串
 }
}
//輸出結(jié)果
JAVA Java JAVA JAva I love Java and you

•為了在匹配的時(shí)候不區(qū)分大小寫, 我們要在創(chuàng)建模板模板時(shí)指定大小寫不敏感
public static void main(String[] args) {
 Pattern p = Pattern.compile("java", Pattern.CASE_INSENSITIVE);//指定為大小寫不敏感的
 Matcher m = p.matcher("java Java JAVA JAva I love Java and you");
 p(m.replaceAll("JAVA"));
}
//輸出結(jié)果
JAVA JAVA JAVA JAVA I love JAVA and you

public static void main(String[] args) {
 Pattern p = Pattern.compile("java", Pattern.CASE_INSENSITIVE);
 Matcher m = p.matcher("java Java JAVA JAva I love Java and you ?");
 StringBuffer sb = new StringBuffer();
 int index = 1;
 while(m.find()){
 //m.appendReplacement(sb, (index++ & 1) == 0 ? "java" : "JAVA"); 較為簡潔的寫法
 if((index & 1) == 0){//偶數(shù)
 m.appendReplacement(sb, "java");
 }else{
 m.appendReplacement(sb, "JAVA");
 }
 index++;
 }
 m.appendTail(sb);//把剩余的字符串加入
 p(sb);
}
//輸出結(jié)果
JAVA java JAVA java I love JAVA and you ?

public static void main(String[] args) {
 Pattern p = Pattern.compile("\\d{3,5}[a-z]{2}");
 String s = "123aa-5423zx-642oi-00";
 Matcher m = p.matcher(s);
 while(m.find()){
 p(m.group());
 }
}
//輸出結(jié)果
123aa
5423zx
642oi

public static void main(String[] args) {
 Pattern p = Pattern.compile("(\\d{3,5})([a-z]{2})");//正則表達(dá)式為3~5個(gè)數(shù)字跟上兩個(gè)字母
 String s = "123aa-5423zx-642oi-00";
 Matcher m = p.matcher(s);
 while(m.find()){
 p(m.group(1));
 }
}
//輸出結(jié)果
123
5423
642

public class Demo12 {
 public static void main(String[] args) {
 BufferedReader br = null;
 try {
 br = new BufferedReader(new FileReader("C:\\emailTest.html"));
 String line = "";
 while((line = br.readLine()) != null){//讀取文件的每一行
 parse(line);//解析其中的email地址
 }
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 }finally {
 if(br != null){
 try {
  br.close();
  br = null;
 } catch (IOException e) {
  e.printStackTrace();
 }
 }
 }
 }

 private static void parse(String line){
 Pattern p = Pattern.compile("[\\w[.-]]+@[\\w[.-]]+\\.[\\w]+");
 Matcher m = p.matcher(line);
 while(m.find()){
 System.out.println(m.group());
 }
 }
}
//輸出結(jié)果
2819531636@qq.com
2819531636@qq.com
2405059759@qq.com
2405059759@qq.com
1013376804@qq.com
...

public class Demo13 {
 private static long codeLines = 0;
 private static long commentLines = 0;
 private static long whiteLines = 0;
 private static String filePath = "C:\\TankOnline";
 public static void main(String[] args) {
 process(filePath);
 System.out.println("codeLines : " + codeLines);
 System.out.println("commentLines : " + commentLines);
 System.out.println("whiteLines : " + whiteLines);
 }
 /**
 * 遞歸查找文件
 * @param pathStr
 */
 public static void process(String pathStr){
 File file = new File(pathStr);
 if(file.isDirectory()){//是文件夾則遞歸查找
 File[] fileList = file.listFiles();
 for(File f : fileList){
 String fPath = f.getAbsolutePath();
 process(fPath);
 }
 }else if(file.isFile()){//是文件則判斷是否是.java文件
 if(file.getName().matches(".*\\.java$")){
 parse(file);
 }
 }
 }
 private static void parse(File file) {
 BufferedReader br = null;
 try {
 br = new BufferedReader(new FileReader(file));
 String line = "";
 while((line = br.readLine()) != null){
 line = line.trim();//清空每行首尾的空格
 if(line.matches("^[\\s&&[^\\n]]*$")){//注意不是以\n結(jié)尾, 因?yàn)樵赽r.readLine()會(huì)去掉\n
  whiteLines++;
 }else if(line.startsWith("/*") || line.startsWith("*") || line.endsWith("*/")){
  commentLines++;
 }else if(line.startsWith("http://") || line.contains("http://")){
  commentLines++;
 }else{
  if(line.startsWith("import") || line.startsWith("package")){//導(dǎo)包不算
  continue;
  }
  codeLines++;
 }
 }
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 } finally {
 if(null != br){
 try {
  br.close();
  br = null;
 } catch (IOException e) {
  e.printStackTrace();
 }
 }
 }
 }
}
//輸出結(jié)果
codeLines : 1139
commentLines : 124
whiteLines : 172

public static void main(String[] args) {
 Pattern p = Pattern.compile(".{3,10}[0-9]");
 String s = "aaaa5bbbb6";//10個(gè)字符
 Matcher m = p.matcher(s);
 if(m.find()){
 System.out.println(m.start() + " - " + m.end());
 }else {
 System.out.println("not match!");
 }
}
//輸出結(jié)果
0 - 10

public static void main(String[] args) {
 Pattern p = Pattern.compile(".{3,10}?[0-9]");//添加了一個(gè)?
 String s = "aaaa5bbbb6";
 Matcher m = p.matcher(s);
 if(m.find()){
 System.out.println(m.start() + " - " + m.end());
 }else {
 System.out.println("not match!");
 }
}
//輸出結(jié)果
0 - 5

public static void main(String[] args) {
 Pattern p = Pattern.compile(".{3,10}+[0-9]");//多了個(gè)+
 String s = "aaaa5bbbb6";
 Matcher m = p.matcher(s);
 if(m.find()){
 System.out.println(m.start() + " - " + m.end());
 }else {
 System.out.println("not match!");
 }
}
//輸出結(jié)果
not match!