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Java?????Java????

?????

?????????String ????????????????????????????????????????????????????????????????????????? String ???????????????????Regular Expression??? Regex?????????????

????????

????????????????????????????????????????????

class JavaAPIDemo {    public static void main(String[] args) {        String str = "123";        if (isNumber(str)) {            int num = Integer.parseInt(str);            System.out.println(num * 2);        }    }    public static boolean isNumber(String str) {        char data[] = str.toCharArray();        for (int x = 0; x < data.length; x++) {            if (data[x] > '9' && data[x] < 'e') {                return false;            }        }        return true;    }}

???????????????????????????????????????????????????

???????

?????????? Perl ???JDK 1.4 ????? Java ?????? java.util.regex ??String ???????????????

???????????????

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "asda$D%as18s1d5a/sd;22@!)odskdaPP0)";        String regex = "[^a-zA-Z0-9]+";        System.out.println(str.replaceAll(regex, ""));    }}

?????????

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "a1258b125c147dd789eee258fff";        String regex = "\\d+";        String[] result = str.split(regex);        System.out.println(Arrays.toString(result));    }}

??????????? double

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "100.1";        String regex = "\\d+(\\.\\d+)?";        System.out.println(str.matches(regex)); // true    }}

?????????

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "1981-20-15";        String regex = "\\d{4}-\\d{2}-\\d{2}";        if (str.matches(regex)) {            System.out.println(new SimpleDateFormat("yyyy-MM-dd").parse(str));        }    }}

????????

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "(010)-51283346";        String regex = "((\\d{3,4})|(\\(\\d{3,4}\\)-))?\\d{7,8}";        System.out.println(str.matches(regex)); // true    }}

????????

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "java_888@163.com";        String regex = "[a-zA-Z0-9]\\w+@\\w+\\.cn|com|com\\.cn|net|gov";        System.out.println(str.matches(regex)); // true    }}

Java util.regex ???

java.util.regex ???? Pattern ? Matcher ?????????????Pattern ??????????Matcher ??????????

????????

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "JakdWEas51da&S&*ayas*(Ddada21321AD5da2@!!0iAS";        String regex = "[^a-zA-Z]+";        Pattern pattern = Pattern.compile(regex);        String[] result = pattern.split(str);        System.out.println(Arrays.toString(result)); // [JakdWEas, da, S, ayas, Ddada, AD, da, iAS]    }}

????

public class JavaDemo01 {    public static void main(String[] args) throws Exception {        String str = "INSERT INTO dept(deptno, dname, loc) VALUES (#{deptno}, #{dname}, #{loc})";        String regex = "#\\{\\w+\\}";        Pattern pattern = Pattern.compile(regex);        Matcher matcher = pattern.matcher(str);        while (matcher.find()) {            System.out.println(matcher.group(0));            System.out.println(matcher.group(0).replaceAll("#|\\{|\\}", ""));        }    }}

???????

?????????????????? Locale ????????????Locale ?????????????ResourceBundle ??????????

Locale ?

Locale ????????????????????????????????

• public Locale(String language)
• public Locale(String language, String country)

????????????? zh_CN ? en_US?

ResourceBundle ??????

ResourceBundle ?????????????? getBundle ? getString?????????? baseName_languageProperties?? cn.mldn.message.Messages_zh_CN.properties?

?????????

public class LocalTest {    public static void main(String[] args) throws UnsupportedEncodingException {        ResourceBundle resourceBundle = ResourceBundle.getBundle("cn.mldn.message.Messages");        String val = resourceBundle.getString("info");        System.out.println(val);    }}

???????

?? MessageFormat ??????????? ResourceBundle ??????????????

???????????

public class LocalTest {    public static void main(String[] args) throws UnsupportedEncodingException {        Locale locale = Locale.CHINA;        ResourceBundle resourceBundle = ResourceBundle.getBundle("cn.mldn.message.Messages", locale);        String val = resourceBundle.getString("info");        System.out.println(MessageFormat.format(val, "liming", new SimpleDateFormat("yyyy-MM-dd").format(new Date())));    }}

??????

UUID ?

UUID ??????????????????????

????? UUID

public class UUIDTest {    public static void main(String[] args) {        System.out.println(UUID.randomUUID());        UUID uuid = UUID.randomUUID();        System.out.println(uuid.toString());    }}

Optional ?

Optional ????? null ????????????????

??????????

public class JavaAPI {    public static void main(String[] args) {        IMessage temp = MessageUtil.getMessage().orElse(new MessageImpl());        MessageUtil.useMessage(temp);    }}

ThreadLocal ?

ThreadLocal ????????????????????

????????????

public class JavaAPI {    public static void main(String[] args) {        new Thread(() -> {            Message message = new Message();            message.setInfo("???????");            Channel.setMessage(message);            Channel.send();        }, "?????A").start();        new Thread(() -> {            Message message = new Message();            message.setInfo("???????");            Channel.setMessage(message);            Channel.send();        }, "?????B").start();        new Thread(() -> {            Message message = new Message();            message.setInfo("???????");            Channel.setMessage(message);            Channel.send();        }, "?????C").start();    }}

Base64 ?????

Java 8 ??? Base64 ???????????

???Base64 ?????

public class Base64Test {    public static void main(String[] args) {        String msg = "1234567890";        String enMsg = new String(Base64.getEncoder().encode(msg.getBytes()));        System.out.println(enMsg);        String oldMsg = new String(Base64.getDecoder().decode(enMsg));        System.out.println(oldMsg);    }}

??

??????????? Java ??????????????????????????????????????? UUID?Optional?ThreadLocal ??????????????????????????????????????????????????????