java工具类代码笔记（判断中文、整数、正负数、获取服务器ip等...）

1.判断是否是整数，包含正数和负数

/**
     * 判断是否是整数包含正负
     */
    public static boolean isInteger(String str){
        Pattern pattern = Pattern.compile("^[-\\+]?[\\d]+$");
        return pattern.matcher(str).matches();
    }

 

2.判断是否包含汉字：

package com.test.character;

public class TestCharacter {

    public static void main(String[] args) {
        System.out.println(isChinese("我是abc"));
        System.out.println(isChinese("i am in china"));
    }

    /**
     * 是否包含汉字
     *
     * @param c
     * @return
     */
    public static boolean isChinese(char c) {
        Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
        if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
                || ub == Character.UnicodeBlock.GENERAL_PUNCTUATION
                || ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
                || ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS) {
            return true;
        } else {
            return false;
        }
    }

    public static boolean isChinese(String str) {
        char[] chars = str.toCharArray();
        for (char c : chars) {
            if (isChinese(c)) {
                return true;
            }
        }
        return false;
    }

}

 

Character.UnicodeBlock.of()方法介绍：https://www.nhooo.com/note/qa0z42.html

Character.UnicodeBlock中的CJK说明：https://blog.csdn.net/yangdan1025/article/details/86586578

 

3.计算字符串的字节长度

package com.test.stringformat;

import java.io.UnsupportedEncodingException;

public class TestStrLength {

    public static void main(String[] args) {
        String str = "你看这串字符串多长abc";
        System.out.println(calStrLength(str));  //30
    }

    /**
     * 计算字符串的字节长度，中文占3个字节（UTF-8格式）
     *
     * @param str
     * @return
     */
    public static int calStrLength(String str) {
        int length = 0;
        try {
            length = str.getBytes("utf-8").length;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return length;
    }
}

 

4.获取xml等标签块中的值

public class XmlUtil {
    
    public static String getNodeText(String xmlString, String nodeName) {
        String beginName = "<" + nodeName + ">";
        String endName = "</" + nodeName + ">";
        int beginIndex = xmlString.indexOf(beginName);
        if(beginIndex == -1){
            return "";
        }else {
            int endIndex = xmlString.indexOf(endName);
            String nodeValue = xmlString.substring(beginIndex + beginName.length(), endIndex);
            return nodeValue;
        }
    }
}

 

5.获取服务端IP、获取ip：

package com.common;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Enumeration;

/**
 * @description 常用用具类
 * @date: 2024-12-28 13:30
 */
public class Util {

    /**
     * 获取服务端IP
     * @return
     */
    public static String getServerIp() {
        String ip = null;
        try {
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            while (interfaces.hasMoreElements()) {
                NetworkInterface currentInterface = interfaces.nextElement();
                if (!currentInterface.isUp() || currentInterface.isLoopback() || currentInterface.isVirtual()) {
                    continue;
                }

                Enumeration<InetAddress> addresses = currentInterface.getInetAddresses();
                while (addresses.hasMoreElements()) {
                    InetAddress currentAddress = addresses.nextElement();
                    if (currentAddress.isLoopbackAddress() || !currentAddress.getHostAddress().contains(":")) {
                        ip = currentAddress.getHostAddress();
                        break;
                    }
                }
             }

        } catch (SocketException e) {
            e.printStackTrace();
        }

        return ip;
    }

    public static void main(String[] args) {
        String ip = Util.getServerIp();
        System.out.println(ip);
    }
}

 

 

 

 

 

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