图像文件扩展名正则表达式模式

([^\s]+(\.(?i)(jpg|png|gif|bmp))$)

描述

(          #Start of the group #1[^\s]+           #  must contains one or more anything (except white space)(     #    start of the group #2\.        #   follow by a dot "."(?i)       #   ignore the case sensive checking for the following characters(      #     start of the group #3jpg  #       contains characters "jpg"|        #       ..orpng #       contains characters "png"|        #       ..orgif #       contains characters "gif"|        #       ..orbmp #       contains characters "bmp")        #     end of the group #3)      #     end of the group #2   $           #  end of the string
)           #end of the group #1

整个组合是指，必须具有1个或多个字符串（但不能有空格），后跟点“。”。 字符串以“ jpg”或“ png”或“ gif”或“ bmp”结尾，而且expand的文件不区分大小写。

此正则表达式模式广泛用于不同文件的广泛检查。 您只需更改结束组合（jpg | png | gif | bmp）即可进行不同的文件扩展名检查，以适应您的需要。

Java正则表达式示例

package com.mkyong.regex;import java.util.regex.Matcher;
import java.util.regex.Pattern;public class ImageValidator{private Pattern pattern;private Matcher matcher;private static final String IMAGE_PATTERN = "([^\\s]+(\\.(?i)(jpg|png|gif|bmp))$)";public ImageValidator(){pattern = Pattern.compile(IMAGE_PATTERN);}/*** Validate image with regular expression* @param image image for validation* @return true valid image, false invalid image*/public boolean validate(final String image){matcher = pattern.matcher(image);return matcher.matches();}
}

符合以下条件的图片文件：

1.“ a.jpg”，“ a.gif”，“ a.png”，“ a.bmp”，
2.“ ..jpg”，“ .. gif”，“ .. png”，“ .. bmp”，
3.“ a.JPG”，“ a.GIF”，“ a.PNG”，“ a.BMP”，
4.“ a.JpG”，“ a.GiF”，“ a.PnG”，“ a.BmP”，
5.“ jpg.jpg”，“ gif.gif”，“ png.png”，“ bmp.bmp”

图片不匹配：

1.“ .jpg”，“。gif”，“。png”，“。bmp” –图像文件名是必需的
2。“。jpg”，“。gif”，“。png”，“。bmp” –第一个字符中不允许有空格
3.“ a.txt”，“ a.exe”，“ a。”，“ a.mp3” –仅允许图像文件扩展名
3.“ jpg”，“ gif”，“ png”，“ bmp” –图像文件扩展名

单元测试– ImageValidator

package com.mkyong.regex;import org.testng.Assert;
import org.testng.annotations.*;/*** Image validator Testing* @author mkyong**/
public class ImageValidatorTest {private ImageValidator imageValidator;@BeforeClasspublic void initData(){imageValidator = new ImageValidator();}@DataProviderpublic Object[][] ValidImageProvider() {return new Object[][]{{new String[] {"a.jpg", "a.gif","a.png", "a.bmp","..jpg", "..gif","..png", "..bmp","a.JPG", "a.GIF","a.PNG", "a.BMP","a.JpG", "a.GiF","a.PnG", "a.BmP","jpg.jpg", "gif.gif","png.png", "bmp.bmp"}}};}@DataProviderpublic Object[][] InvalidImageProvider() {return new Object[][]{{new String[] {".jpg", ".gif",".png",".bmp"," .jpg", " .gif"," .png"," .bmp","a.txt", "a.exe","a.","a.mp3","jpg", "gif","png","bmp"}}};}@Test(dataProvider = "ValidImageProvider")public void ValidImageTest(String[] Image) {for(String temp : Image){boolean valid = imageValidator.validate(temp);System.out.println("Image is valid : " + temp + " , " + valid);Assert.assertEquals(true, valid);}}@Test(dataProvider = "InvalidImageProvider", dependsOnMethods="ValidImageTest")public void InValidImageTest(String[] Image) {for(String temp : Image){boolean valid = imageValidator.validate(temp);System.out.println("Image is valid : " + temp + " , " + valid);Assert.assertEquals(false, valid);}}
}

单元测试–结果

Image is valid : a.jpg , true
Image is valid : a.gif , true
Image is valid : a.png , true
Image is valid : a.bmp , true
Image is valid : ..jpg , true
Image is valid : ..gif , true
Image is valid : ..png , true
Image is valid : ..bmp , true
Image is valid : a.JPG , true
Image is valid : a.GIF , true
Image is valid : a.PNG , true
Image is valid : a.BMP , true
Image is valid : a.JpG , true
Image is valid : a.GiF , true
Image is valid : a.PnG , true
Image is valid : a.BmP , true
Image is valid : jpg.jpg , true
Image is valid : gif.gif , true
Image is valid : png.png , true
Image is valid : bmp.bmp , true
Image is valid : .jpg , false
Image is valid : .gif , false
Image is valid : .png , false
Image is valid : .bmp , false
Image is valid :  .jpg , false
Image is valid :  .gif , false
Image is valid :  .png , false
Image is valid :  .bmp , false
Image is valid : a.txt , false
Image is valid : a.exe , false
Image is valid : a. , false
Image is valid : a.mp3 , false
Image is valid : jpg , false
Image is valid : gif , false
Image is valid : png , false
Image is valid : bmp , false
PASSED: ValidImageTest([Ljava.lang.String;@1d4c61c)
PASSED: InValidImageTest([Ljava.lang.String;@116471f)===============================================com.mkyong.regex.ImageValidatorTestTests run: 2, Failures: 0, Skips: 0
==============================================================================================
mkyong
Total tests run: 2, Failures: 0, Skips: 0
===============================================

想更多地了解正则表达式？ 强烈推荐这本最好的经典书籍-“掌握正则表达式”

翻译自: https://mkyong.com/regular-expressions/how-to-validate-image-file-extension-with-regular-expression/