Selenium Java中ImageIO.read(URL)无法读取图片致Logo对比失败求助

使用Selenium WebDriver Java结合Cucumber做自动化测试，验证Magento Luma站点Logo一致性：计划通过ImageIO读取Logo的URL存为预期图，再用AShot截取页面Logo元素作为实际图对比。但执行BufferedImage buffimg =ImageIO.read(new URL(webImageLoc))时返回null，控制台输出“image == null!”，最终断言失败。

PageObject代码 #

public class HomePage extends BasePage {

    public HomePage(WebDriver driver) {
        super(driver);
    }
    
    // Declaring global parameters
    WebDriverWait wait = new WebDriverWait(driver,Duration.ofSeconds(10));
    
    //Elements for page details 
    @FindBy(xpath = "//a[@aria-label='store logo']//img")
    WebElement logoLuma;

        public boolean compareHomePageLogo() throws IOException {
        boolean results = false;
        WebElement imgLuma = wait.until(ExpectedConditions.elementToBeClickable(logoLuma));
        
        // First downloading the logo image and storing it in local machine
        String webImageLoc = imgLuma.getAttribute("src");
        //System.out.println("URL is: " + new URL(webImageLoc));
        BufferedImage buffimg =ImageIO.read(new URL(webImageLoc));
        System.out.println(buffimg);
        File outputFile = new File(System.getProperty("user.dir")+"\\Screenshots\\expected.png");
        ImageIO.write(buffimg, "png", outputFile);
        
        // Taking screenshot of image element from search results
            Screenshot shot = new AShot().takeScreenshot(driver, imgLuma);
            File screenshotFile = new File(System.getProperty("user.dir") + "\\Screenshots\\actual.png");
        ImageIO.write(shot.getImage(), "png", screenshotFile);
        
        // Comparing both images
        BufferedImage expectedImage = ImageIO.read(outputFile); // Getting expected image
        BufferedImage actualImage = shot.getImage(); // Getting actual image
        
        ImageDiffer imgDiff = new ImageDiffer();
        ImageDiff diff = imgDiff.makeDiff(expectedImage, actualImage); // Storing diff result
        if(diff.hasDiff()) {
            System.out.println("Images are not same.");
            results = false;
        }
        else {
            System.out.println("Images are same.");
            results = true;
        }
        
        return results;
    }
}

Step定义代码 #

@Then("user can see the LUMA image on page")
public void user_can_see_the_luma_image_on_page() {
    hp = new HomePage(driver);
    try {
        Assert.assertTrue("Images are not same.", hp.compareHomePageLogo());
    }
    catch(Exception e) {
        logger.info(e.getMessage());
        Assert.fail();
    }
}

TestRunner代码 #

package testRunner;

import io.cucumber.junit.Cucumber;
import io.cucumber.junit.CucumberOptions;
import org.junit.runner.RunWith;

@RunWith(Cucumber.class)
@CucumberOptions
        (
            features = { ".//src/test/resources/Features/LandingPage.feature" },
            glue = "stepDefinitions",
            plugin = 
            {
                "pretty",
                "html:reports/myreport.html",
                "json:reports/myreport.json",
                "rerun:target/rerun.txt", // Mandatory to capture failures
                "html:target/cucumber-html-report",
                "json:target/cucumber-reports/cucumber.json",
                "junit:target/cucumber-reports/cucumber.xml",
                "com.aventstack.extentreports.cucumber.adapter.ExtentCucumberAdapter:"
            },
                    
            dryRun = false,
            monochrome = true,
               tags = "@temp"
            )

public class TestRunner {

}

报错信息 #

Given user navigates to "https://magento.softwaretestingboard.com/" # stepDefinitions.HomePageSteps.user_navigates_to(java.lang.String)
  When user can see the "Default welcome msg!" on page                # stepDefinitions.HomePageSteps.user_can_see_the_on_page(java.lang.String)
**null**
15:01:19.989 [main] INFO  stepDefinitions.HomePageSteps - **image == null!**
  Then user can see the LUMA image on page                            # stepDefinitions.HomePageSteps.user_can_see_the_luma_image_on_page()
      java.lang.AssertionError
    at org.junit.Assert.fail(Assert.java:87)
    at org.junit.Assert.fail(Assert.java:96)
    at stepDefinitions.HomePageSteps.user_can_see_the_luma_image_on_page(HomePageSteps.java:109)
    at ✽.user can see the LUMA image on page(file:///C:/Users/priyank.shah3/eclipse-workspace/Luma_eCommerce/./src/test/resources/Features/LandingPage.feature:17)

Scenario status ======>FAILED

1. 核心原因确认 #

Magento Luma站点的Logo是SVG格式，而Java原生的ImageIO默认不支持SVG格式的读取，这是返回null的直接原因。

2. 方案一：引入SVG转码库读取 #

添加Apache Batik依赖（用于SVG转PNG），将SVG转为BufferedImage：

• 先在pom.xml中添加依赖：

<dependency>
    <groupId>org.apache.xmlgraphics</groupId>
    <artifactId>batik-transcoder</artifactId>
    <version>1.17</version>
</dependency>

• 修改原图片读取代码：

import org.apache.batik.transcoder.TranscoderInput;
import org.apache.batik.transcoder.TranscoderOutput;
import org.apache.batik.transcoder.image.PNGTranscoder;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

// 替换原ImageIO.read(new URL(webImageLoc))代码段
String webImageLoc = imgLuma.getAttribute("src");
URL svgUrl = new URL(webImageLoc);

PNGTranscoder transcoder = new PNGTranscoder();
TranscoderInput input = new TranscoderInput(svgUrl.openStream());

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
TranscoderOutput output = new TranscoderOutput(outputStream);
transcoder.transcode(input, output);

// 将转码后的字节流转为BufferedImage
BufferedImage buffimg = ImageIO.read(new ByteArrayInputStream(outputStream.toByteArray()));

3. 方案二：使用本地预存的预期图 #

如果不想引入额外依赖，可手动将SVG格式的Logo转为PNG，保存到项目本地目录，直接读取本地文件作为预期图：

// 替换原URL读取代码
BufferedImage buffimg = ImageIO.read(new File(System.getProperty("user.dir") + "\\src\\test\\resources\\expected_logo.png"));

4. 辅助排查：模拟浏览器请求头 #

部分站点会拦截无UA标识的请求，可给URL请求添加浏览器User-Agent：

URL url = new URL(webImageLoc);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36");
BufferedImage buffimg = ImageIO.read(connection.getInputStream());

内容的提问来源于stack exchange，提问作者Priyank Shah