ChromeDriver在Angular应用Selenium自动化中触发空指针异常问题

问题概述 #

• 自动化脚本在Microsoft Edge浏览器运行完全正常，但在Chrome浏览器中实例化ChromeDriver后，执行driver.getTitle()时触发空指针异常
• 应用能成功启动，但获取页面标题操作失败
• 环境信息：
  • Chrome版本：103
  • Selenium版本：4.0.0-alpha-5

核心代码片段 #

System.out.println("Running in Chrome");
System.setProperty("webdriver.chrome.driver", "Drivers" + File.separator + "chromedriver.exe");
ChromeOptions Ioptions = new ChromeOptions();
Ioptions.addArguments("--start-maximized");
WebDriver driver = new ChromeDriver(Ioptions);
driver.get(app_url);
driver.getTitle();

异常栈信息 #

java.lang.NullPointerException
at com.optum.taskTracker.ui.stepDefinitions.Hooks.takescreenshot(Hooks.java:269)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at cucumber.runtime.Utils$1.call(Utils.java:37)
at cucumber.runtime.Timeout.timeout(Timeout.java:13)
at cucumber.runtime.Utils.invoke(Utils.java:31)
at cucumber.runtime.java.JavaHookDefinition.execute(JavaHookDefinition.java:60)
at cucumber.runtime.Runtime.runHookIfTagsMatch(Runtime.java:223)
at cucumber.runtime.Runtime.runHooks(Runtime.java:211)
at cucumber.runtime.Runtime.runAfterHooks(Runtime.java:205)
at cucumber.runtime.model.CucumberScenario.run(CucumberScenario.java:46)
at cucumber.runtime.junit.ExecutionUnitRunner.run(ExecutionUnitRunner.java:91)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at cucumber.runtime.junit.ExamplesRunner.run(ExamplesRunner.java:59)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at cucumber.runtime.junit.ScenarioOutlineRunner.run(ScenarioOutlineRunner.java:53)
at cucumber.runtime.junit.FeatureRunner.runChild(FeatureRunner.java:63)
at cucumber.runtime.junit.FeatureRunner.runChild(FeatureRunner.java:18)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at cucumber.runtime.junit.FeatureRunner.run(FeatureRunner.java:70)
at cucumber.api.junit.Cucumber.runChild(Cucumber.java:93)
at cucumber.api.junit.Cucumber.runChild(Cucumber.java:37)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at cucumber.api.junit.Cucumber.run(Cucumber.java:98)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:768)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:464)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)

排查与解决建议 #

1. 版本兼容性修复 #

Selenium 4.0.0-alpha-5是早期测试版本，对Chrome 103的支持存在缺陷。

• 升级Selenium到稳定版（如4.1.x及以上）
• 确保ChromeDriver版本与Chrome浏览器版本严格匹配（Chrome 103对应ChromeDriver 103.x）

2. 添加页面加载等待 #

Angular应用渲染需要时间，直接调用driver.getTitle()时页面可能未完全加载：

WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
wait.until(ExpectedConditions.titleContains("预期标题关键词"));
String title = driver.getTitle();

3. 修复截图钩子空指针 #

异常栈显示空指针来自Hooks.takescreenshot方法，需检查该方法中driver实例是否初始化：

public void takescreenshot() {
    if(driver != null) {
        // 执行截图逻辑
    }
}

4. 验证ChromeDriver路径 #

确认ChromeDriver路径正确性及文件权限：

String driverPath = "Drivers" + File.separator + "chromedriver.exe";
System.out.println("ChromeDriver路径：" + driverPath);
File driverFile = new File(driverPath);
System.out.println("文件是否存在：" + driverFile.exists());

内容的提问来源于stack exchange，提问作者Little bird