Java16环境下Appium+Serenity框架PageFactory空指针异常求助

安全阿岳

2026-8-25

问题描述

运行基于Serenity BDD的Appium测试框架时抛出异常：

net.serenitybdd.core.exceptions.StepInitialisationException: Failed to create step library for TestAppPage:Cannot invoke "Object.getClass()" because "object" is null

异常触发场景：使用PageFactory初始化的元素执行element.sendKeys(text)操作时抛出；改用driver.findElement(element).sendKeys(userName)方式操作元素则正常运行。

项目相关代码

TestAppPage.java

package pages;

import io.appium.java_client.pagefactory.AndroidFindBy;
import io.appium.java_client.pagefactory.iOSXCUITFindBy;
import net.thucydides.core.annotations.Step;
import org.openqa.selenium.WebElement;

public class TestAppPage extends AppiumBaseScreen {
    @AndroidFindBy(id ="IntegerA")
    @iOSXCUITFindBy(accessibility = "IntegerA")
    private WebElement txtFirstNumberField;

    @AndroidFindBy(id ="IntegerB")
    @iOSXCUITFindBy(accessibility = "IntegerB")
    private WebElement txtSecondNumberField;

    @AndroidFindBy(id ="ComputeSumButton")
    @iOSXCUITFindBy(accessibility = "ComputeSumButton")
    private WebElement btnComputeSum;

    @AndroidFindBy(id ="Answer")
    @iOSXCUITFindBy(accessibility = "Answer")
    private WebElement lblSumResults;

    @Step("Enter 1st number")
    public void enterFirstNumber(int number) {
        setText(String.valueOf(number), txtFirstNumberField);
    }
    @Step("Enter 2nd number")
    public void enterSecondNumber(int number) {
        setText(String.valueOf(number), txtSecondNumberField);
    }
    @Step("Press sum button")
    public void pressSumButton() {
        btnComputeSum.click();
    }

    @Step("Return sum of numbers")
    public String getSumOfNumbers() {
        return lblSumResults.getText();
    }
}

AppiumBaseScreen.java

package pages;

import io.appium.java_client.pagefactory.AppiumFieldDecorator;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.interactions.Actions;
import org.openqa.selenium.support.PageFactory;
import static driver.DriverBase.getAppiumDriver;

public class AppiumBaseScreen {

    public AppiumBaseScreen() {
        PageFactory.initElements(new AppiumFieldDecorator(getAppiumDriver()), this);
    }

    protected void setText(String text, WebElement element) {
        click(element);
        element.clear();
        element.sendKeys(text);
    }

    protected void click(WebElement element) {
        moveFocusOnElement(element);
        element.click();
    }

    protected void moveFocusOnElement(WebElement element) {
        new Actions(getAppiumDriver()).moveToElement(element).perform();
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.appiumpractice</groupId>
    <artifactId>AppiumPractice</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>16</maven.compiler.source>
        <maven.compiler.target>16</maven.compiler.target>
        <serenity.version>3.2.5</serenity.version>
        <serenity.cucumber.version>3.2.5</serenity.cucumber.version>
        <cucumber.version>7.3.3</cucumber.version>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>net.serenity-bdd.maven.plugins</groupId>
                <artifactId>serenity-maven-plugin</artifactId>
                <version>${serenity.version}</version>
                <executions>
                    <execution>
                        <id>serenity-reports</id>
                        <phase>post-integration-test</phase>
                        <goals>
                            <goal>aggregate</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>net.serenity-bdd</groupId>
            <artifactId>serenity-cucumber</artifactId>
            <version>${serenity.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
        <dependency>
            <groupId>org.jeasy</groupId>
            <artifactId>easy-random-core</artifactId>
            <version>5.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>5.2.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.17.2</version>
        </dependency>
        <dependency>
            <groupId>com.googlecode.json-simple</groupId>
            <artifactId>json-simple</artifactId>
            <version>1.1.1</version>
        </dependency>
        <dependency>
            <groupId>com.github.javafaker</groupId>
            <artifactId>javafaker</artifactId>
            <version>1.0.2</version>
        </dependency>
    </dependencies>
</project>

DriverBase.java

package driver;

import io.appium.java_client.AppiumDriver;
import io.appium.java_client.ios.IOSDriver;
import io.appium.java_client.ios.options.XCUITestOptions;
import io.appium.java_client.safari.options.SafariOptions;

import java.net.URL;

public class DriverBase {
    private static AppiumDriver driver;

    public static void initializeDriver(URL appiumURL, XCUITestOptions capabilities) {
       initIOSDriver(appiumURL, capabilities);
    }
    public static void initializeDriver(URL appiumURL, SafariOptions capabilities) {
        initIOSDriver(appiumURL, capabilities);
    }

    public static AppiumDriver getAppiumDriver() {
        return driver;
    }

    private static void initIOSDriver(URL appiumURL, XCUITestOptions capabilities) {
        driver = new IOSDriver(appiumURL, capabilities);
    }

    private static void initIOSDriver(URL appiumURL, SafariOptions capabilities) {
        driver = new IOSDriver(appiumURL, capabilities);
    }
    public static void closeDriver() {
        driver.close();
        driver.quit();
    }
}

问题分析与解决方案

核心原因

Driver初始化时机错误：AppiumBaseScreen构造函数执行时，DriverBase.getAppiumDriver()返回null，导致AppiumFieldDecorator无法正常初始化元素，后续调用元素方法触发空指针相关异常。
Serenity BDD机制冲突：Serenity会自动管理Page对象的生命周期，直接使用原生Selenium的PageFactory会破坏其内部逻辑，导致元素初始化失败。

修复步骤

1. 改用Serenity原生页面对象基类

移除手动PageFactory初始化，继承Serenity的PageObject类，它会自动处理Appium元素的初始化：

package pages;

import net.serenitybdd.core.pages.PageObject;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.interactions.Actions;
import static driver.DriverBase.getAppiumDriver;

public class AppiumBaseScreen extends PageObject {

    protected void setText(String text, WebElement element) {
        click(element);
        element.clear();
        element.sendKeys(text);
    }

    protected void click(WebElement element) {
        moveFocusOnElement(element);
        element.click();
    }

    protected void moveFocusOnElement(WebElement element) {
        new Actions(getAppiumDriver()).moveToElement(element).perform();
    }
}

2. 调整Driver初始化顺序

在测试类的前置钩子中先初始化Driver，再创建Page对象，确保Driver已就绪：

import driver.DriverBase;
import io.appium.java_client.ios.options.XCUITestOptions;
import org.junit.Before;
import java.net.URL;

public class SumTest {
    private TestAppPage testAppPage;

    @Before
    public void setup() throws Exception {
        // 先初始化Driver
        XCUITestOptions options = new XCUITestOptions()
                .setDeviceName("iPhone 14")
                .setApp("/path/to/your/test.app");
        DriverBase.initializeDriver(new URL("http://127.0.0.1:4723"), options);
        
        // 再初始化Page对象并绑定Driver
        testAppPage = new TestAppPage();
        testAppPage.setDriver(DriverBase.getAppiumDriver());
    }
}

3. 添加Serenity-Appium集成依赖

在pom.xml中补充缺失的Appium集成依赖，确保Serenity能正确处理Appium元素：

<dependency>
    <groupId>net.serenity-bdd</groupId>
    <artifactId>serenity-appium</artifactId>
    <version>${serenity.version}</version>
</dependency>
<dependency>
    <groupId>io.appium</groupId>
    <artifactId>java-client</artifactId>
    <version>8.3.0</version>
</dependency>

验证修复

完成上述修改后，重新运行测试，PageFactory初始化的元素可正常执行sendKeys等操作，不会再抛出StepInitialisationException异常。

内容的提问来源于stack exchange，提问作者Bilal

Java16环境下Appium+Serenity框架PageFactory空指针异常求助

项目相关代码 #

TestAppPage.java #

AppiumBaseScreen.java #

pom.xml #

DriverBase.java #

核心原因 #

修复步骤 #

1. 改用Serenity原生页面对象基类 #

2. 调整Driver初始化顺序 #

3. 添加Serenity-Appium集成依赖 #

验证修复 #