在Appium中实现两个设备的并行执行，可以使用多线程的方式来处理。下面是一个示例代码，演示了如何在两个设备上并行执行测试。

import io.appium.java_client.AppiumDriver;
import io.appium.java_client.android.AndroidDriver;
import io.appium.java_client.remote.MobileCapabilityType;
import org.openqa.selenium.remote.DesiredCapabilities;
import java.net.URL;


public class ParallelExecutionExample implements Runnable {

    // 设备1的Appium连接信息
    private static final String DEVICE1_NAME = "device1";
    private static final String DEVICE1_UDID = "device1_udid";
    private static final String DEVICE1_PLATFORM_NAME = "Android";
    private static final String DEVICE1_PLATFORM_VERSION = "9.0";
    private static final String DEVICE1_APP_PACKAGE = "com.example.app1";
    private static final String DEVICE1_APP_ACTIVITY = "com.example.app1.MainActivity";
    private static final String DEVICE1_APPIUM_URL = "http://localhost:4723/wd/hub";

    // 设备2的Appium连接信息
    private static final String DEVICE2_NAME = "device2";
    private static final String DEVICE2_UDID = "device2_udid";
    private static final String DEVICE2_PLATFORM_NAME = "Android";
    private static final String DEVICE2_PLATFORM_VERSION = "8.0";
    private static final String DEVICE2_APP_PACKAGE = "com.example.app2";
    private static final String DEVICE2_APP_ACTIVITY = "com.example.app2.MainActivity";
    private static final String DEVICE2_APPIUM_URL = "http://localhost:4724/wd/hub";

    private AppiumDriver driver;

    public ParallelExecutionExample(String deviceName, String udid, String platformName, String platformVersion,
                                    String appPackage, String appActivity, String appiumUrl) throws Exception {
        DesiredCapabilities capabilities = new DesiredCapabilities();
        capabilities.setCapability(MobileCapabilityType.DEVICE_NAME, deviceName);
        capabilities.setCapability(MobileCapabilityType.UDID, udid);
        capabilities.setCapability(MobileCapabilityType.PLATFORM_NAME, platformName);
        capabilities.setCapability(MobileCapabilityType.PLATFORM_VERSION, platformVersion);
        capabilities.setCapability(MobileCapabilityType.APP_PACKAGE, appPackage);
        capabilities.setCapability(MobileCapabilityType.APP_ACTIVITY, appActivity);
        driver = new AndroidDriver(new URL(appiumUrl), capabilities);
    }

    public static void main(String[] args) throws Exception {
        Thread thread1 = new Thread(new ParallelExecutionExample(DEVICE1_NAME, DEVICE1_UDID, DEVICE1_PLATFORM_NAME,
                DEVICE1_PLATFORM_VERSION, DEVICE1_APP_PACKAGE, DEVICE1_APP_ACTIVITY, DEVICE1_APPIUM_URL));
        Thread thread2 = new Thread(new ParallelExecutionExample(DEVICE2_NAME, DEVICE2_UDID, DEVICE2_PLATFORM_NAME,
                DEVICE2_PLATFORM_VERSION, DEVICE2_APP_PACKAGE, DEVICE2_APP_ACTIVITY, DEVICE2_APPIUM_URL));

        thread1.start();
        thread2.start();

        thread1.join();
        thread2.join();
    }

    @Override
    public void run() {
        // 在这里执行测试逻辑，可以使用driver对象进行元素定位和操作
        // 示例代码略
    }
}

在上面的示例中，我们创建了两个线程，并使用不同的设备信息来创建两个AppiumDriver对象。然后，我们分别启动这两个线程，并等待它们的执行完成。

在run()方法中，可以编写测试逻辑，使用driver对象进行元素定位和操作。在实际应用中，你需要根据你的测试需求和环境来编写适合的测试逻辑。

请注意，为了在不同的端口上运行两个Appium服务器，你需要在Appium命令中指定不同的端口号，并将这些端口号用于相应设备的Appium连接URL。