在Appium中，可以使用MobileSelector类来处理日历日期选择器。下面是一个示例代码，用于选择特定日期：

import io.appium.java_client.MobileBy;
import io.appium.java_client.android.AndroidDriver;
import io.appium.java_client.android.AndroidElement;
import io.appium.java_client.remote.MobileCapabilityType;
import org.openqa.selenium.By;
import org.openqa.selenium.remote.DesiredCapabilities;
import java.net.MalformedURLException;
import java.net.URL;

public class CalendarDatePickerExample {

    public static void main(String[] args) throws MalformedURLException {
        DesiredCapabilities caps = new DesiredCapabilities();
        caps.setCapability(MobileCapabilityType.PLATFORM_NAME, "Android");
        caps.setCapability(MobileCapabilityType.DEVICE_NAME, "deviceName");
        caps.setCapability(MobileCapabilityType.APP, "path/to/your/app.apk");

        AndroidDriver driver = new AndroidDriver<>(new URL("http://localhost:4723/wd/hub"), caps);

        // 找到日期选择器的元素
        AndroidElement datePicker = driver.findElement(MobileBy.AndroidUIAutomator(
                "new UiSelector().className(\"android.widget.DatePicker\")"));

        // 选择年份
        AndroidElement yearPicker = datePicker.findElement(MobileBy.AndroidUIAutomator(
                "new UiSelector().className(\"android.widget.NumberPicker\").instance(0)"));
        yearPicker.sendKeys("2022");

        // 选择月份
        AndroidElement monthPicker = datePicker.findElement(MobileBy.AndroidUIAutomator(
                "new UiSelector().className(\"android.widget.NumberPicker\").instance(1)"));
        monthPicker.sendKeys("5");

        // 选择日期
        AndroidElement dayPicker = datePicker.findElement(MobileBy.AndroidUIAutomator(
                "new UiSelector().className(\"android.widget.NumberPicker\").instance(2)"));
        dayPicker.sendKeys("15");

        // 点击确定按钮
        By doneButton = MobileBy.AndroidUIAutomator(
                "new UiSelector().resourceIdMatches(\".*id/button1\")");
        driver.findElement(doneButton).click();

        // 关闭驱动
        driver.quit();
    }
}

请注意，上述示例代码假设您已经配置了Appium环境，并已将Appium服务器启动在http://localhost:4723。您需要根据自己的实际情况进行相应的修改和调整。