上一篇文章中讲了bootstrap的工作流程，这篇文章开始来研究一下bootstrap可以接受哪些指令（从源码的角度来看，由于appium的项目现在还处在持续更新中，所以有的指令已经实现，某些或许未来会实现，从源码来看的好处是你知道以后或许未来appium能做到哪些功能）。

在bootstrap项目中的io.appium.android.bootstrap.handler包中的类都是对应的相应的指令的类，里面都有execute方法来执行命令。先上上一篇文章中讲的map。

private static HashMap<String, CommandHandler> map = new HashMap<String, CommandHandler>();

  static {
    map.put("waitForIdle", new WaitForIdle());
    map.put("clear", new Clear());
    map.put("orientation", new Orientation());
    map.put("swipe", new Swipe());
    map.put("flick", new Flick());
    map.put("drag", new Drag());
    map.put("pinch", new Pinch());
    map.put("click", new Click());
    map.put("touchLongClick", new TouchLongClick());
    map.put("touchDown", new TouchDown());
    map.put("touchUp", new TouchUp());
    map.put("touchMove", new TouchMove());
    map.put("getText", new GetText());
    map.put("setText", new SetText());
    map.put("getName", new GetName());
    map.put("getAttribute", new GetAttribute());
    map.put("getDeviceSize", new GetDeviceSize());
    map.put("scrollTo", new ScrollTo());
    map.put("find", new Find());
    map.put("getLocation", new GetLocation());
    map.put("getSize", new GetSize());
    map.put("wake", new Wake());
    map.put("pressBack", new PressBack());
    map.put("dumpWindowHierarchy", new DumpWindowHierarchy());
    map.put("pressKeyCode", new PressKeyCode());
    map.put("longPressKeyCode", new LongPressKeyCode());
    map.put("takeScreenshot", new TakeScreenshot());
    map.put("updateStrings", new UpdateStrings());
    map.put("getDataDir", new GetDataDir());
    map.put("performMultiPointerGesture", new MultiPointerGesture());
    map.put("openNotification", new OpenNotification());
  }

我们就按照上面的顺序来讲。首先声明一点，事先了解一下uiautomator的api很有必要，因为这些指令中大多数都是调用uiautomator的方法去操作的，要么直接调用，要么反射调用。我的博客有很多关于这方面的文章，可以先去看看。

click

package io.appium.android.bootstrap.handler;

import com.android.uiautomator.core.UiDevice;
import com.android.uiautomator.core.UiObjectNotFoundException;
import io.appium.android.bootstrap.*;
import org.json.JSONException;

import java.util.ArrayList;
import java.util.Hashtable;

/**
 * This handler is used to click elements in the Android UI.
 * 
 * Based on the element Id, click that element.
 * 
 */
public class Click extends CommandHandler {

  /*
   * @param command The {@link AndroidCommand}
   * 
   * @return {@link AndroidCommandResult}
   * 
   * @throws JSONException
   * 
   * @see io.appium.android.bootstrap.CommandHandler#execute(io.appium.android.
   * bootstrap.AndroidCommand)
   */
  @Override
  public AndroidCommandResult execute(final AndroidCommand command)
      throws JSONException {
    if (command.isElementCommand()) {
      try {
        final AndroidElement el = command.getElement();
        el.click();
        return getSuccessResult(true);
      } catch (final UiObjectNotFoundException e) {
        return new AndroidCommandResult(WDStatus.NO_SUCH_ELEMENT,
            e.getMessage());
      } catch (final Exception e) { // handle NullPointerException
        return getErrorResult("Unknown error");
      }
    } else {
      final Hashtable<String, Object> params = command.params();
      final Double[] coords = { Double.parseDouble(params.get("x").toString()),
          Double.parseDouble(params.get("y").toString()) };
      final ArrayList<Integer> posVals = absPosFromCoords(coords);
      final boolean res = UiDevice.getInstance().click(posVals.get(0),
          posVals.get(1));
      return getSuccessResult(res);
    }
  }
}

控件

如果是控件的话，首先会获得命令中的控件对象，然后调用click方法，我们进入click方法看看

AndroidElement.java

public boolean click() throws UiObjectNotFoundException {
    return el.click();
  }

private final UiObject el;

return getSuccessResult(true);

从字面意思来看，走到这一步肯定就是告诉调用者，我只想成功了，跟你说一声。然后我们来看看这个方法里面的具体实现。

/**
   * Returns success along with the payload.
   * 
   * @param value
   * @return {@link AndroidCommandResult}
   */
  protected AndroidCommandResult getSuccessResult(final Object value) {
    return new AndroidCommandResult(WDStatus.SUCCESS, value);
  }

SUCCESS (0, "The command executed successfully."), 

JSONObject json;
public AndroidCommandResult(final WDStatus status, final Object val) {
    json = new JSONObject();
    try {
      json.put("status", status.code());
      json.put("value", val);
    } catch (final JSONException e) {
      Logger.error("Couldn't create android command result!");
    }
  }

坐标

如果是坐标的话，程序会获得命令里的坐标参数，保存在Double数组中。

final Hashtable<String, Object> params = command.params();
final Double[] coords = { Double.parseDouble(params.get("x").toString()),
          Double.parseDouble(params.get("y").toString()) };

/**
   * Given a position, it will return either the position based on percentage
   * (by passing in a double between 0 and 1) or absolute position based on the
   * coordinates entered.
   * 
   * @param coordVals
   * @return ArrayList<Integer>
   */
  protected static ArrayList<Integer> absPosFromCoords(final Double[] coordVals) {
    final ArrayList<Integer> retPos = new ArrayList<Integer>();
    final UiDevice d = UiDevice.getInstance();

    final Double screenX = (double) d.getDisplayWidth();
    final Double screenY = (double) d.getDisplayHeight();

    if (coordVals[0] < 1 && coordVals[1] < 1) {
      retPos.add((int) (screenX * coordVals[0]));
      retPos.add((int) (screenY * coordVals[1]));
    } else {
      retPos.add(coordVals[0].intValue());
      retPos.add(coordVals[1].intValue());
    }

    return retPos;
  }

经过上面的一番操作以后，会得到确切坐标值保存在数组中返回。

然后程序调用UiDevice的click方法点击啦：

final boolean res = UiDevice.getInstance().click(posVals.get(0), posVals.get(1));