[Android] Android中动态添加Panel的框架代码

项目经常会有这种需求，就是想动态的在某个界面上添加一个Panel。比如，有一个按钮，点击后会显示下拉菜单式的界面。这种需求，就属于动态添加一个Panel。需求多了，就要研究是否可以抽象出通用的框架代码，以方便开发，所以就有了以下内容。

这里说是框架，说的大了点，其实没有那么复杂，只是一个容易扩展的基类而已。不过至少算是框架类的代码。

package arui;import android.app.Activity;import android.os.Handler;import android.os.Looper;import android.os.Message;import android.view.Gravity;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup.LayoutParams;import android.view.ViewManager;import android.widget.FrameLayout;/** * Base class for panel. *  */public abstract class BasePanel {/** * left up position */public static final int LEFT_UP = 1;/** * right up position */public static final int RIGHT_UP = 2;/** * left bottom position */public static final int LEFT_BOTTOM = 3;/** * right bottom position */public static final int RIGHT_BOTTOM = 4;private static final int DEFAULT_MARGIN = 10;private static final int SHOW_PANEL = 0;private Activity activity;private LayoutParams parameters;private View view = null;private int layoutId;/** * constructor. *  * @param activity *            this panel will be attached to the activity * @param layoutId *            the panel's layout id */public BasePanel(Activity activity, int layoutId) {this.activity = activity;this.layoutId = layoutId;}/** * The developer can use this method to add the panel to the Activity. *  * @param act *            Activity * @param params *            LayoutParams */public void attach(LayoutParams params) {parameters = params;mHandler.sendMessage(mHandler.obtainMessage(SHOW_PANEL));}/** * The developer can use this method to add the panel to the Activity. *  * @param act *            Activity * @param position *            int. You can use BasePanel.LEFT_UP,BasePanel.RIGHT_UP, *            BasePanel.RIGHT_BOTTOM or BasePanel.LEFT_BOTTOM. */public void attach(int position) {attach(position, DEFAULT_MARGIN, DEFAULT_MARGIN, DEFAULT_MARGIN,DEFAULT_MARGIN);}/** * The developer can use this method to add the panel to the Activity. *  * @param act *            Activity * @param position *            int. You can use BasePanel.LEFT_UP,BasePanel.RIGHT_UP, *            BasePanel.RIGHT_BOTTOM or BasePanel.LEFT_BOTTOM. * @param leftMargin *            int, left margin. * @param topMargin *            int, top margin. * @param rightMargin *            int, right margin. * @param bottomMargin *            int, bottom margin. *  */public void attach(int position, int leftMargin, int topMargin,int rightMargin, int bottomMargin) {FrameLayout.LayoutParams params = null;params = new FrameLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);params.setMargins(leftMargin, topMargin, rightMargin, bottomMargin);switch (position) {case LEFT_UP:params.gravity = Gravity.LEFT;break;case RIGHT_UP:params.gravity = Gravity.RIGHT;break;case LEFT_BOTTOM:params.gravity = Gravity.LEFT | Gravity.BOTTOM;break;case RIGHT_BOTTOM:params.gravity = Gravity.RIGHT | Gravity.BOTTOM;break;default:break;}attach(params);}/** * The developer can use this method to remove the panel from the Activity. *  */public void remove() {if (view != null) {ViewManager mViewManager = (ViewManager) view.getParent();if (mViewManager != null) {mViewManager.removeView(view);}}}private Handler mHandler = new Handler(Looper.getMainLooper()) {@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case SHOW_PANEL:if (view == null) {LayoutInflater factory = LayoutInflater.from(activity);view = factory.inflate(layoutId, null);}dealwithPanel(view);remove();activity.addContentView(view, parameters);break;}}};/** * do something with this panel. *  * @param view *            View of the panel */public abstract void dealwithPanel(View view);}

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