Android实现滑动侧边栏

在Android应用开发中，滑动侧边栏经常使用，今天我也试着自己进行了一个简单的实践，虽然功能还不是很强大，但是可以保留下来为以后的开发使用，有需要时在进行简单的修改。实现一个滑动侧边栏思路也很简单：

1.重写一个SlidingMenu类继承ViewGroup，病危该ViewGroup添加两个子布局，分别为菜单和主界面显示；

2.为了得到一个滑动的效果，选择Scroller帮助我们实现，配合ViewGroup下的computeScroll方法实现界面的更新；

3.利用一个boolean来记录菜单是否打开，在菜单打开的状态下向右滑动不会响应，在菜单关闭的情况向左滑动不会响应；

4.为了得到一个良好的交互，我们可以为界面滑动与手指移动的距离定义一个比例，如每次触摸事件发生，界面移动的距离仅为手指移动距离的一半；

下面是两张效果图，界面没怎么布局，大家凑合看

SlidingMenu实现代码：

package com.example.test; 
 
import android.content.Context; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Scroller; 
 
public class SlidingMenu extends ViewGroup { 
 
 private static final String TAG = SlidingMenu.class.getName(); 
 
 private enum Scroll_State { 
 Scroll_to_Open, Scroll_to_Close; 
 } 
 
 private Scroll_State state; 
 private int mMostRecentX; 
 private int downX; 
 private boolean isOpen = false; 
 
 private View menu; 
 private View mainView; 
 
 private Scroller mScroller; 
 
 private onSlidingMenuListener onSlidingMenuListener; 
 
 public SlidingMenu(Context context, View main, View menu) { 
 super(context); 
 // TODO Auto-generated constructor stub 
 setMainView(main); 
 setMenu(menu); 
 init(context); 
 } 
 
 private void init(Context context) { 
 mScroller = new Scroller(context); 
 } 
 
 @Override 
 protected void onLayout(boolean arg0, int l, int t, int r, int b) { 
 // TODO Auto-generated method stub 
 mainView.layout(l, t, r, b); 
 menu.layout(-menu.getMeasuredWidth(), t, 0, b); 
 } 
 
 public void setMainView(View view) { 
 mainView = view; 
 addView(mainView); 
 } 
 
 public void setMenu(View view) { 
 menu = view; 
 addView(menu); 
 } 
 
 @Override 
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
 // TODO Auto-generated method stub 
 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
 mainView.measure(widthMeasureSpec, heightMeasureSpec); 
 menu.measure(widthMeasureSpec - 150, heightMeasureSpec); 
 } 
 
 @Override 
 public boolean onTouchEvent(MotionEvent event) { 
 switch (event.getAction()) { 
 case MotionEvent.ACTION_DOWN: 
  mMostRecentX = (int) event.getX(); 
  downX = (int) event.getX(); 
  break; 
 case MotionEvent.ACTION_MOVE: 
  int moveX = (int) event.getX(); 
  int deltaX = mMostRecentX - moveX; 
  // 如果在菜单打开时向右滑动及菜单关闭时向左滑动不会触发Scroll事件 
  if ((!isOpen && (downX - moveX) < 0) 
   || (isOpen && (downX - moveX) > 0)) { 
  scrollBy(deltaX / 2, 0); 
  } 
  mMostRecentX = moveX; 
  break; 
 case MotionEvent.ACTION_UP: 
  int upX = (int) event.getX(); 
  int dx = upX - downX; 
  if (!isOpen) {// 菜单关闭时 
  // 向右滑动超过menu一半宽度才会打开菜单 
  if (dx > menu.getMeasuredWidth() / 3) { 
   state = Scroll_State.Scroll_to_Open; 
  } else { 
   state = Scroll_State.Scroll_to_Close; 
  } 
  } else {// 菜单打开时 
  // 当按下时的触摸点在menu区域时，只有向左滑动超过menu的一半，才会关闭 
  // 当按下时的触摸点在main区域时，会立即关闭 
  if (downX < menu.getMeasuredWidth()) { 
   if (dx < -menu.getMeasuredWidth() / 3) { 
   state = Scroll_State.Scroll_to_Close; 
   } else { 
   state = Scroll_State.Scroll_to_Open; 
   } 
  } else { 
   state = Scroll_State.Scroll_to_Close; 
  } 
  } 
  smoothScrollto(); 
  break; 
 default: 
  break; 
 } 
 return true; 
 } 
 
 private void smoothScrollto() { 
 int scrollx = getScrollX(); 
 switch (state) { 
 case Scroll_to_Close: 
  mScroller.startScroll(scrollx, 0, -scrollx, 0, 500); 
  if (onSlidingMenuListener != null && isOpen) { 
  onSlidingMenuListener.close(); 
  } 
  isOpen = false; 
  break; 
 case Scroll_to_Open: 
  mScroller.startScroll(scrollx, 0, 
   -scrollx - menu.getMeasuredWidth(), 0, 500); 
  if (onSlidingMenuListener != null && !isOpen) { 
  onSlidingMenuListener.close(); 
  } 
  isOpen = true; 
  break; 
 default: 
  break; 
 } 
 } 
 
 @Override 
 public void computeScroll() { 
 if (mScroller.computeScrollOffset()) { 
  scrollTo(mScroller.getCurrX(), 0); 
 } 
 invalidate(); 
 } 
 
 public void open() { 
 state = Scroll_State.Scroll_to_Open; 
 smoothScrollto(); 
 } 
 
 public void close() { 
 state = Scroll_State.Scroll_to_Close; 
 smoothScrollto(); 
 } 
 
 public boolean isOpen() { 
 return isOpen; 
 } 
 
 public void setonSlidingMenuListener( 
  onSlidingMenuListener onSlidingMenuListener) { 
 this.onSlidingMenuListener = onSlidingMenuListener; 
 } 
 
 public interface onSlidingMenuListener { 
 public void open(); 
 
 public void close(); 
 } 
 
} 

在MainActivity中进行调用

package com.example.test; 
 
import android.os.Bundle; 
import android.support.v4.app.FragmentActivity; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
 
public class MainActivity extends Activity { 
 
 private Button openButton; 
 private Button closeButton; 
 private SlidingMenu mSlidingMenu; 
 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 mSlidingMenu = new SlidingMenu(this, LayoutInflater 
  .from(this).inflate(R.layout.fragment1, null), LayoutInflater 
  .from(this).inflate(R.layout.fragment2, null)); 
 setContentView(mSlidingMenu);//注意setContentView需要换为我们的SlidingMenu 
 openButton = (Button) findViewById(R.id.button1); 
 closeButton = (Button) findViewById(R.id.button_close); 
 openButton.setonClickListener(new onClickListener() { 
  
  @Override 
  public void onClick(View arg0) { 
  // TODO Auto-generated method stub 
  mSlidingMenu.open(); 
  } 
 }); 
 closeButton.setonClickListener(new onClickListener() { 
  
  @Override 
  public void onClick(View arg0) { 
  // TODO Auto-generated method stub 
  mSlidingMenu.close(); 
  } 
 }); 
 } 
 
} 

更多关于滑动功能的文章，请点击专题： 《Android滑动功能》

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