1. 程式人生 > >Android 使用ViewPager實現左右迴圈滑動圖片

Android 使用ViewPager實現左右迴圈滑動圖片

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ViewPager這個小demo實現的是可以左右迴圈滑動圖片,下面帶索引,滑到最後一頁在往右滑動就要第一頁,第一頁往左滑動就到最後一頁,先上效果圖,用美女圖片是我一貫的作風,呵呵


1.    首先看一些layout下的xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >       <android.support.v4.view.ViewPager
          android:id="@+id/viewPager"          android:layout_width="fill_parent"          android:layout_height="wrap_content" />
            <RelativeLayout
          android:layout_width="fill_parent"          android:layout_height="wrap_content"         android:orientation="vertical" >
            <LinearLayout              android:id="@+id/viewGroup"              android:layout_width="fill_parent"              android:layout_height="wrap_content"              android:layout_alignParentBottom="true"             android:layout_marginBottom="30dp"              android:gravity="center_horizontal"              android:orientation="horizontal" >          </LinearLayout>      </RelativeLayout>  </FrameLayout>

使用ViewPager首先需要引入android-support-v4.jar這個jar包。自己不要忘記加

package com.example.viewpagerdemo;import android.app.Activity;import android.os.Bundle;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.view.View;import android.view.ViewGroup;import android.view.ViewGroup.LayoutParams;import android.widget.ImageView;import android.widget.LinearLayout;public class TwoActivity extends Activity implements OnPageChangeListener/**  * ViewPager  */ private ViewPager viewPager;  /**  * 裝點點的ImageView陣列  */ private ImageView[] tips;  /**  * 裝ImageView陣列  */ private ImageView[] mImageViews;  /**  * 圖片資源id  */ private int[] imgIdArray ; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  ViewGroup group = (ViewGroup)findViewById(R.id.viewGroup);  viewPager = (ViewPager) findViewById(R.id.viewPager);    //載入圖片資源ID  imgIdArray = new int[]{R.drawable.item01, R.drawable.item02, R.drawable.item03, R.drawable.item04,    R.drawable.item05,R.drawable.item06, R.drawable.item07, R.drawable.item08};      //將點點加入到ViewGroup中  tips = new ImageView[imgIdArray.length];  for(int i=0; i<tips.length; i++){   ImageView imageView = new ImageView(this);      imageView.setLayoutParams(new LayoutParams(10,10));      tips[i] = imageView;      if(i == 0){       tips[i].setBackgroundResource(R.drawable.page_indicator_focused);      }else{       tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused);      }            LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(new ViewGroup.LayoutParams(LayoutParams.WRAP_CONTENT,                      LayoutParams.WRAP_CONTENT));      layoutParams.leftMargin = 5;      layoutParams.rightMargin = 5;      group.addView(imageView, layoutParams);  }      //將圖片裝載到陣列中  mImageViews = new ImageView[imgIdArray.length];  for(int i=0; i<mImageViews.length; i++){   ImageView imageView = new ImageView(this);   mImageViews[i] = imageView;   imageView.setBackgroundResource(imgIdArray[i]);  }    //設定Adapter  viewPager.setAdapter(new MyAdapter());  //設定監聽,主要是設定點點的背景  viewPager.setOnPageChangeListener(this);  //設定ViewPager的預設項, 設定為長度的100倍,這樣子開始就能往左滑動  viewPager.setCurrentItem((mImageViews.length) * 100);   }  /**  *   * @author xiaanming  *  */ public class MyAdapter extends PagerAdapter{  @Override  public int getCount() {   return Integer.MAX_VALUE;  }  @Override  public boolean isViewFromObject(View arg0, Object arg1) {   return arg0 == arg1;  }  @Override  public void destroyItem(View container, int position, Object object) {   ((ViewPager)container).removeView(mImageViews[position % mImageViews.length]);     }  /**   * 載入圖片進去,用當前的position 除以 圖片陣列長度取餘數是關鍵   */  @Override  public Object instantiateItem(View container, int position) {   ((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0);   return mImageViews[position % mImageViews.length];  }       } @Override public void onPageScrollStateChanged(int arg0) {   } @Override public void onPageScrolled(int arg0, float arg1, int arg2) {   } @Override public void onPageSelected(int arg0) {  setImageBackground(arg0 % mImageViews.length); }  /**  * 設定選中的tip的背景  * @param selectItems  */ private void setImageBackground(int selectItems){  for(int i=0; i<tips.length; i++){   if(i == selectItems){    tips[i].setBackgroundResource(R.drawable.page_indicator_focused);   }else{    tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused);   }  } }}


程式碼下載


上面的程式碼中,當只有3張圖片或者2張圖片的時候,滑動存在BUG問題的修改如下

  • destroyItem(View container, int position, Object object)方法中不removeView

 @Override  public void destroyItem(View container, int position, Object object) {//   ((ViewPager)container).removeView(mImageViews[position % mImageViews.length]);  }

  • instantiateItem(View container, int position)增加異常撲捉

 @Override  public Object instantiateItem(View container, int position) {   try {      ((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0);   }catch(Exception e){    //handler something   }   return mImageViews[position % mImageViews.length];  }

           

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這裡寫圖片描述