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Android巧用ViewPager实现左右循环滑动图片

2019年07月24日  | 移动技术网IT编程  | 我要评论

批评是一剂吗啡,蒋米茹,kizcorp

viewpager这个小demo实现的是可以左右循环滑动图片，下面带索引，滑到最后一页在往右滑动就要第一页，第一页往左滑动就到最后一页，先上效果图：

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这个jar包，自己不要忘记加

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; 
   
  /** 
   * 装点点的imageview数组 
   */ 
  private imageview[] tips; 
   
  /** 
   * 装imageview数组 
   */ 
  private imageview[] mimageviews; 
   
  /** 
   * 图片资源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); 
     
    //载入图片资源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}; 
     
     
    //将点点加入到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); 
    } 
     
     
    //将图片装载到数组中 
    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]); 
    } 
     
    //设置adapter 
    viewpager.setadapter(new myadapter()); 
    //设置监听，主要是设置点点的背景 
    viewpager.setonpagechangelistener(this); 
    //设置viewpager的默认项, 设置为长度的100倍，这样子开始就能往左滑动 
    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]); 
       
    } 
 
    /** 
     * 载入图片进去，用当前的position 除以 图片数组长度取余数是关键 
     */ 
    @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); 
  } 
   
  /** 
   * 设置选中的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); 
      } 
    } 
  } 
 
}

源码下载： 

2、上面的代码中，当只有3张图片或者2张图片的时候，滑动存在bug问题的修改如下
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)增加异常扑捉

@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]; 
  }

以上就是本文的全部内容，希望对大家学习android软件编程有所帮助。

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