今天用AS学做了一个简单的图片切换小程序
其中用到了一个ImageSwitcher的类通过设置一个ViewFactory工厂，实现其makeView()方法来创建显示图片的View。和和一个叫做“画廊类”的Gallery类，来陈列图片资源；
方法setImageResource用来显示指定的图片资源。
1.声明所需的变量 private Gallery gallery ; private ImageSwitcher imageSwitcher ;将7张图片放入/res/drawable目录下，声明一个数组把图片资源放到数组里private int[] res={R.drawable.grid_view_02,R.drawable.grid_view_03,R.drawable.grid_view_04,R.drawable.grid_view_05,R.drawable.grid_view_06,R.drawable.grid_view_12,R.drawable.grid_view_14};2.MainActivity.java
package com.example.ch.imageswitchingandshowing; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.widget.AdapterView; import android.widget.BaseAdapter; import android.widget.Gallery; import android.widget.ImageSwitcher; import android.widget.ImageView; import android.widget.ViewSwitcher; import java.util.Iterator; public class MainActivity extends AppCompatActivity { private Gallery gallery; private ImageSwitcher imageSwitcher; private int[] res={R.drawable.grid_view_02,R.drawable.grid_view_03,R.drawable.grid_view_04, R.drawable.grid_view_05,R.drawable.grid_view_06,R.drawable.grid_view_12,R.drawable.grid_view_14}; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); gallery=(Gallery)findViewById(R.id.gallery); imageSwitcher=(ImageSwitcher)findViewById(R.id.imageSwitcher); //buju imageSwitcher.setFactory(new ViewSwitcher.ViewFactory() { @Override public View makeView() { ImageView imageView= new ImageView(MainActivity.this); imageView.setBackgroundColor(0xff000000); imageView.setScaleType(ImageView.ScaleType.FIT_CENTER); imageView.setLayoutParams(new ImageSwitcher.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); return imageView; } }); imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));//设置进入的动态效果，叠进 imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out)); //下面这一步是准备Gallery工作，获得信息。 gallery.setAdapter(new BaseAdapter() { @Override //获得<span style="font-family: 宋体;">gallery里的图片个数（item）</span> public int getCount() { return res.length; } @Override public Object getItem(int position) { return position; } @Override <span style="color: rgb(51, 51, 51); font-family: 宋体; font-size: 14px; line-height: 28px; text-indent: 28px; background-color: rgb(249, 249, 249);">//至于getItemId(int position)，它返回的是该postion对应item的id</span> public long getItemId(int position) { return position; } @Override //得到画廊中的一个图片 public View getView(int position, View convertView, ViewGroup parent) { ImageView imageView = new ImageView(MainActivity.this); imageView.setLayoutParams(new Gallery.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)); imageView.setAdjustViewBounds(true); imageView.setImageResource(res[position]); return imageView; } }); //选中画廊中的item监听事件 gallery.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { @Override //选中了就将图片给到<span style="font-family: 宋体;">imageSwitcher中</span> public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { imageSwitcher.setImageResource(res[position]); } @Override public void onNothingSelected(AdapterView<?> parent) { } }); } }layout布局文件：
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.ch.imageswitchingandshowing.MainActivity"> <ImageSwitcher android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/imageSwitcher" android:layout_alignParentTop="true" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" /> <Gallery android:layout_width="match_parent" android:layout_height="60dp" android:id="@+id/gallery" android:spacing="20dp"//展览图片时，设置相邻图片的间距 android:gravity="center_vertical" android:layout_alignBottom="@+id/imageSwitcher" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" /> </RelativeLayout> 托这两个控件时不要使这两者的区域有重叠部分。 效果如下所示：
