Android image browser example

This article describes a basic Android image browser code, which is imitated from the original version of Google. The main implementation processes and methods are implemented in the code. Specific improvements need to be added by yourself. There are many comments in the code, which can be To help novices quickly understand the code, some image resources are used.

The main function codes are as follows:

package com.android.coding;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.Gallery.LayoutParams;
import android.widget.ViewSwitcher.ViewFactory;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
public class ViewPicturesActivity extends Activity {
 ImageSwitcher imageSwitcher; //声明ImageSwitcher对象，图片显示区域
 Gallery gallery;       //声明Gallery对象，图片列表索引
 int imagePosition;      //标记图片数组下标，用于循环显示
 //声明图片整型数组
 private int[] images = {
  R.drawable.image1,R.drawable.image2,
  R.drawable.image3,R.drawable.image4,
  R.drawable.image5,R.drawable.image6,
  R.drawable.image7,R.drawable.image8,
  R.drawable.image9,R.drawable.image10,
  R.drawable.image11,R.drawable.image12,
  R.drawable.image13,R.drawable.image14,
  R.drawable.image15,R.drawable.image16,
  R.drawable.image17};
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    //通过控件的ID获得imageSwitcher的对象
    imageSwitcher = (ImageSwitcher) findViewById(R.id.switcher);
    //设置自定义的图片显示工厂类
    imageSwitcher.setFactory(new MyViewFactory(this));
    //通过控件的ID获得gallery的对象
    gallery = (Gallery) findViewById(R.id.gallery);
    //设置自定义的图片适配器
    gallery.setAdapter(new ImageAdapter(this)); 
    //实现被选中的事件监听器
    gallery.setOnItemSelectedListener(new OnItemSelectedListener() {        
  @Override
  public void onItemSelected(AdapterView<?> parent, View view,
   int position, long id) {
  //通过求余数，循环显示图片
  imageSwitcher.setImageResource(images[position%images.length]);  
  }
  @Override
  public void onNothingSelected(AdapterView<?> parent) {
  // TODO Auto-generated method stub  
  }
 });    
  }
   
  //自定义图片适配器，继承BaseAdapter
  class ImageAdapter extends BaseAdapter{   
 private Context context; //定义上下文
  
 //参数为上下文的构造方法
 public ImageAdapter(Context context) {
  this.context = context;
 }
    
 //得到图片的大小
 @Override
 public int getCount() {  //设置为整型的最大数
  return Integer.MAX_VALUE;
 }
 
 //得到指定图片的对象
 @Override
 public Object getItem(int position) {  
  return null;
 }
  
 //得到指定图片的对象的ID
 @Override
 public long getItemId(int position) {  
  return 0;
 }
 
 //显示图标列表
 @Override
 public View getView(int position, View convertView, ViewGroup parent) {
  ImageView iv = new ImageView(context); //创建ImageView对象
  iv.setImageResource(images[position%images.length]);  //设置循环显示图片
  iv.setAdjustViewBounds(true); //图片自动调整显示
  //设置图片的宽和高
  iv.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
  return iv; //返回ImageView对象
 }   
  }
   
  //自定义图片显示工厂类，继承ViewFactory
  class MyViewFactory implements ViewFactory{
 private Context context; //定义上下文
  
 //参数为上下文的构造方法
 public MyViewFactory(Context context) {
  this.context = context;
 }
 
 //显示图标区域
   @Override
 public View makeView() {
  ImageView iv = new ImageView(context); //创建ImageView对象
  iv.setScaleType(ImageView.ScaleType.FIT_CENTER); //图片自动居中显示
  //设置图片的宽和高
  iv.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
  return iv; //返回ImageView对象
 }   
  }  
}

The description in this article is only the main function code part, and readers can further improve it. The image viewer can also be extended to many practical Android image operation functions. These are skills that a novice Android application developer should master.

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