Android学习之-----Gallery

在Android中，画廊控件Gallery用来显示图片列表，可以用手指直接拖动图片左右移动。Gallery只能水平显示一行，且Gallery列表中的图片会根据不同的拖动情况向左或向右移动，直到显示到最后一个图片为止

1.XML布局

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:orientation="vertical" >
 6
 7     <ImageView
 8         android:id="@+id/imageView"
 9         android:layout_width="match_parent"
10         android:layout_height="650dp" >
11     </ImageView>
12
13     <Gallery
14         android:id="@+id/gallery"
15         android:layout_width="match_parent"
16         android:layout_height="wrap_content"
17         android:spacing="5dp" >
18     </Gallery>
19
20 </LinearLayout>

在Gallery属性标签中，android:spacing="5dp"属性用于指定Gallery列表图片之间的间隔为2dp。

2.实现适配器

要实现Gallery画廊控件功能，需要一个容器来存放Gallery显示的图片。我们可以使用一个继承自BaseAdapter类的派生类ImageAdapter来装这些图片。

代码如：

 1 package com.example.gallery;
 2
 3 import android.os.Bundle;
 4 import android.app.Activity;
 5 import android.content.Context;
 6 import android.view.Menu;
 7 import android.view.View;
 8 import android.view.ViewGroup;
 9 import android.widget.AdapterView;
10 import android.widget.AdapterView.OnItemClickListener;
11 import android.widget.BaseAdapter;
12 import android.widget.Gallery;
13 import android.widget.ImageView;
14
15 public class MainActivity extends Activity {
16     private ImageView mImageView;
17     private Gallery mGallery;
18     private int[] images = { R.drawable.m1, R.drawable.m2, R.drawable.m3,
19             R.drawable.m4, R.drawable.m5, };
20
21     @Override
22     protected void onCreate(Bundle savedInstanceState) {
23         super.onCreate(savedInstanceState);
24         setContentView(R.layout.activity_main);
25         mImageView = (ImageView) this.findViewById(R.id.imageView);
26         mGallery = (Gallery) this.findViewById(R.id.gallery);
27         mGallery.setAdapter(new ImagesAdapter(this));
28         mGallery.setOnItemClickListener(new OnItemClickListener() {
29             @Override
30             public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
31                     long arg3) {
32                 mImageView.setBackgroundResource(images[arg2]);
33             }
34         });
35     }
36
37     public class ImagesAdapter extends BaseAdapter {
38         private Context context;
39
40         public ImagesAdapter(Context context) {
41             this.context = context;
42         }
43
44         @Override
45         public int getCount() {
46             // TODO Auto-generated method stub
47             return images.length;
48         }
49
50         @Override
51         public Object getItem(int position) {
52             // TODO Auto-generated method stub
53             return images[position];
54         }
55
56         @Override
57         public long getItemId(int position) {
58             // TODO Auto-generated method stub
59             return position;
60         }
61
62         @Override
63         public View getView(int position, View arg1, ViewGroup arg2) {
64             ImageView imageView = new ImageView(context);
65             imageView.setImageResource(images[position]);
66             imageView.setLayoutParams(new Gallery.LayoutParams(200, 200));
67             imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
68             return imageView;
69         }
70     }
71
72     @Override
73     public boolean onCreateOptionsMenu(Menu menu) {
74         // Inflate the menu; this adds items to the action bar if it is present.
75         getMenuInflater().inflate(R.menu.main, menu);
76         return true;
77     }
78
79 }