Android图片浏览源码解读
发布时间：2010/11/10 11:48:10 来源：城市学习网 编辑：ziteng
Android手机操作系统的应用方式灵活，简单，深受广大编程爱好者的喜爱。尤其是它的开源代码，使得我们能够方便的得到自己想要的功能需求。今天我们就为大家带来了有关Android图片浏览的相关方法。
首先是Android图片浏览中layout xml:
1.< ?xml version="1.0" encoding="utf-8"?>
2.< RelativeLayout xmlns:android="http://schemas.Android.com/apk/res/Android"
3.Android:layout_width="fill_parent"
4.Android:layout_height="fill_parent">
5.< ImageSwitcher Android:id="@+id/switcher"
6.Android:layout_width="fill_parent"
7.Android:layout_height="fill_parent"
8.Android:layout_alignParentTop="true"
9.Android:layout_alignParentLeft="true"
10./>
11.< Gallery Android:id="@+id/gallery"
12.Android:background="#55000000"
13.Android:layout_width="fill_parent"
14.Android:layout_height="60dp"
15.Android:layout_alignParentBottom="true"
16.Android:layout_alignParentLeft="true"
17.Android:gravity="center_vertical"
18.Android:spacing="16dp"
19./>
20.< /RelativeLayout>
layout里面用到了前面所说的两个控件，ImageSwitcher用啦显示全图，Gallery用来显示缩略图。着重看看ImageSwitcher,在ImageSwitcher1中需要实现ViewSwitcher.ViewFactory这个接口，这个接口里有个方法makeView，这样就产生了用来显示图片的view. ImageSwitcher调用过程是这样的，首先要有一个Factory为它提供一个View，然后ImageSwitcher就可以初始化各种资源了。注意在使用一个ImageSwitcher之前，一定要调用setFactory方法，要不setImageResource这个方法会报空指针异常。
下面是Android图片浏览代码：
1.package com.zx.imageswitcher;
2.import Android.app.Activity;
3.import Android.content.Context;
4.import Android.os.Bundle;
5.import Android.view.View;
6.import Android.view.ViewGroup;
7.import Android.view.animation.AnimationUtils;
8.import Android.widget.AdapterView;
9.import Android.widget.BaseAdapter;
10.import Android.widget.Gallery;
11.import Android.widget.ImageSwitcher;
12.import Android.widget.ImageView;
13.import Android.widget.ViewSwitcher;
14.import Android.widget.Gallery.LayoutParams;
15.public class ImageSwitcherTest extends Activity implements
16.AdapterView.OnItemSelectedListener, ViewSwitcher.ViewFactory{
17.private ImageSwitcher mSwitcher;
18.private Integer[] mThumbIds = {
19.R.drawable.sample_thumb_0, R.drawable.sample_thumb_1,
20.R.drawable.sample_thumb_2, R.drawable.sample_thumb_3,
21.R.drawable.sample_thumb_4, R.drawable.sample_thumb_5,
22.R.drawable.sample_thumb_6, R.drawable.sample_thumb_7};
23.private Integer[] mImageIds = {
24.R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2,
25.R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5,
26.R.drawable.sample_6, R.drawable.sample_7};
27./** Called when the activity is first created. */
28.@Override
29.public void onCreate(Bundle savedInstanceState) {
30.super.onCreate(savedInstanceState);
31.setContentView(R.layout.main);
32.mSwitcher = (ImageSwitcher) findViewById(R.id.switcher);
33.mSwitcher.setFactory(this);
34.mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
35.Android.R.anim.fade_in));
36.mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
37.Android.R.anim.fade_out));
38.Gallery g = (Gallery) findViewById(R.id.gallery);
39.g.setAdapter(new ImageAdapter(this));
40.g.setOnItemSelectedListener(this);
41.}
42./* [NextPage] 43.* override for ViewSwitcher.ViewFactory#makeView()
44.*/
45.public View makeView() {
46.ImageView i = new ImageView(this);
47.i.setBackgroundColor(0xFF000000);
48.i.setScaleType(ImageView.ScaleType.FIT_CENTER);
49.i.setLayoutParams(new ImageSwitcher.LayoutParams
(LayoutParams.FILL_PARENT,
50.LayoutParams.FILL_PARENT));
51.return i;
52.}
53./*
54.* override for
55.* AdapterView.OnItemSelectedListener#onItemSelected()
56.*/
57.public void onItemSelected(AdapterView parent,
View v, int position, long id) {
58.mSwitcher.setImageResource(mImageIds[position]);
59.}
60./*
61.* override for AdapterView.OnItemSelectedListener
#onNothingSelected()
62.*/
63.public void onNothingSelected(AdapterView< ?> arg0) {
64.// TODO Auto-generated method stub
65.}
66.public class ImageAdapter extends BaseAdapter {
67.public ImageAdapter(Context c) {
68.mContext = c;
69.}
70.public int getCount() {
71.return mThumbIds.length;
72.}
73.public Object getItem(int position) {
74.return position;
75.}
76.public long getItemId(int position) {
77.return position;
78.}
79.public View getView(int position, View convertView,
ViewGroup parent) {
80.ImageView i = new ImageView(mContext);
81.i.setImageResource(mThumbIds[position]);
82.i.setAdjustViewBounds(true);
83.i.setLayoutParams(new Gallery.LayoutParams(
84.LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
85.i.setBackgroundResource(R.drawable.picture_frame);
86.return i;
87.}
88.private Context mContext;
89.}
90.}
从Android图片浏览的代码中看到还实现了AdapterView.OnItemSelectedListener，这样就需要重写onItemSelected()方法，然后在该方法中：mSwitcher.setImageResource(mImageIds[position]);这样就实现了图片在ImageSwitcher中的切换。
