本 文主要是写关于ImageSwitcher结合Gallery组件如何展示SDCard中的资源图片,相信大家都看过API Demo 中也有关于这个例子的,但API Demo 中的例子是展示工程中Drawable目录下的资源图片,这样调用系统的API比较容易实现,但我们在开发项目过程中,但有些图片还不能完全确定下来,例 如需要展示相机拍照的图片,SDCard中某个目录下的资源图片等功能。其实系统中也提供相应的API给我们应用去实现该功能,下面就用异于API Demo中例子方式展示下如何实现该功能。
一:定义布局文件:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="#55000000" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="Welcome to"
android:textSize="20sp"/>
<ImageSwitcher
android:id="@+id/switcher"
android:layout_width="wrap_content"
android:layout_height="350dip"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true" />
<Gallery
android:id="@+id/mygallery"
android:layout_width="fill_parent"
android:layout_height="80dp"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:gravity="center_vertical"
android:spacing="16dp" />
</LinearLayout>
2.java文件:
package com.test;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.Gallery.LayoutParams;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.ViewSwitcher.ViewFactory;
public class ImageSwitcherFromSD extends Activity implements
OnItemSelectedListener, ViewFactory {
private List<String> imagePathList;
private String[] list;
private ImageSwitcher mSwitcher;
private Gallery mGallery;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imagePathList=getImagePathFromSD();
list = imagePathList.toArray(new String[imagePathList.size()]);
// 设定Switcher */
mSwitcher = (ImageSwitcher) findViewById(R.id.switcher);
mSwitcher.setFactory(this);
// 设定载入Switcher的模式 */
mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
android.R.anim.fade_in));
// 设定输出Switcher的模式 */
mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
android.R.anim.fade_out));
mSwitcher.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast.makeText(ImageSwitcherFromSD.this, "你点击了ImageSwitch上的图片",
Toast.LENGTH_SHORT).show();
}
});
mGallery = (Gallery) findViewById(R.id.mygallery);
// 新增几ImageAdapter并设定给Gallery对象 */
mGallery.setAdapter(new ImageAdapter(this, getImagePathFromSD()));
mGallery.setOnItemSelectedListener(this);
// 设定一个itemclickListener事件
mGallery.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
Toast.makeText(ImageSwitcherFromSD.this, "你点击了Gallery上的图片",
Toast.LENGTH_SHORT).show();
}
});
}
// 从SD卡中获取资源图片的路径 */
private List<String> getImagePathFromSD() {
// 设定目前所在路径 */
List<String> it = new ArrayList<String>();
//根据自己的需求读取SDCard中的资源图片的路径
String imagePath = Environment.getExternalStorageDirectory().toString();
File mFile = new File(imagePath);
File[] files = mFile.listFiles();
// 将所有文件存入ArrayList中
for (int i = 0; i < files.length; i++) {
File file = files[i];
if (checkIsImageFile(file.getPath()))
it.add(file.getPath());
}
return it;
}
// 判断是否相应的图片格式
private boolean checkIsImageFile(String fName) {
boolean isImageFormat;
// 取得扩展名
String end = fName
.substring(fName.lastIndexOf(".") + 1, fName.length())
.toLowerCase();
// 按扩展名的类型决定MimeType
if (end.equals("jpg") || end.equals("gif") || end.equals("png")
|| end.equals("jpeg") || end.equals("bmp")) {
isImageFormat = true;
} else {
isImageFormat = false;
}
return isImageFormat;
}
// 改写BaseAdapter自定义一ImageAdapter class
class ImageAdapter extends BaseAdapter {
// 声明变量
int mGalleryItemBackground;
private Context mContext;
private List<String> lis;
// ImageAdapter的构造符
public ImageAdapter(Context c, List<String> li) {
mContext = c;
lis = li;
//使用res/values/attrs.xml中的<declare-styleable>定义 的Gallery属性.
TypedArray mTypeArray = obtainStyledAttributes(R.styleable.Gallery);
// 取得Gallery属性的Index id
mGalleryItemBackground = mTypeArray.getResourceId(
R.styleable.Gallery_android_galleryItemBackground, 0);
// 让对象的styleable属性能够反复使用
mTypeArray.recycle();
}
// 重写的方法getCount,传回图片数目
public int getCount() {
return lis.size();
}
// 重写的方法getItem,传回position
public Object getItem(int position) {
return position;
}
//重写的方法getItemId,传并position
public long getItemId(int position) {
return position;
}
// 重写方法getView,传并几View对象
public View getView(int position, View convertView, ViewGroup parent) {
// 产生ImageView对象
ImageView i = new ImageView(mContext);
// 设定图片给imageView对象
Bitmap bm = BitmapFactory.decodeFile(lis.get(position).toString());
i.setImageBitmap(bm);
// 重新设定图片的宽高
i.setScaleType(ImageView.ScaleType.FIT_XY);
// 重新设定Layout的宽高
i.setLayoutParams(new Gallery.LayoutParams(136, 88));
//设定Gallery背景图
i.setBackgroundResource(mGalleryItemBackground);
// 传回imageView对象
return i;
}
}
@Override
public View makeView() {
ImageView iv = new ImageView(this);
iv.setBackgroundColor(0xFF000000);
iv.setScaleType(ImageView.ScaleType.FIT_CENTER);
iv.setLayoutParams(new ImageSwitcher.LayoutParams(
LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
return iv;
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position,
long id) {
// TODO Auto-generated method stub
String photoURL = list[position];
Log.i("A", String.valueOf(position));
mSwitcher.setImageURI(Uri.parse(photoURL));
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
// TODO Auto-generated method stub
}
}
3.执行效果: