Android照片墙的实现
发布时间：2020-12-15 03:20:23 所属栏目：Java 来源：网络整理
导读：今天PHP站长网 52php.cn把收集自互联网的代码分享给大家，仅供参考。 RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_widt
|
以下代码由PHP站长网 52php.cn收集自互联网 现在PHP站长网小编把它分享给大家，仅供参考 <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=".MainActivity">
<GridView
android:id="@+id/photo_wall"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:columnWidth="90dip"
android:gravity="center"
android:numColumns="auto_fit"
android:stretchMode="columnWidth"
android:verticalSpacing="10dip" />
</RelativeLayout>
Constant.java public class Constant {
public static String[] imgs = new String[]{
"http://img5.douban.com/view/photo/thumb/public/p1042461956.jpg","http://img5.douban.com/lpic/s28035816.jpg","http://img3.douban.com/lpic/s28049685.jpg","http://img5.douban.com/lpic/s28004598.jpg","http://img5.douban.com/lpic/s28050639.jpg","http://img3.douban.com/lpic/s28056884.jpg","http://img5.douban.com/lpic/s28036379.jpg","http://img5.douban.com/lpic/s28045199.jpg","http://img3.douban.com/lpic/s28034923.jpg","http://img5.douban.com/lpic/s28067039.jpg","http://img3.douban.com/spic/s28000872.jpg","http://img3.douban.com/view/movie_poster_cover/mpst/public/p2237747953.jpg","http://img5.douban.com/view/movie_poster_cover/mpst/public/p2240110789.jpg","http://img5.douban.com/view/movie_poster_cover/mpst/public/p2235609577.jpg","http://img5.douban.com/view/movie_poster_cover/mpst/public/p2233113686.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2225188257.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2201518484.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2229383316.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2222477444.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2230484792.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2204911658.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2210568759.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2201468648.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2226169113.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2221319641.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2231932406.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2208286457.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2203481530.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2232079769.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2224484447.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2233767512.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2202114105.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2209761319.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2230222544.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2220776342.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2233840624.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2194199028.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2233260210.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2210832820.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2203693875.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2231791943.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2203838902.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2220218254.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2215268072.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2219669553.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2208934451.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2225669293.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2225986472.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2199678535.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2230471461.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2204888387.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2224389662.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2207808539.jpg","http://img5.douban.com/view/movie_poster_cover/lpst/public/p2225291257.jpg","http://img3.douban.com/view/movie_poster_cover/lpst/public/p2230505723.jpg"
};
}
ImageLoaderAdapter.java package com.jackie.photowall;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.util.LruCache;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;
/**
* Created by Jackie on 5/14/15.
*/
public class ImageLoaderAdapter extends BaseAdapter implements AbsListView.OnScrollListener {
private Activity mActivity;
private GridView mGridView;
private LayoutInflater mInflater;
/**
* 图片缓存技术的核心类，用于缓存所有下载好的图片，在程序内存达到设定值时会将最少最近使用的图片移除掉。
*/
private LruCache<String,Bitmap> mMemoryCache;
/**
* 记录所有正在下载或等待下载的任务。
*/
private Set<ImageLoaderTask> mImageLoaderTasks;
/**
* 第一张可见图片的下标
*/
private int mFirstVisibleItem;
/**
* 可见区域一屏有多少张图片
*/
private int mVisibleItemCount;
/**
* 代表第一次进来不滑动的时候自动加载图片
*/
private boolean mIsFirstLoader = true;
public ImageLoaderAdapter(GridView mGridView,Activity mActivity) {
this.mActivity = mActivity;
this.mGridView = mGridView;
mInflater = LayoutInflater.from(mActivity);
mImageLoaderTasks = new HashSet<ImageLoaderTask>();
/**
* 获取应用给app分配的内存空间
*/
int maxMemory = (int) Runtime.getRuntime().maxMemory();
/**
* 给图片分配合理的内容空间
*/
int cacheSize = maxMemory / 8;
mMemoryCache = new LruCache<String,Bitmap>(cacheSize) {
@Override
protected int sizeOf(String key,Bitmap bitmap) {
return bitmap.getByteCount();
}
};
mGridView.setOnScrollListener(this);
}
@Override
public int getCount() {
return Constant.imgs != null && Constant.imgs.length > 0 ? Constant.imgs.length : 0;
}
@Override
public Object getItem(int position) {
return Constant.imgs[position];
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position,View convertView,ViewGroup arg2) {
final String url = (String) getItem(position);
ViewHolder holder = null;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.img_item,null);
holder = new ViewHolder();
holder.imageview = (ImageView) convertView.findViewById(R.id.imageview);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
/**
* 给ImageView设置一个Tag，保证异步加载图片时不会乱序
*/
holder.imageview.setTag(url);
setImageView(url,holder.imageview);
return convertView;
}
/**
* 首先用url到缓存中找 如果没有就显示默认图片 如果缓存中有 就显示
*
* @param url 要显示图片的url
* @param imageview
*/
private void setImageView(String url,ImageView imageview) {
Bitmap bitmap = mMemoryCache.get(url);
if (bitmap != null && imageview != null) {
imageview.setImageBitmap(bitmap);
} else {
// imageview.setImageResource(R.drawable.empty_photo);
}
}
class ViewHolder {
ImageView imageview;
}
/**
* view 就是GridView
* firstVisibleItem 可见 第一个条目
* visibleItemCount 可见的总条目
* totalItemCount 要加载的总条目
*/
@Override
public void onScroll(AbsListView view,int firstVisibleItem,int visibleItemCount,int totalItemCount) {
mFirstVisibleItem = firstVisibleItem;
mVisibleItemCount = visibleItemCount;
if (mIsFirstLoader && visibleItemCount > 0) {
loadImages(firstVisibleItem,visibleItemCount);
mIsFirstLoader = false;
}
}
@Override
public void onScrollStateChanged(AbsListView view,int scrollState) {
// 仅当GridView静止时才去下载图片，GridView滑动时取消所有正在下载的任务
if (scrollState == SCROLL_STATE_IDLE) {
loadImages(mFirstVisibleItem,mVisibleItemCount);
} else {
cancelAllTasks();
}
}
private void cancelAllTasks() {
if (mImageLoaderTasks != null) {
for (ImageLoaderTask task : mImageLoaderTasks) {
task.cancel(false);
}
}
}
private void loadImages(int firstVisibleItem,int visibleItemCount) {
for (int i = firstVisibleItem; i < firstVisibleItem + visibleItemCount; i++) {
String imagUrl = Constant.imgs[i];
Bitmap bitmap = getBitmapFromMemory(imagUrl);
if (bitmap == null) {//从网络获取
ImageLoaderTask task = new ImageLoaderTask();
mImageLoaderTasks.add(task);
task.execute(imagUrl);
} else {//从缓存获取
ImageView imageView = (ImageView) mGridView.findViewWithTag(imagUrl);
if (imageView != null && bitmap != null) {
imageView.setImageBitmap(bitmap);
}
}
}
}
private Bitmap getBitmapFromMemory(String key) {
return mMemoryCache.get(key);
}
private class ImageLoaderTask extends AsyncTask<String,Void,Bitmap> {
String url = null;
@Override
protected Bitmap doInBackground(String... param) {
url = param[0];
/**
* 从网络上加载的图片 如果bitmap不为null 就加载到内存之中
*/
Bitmap bitmap = downLoadImage(url);
if (bitmap != null) {
// 图片下载完成后缓存到LrcCache中
addBitmapToMemoryCache(url,bitmap);
}
return bitmap;
}
@Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
ImageView imageView = (ImageView) mGridView.findViewWithTag(url);
if (imageView != null && bitmap != null) {
imageView.setImageBitmap(bitmap);
}
/**
* 下载完了以后把该任务从集合中移除 可能有些人会说为什么要用hashset集合 因为他可以的任务不重复
*/
mImageLoaderTasks.remove(this);
}
}
public Bitmap downLoadImage(String imgUrl) {
Bitmap bitmap = null;
HttpURLConnection connection = null;
try {
URL url = new URL(imgUrl);
connection = (HttpURLConnection) url.openConnection();
connection.setConnectTimeout(5 * 1000);
connection.setReadTimeout(10 * 1000);
connection.setDoInput(true);
bitmap = BitmapFactory.decodeStream(connection.getInputStream());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
}
return bitmap;
}
/**
* 把图片加载到内存之中
*
* @param url 图片的url
* @param bitmap url对应的图片
*/
public void addBitmapToMemoryCache(String url,Bitmap bitmap) {
if (getBitmapFromMemory(url) == null) {
mMemoryCache.put(url,bitmap);
}
}
}
效果图：
以上内容由PHP站长网【52php.cn】收集整理供大家参考研究 如果以上内容对您有帮助，欢迎收藏、点赞、推荐、分享。 （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
