ImageLoader的使用
package com.example.bitmap_demo;
import android.content.Context;
import android.content.DialogInterface;
import android.graphics.drawable.Drawable;
import android.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
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 com.example.bitmap_demo.utils.MyUtils;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity implements AbsListView.OnScrollListener {
private boolean mIsGridViewIdle = true;
private int mImageWidth = 0;
private boolean mIsWifi = false;
private boolean mCanGetBitmapFromNetWork = false;
ImageLoader mImageLoader;
private GridView mImageGridView;
private BaseAdapter mImageAdapter;
private ArrayList<String> mUrList=new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initData();
initView();
mImageLoader = ImageLoader.build(MainActivity.this);
}
private void initView() {
mImageGridView = (GridView) findViewById(R.id.gridView);
mImageAdapter = new ImageAdapter(this);
mImageGridView.setAdapter(mImageAdapter);
mImageGridView.setOnScrollListener(this);
if (!mIsWifi) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("初次使用会从网络下载大概5MB的图片，确认要下载吗？");
builder.setTitle("注意");
builder.setPositiveButton("是", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
mCanGetBitmapFromNetWork = true;
mImageAdapter.notifyDataSetChanged();
}
});
builder.setNegativeButton("否", null);
builder.show();
}
}
private void initData() {
String[] imageUrls = {
"http://b.hiphotos.baidu.com/zhidao/pic/item/a6efce1b9d16fdfafee0cfb5b68f8c5495ee7bd8.jpg",
"http://pic47.nipic.com/20140830/7487939_180041822000_2.jpg",
"http://pic41.nipic.com/20140518/4135003_102912523000_2.jpg",
"http://img2.imgtn.bdimg.com/it/u=1133260524,1171054226&fm=21&gp=0.jpg",
"http://h.hiphotos.baidu.com/image/pic/item/3b87e950352ac65c0f1f6e9efff2b21192138ac0.jpg",
"http://pic42.nipic.com/20140618/9448607_210533564001_2.jpg",
"http://pic10.nipic.com/20101027/3578782_201643041706_2.jpg",
"http://picview01.baomihua.com/photos/20120805/m_14_634797817549375000_37810757.jpg",
"http://img2.3lian.com/2014/c7/51/d/26.jpg",
"http://img3.3lian.com/2013/c1/34/d/93.jpg",
"http://b.zol-img.com.cn/desk/bizhi/image/3/960x600/1375841395686.jpg",
"http://picview01.baomihua.com/photos/20120917/m_14_634834710114218750_41852580.jpg",
"http://cdn.duitang.com/uploads/item/201311/03/20131103171224_rr2aL.jpeg",
"http://imgrt.pconline.com.cn/images/upload/upc/tx/wallpaper/1210/17/c1/spcgroup/14468225_1350443478079_1680x1050.jpg",
"http://pic41.nipic.com/20140518/4135003_102025858000_2.jpg",
"http://www.1tong.com/uploads/wallpaper/landscapes/200-4-730x456.jpg",
"http://pic.58pic.com/58pic/13/00/22/32M58PICV6U.jpg",
"http://picview01.baomihua.com/photos/20120629/m_14_634765948339062500_11778706.jpg",
"http://h.hiphotos.baidu.com/zhidao/wh%3D450%2C600/sign=429e7b1b92ef76c6d087f32fa826d1cc/7acb0a46f21fbe09cc206a2e69600c338744ad8a.jpg",
"http://pica.nipic.com/2007-12-21/2007122115114908_2.jpg",
"http://cdn.duitang.com/uploads/item/201405/13/20140513212305_XcKLG.jpeg",
"http://photo.loveyd.com/uploads/allimg/080618/1110324.jpg",
"http://img4.duitang.com/uploads/item/201404/17/20140417105820_GuEHe.thumb.700_0.jpeg",
"http://cdn.duitang.com/uploads/item/201204/21/20120421155228_i52eX.thumb.600_0.jpeg",
"http://img4.duitang.com/uploads/item/201404/17/20140417105856_LTayu.thumb.700_0.jpeg",
"http://img04.tooopen.com/images/20130723/tooopen_20530699.jpg",
"http://www.qjis.com/uploads/allimg/120612/1131352Y2-16.jpg",
"http://pic.dbw.cn/0/01/33/59/1335968_847719.jpg",
"http://a.hiphotos.baidu.com/image/pic/item/a8773912b31bb051a862339c337adab44bede0c4.jpg",
"http://h.hiphotos.baidu.com/image/pic/item/f11f3a292df5e0feeea8a30f5e6034a85edf720f.jpg",
"http://img0.pconline.com.cn/pconline/bizi/desktop/1412/ER2.jpg",
"http://pic.58pic.com/58pic/11/25/04/91v58PIC6Xy.jpg",
"http://img3.3lian.com/2013/c2/32/d/101.jpg",
"http://pic25.nipic.com/20121210/7447430_172514301000_2.jpg",
"http://img02.tooopen.com/images/20140320/sy_57121781945.jpg",
"http://www.renyugang.cn/emlog/content/plugins/kl_album/upload/201004/852706aad6df6cd839f1211c358f2812201004120651068641.jpg"
};
for (String url : imageUrls) {
mUrList.add(url);
}
int screenWidth = MyUtils.getScreenMetrics(this).widthPixels;
int space = (int)MyUtils.dp2px(this, 20f);
mImageWidth = (screenWidth - space) / 3;
mIsWifi = MyUtils.isWifi(this);
if (mIsWifi) {
mCanGetBitmapFromNetWork = true;
}
}
private class ImageAdapter extends BaseAdapter {
private final Drawable mDefaultBitmapDrawable;
private LayoutInflater mInflater;
public ImageAdapter(Context context) {
mInflater=LayoutInflater.from(context);
mDefaultBitmapDrawable = context.getResources().getDrawable(R.drawable.ic_launcher_background);
}
@Override
public int getCount() {
return mUrList.size();
}
@Override
public Object getItem(int position) {
return mUrList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder=null;
if (convertView==null){
convertView=mInflater.inflate(R.layout.item,parent,false);
holder=new ViewHolder();
holder.imageView=convertView.findViewById(R.id.image);
convertView.setTag(holder);
}else {
holder= (ViewHolder) convertView.getTag();
}
ImageView imageView=holder.imageView;
final String tag= (String) imageView.getTag();
final String uri= (String) getItem(position);
if(!uri.equals(tag)){
imageView.setImageDrawable(mDefaultBitmapDrawable);
}
if(mIsGridViewIdle&&mCanGetBitmapFromNetWork){
imageView.setTag(uri);
mImageLoader.bindBitmap(uri,imageView,mImageWidth,mImageWidth);
}
return convertView;
}
}
private static class ViewHolder {
public ImageView imageView;
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// 静止的时候才会加载图片
if (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_IDLE) {
mIsGridViewIdle = true;
mImageAdapter.notifyDataSetChanged();
} else {
mIsGridViewIdle = false;
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// ignored
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:orientation="vertical"
android:padding="5dp"
android:layout_height="match_parent">
<GridView
android:id="@+id/gridView"
android:numColumns="3"
android:horizontalSpacing="5dp"
android:verticalSpacing="5dp"
android:listSelector="@android:color/transparent"
android:stretchMode="columnWidth"
android:layout_width="match_parent"
android:layout_height="match_parent"></GridView>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="match_parent">
<com.example.bitmap_demo.SquareImageView
android:id="@+id/image"
android:scaleType="centerCrop"
android:src="@drawable/ic_launcher_background"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
ids.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<item name="imageloader_uri" type="id"/>
</resources>
package com.example.bitmap_demo.utils;
import java.io.Closeable;
import java.io.IOException;
import java.util.List;
import android.app.ActivityManager;
import android.app.ActivityManager.RunningAppProcessInfo;
import android.content.Context;
import android.content.res.TypedArray;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.WindowManager;
public class MyUtils {
public static String getProcessName(Context cxt, int pid) {
ActivityManager am = (ActivityManager) cxt
.getSystemService(Context.ACTIVITY_SERVICE);
List runningApps = am.getRunningAppProcesses();
if (runningApps == null) {
return null;
}
for (RunningAppProcessInfo procInfo : runningApps) {
if (procInfo.pid == pid) {
return procInfo.processName;
}
}
return null;
}
public static void close(Closeable closeable) {
try {
if (closeable != null) {
closeable.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static DisplayMetrics getScreenMetrics(Context context) {
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics dm = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(dm);
return dm;
}
public static float dp2px(Context context, float dp) {
return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp,
context.getResources().getDisplayMetrics());
}
public static boolean isWifi(Context context) {
ConnectivityManager connectivityManager = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetInfo = connectivityManager.getActiveNetworkInfo();
if (activeNetInfo != null
&& activeNetInfo.getType() == ConnectivityManager.TYPE_WIFI) {
return true;
}
return false;
}
public static void executeInThread(Runnable runnable) {
new Thread(runnable).start();
}
}