从网上加载图片，图片不会错乱，可以缓存
好几个类
封装类就不写了Bean包的MenuInfo类
为了代码的整齐，几乎每一个类都是分包操作
ImageLoaderAsyncTask类异步图片加载类，
public class ImageLoaderAsyncTask extends AsyncTask <String,Void,Bitmap>{
private ImageCallBack imageCallBack;
public interface ImageCallBack{
void callBack(Bitmap bitmap);
}
public ImageLoaderAsyncTask(ImageCallBack imageCallBack){
this.imageCallBack = imageCallBack;
}
@Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
imageCallBack.callBack(bitmap);
}
@Override
protected Bitmap doInBackground(String... params) {
try {
String path = params[0];
URL url = new URL(path);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(5*1000);
connection.setReadTimeout(5*1000);
//与服务器建立连接
connection.connect();
//服务器响应
int code = connection.getResponseCode();
if(code == 200){
InputStream is = connection.getInputStream();
return BitmapFactory.decodeStream(is);
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
StreamTools类
public class StreamTools {
public static String readFromeNetWork(InputStream is){
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = is.read(buffer)) != -1){
baos.write(buffer,0,len);
}
//关闭流
is.close();
return baos.toString();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
MyBaseAdapter类
public class MyBaseAdapter extends BaseAdapter {
private static final String TAG = "MyBaseAdapter";
private Context context;
private List<MenuInfo.ResultBean.DataBean> list;
//配置图片的缓存选项
private DisplayImageOptions options;
private boolean isScroll = true;
public MyBaseAdapter(Context context, List<MenuInfo.ResultBean.DataBean> list) {
this.context = context;
this.list = list;
//配置是否对图片进行缓存
options = new DisplayImageOptions.Builder()
.cacheInMemory(true)//是否内存缓存
.cacheOnDisk(true)//是否sdcard缓存
.build();//构建图片缓存的选项
}
@Override
public int getCount() {
return list != null ? list.size() : 0;
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
/**
* 加载更多
*/
public void loadMore(List<MenuInfo.ResultBean.DataBean> lists,boolean isLast) {
for (MenuInfo.ResultBean.DataBean dataBean : lists) {
if(isLast) {
//添加数据
list.add(dataBean);
}else{
//添加到最前面
list.add(0,dataBean);
}
}
}
//监听listview是否滚动
public void isSroll(boolean isScroll){
this.isScroll = isScroll;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = null;
if (convertView == null) {
viewHolder = new ViewHolder();
convertView = convertView.inflate(context, R.layout.item, null);
viewHolder.ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);
viewHolder.tvContent = (TextView) convertView.findViewById(R.id.tvContent);
convertView.setTag(viewHolder);
}else{
viewHolder = (ViewHolder) convertView.getTag();
}
//设置文本信息
viewHolder.tvContent.setText(list.get(position).getTags());
//将图片的uri作为这个图片一个Tag
viewHolder.ivIcon.setTag(list.get(position).getAlbums().get(0));
//设置默认的图片 用 setImageResource() 方法替代 setBackgroundResource()
viewHolder.ivIcon.setImageResource(R.mipmap.ic_launcher);
//viewHolder.ivIcon.setBackgroundResource(R.mipmap.ic_launcher); 不可以
//使用ImgeLoader加载图片,可以缓存
//ImageLoader.getInstance().displayImage(list.get(position).getAlbums().get(0),ivIcon,options);
//ImageLoader.getInstance().displayImage(list.get(position).getAlbums().get(0),ivIcon);
if(isScroll) {
loadImage(list.get(position).getAlbums().get(0), viewHolder.ivIcon);
}
return convertView;
}
static class ViewHolder{
ImageView ivIcon;
TextView tvContent;
}
//加载图片
private void loadImage(final String url, final ImageView ivIcon) {
new ImageLoaderAsyncTask(new ImageLoaderAsyncTask.ImageCallBack() {
@Override
public void callBack(Bitmap bitmap) {
//ivIcon.setBackgroundResource(R.mipmap.ic_launcher);
if (bitmap != null) {
//拿到服务器获取过来的图片地址与之前你所设置的tag(图片地址)进行比较，如果相同，就是同一张图片
if(ivIcon.getTag() != null && url.equals(ivIcon.getTag())) {
ivIcon.setTag(url);
Log.d(TAG, "url : "+url+" tag : "+ivIcon.getTag());
ivIcon.setImageBitmap(bitmap);
}
} else {
Log.e(TAG, "callBack : 加载失败");
}
}
}).execute(url);
}
}
MyApplication类
public class MyApplication extends Application {
private static final String TAG = "MyApplication";
@Override
public void onCreate() {
super.onCreate();
try {
//缓存路径
File cacheDir = StorageUtils.getOwnCacheDirectory(this, Environment.getExternalStorageDirectory().getPath());
Log.d(TAG, "onCreate: "+Environment.getExternalStorageDirectory().getPath());
ImageLoaderConfiguration configuration = new ImageLoaderConfiguration.Builder(this)
.threadPoolSize(3)//配置线程数量
.memoryCache(new LruMemoryCache(2 * 1024 * 1024))//内存缓存图片 2M
.diskCache(new UnlimitedDiskCache(cacheDir))//配饰sdcard缓存路径
.diskCacheSize(50 * 1024 * 1024)//sdcard上缓存50M的图片
.diskCacheFileCount(100)//缓存文件的数量 100个
.diskCacheFileNameGenerator(new Md5FileNameGenerator())
.build();
//配置缓存选项
ImageLoader.getInstance().init(configuration);
} catch (Exception e) {
e.printStackTrace();
}
}
}
MainActivity类
public class MainActivity extends AppCompatActivity implements XListView.IXListViewListener {
private XListView lv;
private ProgressDialog dialog;
private int pageIndex = 1;
private MyBaseAdapter adapter;
//是否上拉
private boolean isLoadMore = true;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = (XListView) findViewById(R.id.lv);
//设置是否允许上拉加载更多
lv.setPullLoadEnable(true);
lv.setXListViewListener(this);
lv.setOnScrollListener(new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
switch (scrollState){
case AbsListView.OnScrollListener.SCROLL_STATE_IDLE:
if(adapter != null){
adapter.isSroll(true);
}
break;
case AbsListView.OnScrollListener.SCROLL_STATE_FLING:
if(adapter != null){
adapter.isSroll(false);
}
break;
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
}
});
//设置适配器
getData("http://apis.juhe.cn/cook/query.php?menu="+
URLEncoder.encode("秘制红烧肉")+"&key="+
URLEncoder.encode("a7a42220c5c1c5268be7ba25af764f6c")+"&pn="+pageIndex);
}
//这是请求菜谱信息操作
private void getData(String path){
new AsyncTask<String,Void,String >(){
@Override
protected void onPreExecute() {
super.onPreExecute();
//执行加载进度框
dialog = new ProgressDialog(MainActivity.this);
dialog.setMessage("玩命加载中...");
dialog.show();
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
//隐藏进度条
dialog.dismiss();
if(s != null){
Gson gson = new Gson();
MenuInfo menuInfo = gson.fromJson(s,MenuInfo.class);
//设置数据
if(adapter == null) {
adapter = new MyBaseAdapter(MainActivity.this, menuInfo.getResult().
getData());
lv.setAdapter(adapter);
}else{
adapter.loadMore(menuInfo.getResult().getData(),isLoadMore);
//刷新适配器
adapter.notifyDataSetChanged();
}
}
}
@Override
protected String doInBackground(String... params) {
try {
String path = params[0];
URL url = new URL(path);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(5*1000);
connection.setReadTimeout(5*1000);
//与服务器建立连接
connection.connect();
//服务器响应
int code = connection.getResponseCode();
if(code == 200){
InputStream is = connection.getInputStream();
String str = StreamTools.readFromeNetWork(is);
//将网络数据缓存到sdcard / SQLite SharedPerfrenced
File file = new File(Environment.getExternalStorageDirectory(),"menuinfo.txt");
if (!file.exists()){
file.createNewFile();
}
OutputStream os = new FileOutputStream(file);
os.write(str.getBytes());
//关闭流
is.close();
os.close();
return str;
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}.execute(path);
}
@Override
public void onRefresh() {
//执行网络请求
isLoadMore = false;
++pageIndex;
getData("http://apis.juhe.cn/cook/query.php?menu="+
URLEncoder.encode("秘制红烧肉")+"&key="+
URLEncoder.encode("a7a42220c5c1c5268be7ba25af764f6c")+"&pn="+pageIndex);
//停止刷新
lv.stopRefresh(true);
}
@Override
public void onLoadMore() {
isLoadMore = true;
++pageIndex;
getData("http://apis.juhe.cn/cook/query.php?menu="+
URLEncoder.encode("秘制红烧肉")+"&key="+
URLEncoder.encode("a7a42220c5c1c5268be7ba25af764f6c")+"&pn="+pageIndex);
//停止显示上拉的V
lv.stopLoadMore();
}
}