本文简单汇总Android中图片加载库的使用，并非深度源码的解析。
Android-Universal-Image-Loader
项目地址：Android-Universal-Image-Loader
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// 初始化相关
ImageLoader imageLoader = ImageLoader.getInstance();
// Get singleton instance
imageLoader.init(ImageLoaderConfiguration.createDefault(BDApplication.instance()));
// 使用方式1：根据uri显示到ImageView上，是否异步要根据option.isSyncLoading
// Load image, decode it to Bitmap and display Bitmap in ImageView (or any other view
// which implements ImageAware interface)
imageLoader.displayImage(imageUri, imageView);
// 使用方式2：在回调里处理
// Load image, decode it to Bitmap and return Bitmap to callback
imageLoader.loadImage(imageUri,
new SimpleImageLoadingListener() {
public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
// Do whatever you want with Bitmap
}
});
// 使用方式3：同步返回bitmap
// Load image, decode it to Bitmap and return Bitmap synchronously
Bitmap bmp = imageLoader.loadImageSync(imageUri);
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另外，可以配置显示图片的样式，设置option的BitmapDisplayer。UIL提供了FadeInBitmapDisplayer渐显样式、SimpleBitmapDisplayer、RoundedBitmapDisplayer、CircleBitmapDisplayer、RoundedVignetteBitmapDisplayer圆角显示颜色会有个渐变的效果 这5中Displayer。
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private ImageLoaderUtil() {
// 正常图片
optionsNormal =
new DisplayImageOptions.Builder()
.showImageOnLoading(R.drawable.ic_stub)
.showImageForEmptyUri(R.drawable.ic_stub)
.showImageOnFail(R.drawable.ic_stub).cacheInMemory(
true)
.cacheOnDisk(
true).considerExifParams(
true)
.displayer(
new SimpleBitmapDisplayer()).build();
// 圆角矩形
optionsRounded =
new DisplayImageOptions.Builder()
.showImageOnLoading(R.drawable.ic_stub)
.showImageForEmptyUri(R.drawable.ic_stub)
.showImageOnFail(R.drawable.ic_stub).cacheInMemory(
true)
.cacheOnDisk(
true).considerExifParams(
true)
.displayer(
new RoundedBitmapDisplayer(
10)).build();
// 圆圈图片
optionsCircle =
new DisplayImageOptions.Builder()
.showImageOnLoading(R.drawable.ic_stub)
.showImageForEmptyUri(R.drawable.ic_stub)
.showImageOnFail(R.drawable.ic_stub).cacheInMemory(
true)
.cacheOnDisk(
true).considerExifParams(
true)
.displayer(
new CircleBitmapDisplayer(
4)).build();
imageLoader = ImageLoader.getInstance();
imageLoader.init(ImageLoaderConfiguration.createDefault(BDApplication.instance()));
animateFirstListener =
new AnimateFirstDisplayListener();
}
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总体架构图：
流程图：
参考文档：
Android Universal Image Loader 源码分析
google/volley
官方项目地址：volley
fork项目地址：volley-mstian06
Demo项目地址：android-cn/volley-demo
类继承关系图：
总体设计图
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// 初始化相关
public
class RequestManager {
public
static RequestQueue mRequestQueue = newRequestQueue();
private
static
final
int MEM_CACHE_SIZE =
1024 *
1024 * ((ActivityManager) AppData.getContext()
.getSystemService(Context.ACTIVITY_SERVICE)).getMemoryClass() /
3;
private
static ImageLoader mImageLoader =
new ImageLoader(mRequestQueue,
new BitmapLruCache(MEM_CACHE_SIZE));
private
static DiskBasedCache mDiskCache = (DiskBasedCache) mRequestQueue.getCache();
private RequestManager(){
}
// DiskLruCache缓存，自定义路径、大小
private static Cache openCache() {
return
new DiskBasedCache(CacheUtils.getExternalCacheDir(AppData.getContext()),
10 *
1024 *
1024);
}
private static RequestQueue newRequestQueue() {
RequestQueue requestQueue =
new RequestQueue(openCache(),
new BasicNetwork(
new HurlStack()));
requestQueue.start();
return requestQueue;
}
public static void addRequest(Request request, Object tag) {
if (tag !=
null) {
request.setTag(tag);
}
mRequestQueue.add(request);
}
public static void cancelAll(Object tag) {
mRequestQueue.cancelAll(tag);
}
public
static ImageLoader.
ImageContainer loadImage(String requestUrl,
ImageLoader.ImageListener imageListener) {
return loadImage(requestUrl, imageListener,
0,
0);
}
public
static ImageLoader.
ImageContainer loadImage(String requestUrl,
ImageLoader.ImageListener imageListener,
int maxWidth,
int maxHeight) {
return mImageLoader.get(requestUrl, imageListener, maxWidth, maxHeight);
}
}
public
class CacheUtils {
public static File getExternalCacheDir(final Context context) {
if (hasExternalCacheDir())
return context.getExternalCacheDir();
// Before Froyo we need to construct the external cache dir ourselves
final String cacheDir =
"/Android/data/" + context.getPackageName() +
"/cache/";
return
new File(Environment.getExternalStorageDirectory().getPath() + cacheDir);
}
public static boolean hasExternalCacheDir() {
return Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO;
}
}
// LruCache内存缓存
public
class BitmapLruCache extends LruCache<String, Bitmap> implements ImageLoader.ImageCache {
public BitmapLruCache(int maxSize) {
super(maxSize);
}
protected int sizeOf(String key, Bitmap bitmap) {
return ImageUtils.getBitmapSize(bitmap);
}
public Bitmap getBitmap(String url) {
return get(url);
}
public void putBitmap(String url, Bitmap bitmap) {
put(url, bitmap);
}
}
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应用：
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// case1: StringRequest
StringRequest request =
new StringRequest(StringUtil.preUrl(etUrl.getText().toString().trim()),
new Listener<String>() {
public void onResponse(String response) {
tvResult.setText(response);
}
},
new ErrorListener() {
public void onErrorResponse(VolleyError arg0) {
ToastUtil.showToast(getActivity(), getResources().getString(R.string.request_fail_text));
}
});
RequestManager.addRequest(request,
this);
// case2: JsonObjectRequest，同理JsonArrayRequest
JsonObjectRequest request =
new JsonObjectRequest(StringUtil.preUrl(Constants.DEFAULT_JSON_REQUEST_URL),
null,
new Listener<JSONObject>() {
public void onResponse(JSONObject response) {
try {
// 解析JSON代码...
JSONArray seriesArray = factory.getJSONArray(
"serieslist");
carDataList.clear();
for (
int i =
0; i < seriesArray.length(); i++) {
JSONObject series = seriesArray.getJSONObject(i);
Map<String, String> seriesMap =
new HashMap<String, String>();
seriesMap.put(
"name", series.getString(
"name"));
seriesMap.put(
"level",
"级别："+series.getString(
"levelname"));
seriesMap.put(
"price",
"价格："+series.getString(
"price"));
carDataList.add(seriesMap);
}
adapter.notifyDataSetChanged();
}
catch (Exception e) {
ToastUtil.showToast(getActivity(), getResources().getString(R.string.request_fail_text));
}
}
},
new ErrorListener() {
public void onErrorResponse(VolleyError arg0) {
ToastUtil.showToast(getActivity(), getResources().getString(R.string.request_fail_text));
}
});
RequestManager.addRequest(request,
this);
// case3: ImageRequest
ImageRequest request=
new ImageRequest(StringUtil.preUrl(imageUrl),
new Listener<Bitmap>() {
public void onResponse(Bitmap bitmap) {
imageView.setImageBitmap(bitmap);
}},
0,
0, Config.RGB_565,
new ErrorListener() {
public void onErrorResponse(VolleyError arg0) {
imageView.setImageResource(R.drawable.ic_empty);
}
});
RequestManager.addRequest(request,
this);
// case4: ImageLoader
ImageListener listener=ImageLoader.getImageListener(imageView, R.drawable.ic_empty, R.drawable.ic_error);
ImageLoader.ImageContainer container = RequestManager.loadImage(StringUtil.preUrl(imageUrl), listener);
//在ImageView上存储当前请求的Container，用于取消请求
imageView.setTag(container);
// case5: NetworkImageView
NetworkImageView networkImageView=(NetworkImageView)imageView;
networkImageView.setDefaultImageResId(R.drawable.ic_empty);
networkImageView.setErrorImageResId(R.drawable.ic_error);
networkImageView.setImageUrl(StringUtil.preUrl(imageUrl), RequestManager.getImageLoader());
// case6: Post请求，重写getParams方法，传递Post参数
StringRequest request =
new StringRequest(Method.POST, StringUtil.preUrl(etUrl.getText().toString().trim()), listener, errorListener) {
//重写getParams设置post请求的参数
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> paramMap =
new HashMap<String, String>();
try {
String paramsStr = etParams.getText().toString().trim();
String[] paramsArray = paramsStr.split(
";");
for (String param : paramsArray) {
paramMap.put(keyValueArray[
0].trim(), keyValueArray.length >
1 ? keyValueArray[
1].trim() :
"");
}
}
catch (Exception e) {
ToastUtil.showToast(getActivity(),
"参数格错误");
}
return paramMap;
}
};
RequestManager.addRequest(request,
this);
// 注：JsonObjectRequest可根据第二个参数来决定是GET还是POST
public JsonObjectRequest(String url, JSONObject jsonRequest, Listener<JSONObject> listener,
ErrorListener errorListener) {
this(jsonRequest ==
null ? Method.GET : Method.POST, url, jsonRequest,
listener, errorListener);
}
// case7: 自定义Request，使用GSON解析JSON
public
class GsonRequest<T> extends Request<T> {
private
final Gson gson =
new Gson();
private
final Class<T> clazz;
private
final Map<String, String> headers;
private
final Listener<T> listener;
public GsonRequest(String url, Class<T> clazz, Map<String, String> headers,
Listener<T> listener, ErrorListener errorListener) {
super(Method.GET, url, errorListener);
this.clazz = clazz;
this.headers = headers;
this.listener = listener;
}
public Map<String, String> getHeaders() throws AuthFailureError {
return headers !=
null ? headers :
super.getHeaders();
}
protected void deliverResponse(T response) {
listener.onResponse(response);
}
protected Response<T> parseNetworkResponse(NetworkResponse response) {
try {
// String json = Test.getFromAssets("test.txt", AppData.getContext());//yes
// String json = new String(response.data, HttpHeaderParser.parseCharset(response.headers));//no
String json =
new String(response.data);
return Response.success(
gson.fromJson(json, clazz), HttpHeaderParser.parseCacheHeaders(response));
}
catch (JsonSyntaxException e) {
e.printStackTrace();
return Response.error(
new ParseError(e));
}
catch (Exception e) {
e.printStackTrace();
return Response.error(
new ParseError(e));
}
}
}
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参考文档
Volley 源码解析
Android Volley完全解析(一)，初识Volley的基本用法
glide(未研究)
项目地址：glide
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// For a simple view:
public void onCreate(Bundle savedInstanceState) {
...
ImageView imageView = (ImageView) findViewById(R.id.my_image_view);
Glide.with(
this).load(
"http://goo.gl/gEgYUd").into(imageView);
}
// For a simple image list:
public View getView(int position, View recycled, ViewGroup container) {
final ImageView myImageView;
if (recycled ==
null) {
myImageView = (ImageView) inflater.inflate(R.layout.my_image_view, container,
false);
}
else {
myImageView = (ImageView) recycled;
}
String url = myUrls.get(position);
Glide
.with(myFragment)
.load(url)
.centerCrop()
.placeholder(R.drawable.loading_spinner)
.crossFade()
.into(myImageView);
return myImageView;
}
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square/picasso
项目地址：square/picasso
使用
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public void getView(int position, View convertView, ViewGroup parent) {
SquaredImageView view = (SquaredImageView) convertView;
if (view ==
null) {
view =
new SquaredImageView(context);
}
String url = getItem(position);
Picasso.with(context).load(url).into(view);
}
Picasso.with(context)
.load(url)
.placeholder(R.drawable.user_placeholder)
.error(R.drawable.user_placeholder_error)
.into(imageView);
Picasso.with(context).load(R.drawable.landing_screen).into(imageView1);
Picasso.with(context).load(
"file:///android_asset/DvpvklR.png").into(imageView2);
Picasso.with(context).load(
new File(...)).into(imageView3);
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参考文档
官方文档
Android图片加载库Picasso源码分析
picasso-强大的Android图片下载缓存库
facebook/fresco(待研究)
项目地址：facebook/fresco
应用
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Uri uri = Uri.parse(
"https://raw.githubusercontent.com/facebook/fresco/gh-pages/static/logo.png");
SimpleDraweeView draweeView = (SimpleDraweeView) findViewById(R.id.my_image_view);
draweeView.setImageURI(uri);
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参考文档
中文站
FaceBook推出的Android图片加载库-Fresco
Android图片加载神器之Fresco-加载图片基础
Fresco图片框架内部实现原理探索
android-async-http
项目地址：android-async-http
最主要的类：
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AsyncHttpResponseHandler
AsyncHttpClient
AsyncHttpRequest
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类继承关系图：
流程图
使用比较简单：
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AsyncHttpClient client =
new AsyncHttpClient();
client.get(
"https://www.google.com",
new AsyncHttpResponseHandler() {
public void onStart() {
// called before request is started
}
public void onSuccess(int statusCode, Header[] headers, byte[] response) {
// called when response HTTP status is "200 OK"
}
public void onFailure(int statusCode, Header[] headers, byte[] errorResponse, Throwable e) {
// called when response HTTP status is "4XX" (eg. 401, 403, 404)
}
public void onRetry(int retryNo) {
// called when request is retried
}
});
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建议使用静态单例:
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import com.loopj.android.http.*;
public
class TwitterRestClient {
private
static
final String BASE_URL =
"https://api.twitter.com/1/";
private
static AsyncHttpClient client =
new AsyncHttpClient();
public static void get(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
client.get(getAbsoluteUrl(url), params, responseHandler);
}
public static void post(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
client.post(getAbsoluteUrl(url), params, responseHandler);
}
private static String getAbsoluteUrl(String relativeUrl) {
return BASE_URL + relativeUrl;
}
}
// 使用
import org.json.*;
import com.loopj.android.http.*;
class TwitterRestClientUsage {
public void getPublicTimeline() throws JSONException {
TwitterRestClient.get(
"statuses/public_timeline.json",
null,
new JsonHttpResponseHandler() {
public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
// If the response is JSONObject instead of expected JSONArray
}
public void onSuccess(int statusCode, Header[] headers, JSONArray timeline) {
// Pull out the first event on the public timeline
JSONObject firstEvent = timeline.get(
0);
String tweetText = firstEvent.getString(
"text");
// Do something with the response
System.out.println(tweetText);
}
});
}
}
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参考文档
官网
android-async-http框架库使用基础
square/okhttp
项目地址
square/okhttp
square/retrofit
项目地址
square/retrofit
ThinkAndroid
项目地址：ThinkAndroid
参考文章：
Android Universal Image Loader 源码分析-codekk
Volley 源码解析-codekk
Android Volley完全解析(一)，初识Volley的基本用法-guolin
Android 三大图片缓存原理、特性对比-Trnea