Github源码地址：https://github.com/JakeWharton/picasso2-okhttp3-downloader
使用方法：
Gradle:
compile 'com.jakewharton.picasso:picasso2-okhttp3-downloader:1.1.0'
调用：
OkHttpClient client = // ...
Picasso picasso = new Picasso.Builder(context)
.downloader(new OkHttp3Downloader(client))
.build()
以下是源码：（只有一个类）
package com.jakewharton.picasso; import android.content.Context;
import android.net.Uri;
import android.os.StatFs;
import com.squareup.picasso.Downloader;
import com.squareup.picasso.NetworkPolicy;
import java.io.File;
import java.io.IOException;
import okhttp3.Cache;
import okhttp3.CacheControl;
import okhttp3.Call;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.ResponseBody; public final class OkHttp3Downloader implements Downloader {
private static final String PICASSO_CACHE = "picasso-cache";
private static final int MIN_DISK_CACHE_SIZE = 5 * 1024 * 1024; // 5MB
private static final int MAX_DISK_CACHE_SIZE = 50 * 1024 * 1024; // 50MB private static File defaultCacheDir(Context context) {
File cache = new File(context.getApplicationContext().getCacheDir(), PICASSO_CACHE);
if (!cache.exists()) {
//noinspection ResultOfMethodCallIgnored
cache.mkdirs();
}
return cache;
} private static long calculateDiskCacheSize(File dir) {
long size = MIN_DISK_CACHE_SIZE; try {
StatFs statFs = new StatFs(dir.getAbsolutePath());
long available = ((long) statFs.getBlockCount()) * statFs.getBlockSize();
// Target 2% of the total space.
size = available / 50;
} catch (IllegalArgumentException ignored) {
} // Bound inside min/max size for disk cache.
return Math.max(Math.min(size, MAX_DISK_CACHE_SIZE), MIN_DISK_CACHE_SIZE);
} /**
* Creates a {@link Cache} that would have otherwise been created by calling
* {@link #OkHttp3Downloader(Context)}. This allows you to build your own {@link OkHttpClient}
* while still getting the default disk cache.
*/
public static Cache createDefaultCache(Context context) {
File dir = defaultCacheDir(context);
return new Cache(dir, calculateDiskCacheSize(dir));
} private static OkHttpClient createOkHttpClient(File cacheDir, long maxSize) {
return new OkHttpClient.Builder()
.cache(new Cache(cacheDir, maxSize))
.build();
} private final Call.Factory client;
private final Cache cache; /**
* Create new downloader that uses OkHttp. This will install an image cache into your application
* cache directory.
*/
public OkHttp3Downloader(Context context) {
this(defaultCacheDir(context));
} /**
* Create new downloader that uses OkHttp. This will install an image cache into the specified
* directory.
*
* @param cacheDir The directory in which the cache should be stored
*/
public OkHttp3Downloader(File cacheDir) {
this(cacheDir, calculateDiskCacheSize(cacheDir));
} /**
* Create new downloader that uses OkHttp. This will install an image cache into your application
* cache directory.
*
* @param maxSize The size limit for the cache.
*/
public OkHttp3Downloader(final Context context, final long maxSize) {
this(defaultCacheDir(context), maxSize);
} /**
* Create new downloader that uses OkHttp. This will install an image cache into the specified
* directory.
*
* @param cacheDir The directory in which the cache should be stored
* @param maxSize The size limit for the cache.
*/
public OkHttp3Downloader(File cacheDir, long maxSize) {
this(createOkHttpClient(cacheDir, maxSize));
} public OkHttp3Downloader(OkHttpClient client) {
this.client = client;
this.cache = client.cache();
} public OkHttp3Downloader(Call.Factory client) {
this.client = client;
this.cache = null;
} @Override public Response load(Uri uri, int networkPolicy) throws IOException {
CacheControl cacheControl = null;
if (networkPolicy != 0) {
if (NetworkPolicy.isOfflineOnly(networkPolicy)) {
cacheControl = CacheControl.FORCE_CACHE;
} else {
CacheControl.Builder builder = new CacheControl.Builder();
if (!NetworkPolicy.shouldReadFromDiskCache(networkPolicy)) {
builder.noCache();
}
if (!NetworkPolicy.shouldWriteToDiskCache(networkPolicy)) {
builder.noStore();
}
cacheControl = builder.build();
}
} Request.Builder builder = new Request.Builder().url(uri.toString());
if (cacheControl != null) {
builder.cacheControl(cacheControl);
} okhttp3.Response response = client.newCall(builder.build()).execute();
int responseCode = response.code();
if (responseCode >= 300) {
response.body().close();
throw new ResponseException(responseCode + " " + response.message(), networkPolicy,
responseCode);
} boolean fromCache = response.cacheResponse() != null; ResponseBody responseBody = response.body();
return new Response(responseBody.byteStream(), fromCache, responseBody.contentLength());
} @Override public void shutdown() {
if (cache != null) {
try {
cache.close();
} catch (IOException ignored) {
}
}
}
}