首先尝试脱机磁盘缓存,然后联机并获取映像
首先将 OkHttp 添加到 app 模块的 gradle 构建文件中
compile 'com.squareup.picasso:picasso:2.5.2'
compile 'com.squareup.okhttp:okhttp:2.4.0'
compile 'com.jakewharton.picasso:picasso2-okhttp3-downloader:1.0.2'
然后创建一个扩展 Application 的类
import android.app.Application;
import com.squareup.picasso.OkHttpDownloader;
import com.squareup.picasso.Picasso;
public class Global extends Application {
@Override
public void onCreate() {
super.onCreate();
Picasso.Builder builder = new Picasso.Builder(this);
builder.downloader(new OkHttpDownloader(this,Integer.MAX_VALUE));
Picasso built = builder.build();
built.setIndicatorsEnabled(true);
built.setLoggingEnabled(true);
Picasso.setSingletonInstance(built);
}
}
将它添加到 Manifest 文件,如下所示:
<application
android:name=".Global"
.. >
</application>
正常使用
Picasso.with(getActivity())
.load(imageUrl)
.networkPolicy(NetworkPolicy.OFFLINE)
.into(imageView, new Callback() {
@Override
public void onSuccess() {
//Offline Cache hit
}
@Override
public void onError() {
//Try again online if cache failed
Picasso.with(getActivity())
.load(imageUrl)
.error(R.drawable.header)
.into(imageView, new Callback() {
@Override
public void onSuccess() {
//Online download
}
@Override
public void onError() {
Log.v("Picasso","Could not fetch image");
}
});
}
});