使用RxJava+OKhttp3进行图片下载

package test.ban.com.rx_project;/**
* Created by apple on 16/8/5.
*/

import java.io.IOException;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import rx.Observable;
import rx.Subscriber;

/**
* 作者：ban on 16/8/5 16:21
*/
public class DownloadUtils {

private OkHttpClient mOkHttpClient;

public DownloadUtils() {
mOkHttpClient = new OkHttpClient();
}

/**
* 声明一个被观察者对象作为结果返回
*
* @param path
* @return
*/
public Observable<byte[]> downloadIamge(final String path) {

return Observable.create(new Observable.OnSubscribe<byte[]>() {
@Override
public void call(final Subscriber<? super byte[]> subscriber) {

if (!subscriber.isUnsubscribed()) {
//访问网络操作
Request request = new Request.Builder().url(path).build();
mOkHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
subscriber.onError(e);
}

@Override
public void onResponse(Call call, Response response) throws IOException {
if (response.isSuccessful()) {
byte[] data = response.body().bytes();
if (data != null) {
subscriber.onNext(data);
}
}
subscriber.onCompleted();
}
});
}
}
});
}
}

package test.ban.com.rx_project;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import rx.Subscriber;
import rx.android.schedulers.AndroidSchedulers;
import rx.schedulers.Schedulers;

public class MainActivity extends Activity {

private static final String TAG = "MainActivity";
private Button mButton;
private ImageView mImageView;
private final String PATH = "https://ss0.bdstatic" +
".com/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png";
private DownloadUtils mDownloadUtils;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

mDownloadUtils = new DownloadUtils();
mButton = (Button) findViewById(R.id.button);
mImageView = (ImageView) findViewById(R.id.imageView2);

mButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//使用http协议获取数据
mDownloadUtils.downloadIamge(PATH)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<byte[]>() {
@Override
public void onCompleted() {
Log.e(TAG, "=====onCompleted=====");
//这里一般处理对话框消失
}

@Override
public void onError(Throwable e) {
Log.e(TAG, "onError: ", e);
}

@Override
public void onNext(byte[] bytes) {
Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes
.length);
mImageView.setImageBitmap(bitmap);
}

});
}
});

}
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="test.ban.com.rx_project.MainActivity">

<Button
android:text="Button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="130dp"
android:id="@+id/button"/>

<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@mipmap/ic_launcher"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="108dp"
android:id="@+id/imageView2"/>
</RelativeLayout>

需要的权限：<uses-permission android:name="android.permission.INTERNET"/>