- RxJava接入
- RxJava 简单用法
- Retrofit 简单使用
- RxJava + Retrofit
在 gradle 里接入 RxJava2，RxJava3 已经出了，RxJava 地址
implementation 'io.reactivex.rxjava2:rxandroid:2.0.1'
implementation 'io.reactivex.rxjava2:rxjava:2.0.7'
- 创建被观察者
- 创建观察者
- 订阅
常用的创建操作符
- creat
- just creat 操作符：
Observable observable = Observable.create(new ObservableOnSubscribe<Object>() {
@Override
public void subscribe(ObservableEmitter<Object> e) throws Exception {
e.onNext("hello");
e.onNext("RxJava");
e.onComplete();
}
});
如果有类型需求可以用泛型加入需要的类型，例如：
Observable<String> observable = Observable.create(new ObservableOnSubscribe<String>() {
@Override
public void subscribe(ObservableEmitter<String> e) throws Exception {
}
});
ObservableEmitter 作为发射器，一共有三种发射方式
- void onNext(T value) ---------- 可以无限调用
- void onComplete()-------------- 可以重复调用，但是观察者只会接收一次
- void onError(Throwable error)------ 与onComplete 互斥，且不能重复调用，第二次调用会报异常
just 操作符:
String url = "http://www.baidu.com";
Observable<String> observable1 = Observable.just(url);
Observer observer = new Observer<String>() {
@Override
public void onSubscribe(Disposable d) {
Log.d("rxjava", "方法：onSubscribe: ");
}
@Override
public void onNext(String string) {
Log.d("rxjava", "方法：onNext: " + string);
temp += string + "\t";
mTextView.setText(temp);
}
@Override
public void onError(Throwable e) {
Log.d("rxjava", "方法：onError: " + e.getMessage());
}
@Override
public void onComplete() {
Log.d("rxjava", "方法：onComplete: ");
}
};
observable.subscribe(observer);
- 创建操作 Create, Defer, Empty/Never/Throw, From, Interval, Just, Range, Repeat, Start, Timer
- 变换操作 Buffer, FlatMap, GroupBy, Map, Scan和Window
- 过滤操作 Debounce, Distinct, ElementAt, Filter, First, IgnoreElements, Last, Sample, Skip, SkipLast, Take, TakeLast
- 组合操作 And/Then/When, CombineLatest, Join, Merge, StartWith, Switch, Zip
- 错误处理 Catch和Retry
- 辅助操作 Delay, Do, Materialize/Dematerialize, ObserveOn, Serialize, Subscribe, SubscribeOn, TimeInterval, Timeout, Timestamp, Using
- 条件和布尔操作 All, Amb, Contains, DefaultIfEmpty, SequenceEqual, SkipUntil, SkipWhile, TakeUntil, TakeWhile
- 算术和集合操作 Average, Concat, Count, Max, Min, Reduce, Sum
- 转换操作 To
- 连接操作 Connect, Publish, RefCount, Replay
- 反压操作 用于增加特殊的流程控制策略的操作符
下面以从Url 中下载图片为例，展示简单的使用方法。
public class RxDownloadActivity extends AppCompatActivity {
private static final String TAG = "RxDownloadActivity";
// 网络图片的链接地址
private final static String PATH = "https://alifei03.cfp.cn/creative/vcg/veer/1600water/veer-132668332.jpg";
// 弹出加载框
private ProgressDialog mProgressDialog;
private ImageView mImage;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_rx_download);
mImage = findViewById(R.id.image);
}
public void rxJavaDownloadImageAction(View view) {
Observable.just(PATH)// todo 第二步
//todo 第三步
.map(new Function<String, Bitmap>() {
@NonNull
@Override
public Bitmap apply(@NonNull String s) throws Exception {
URL url = new URL(PATH);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setConnectTimeout(5000);
int responseCode = httpURLConnection.getResponseCode(); // 才开始 request
if (responseCode == HttpURLConnection.HTTP_OK) {
InputStream inputStream = httpURLConnection.getInputStream();
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
return bitmap;
}
return null;
}
})
//切换线程
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Bitmap>() {
@Override
public void onSubscribe(Disposable d) {
//todo 第一步
Log.d(TAG, "方法：onSubscribe: ");
mProgressDialog = new ProgressDialog(RxDownloadActivity.this);
mProgressDialog.setTitle("run");
mProgressDialog.show();
}
// TODO 第四步
// 拿到事件
@Override
public void onNext(Bitmap bitmap) {
Log.d(TAG, "方法：onNext: ");
mImage.setImageBitmap(bitmap);
}
@Override
public void onError(Throwable e) {
Log.d(TAG, "方法：onError: "+e.getMessage());
}
// TODO 第五步
// 完成事件
@Override
public void onComplete() {
if (mProgressDialog != null)
mProgressDialog.dismiss();
}
});
}
}
xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
tools:context=".RxDownloadActivity">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="rxJavaDownloadImageAction"
android:text="RxJava方式下载图片功能" />
<ImageView
android:id="@+id/image"
android:layout_marginTop="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
遇到 No Network Security Config specified, using platform default 问题 提示你没有使用网络安全配置
android9.0（28）以后，系统默认不在支持http请求，当我们在发送http请求时会出现以下提示，并且请求网络失败。
implementation "com.squareup.retrofit2:retrofit:2.9.0"
implementation "com.squareup.retrofit2:converter-gson:2.9.0"
public interface WangAndroidApi {
@GET("project/tree/json")
Call<ProjectBean> getProject1();
}
public class HttpUtil {
public static String BASE_URL = "https://www.wanandroid.com/";
public static void setBaseUrl(String baseUrl) {
BASE_URL = baseUrl;
}
//retrofit 第四步 创建Retrofit对象
public static Retrofit getRetrofit() {
return new Retrofit.Builder()
.baseUrl(BASE_URL) //设置网络请求的Url地址
.addConverterFactory(GsonConverterFactory.create()) //设置数据解析器
.build();
}
}
HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
@Override
public void log(String message) {
try {
String text = URLDecoder.decode(message, "utf-8");
Log.e("OKHttp-----", text);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
Log.e("OKHttp-----", message);
}
}
});
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);// 四个级别：NONE,BASIC,HEADER,BODY; BASEIC:请求/响应行; HEADER:请求/响应行 + 头; BODY:请求/响应航 + 头 + 体;
//加配http 请求参数
OkHttpClient.Builder builder = new OkHttpClient.Builder();
OkHttpClient okHttpClient = builder
.addInterceptor(interceptor)
.addNetworkInterceptor(new StethoInterceptor()) //调试神器
.readTimeout(10000, TimeUnit.SECONDS)
.connectTimeout(10000, TimeUnit.SECONDS)
.writeTimeout(10000, TimeUnit.SECONDS)
.build();
return new Retrofit.Builder()
.baseUrl(BASE_URL) //设置网络请求的Url地址
.client(okHttpClient)
.addConverterFactory(GsonConverterFactory.create()) //设置数据解析器
.build();
WangAndroidApi api = HttpUtil.getRetrofit().create(WangAndroidApi.class);
Call<ProjectBean> call = api.getProject1();
call.enqueue(new Callback<ProjectBean>() {
@Override
public void onResponse(Call<ProjectBean> call, Response<ProjectBean> response) {
// 处理返回的数据
System.out.println(response.body().toString());
mTextView.setText(response.body().toString());
}
@Override
public void onFailure(Call<ProjectBean> call, Throwable t) {
}
});
以上是Retrofit 进行网络请求的简单操作
RxJava + Retrofit 与 纯Retrofit 的差别：
public interface WangAndroidApi {
@GET("project/tree/json")
Observable<ProjectBean> getProject();
}
返回的从 Call 变成了 Observable
WangAndroidApi api = HttpUtil.getRetrofit().create(WangAndroidApi.class);
api.getProject().subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<ProjectBean>() {
@Override
public void accept(@NonNull ProjectBean projectBean) throws Exception {
// 处理返回的数据
System.out.println(projectBean.toString());
mTextView.setText(projectBean.toString());
}
});