前言
RxJava 的观察者模式大致如下图：
RxJava 还内置了一个实现了 Observer 的抽象类：Subscriber。
开始之前请进行gradle的配置
/rxjava/
compile 'io.reactivex:rxjava:1.1.3'
compile 'io.reactivex:rxandroid:1.0.1'
/rxjava的混淆/
compile 'com.artemzin.rxjava:proguard-rules:1.1.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta3'
compile 'com.squareup.retrofit2:retrofit:2.0.0-beta3'
compile 'com.squareup.retrofit2:adapter-rxjava:2.0.0-beta3'
使用特性详解
1.线程切换Scheduler
subscribeOn() 和 observeOn() 两个方法来对线程进行控制
subscribeOn(): 指定 subscribe() 所发生的线程，即 Observable.OnSubscribe 被激活时所处的线程。或者叫做事件产生的线程。
observeOn(): 指定 Subscriber 所运行在的线程。或者叫做事件消费的线程。
示例：
Observable.just(1, 2, 3, 4) // IO 线程，由 subscribeOn() 指定
//被创建的事件的内容 1、2、3、4 将会在 IO 线程发出
.subscribeOn(Schedulers.io())
.observeOn(Schedulers.newThread())
.map(new Func1() {
@Override
public String call(Integer integer) {
Log.e(TAG, Thread.currentThread().getName() + "Schedulers.newThread()");
return "call" + integer;
}
}) // 新线程，由 observeOn() 指定
.observeOn(Schedulers.io())
.map(new Func1() {
@Override
public Integer call(String s) {
Log.i(TAG, Thread.currentThread().getName() + "Schedulers.io()");
final char[] chars = s.toCharArray();
int res = -1;
for (char c : chars) {
res += c;
}
return res;
}
}) // 指定 Subscriber 的回调发生在主线程
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber() { // Android 主线程，由 observeOn() 指定
@Override
public void onCompleted() {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onCompleted");
}
@Override
public void onError(Throwable e) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onError:" + e.toString());
}
@Override
public void onNext(Integer integer) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onNext:" + integer);
}
});
经历了两次变换，int->String ;String->int;然后提交。
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2.变换
a.一对一，map
List lists = new ArrayList<>();
lists.add(new Student(10, "jack", Arrays.asList("数学", "语文", "英语")));
lists.add(new Student(20, "helen", Arrays.asList("物理", "化学")));
lists.add(new Student(30, "alice", Arrays.asList("生物", "地理")));
Observable.from(lists)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.map(new Func1() {
@Override
public Integer call(Student student) {
try {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->call:" + student.toString());
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
return student.getAge();
}
})
.subscribe(new Action1() {
@Override
public void call(Integer integer) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->call:" + integer);
}
});
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b.一对多，flatmap
List lists = new ArrayList<>();
lists.add(new Student(10, "jack", Arrays.asList("数学", "语文", "英语")));
lists.add(new Student(20, "helen", Arrays.asList("物理", "化学")));
lists.add(new Student(30, "alice", Arrays.asList("生物", "地理")));
Observable.from(lists)
.subscribeOn(Schedulers.io()) // 被创建的事件的内容 1、2、3、4 将会在 IO 线程发出,也叫事件产生的线程
.observeOn(AndroidSchedulers.mainThread()) // 指定 Subscriber 的回调发生在主线程,也叫事件消费的线程
.flatMap(new Func1>() {
@Override
public Observable call(Student student) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
return Observable.from(student.getCourses());
}
})
.subscribe(new Subscriber() {
@Override
public void onCompleted() {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onCompleted");
}
@Override
public void onError(Throwable e) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onError:" + e.toString());
}
@Override
public void onNext(String s) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onNext:" + s);
}
});
打印所有学生的课程
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c.对 Observable自身变换，compose
Transformer实际上就是一个Func1
换言之就是：可以通过它将一种类型的Observable转换成另一种类型的Observable。
Observable.Transformer myTransformer = new Observable.Transformer() {
@Override
public Observable call(Observable observable) {
return observable
.map(new Func1() {
@Override
public String call(Integer integer) {
String info = "myTransforer:" + integer;
Log.i(TAG, "转换Obserable->Thread:" + Thread.currentThread().toString() + "->call:" + info);
return info;
}
});
}
};
Observable.just(1, 2, 3).compose(myTransformer)
.subscribe(new Action1() {
@Override
public void call(String s) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->call:" + s);
}
});
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3.过滤 Filter
查找，学生中学习语文的同学的名字.
List lists = new ArrayList<>();
lists.add(new Student(10, "jack", Arrays.asList("数学", "语文", "英语")));
lists.add(new Student(20, "helen", Arrays.asList("物理", "化学", "语文")));
lists.add(new Student(30, "alice", Arrays.asList("生物", "地理")));
Observable.from(lists)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.filter(new Func1() {
@Override
public Boolean call(Student student) {
return student.getCourses().contains("语文");
}
}).subscribe(new Subscriber() {
@Override
public void onCompleted() {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onCompleted");
}
@Override
public void onError(Throwable e) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onError:" + e.toString());
}
@Override
public void onNext(Student s) {
Log.d(TAG, "Thread:" + Thread.currentThread().toString() + "->onNext:" + s.getName());
}
});
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4.Retrofit & RxJava
添加依赖
compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta3'
compile 'com.squareup.retrofit2:retrofit:2.0.0-beta3'
compile 'com.squareup.retrofit2:adapter-rxjava:2.0.0-beta3'
private Subscription subscription;
public void onRetrofit(View view) throws IOException {
final GithubApi GithubApi = GithubService.createGithubService();
//第一种，自己创建子线程请求
// final Call> call = GithubApi.getGroupList("square", "retrofit");
// new Thread(){
// @Override
// public void run() {
// final Response> execute;
// try {
// //网络请求不能再主线程
// execute = call.execute();
// final List constructors = execute.body();
// for (Constructor constructor : constructors){
// Log.d(TAG, constructor.toString());
// }
// } catch (IOException e) {
// e.printStackTrace();
// }
// }
// }.start();
/**
* 方法二，通过RxJava,进行线程的切换
* 1.Retrofit的配置需要改 .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
* 2.接口需要改
* Observable> contributorsRx(@Path("owner") String owner, @Path("repo") String repo);
* 3.需要在 Activity的onDestroy方法解注册
*/
subscription = GithubApi.contributorsRx("square", "retrofit")
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber>() {
@Override
public void onCompleted() {
}
@Override
public void onError(Throwable e) {
}
@Override
public void onNext(List constructors) {
for (Constructor constructor : constructors) {
Log.d(TAG, constructor.toString());
}
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
if (subscription != null) {
subscription.unsubscribe();
}
}
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附上
public interface GithubApi {
@GET("/repos/{owner}/{repo}/contributors")
Call> getGroupList(@Path("owner") String owner, @Path("repo") String repo);
@GET("/repos/{owner}/{repo}/contributors")
Observable> contributorsRx(@Path("owner") String owner, @Path("repo") String repo);
}
public class GithubService {
public static GithubApi createGithubService() {
Retrofit.Builder builder = new Retrofit.Builder()
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.addConverterFactory(GsonConverterFactory.create())
.baseUrl("https://api.github.com");
return builder.build().create(GithubApi.class);
}
}
5.RxJava replace AsyncTask
/*new AsyncTask() {
@Override
protected User doInBackground(String... params) {
return _githubService.getUser(params[0]);
}
@Override
protected void onPostExecute(User user) {
_adapter.add(format("%s = [%s: %s]", _username.getText(), user.name, user.email));
}
}.execute(_username.getText().toString());*/
_githubService.user(_username.getText().toString())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer() {
@Override
public void onCompleted() {
}
@Override
public void onError(Throwable e) {
}
@Override
public void onNext(User user) {
_adapter.add(format("%s = [%s: %s]",
_username.getText(),
user.name,
user.email));
}
});
示例代码路径： Jack_Rxjava_demo
参考资料
- 给 Android 开发者的 RxJava 详解