Andorid jar库源码Bolts原理解析

Bolts：
　　作用：
　　　　用于链式执行跨线程代码，且传递数据

　　栗子：
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Task.call(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return true;
}
}, Task.UI_THREAD_EXECUTOR);

Task.callInBackground(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return false;
}
});

Task.callInBackground(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return true;
}
}).onSuccess(new Continuation<Boolean, Object>() {
@Override
public Object then(Task<Boolean> task) throws Exception {
if (task.getResult()) {
return null;
} else {
return new Object();
}
}
}, Task.BACKGROUND_EXECUTOR).continueWith(new Continuation<Object, Object>() {
@Override
public Object then(Task<Object> task) throws Exception {
if (task.getResult() == null) {
Toast.makeText(getBaseContext(), "null", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getBaseContext(), "not null", Toast.LENGTH_SHORT).show();
}

return null;
}
}, Task.UI_THREAD_EXECUTOR);
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　　源码解读：
　　在内部通过维护多中 ExecutorService 对象，并且通过串联的方式进行调用。

　　并且通过维护内部变量在，在指定流程处，就是特定的，值，值通过Task的对象getResult拿到。

　　UIThread

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/**
* An {@link java.util.concurrent.Executor} that runs tasks on the UI thread.
*/
private static class UIThreadExecutor implements Executor {
@Override
public void execute(Runnable command) {
new Handler(Looper.getMainLooper()).post(command);
}
}
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　　BackgroundThread