Android 子线程异步更新 UI 线程框架 Handler 模版

前言

最新利用安卓开发一个扫描银行卡号码的程序，识别过程包括了多个步骤，比较费时，需要放到后台线程去处理，不然就阻塞主线程延迟响应了，这时再增加一个进度条就完美了。后来发现 Handler 十分好用，通过 FutuerTask 反馈识别任务是否完成，未完成就由 Handler sendMessage 到 ui 线程去更新 ProgressBar 进度条状态，这里设计了一个接口类和一个线程类，适合完成耗时并需要更新 ui 主线程的工作。

1. 这里以更新进度条 progressbar 为例，代码如下

接口类 ProgressWork

import java.util.concurrent.Future;public interface ProgressWork<V> {/*** the work should be take into this method* @return future work*/Future<V> doInBackground();/*** the worker would get progress from this method* @return*/int updateProgress(); // 注意这里，这里是获取中间更新的信息，//比如进度条的进度，可根据自己需要修改/*** the caller should implement this method to get the result</br>* showing on the ui view* @param result*/void callBackResult(V result);
}

子线程类 ProgressAsyncWork

import java.util.concurrent.Future;public class ProgressAsyncWork<V> extends Thread{ProgressWork progressWork;/*** offer by the caller* need to overwrite doInBackground() function*/Future<V> task;/*** the result returning from FutureTask*/private V result;public ProgressAsyncWork(ProgressWork progressWork, Handler postHandler) {this.progressWork = progressWork;this.postHandler = postHandler;}public V getResult() {return result;}@Overridepublic void run() {// get the work thread doing in backgroundtask = progressWork.doInBackground();work();}private void work() {do {if (task.isDone()) {// set resulttry {result = task.get();// callback when the work doneprogressWork.callBackResult(result);} catch (Exception e) {e.printStackTrace();} finally {break;}}progressWork.updateProgress();try {Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}} while (true);}
}

2. 上面的代码直接可以复制到项目里就可以了，下面看看如何使用，下面的 work 放在 Activity 中

如何使用：

public void work() {final FutureTask<String> task;ProgressWork<String> progressWork;// set bar visiblemProgressBar.setVisibility(View.VISIBLE);// new a FutureTasknew Thread(task = new FutureTask<>(new Callable<String>() {@Overridepublic String call() throws Exception {// start workString error = "error Message";try {// do your work here// 耗时操作} catch (Exception e) {e.printStackTrace();return error;}return error;}})).start();final Handler postHandler = new Handler() {@Overridepublic void handleMessage(Message msg) {mProgressBar.setProgress(msg.arg1);if (msg.arg1 >= 100 || task.isDone()) {mProgressBar.setVisibility(View.GONE);TextView mTextMessage = (TextView) findViewById(R.id.message_scan);// 设置文本信息显示最终耗时任务的结果mTextMessage.setText((String)msg.obj);}}};progressWork = new ProgressWork<String>() {@Overridepublic Future<String> doInBackground() {return task;}@Overridepublic int updateProgress() {Message msg = postHandler.obtainMessage();msg.arg1 = getProgress(); // 该方法自己实现，返回进度条的进度postHandler.sendMessage(msg);CommonUtils.info("progress: " + msg.arg1);return getProgress();}@Overridepublic void callBackResult(String result) {Message msg = postHandler.obtainMessage();msg.obj = result;postHandler.sendMessage(msg);}};// begin work the progressbarnew ProgressAsyncWork<String>(progressWork).start();}

以上就是这么多，如有问题请反馈哦