Question

我正在尝试使用此处下载的库异步读取Android设备上的Arduino字符串

https://github.com/mik3y/usb-serial-for-android

我设法做到了，但代码只工作一次而不是循环周期。我已经尝试在asyncTask中执行但是程序崩溃了，所以我设法通过执行runnable in循环来执行循环，但程序在每次执行runnable时冻结，并在runnable结束工作时取消冻结。

这是用于从usb读取的代码：

try
{
     UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
     driver = UsbSerialProber.acquire(manager);
     if (driver != null) {

            driver.open();
            driver.setBaudRate(9600);
            new Thread(runnable).start();
            buffer = new byte[3000];
                    numBytesRead = driver.read(buffer, 3000);
                String str = new String(buffer, "UTF-8");
                buffer = null;
                numBytesRead = 0;
        }
}
catch(Exception ex){//do nothing}

我构造了runnable以这种方式执行：

@Override
protected void onCreate(Bundle savedInstanceState) {
try
{
UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
     driver = UsbSerialProber.acquire(manager);
     if (driver != null) {

            driver.open();
            driver.setBaudRate(9600);
            handler.postDelayed(runnable, 1);
        }
}
catch(Exception ex){//do nothing}
}



private Runnable runnable = new Runnable() {
       @Override
       public void run() {
           try {
                buffer = new byte[3000];
                numBytesRead = driver.read(buffer, 3000);
                String str = new String(buffer, "UTF-8");
                buffer = null;
                numBytesRead = 0;
            handler.postDelayed(this, 1);  //here is where the runnable is executed again. This generates the loop
              } 
        catch (IOException e) {//do nothing}    
       }
    };

希望你能帮忙！

Answer 1

解决！

我在

中更改了参数1

handler.postDelayed(runnable, 1);

和

handler.postDelayed(this, 1);

到

handler.postDelayed(runnable, 0);
handler.postDelayed(this, 0);

我也改变了缓冲区大小：

buffer = new byte[3000];
numBytesRead = driver.read(buffer, 3000);

从3000到40，这就是程序如此缓慢的原因。

无论如何，谢谢！

android异步读取usb

1 个答案: