onewireaccessprovider.java

这是一个以JAVA编写的程序,本人还没有试过,是一个简单的温度控制系统

   }

   /**
    * Finds, opens, and verifies the specified adapter on the
    * indicated port.
    *
    * @param adapterName string name of the adapter (match to result
    *             of call to getAdapterName() method in DSPortAdapter)
    * @param portName string name of the port used in the method
    *             selectPort() in DSPortAdapter
    *
    * @return  <code>DSPortAdapter</code> if adapter present
    *
    * @throws OneWireIOException when communcation with the adapter fails
    * @throws OneWireException when the port or adapter not present
    */
   public static DSPortAdapter getAdapter (String adapterName,
                                           String portName)
      throws OneWireIOException, OneWireException
   {
      DSPortAdapter adapter, found_adapter = null;

      // check for override
      if (useOverrideAdapter)
         return overrideAdapter;

      // enumerature through available adapters to find the correct one
      for (Enumeration adapter_enum = enumerateAllAdapters();
              adapter_enum.hasMoreElements(); )
      {
         // cast the enum as a DSPortAdapter
         adapter = ( DSPortAdapter ) adapter_enum.nextElement();

         // see if this is the type of adapter we want
         if ((found_adapter != null) ||
            (!adapter.getAdapterName().equals(adapterName)))
         {
            // not this adapter, then just cleanup
            try
            {
               adapter.freePort();
            }
            catch (Exception e)
            {
               // DRAIN
            }
            continue;
         }

         // attempt to open and verify the adapter
         if (adapter.selectPort(portName))
         {
            adapter.beginExclusive(true);

            try
            {
               // check for the adapter
               if (adapter.adapterDetected())
                  found_adapter = adapter;
               else
               {

                  // close the port just opened
                  adapter.freePort();

                  throw new OneWireException("Port found \"" + portName
                                             + "\" but Adapter \"" + adapterName
                                             + "\" not detected");
               }
            }
            finally
            {
               adapter.endExclusive();
            }
         }
         else
            throw new OneWireException(
               "Specified port \"" + portName
               + "\" could not be selected for adapter \"" + adapterName
               + "\"");
      }

      // if adapter found then return it
      if (found_adapter != null)
         return found_adapter;

      // adapter by that name not found
      throw new OneWireException("Specified adapter name \"" + adapterName
                                 + "\" is not known");
   }

   /**
    * Finds, opens, and verifies the default adapter and
    * port.  Looks for the default adapter/port in the following locations:
    * <p>
    * <ul>
    * <li> Use adapter/port in System.properties for onewire.adapter.default,
    *      and onewire.port.default properties tags.</li>
    * <li> Use adapter/port from onewire.properties file in current directory
    *      or < java.home >/lib/ (Desktop) or /etc/ (TINI)</li>
    * <li> Use smart default
    *      <ul>
    *      <li> Desktop
    *           <ul>
    *           <li> First, TMEX default (Win32 only)
    *           <li> Second, if TMEX not present, then DS9097U/(first serial port)
    *           </ul>
    *      <li> TINI, TINIExternalAdapter on port serial1
    *      </ul>
    * </ul>
    *
    * @return  <code>DSPortAdapter</code> if default adapter present
    *
    * @throws OneWireIOException when communcation with the adapter fails
    * @throws OneWireException when the port or adapter not present
    */
   public static DSPortAdapter getDefaultAdapter ()
      throws OneWireIOException, OneWireException
   {
      if (useOverrideAdapter)
      {
          return overrideAdapter;
      }

      return getAdapter(getProperty("onewire.adapter.default"),
                        getProperty("onewire.port.default"));
   }

   /**
    * Gets the specfied onewire property.
    * Looks for the property in the following locations:
    * <p>
    * <ul>
    * <li> In System.properties
    * <li> In onewire.properties file in current directory
    *      or < java.home >/lib/ (Desktop) or /etc/ (TINI)
    * <li> 'smart' default if property is 'onewire.adapter.default'
    *      or 'onewire.port.default'
    * </ul>
    *
    * @param propName string name of the property to read
    *
    * @return  <code>String</code> representing the property value or <code>null</code> if
    *          it could not be found (<code>onewire.adapter.default</code> and
    *          <code>onewire.port.default</code> may
    *          return a 'smart' default even if property not present)
    */
   public static String getProperty (String propName)
   {
      try
      {
        if (useOverrideAdapter)
        {
            if (propName.equals("onewire.adapter.default"))
                return overrideAdapter.getAdapterName();
            if (propName.equals("onewire.port.default"))
                return overrideAdapter.getPortName();
        }
      }
      catch(Exception e)
      {
        //just drain it and let the normal method run...
      }

      Properties      onewire_properties = new Properties();
      FileInputStream prop_file          = null;
      String          ret_str            = null;
      DSPortAdapter   adapter_instance;
      Class           adapter_class;

      // try system properties
      try
      {
         ret_str = System.getProperty(propName, null);
      }
      catch (Exception e)
      {
         ret_str = null;
      }

      // if defaults not found then try onewire.properties file
      if (ret_str == null)
      {

         // loop to attempt to open the onewire.properties file in two locations
         // .\onewire.properties or <java.home>\lib\onewire.properties
         String path = new String("");

         for (int i = 0; i <= 1; i++)
         {

            // attempt to open the onewire.properties file
            try
            {
               prop_file = new FileInputStream(path + "onewire.properties");
            }
            catch (Exception e)
            {
               prop_file = null;
            }

            // if open, then try to read value
            if (prop_file != null)
            {

               // attempt to read the onewire.properties
               try
               {
                  onewire_properties.load(prop_file);

                  ret_str = onewire_properties.getProperty(propName, null);
               }
               catch (Exception e)
               {
                  ret_str = null;
               }
            }

            // check to see if we now have the value
            if (ret_str != null)
               break;

            // try the second path
            path = System.getProperty("java.home") + File.separator + "lib"
                   + File.separator;
         }
      }

      // if defaults still not found then check TMEX default
      if (ret_str == null)
      {
         try
         {
            if (propName.equals("onewire.adapter.default"))
               ret_str = TMEXAdapter.getDefaultAdapterName();
            else if (propName.equals("onewire.port.default"))
               ret_str = TMEXAdapter.getDefaultPortName();

            // if did not get real string then null out
            if (ret_str != null)
            {
               if (ret_str.length() <= 0)
                  ret_str = null;
            }
         }
         catch (Exception e)
         {
            // DRAIN
         }
         catch (Error e)
         {
            // DRAIN
         }

      }

      // if STILL not found then just pick DS9097U on 'smartDefaultPort'
      if (ret_str == null)
      {
         if (propName.equals("onewire.adapter.default"))
            ret_str = "DS9097U";
         else if (propName.equals("onewire.port.default"))
         {
            try
            {
               adapter_class    =
                  Class.forName("com.dalsemi.onewire.adapter.USerialAdapter");
               adapter_instance = ( DSPortAdapter ) adapter_class.newInstance();

               // check if has any ports (common javax.comm problem)
               if (adapter_instance.getPortNames().hasMoreElements())
                  ret_str =
                     ( String ) adapter_instance.getPortNames().nextElement();
            }
            catch (Exception e)
            {
               // DRAIN
            }
            catch (Error e)
            {
               // DRAIN
            }
         }
      }

      return ret_str;
   }

   /**
    * Sets an overriding adapter.  This adapter will be returned from
    * getAdapter and getDefaultAdapter despite what was requested.
    *
    * @param adapter adapter to be the override
    *
    * @see    #getAdapter
    * @see    #getDefaultAdapter
    * @see    #clearUseOverridingAdapter
    */
   public static void setUseOverridingAdapter(DSPortAdapter adapter)
   {
        useOverrideAdapter = true;
        overrideAdapter = adapter;
   }

   /**
    * Clears the overriding adapter.  The operation of
    * getAdapter and getDefaultAdapter will be returned to normal.
    *
    * @see    #getAdapter
    * @see    #getDefaultAdapter
    * @see    #setUseOverridingAdapter
    */
   public static void clearUseOverridingAdapter()
   {
        useOverrideAdapter = false;
        overrideAdapter = null;
   }
}