我写了一个程序使用applet通过rxtxComm.jar访问串口,我更改了java.policy,所以applet可以在没有签名的情况下访问串口。当程序在Windows上运行时,它是有效的。但是在ubuntu上有一些execptions(java.lang.reflect.InvocationTargetException 和“npobject 上的错误调用方法”)。为了解决这个问题,我用了很多次谷歌,我无法解决。有人有同样的问题吗?这是关于这个程序的代码。
打印.html:
function print() {
var zplText = $("#zplText").val();
document.printApplet.print(zplText);
}
<textarea rows="5" cols="6" id="zplText"></textarea>
<a href="#" onClick="print()">print</a>
<applet id="printApplet" alt="" codebase=.. code="zpl/ZplPrint.class">
<PARAM NAME="archive" VALUE="../lib/RXTXcomm.jar">
</applet>
ZplPrint.java:
public class ZplPrint extends Applet {
static String zpl;
static CommPortIdentifier portId;
static CommPort commPort;
static SerialPort serialPort;
@SuppressWarnings("rawtypes")
static Enumeration portList;
static OutputStream out;
public void print(String zplText) {
zpl = zplText;
if (zpl == null) {
return;
}
byte[] zplByte = zpl.getBytes();
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
try {
commPort = portId.open(portId.getName(), 2000);
serialPort = (SerialPort) commPort;
serialPort.setSerialPortParams(9600, SerialPort.DATABITS_8, SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
out = serialPort.getOutputStream();
out.write(zplByte);
commPort.close();
} catch (PortInUseException e) {
e.printStackTrace();
} catch (UnsupportedCommOperationException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (NullPointerException e) {
e.printStackTrace();
}
System.out.println("Find CommPort: " + portId.getName());
}
}
}
java.policy:
- 权限 java.lang.RuntimePermission "loadLibrary.rxtxSerial";
- 权限 java.io.FilePermission "${java.home}${/}lib${/}ext${/}x86${/}rxtxSerial.dll", "read";
- 权限 java.util.PropertyPermission "gnu.io.log.mode", "read";
- 权限 java.util.PropertyPermission "gnu.io.SerialPorts", "write,read";
- 权限 java.util.PropertyPermission "gnu.io.rxtx.SerialPorts", "read,write";
- 权限 java.util.PropertyPermission "gnu.io.ParallelPorts", "read";
- 权限 java.util.PropertyPermission "gnu.io.rxtx.ParallelPorts", "read";
- 权限 java.lang.RuntimePermission "modifyThreadGroup";
- 权限 java.lang.RuntimePermission "modifyThread";
第一行和第二行与ubuntu不同,当ubuntu是:
- 权限 java.lang.RuntimePermission "loadLibrary.librxtxSerial";
- 权限 java.io.FilePermission "${java.home}${/}lib${/}amd64${/}librxtxSerial.so", "read";