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[英]Applet Error - java.lang.reflect.InvocationTargetException
[英]Java Applet getting error java.lang.reflect.InvocationTargetException
首先,我只是java的新手。
下面是我的小程序代码,它编译时会提示(注意:CallApplet.java 使用了未经检查或不安全的操作。注意:使用 -Xlint:unchecked 重新编译以了解详细信息。)但没有错误。
更新
当我通过 javascript 调用 mprintt 方法时出现此错误。 如您所见,它尝试调用 DLL 实例。
import javax.swing.*;
import javax.print.*;
import java.util.ArrayList;
import com.sun.jna.Library;
import com.sun.jna.Native;
import java.awt.print.*;
import java.security.*;
public class CallApplet extends JApplet {
JTextField output;
public void init() {
output = new JTextField(20);
add(output);
validate();
}
public void setMessage(String message) {
output.setText(message);
}
public String getPrinters() {
PrintService[] printServices = PrintServiceLookup.lookupPrintServices(null, null);
ArrayList<String> myStringArray = new ArrayList<String>();
String s = new String();
int i = 0;
for (PrintService printer : printServices) {
myStringArray.add(printer.getName());
if (i > 0) {
s = s + ",";
}
s = s + "\"" + printer.getName() + "\"";
i++;
}
s = "[" + s + "]";
String[] simpleArray = new String[ myStringArray.size() ];
myStringArray.toArray( simpleArray );
return s;
}
public void jPrint(String printer) {
if (printer.length() <= 0) {
return;
}
//output.setText(printer);
//TcsPrint tcsPrinter = new TcsPrint();
//tcsPrinter.print(printer);
}
public interface TscLibDll extends Library {
TscLibDll INSTANCE = (TscLibDll) AccessController.doPrivileged(new PrivilegedAction () {
public Object run() {
return Native.loadLibrary ("TSCLIB", TscLibDll.class);
}
});
int about ();
int openport (String pirnterName);
int closeport ();
int sendcommand (String printerCommand);
int setup (String width,String height,String speed,String density,String sensor,String vertical,String offset);
int downloadpcx (String filename,String image_name);
int barcode (String x,String y,String type,String height,String readable,String rotation,String narrow,String wide,String code);
int printerfont (String x,String y,String fonttype,String rotation,String xmul,String ymul,String text);
int clearbuffer ();
int printlabel (String set, String copy);
int formfeed ();
int nobackfeed ();
int windowsfont (int x, int y, int fontheight, int rotation, int fontstyle, int fontunderline, String szFaceName, String content);
}
public void mprintt(String printer) {
TscLibDll.INSTANCE.openport(printer);
TscLibDll.INSTANCE.sendcommand("REM ***** This is a test by JAVA. *****");
TscLibDll.INSTANCE.setup("35", "15", "3", "8", "0", "3", "-1");
TscLibDll.INSTANCE.clearbuffer();
TscLibDll.INSTANCE.printerfont ("290", "8", "3", "0", "1", "1", "ARTICLE NO");
TscLibDll.INSTANCE.barcode("290", "35", "128", "50", "1", "0", "2", "2", "123456789");
TscLibDll.INSTANCE.printlabel("1", "1");
TscLibDll.INSTANCE.closeport();
}
}
下面是我的html
<html>
<body>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
<script type='text/javascript'>
var printers;
function selectPrinter()
{
applet = document.getElementById('output');
printers = applet.getPrinters();
}
</script>
<br>
<applet
id='output'
code='CallApplet.class'
archive='.,./jna.jar'
width=100
height=100>
</applet>
<input type="button" onclick="selectPrinter()" value="Show Printers" /> <input type="button" onclick="goPrint" value="Print" />
<select name="printers">
</select>
dsdsdg
</body>
</html>
正如你们所看到的,我正在使用 jna.jar 加载自定义热敏打印机 DLL。
我收到错误“java.lang.reflect.InvocationTargetException”,我认为这更多是由于小程序和 jna 的并发症。
请让我知道如何克服这个问题并通过此 DLL 打印此小程序。
通常 InvocationTargetException 只是包装根异常。 根异常应该在堆栈跟踪中列出,或者可以使用“getCause()”方法访问。 发布堆栈跟踪可能会有所帮助。
我会尝试简化以找到错误或获取 tcbcw 所述的堆栈跟踪。 尝试仅从小程序访问打印服务,这行得通吗? 切片代码并找到错误,或者获取堆栈跟踪,我们无能为力。
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