下面是applet代码，它使用jna.jar（https://github.com/twall/jna）来访问system32中的DLL文件。
import javax.swing.*;
import javax.print.*;
import java.security.*;
import java.util.ArrayList;
import com.sun.jna.Library;
import com.sun.jna.Native;
import java.awt.*;
import java.awt.event.*;
import java.io.PrintWriter;
import java.io.StringWriter;
import com.sun.jna.Pointer;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinUser;
import com.sun.jna.platform.win32.WinUser.WNDENUMPROC;
import com.sun.jna.win32.StdCallLibrary;
public class CallApplet extends JApplet implements ActionListener {
/**
*
*/
private static final long serialVersionUID = 4654357272074276081L;
static JTextField output;
private final String ButtonText = "Print";
public void init() {
Container contentHolder = getContentPane();
contentHolder.setLayout(new BorderLayout(18,18));
output = new JTextField(20);
//add(output);
contentHolder.add(output, BorderLayout.CENTER);
JPanel buttonPanel = new JPanel();
JButton b = new JButton(ButtonText);
b.addActionListener(this);
buttonPanel.add(b);
contentHolder.add(buttonPanel, BorderLayout.SOUTH);
validate();
}
public void actionPerformed(ActionEvent evt)
{
//get the text of the button that was pushed
String command = evt.getActionCommand();
output.setText(command);
// if myButton was pressed, output a message
if(ButtonText.equals(command)) {
try {
this.mprintt("TSC TTP-244 Plus");
} catch (Exception e) {
}
}
}
public void setMessage(String message) {
output.setText(message);
}
public interface TscLibDll extends Library {
TscLibDll INSTANCE = (TscLibDll) 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) {
try {
//TscLibDll.INSTANCE.about();
TscLibDll.INSTANCE.openport(printer);
//TscLibDll.INSTANCE.downloadpcx("C:\\UL.PCX", "UL.PCX");
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.sendcommand("PUTPCX 550,10,\"UL.PCX\"");
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.windowsfont(400, 200, 48, 0, 3, 1, "arial", "DEG 0");
//TscLibDll.INSTANCE.windowsfont(400, 200, 48, 90, 3, 1, "arial", "DEG 90");
//TscLibDll.INSTANCE.windowsfont(400, 200, 48, 180, 3, 1, "arial", "DEG 180");
//TscLibDll.INSTANCE.windowsfont(400, 200, 48, 270, 3, 1, "arial", "DEG 270");
TscLibDll.INSTANCE.printlabel("1", "1");
TscLibDll.INSTANCE.closeport();
output.setText("printed");
} catch (Exception e) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
output.setText(sw.toString());
}
}
}
我的Html代码
<html>
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<applet codebase ="." code="CallApplet.class"
archive="CallApplet.jar,jna.jar,platform.jar"
height="100" width="100"/>
</body>
</html>
当我尝试点击打印时，我可以看到applet已加载并且浏览器中的所有swing元素都没有做任何事情。在eclipse运行中它运行正常。
我知道这是安全问题所以我还添加了策略（C：\ Program Files \ Java \ jre7 \ lib \ security \ java.policy文件）
grant codeBase "http://localhost:8080/appletproj/*" {
permission java.security.AllPermission;
};
堆栈跟踪
Exception in thread "AWT-EventQueue-7" java.lang.NoClassDefFoundError: com/sun/jna/Library
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.defineClassHelper(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.access$100(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Unknown Source)
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at CallApplet.mprintt(CallApplet.java:185)
at CallApplet.actionPerformed(CallApplet.java:60)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: com.sun.jna.Library
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 55 more
但即便如此也无济于事。请指导我哪里出错了。
解
坦率地说，我没有得到解决方案，而不是安全问题所以创建了一个带有实际错误的新问题
因此，要获得我启用java控制台（由andrew建议）的确切错误，您可以go here了解如何执行此操作。
更新
几天后我就开始工作了，问题是jna.jar和platform.jar已经签名了，所以每当我用jarsigner签名时它都没用过，我从来没有得到任何错误（所以我从来没有看过它们），当我用jarsigner验证它时，我想通了。然后我取消签名并使用与我的jar一起使用的相同密钥签名（希望它会帮助其他人）
答案 0 :(得分：1)
..还增加了政策..但即使这样也无济于事。
政策文件很少（如果有的话）是一个好主意。如果需要信任代码，请对存档进行数字签名。