当我从Netbeans运行时，我的Java Applet工作正常，并且创建的jar文件也可以正常工作。但是，当我将applet嵌入浏览器时，我有这个错误“RuntimeException java.lang.reflect.InvocationTargetException”我已经浏览了调试此错误，但我似乎无法找到我的代码的解决方案。请帮忙。谢谢。
以下是我的代码：
SerialTest.java （这是我的主类，在main方法中，我调用applet，以便在Java控制台中打印的任何内容都将打印在applet中）
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Enumeration;
import java.util.Scanner;
public class SerialTest implements SerialPortEventListener {
SerialPort serialPort;
/**
* The port we're normally going to use.
*/
public static final String PORT_NAMES[] = {
"/dev/cu.usbserial-A9014NQP" //, Mac OS X
//"/dev/ttyUSB0", // Linux
//"COM3", // Windows
};
/**
* A BufferedReader which will be fed by a InputStreamReader converting the
* bytes into characters making the displayed results codepage independent
*/
public BufferedReader input;
/**
* The output stream to the port
*/
public OutputStream output;
/**
* Milliseconds to block while waiting for port open
*/
public static final int TIME_OUT = 2000;
/**
* Default bits per second for COM port.
*/
public static final int DATA_RATE = 9600;
public void initialize() {
CommPortIdentifier portId = null;
Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();
//First, Find an instance of serial port as set in PORT_NAMES.
while (portEnum.hasMoreElements()) {
CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
for (String portName : PORT_NAMES) {
if (currPortId.getName().equals(portName)) {
portId = currPortId;
break;
}
}
}
if (portId == null) {
//portnotdetected = "Could not find COM port.";
System.out.println("Could not find COM port.");
return;
}
try {
// open serial port, and use class name for the appName.
serialPort = (SerialPort) portId.open(this.getClass().getName(),
TIME_OUT);
// set port parameters
serialPort.setSerialPortParams(DATA_RATE,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
// open the streams
input = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));
output = serialPort.getOutputStream();
// add event listeners
serialPort.addEventListener(this);
serialPort.notifyOnDataAvailable(true);
} catch (Exception e) {
System.err.println(e.toString());
}
}
/**
* This should be called when you stop using the port. This will prevent
* port locking on platforms like Linux.
*/
public synchronized void close() {
if (serialPort != null) {
serialPort.removeEventListener();
serialPort.close();
}
}
/**
* Handle an event on the serial port. Read the data and print it.
*/
public synchronized void serialEvent(SerialPortEvent oEvent) {
if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
try {
String inputLine = input.readLine().trim();
//String readID = inputLine.substring(1);
System.out.println("Read Tag ID: " + inputLine); //this is the tagID read
Connection conn = null;
try {
String userName = "root";
String password = "root";
String url = "jdbc:mysql://localhost:8889/RFID";
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection(url, userName, password);
//System.out.println("Database connection established");
Statement stmt = null;
ResultSet rs = null;
//SQL query command
String SQL = "SELECT * FROM Inventory WHERE (SerialID = '" + inputLine + "')";
//String SQL = "SELECT * FROM Inventory";
stmt = conn.createStatement();
rs = stmt.executeQuery(SQL);
if (rs != null && rs.next()) {
String SerialID = rs.getString("SerialID");
String name = rs.getString("Name");
String description = rs.getString("Description");
if (inputLine.equals(SerialID)) {
System.out.println(SerialID + "\t " + name + "\t " + description + "\n"); //from Database
}
} else {
System.out.println("Sorry Tag ID " + inputLine + " not found database \n");
}
} catch (Exception e) {
System.err.println("Cannot connect to database server");
e.printStackTrace();
}
} catch (Exception e) {
System.err.println(e.toString());
}
}
// Ignore all the other eventTypes, but you should consider the other ones.
}
public static void main(String[] args) throws Exception {
new SerialApp();
SerialTest main = new SerialTest();
main.initialize();
Thread t = new Thread() {
public void run() {
//the following line will keep this app alive for 1000 seconds,
//waiting for events to occur and responding to them (printing incoming messages to console).
try {
Thread.sleep(1000000);
} catch (InterruptedException ie) {
}
}
};
t.start();
System.out.println("Started");
/*
Scanner scanner = new Scanner(System.in);
String userInput = scanner.next();
if ("q".equals(userInput)) {
System.exit(0);
}
*/
}
}
SerialApp.java （这是我创建applet的地方）
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.JApplet;
import javax.swing.JFrame;
public class SerialApp extends JApplet implements Runnable, ActionListener
{
public JFrame frame;
public TextArea textArea;
public Thread reader;
public Thread reader2;
public boolean quit;
public final PipedInputStream pin=new PipedInputStream();
public final PipedInputStream pin2=new PipedInputStream();
Thread errorThrower; // just for testing (Throws an Exception at this Console
public void init() {
}
public SerialApp()
{
// create all components and add them
frame=new JFrame("RFID");
Dimension screenSize=Toolkit.getDefaultToolkit().getScreenSize();
Dimension frameSize=new Dimension((int)(screenSize.width/2),(int)(screenSize.height/2));
int x=(int)(frameSize.width/2);
int y=(int)(frameSize.height/2);
frame.setBounds(x,y,frameSize.width,frameSize.height);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
textArea=new TextArea();
textArea.setEditable(false);
Container container = getContentPane();// Get the content pane of the frame
container.setLayout(new BorderLayout());
container.add(textArea, BorderLayout.CENTER);
//Button button=new Button("clear"); //create button
/*
Panel panel=new Panel();
panel.setLayout(new BorderLayout());
panel.add(textArea,BorderLayout.CENTER);
//panel.add(button,BorderLayout.SOUTH); //button location
*/
frame.add(container);
frame.setVisible(true);
//button.addActionListener(this); //add button
try
{
PipedOutputStream pout=new PipedOutputStream(this.pin);
System.setOut(new PrintStream(pout,true));
}
catch (java.io.IOException io)
{
textArea.append("Couldn't redirect STDOUT to this console\n"+io.getMessage());
}
catch (SecurityException se)
{
textArea.append("Couldn't redirect STDOUT to this console\n"+se.getMessage());
}
try
{
PipedOutputStream pout2=new PipedOutputStream(this.pin2);
System.setErr(new PrintStream(pout2,true));
}
catch (java.io.IOException io)
{
textArea.append("Couldn't redirect STDERR to this console\n"+io.getMessage());
}
catch (SecurityException se)
{
textArea.append("Couldn't redirect STDERR to this console\n"+se.getMessage());
}
quit=false; // signals the Threads that they should exit
// Starting two seperate threads to read from the PipedInputStreams
//
reader=new Thread(this);
reader.setDaemon(true);
reader.start();
//
reader2=new Thread(this);
reader2.setDaemon(true);
reader2.start();
}
public synchronized void actionPerformed(ActionEvent evt)
{
textArea.setText("");
}
public synchronized void run()
{
try
{
while (Thread.currentThread()==reader)
{
try { this.wait(100);}catch(InterruptedException ie) {}
if (pin.available()!=0)
{
String input=this.readLine(pin);
textArea.append(input);
}
if (quit) return;
}
while (Thread.currentThread()==reader2)
{
try { this.wait(100);}catch(InterruptedException ie) {}
if (pin2.available()!=0)
{
String input=this.readLine(pin2);
textArea.append(input);
}
if (quit) return;
}
} catch (Exception e)
{
textArea.append("\nConsole reports an Internal error.");
textArea.append("The error is: "+e);
}
// just for testing (Throw a Nullpointer after 1 second)
if (Thread.currentThread()==errorThrower)
{
try { this.wait(1000); }catch(InterruptedException ie){}
throw new NullPointerException("Application test: throwing an NullPointerException It should arrive at the console");
}
}
public synchronized String readLine(PipedInputStream in) throws IOException
{
String input="";
do
{
int available=in.available();
if (available==0) break;
byte b[]=new byte[available];
in.read(b);
input=input+new String(b,0,b.length);
}while( !input.endsWith("\n") && !input.endsWith("\r\n") && !quit);
return input;
}
}
applet.html
<html>
<head>
<title>Applet</title>
</head>
<body>
<applet code="SerialTest.class" archive="SerialApplet.jar" width="550" height="550">
</applet>
</body>
</html>
答案 0 :(得分：2)
我有这个错误“RuntimeException java.lang.reflect.InvocationTargetException“
这是因为您将applet代码标记为：
<applet code="SerialTest.class" archive="SerialApplet.jar" width="550" height="550">
并且SerialTest不是Applet ..Applets不使用main方法来执行。相反，他们使用init()和start()方法开始。请查看以下官方教程以了解有关Applet的更多信息：Java Applets
答案 1 :(得分：0)
我有这个错误“RuntimeException java.lang.reflect.InvocationTargetException“
因为，您正在推翻java Applet的沙箱提供的规则。我想，gnu.io.SerialPort与此有关。请点击此处了解有关applet沙箱的更多信息：What Applets Can and Cannot Do