带有 JDBC 的 Applet - java.security.AccessControlException:访问被拒绝 [英] Applet with JDBC - java.security.AccessControlException: access denied

问题描述

//JDBC using Applet
/*
<applet code = JDBC1 height = 170 width = 350 >
</applet>
*/

import javax.swing.*; //JApplet,JLabel,JButton

import java.applet.*; //Applet
import java.awt.*; //Layout

import java.awt.event.*; //Events

import java.sql.*; //JDBC

public class JDBC1 extends Applet implements Runnable,ActionListener
{
JFrame frame ;
JPanel panel1;
JLabel lblNo,lblName,lblBdate ;
JTextField txtNo,txtName,txtBdate;
JButton btn;

Statement st1;
Connection cn;
ResultSet rs;

    public JDBC1()
    {
        try
        {
            panel1 = new JPanel ();
            panel1.setLayout(new GridLayout(0,2));

            lblNo = new JLabel ("Roll No : ");
            panel1.add(lblNo);

            txtNo = new JTextField(15);
            panel1.add(txtNo);

            lblName = new JLabel ("Name : ");
            panel1.add(lblName);

            txtName = new JTextField(15);
            panel1.add(txtName);

            lblBdate = new JLabel ("Birth Date : ");
            panel1.add(lblBdate);

            txtBdate = new JTextField(15);
            panel1.add(txtBdate); //Add textarea to the panel.

            add(panel1); //Add panel to the aaplet.

            btn = new JButton ("First");
            add(btn); //Add button to the applet.
            btn.addActionListener(this);

            btn = new JButton ("Next");
            add(btn);
            btn.addActionListener(this);

            btn = new JButton ("Last");
            add(btn);
            btn.addActionListener(this);

            btn = new JButton ("Prev");
            add(btn);
            btn.addActionListener(this);

            btn = new JButton ("Save");
            add(btn);
            btn.addActionListener(this);

            btn = new JButton ("Reset");
            add(btn);
            btn.addActionListener(this);

            btn = new JButton ("Delete");
            add(btn);
            btn.addActionListener(this);

            btn = new JButton ("Update");
            add(btn);
            btn.addActionListener(this);

            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); //Load the JDBC-ODBC bridge driver
            cn = DriverManager.getConnection("jdbc:odbc:STUDENT_MYDSN"); // conection to databse

            st1 = cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);

            String query = "select * from Student";
            rs = st1.executeQuery(query);

        }

        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    public void init()
    {
        try
        {
            Thread th = new Thread (this);
            th.start(); 
        }
        catch(Exception ex)
        {
            System.out.println(ex.toString());
        }
    }


    public void run ()
    {
        try
        {

            while(true)
            {
                JDBC1 my = new JDBC1();
                repaint();
                Thread.sleep(1000);
            }
        }
        catch(Exception ex)
        {
            System.out.println(ex.toString());
        }
    }

    public void paint (Graphics g)
    {
        super.paint(g);
        java.util.Date dt = new java.util.Date();
        String myDate = dt+"";
        g.drawString(myDate,100,150);
    }

    void getRecord()
    {
        try
        {
            txtNo.setText((String) rs.getObject(1));
        }

        catch (Exception e)
        {
            System.out.println(e.toString());
        }
    }

    public void actionPerformed(ActionEvent e)
    {
        try
        {
            String name = ((JButton) e.getSource()).getText();

            if (name == "First")
            {

                System.out.println("First");
            }

            if (name == "Prev")
            {
                System.out.println("Prev");
            }

            if (name == "Next")
            {
                System.out.println("Next");
            }

            if (name == "Last")
            {
                System.out.println("First");
            }

            if (name == "Save")
            {
                System.out.println("First");
            }

            if (name == "Delete")
            {
                System.out.println("First");
            }

            if (name == "Update")
            {
                System.out.println("First");
            }

            if (name == "Reset")
            {
                System.out.println("First");
            }
        }

        catch (Exception ex)
        {
            System.out.println(ex.toString());
            ex.printStackTrace();
        }
    }

}

通过将此 Applet 与 JDBC 结合使用，我将收到以下错误

By using this Applet with JDBC , I will getting below error

java.security.AccessControlException: access denied ("java.util.PropertyPermission" "file.encoding"
            at java.security.AccessControlContext.checkPermission(AccessControlContext.java:366)
            at java.security.AccessController.checkPermission(AccessController.java:560)
            at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
            at java.lang.SecurityManager.checkPropertyAccess(SecurityManager.java:1302)
            at java.lang.System.getProperty(System.java:706)
            at sun.jdbc.odbc.JdbcOdbcConnection.initialize(JdbcOdbcConnection.java:142)
            at sun.jdbc.odbc.JdbcOdbcDriver.connect(JdbcOdbcDriver.java:174)
            at java.sql.DriverManager.getConnection(DriverManager.java:579)
            at java.sql.DriverManager.getConnection(DriverManager.java:243)
            at JDBC1.<init>(JDBC1.java:87)
            at JDBC1.run(JDBC1.java:123)
            at java.lang.Thread.run(Thread.java:722)

推荐答案

如果不采取措施授予小程序适当的权限，您将无法在小程序中运行 JDBC.Oracle 的本教程详细介绍了该主题.

You won't be able to run JDBC in an applet without taking steps to give the applet appropriate permissions. The topic is covered in detail by this tutorial from Oracle.

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