Japplet 表单从数据库检索值

Question

我对 JApplet 很陌生，这就是我现在所做的。

package myform;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.swing.JComboBox;

public class Form extends javax.swing.JApplet {

    /** Initializes the applet Form */
    public void init() {
        try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                public void run() {
                    initComponents();
                }
            });
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        JComboBox list = new JComboBox();
        try
        {
String connstr="jdbc:oracle:thin:@localhost:1521/XE";
String uname="epolicia";
String pass="admin";
Class.forName("oracle.jdbc.OracleDriver").newInstance();
Connection connect =DriverManager.getConnection(connstr,uname,pass);
 System.out.println("Oracle driver is loaded");  
Statement state=connect.createStatement();
 ResultSet rs = state.executeQuery("SELECT * FROM ZONE");

 while (rs.next()) {
     list.addItem(rs.getString(1));
     //System.out.println(rs.getString(1));
 }

        }
        catch(Exception ex)
        {
list.addItem(ex);
        }
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jTextField1 = new javax.swing.JTextField();
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jTextField2 = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        zoneList = new javax.swing.JComboBox();
        addDistrict = new javax.swing.JButton();
        cancelDistrict = new javax.swing.JButton();
        jLabel4 = new javax.swing.JLabel();

        jLabel1.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
        jLabel1.setText("District ID :");

        jLabel2.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
        jLabel2.setText("District Name :");

        jLabel3.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
        jLabel3.setText("Zone :");

        addDistrict.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
        addDistrict.setText("Add");
        addDistrict.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                addDistrictActionPerformed(evt);
            }
        });

        cancelDistrict.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
        cancelDistrict.setText("Cancel");
        cancelDistrict.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                cancelDistrictActionPerformed(evt);
            }
        });

        jLabel4.setFont(new java.awt.Font("Times New Roman", 1, 24)); // NOI18N
        jLabel4.setText("Add New District");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(101, 101, 101)
                        .addComponent(addDistrict)
                        .addGap(28, 28, 28)
                        .addComponent(cancelDistrict))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(47, 47, 47)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jLabel1)
                            .addComponent(jLabel2)
                            .addComponent(jLabel3))
                        .addGap(28, 28, 28)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jTextField1, javax.swing.GroupLayout.DEFAULT_SIZE, 157, Short.MAX_VALUE)
                            .addComponent(jTextField2)
                            .addComponent(zoneList, javax.swing.GroupLayout.PREFERRED_SIZE, 128, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(101, 101, 101)
                        .addComponent(jLabel4, javax.swing.GroupLayout.PREFERRED_SIZE, 190, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(87, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(19, 19, 19)
                .addComponent(jLabel4)
                .addGap(36, 36, 36)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel1))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel2))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(zoneList, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel3))
                .addGap(36, 36, 36)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(addDistrict)
                    .addComponent(cancelDistrict))
                .addContainerGap(112, Short.MAX_VALUE))
        );
    }// </editor-fold>

    private void addDistrictActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
    }

    private void cancelDistrictActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        System.exit(0);

}


    // Variables declaration - do not modify
    private javax.swing.JButton addDistrict;
    private javax.swing.JButton cancelDistrict;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JComboBox zoneList;
    // End of variables declaration

}

而且，我得到此输出

但是，值未显示在组合框中。我需要像 <%=rs.getString(2)%>

请帮助我！提前致谢

Answer 1

您已创建 2 个组合框：list 和 zoneList。您正在从数据库填充 list 并在 UI 上显示 zoneList。这就是 zoneList 为空的原因。