java 下拉框级联及相关（转）

package swing.combox;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Rectangle;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class YearMonthDay extends JFrame {

    private static final long serialVersionUID = 1L;
    private final int STARTYEAR = 2000;//年份的开始值
     private final int ENDYEAR = 2020;//年份的结束值
     
     JPanel contentPane;
     //年月日的选择框
     JComboBox<String> 
      cboYear = new JComboBox<String>(),
      cboMonth = new JComboBox<String>(),
      cboDay = new JComboBox<String>();
     
     //年月日标签
     JLabel jLabel1 = new JLabel();
     JLabel jLabel2 = new JLabel();
     JLabel jLabel3 = new JLabel();
     public YearMonthDay() {
      
       setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       jbInit();
      
     }
     private void jbInit(){
      
      contentPane = (JPanel) getContentPane();
      contentPane.setLayout(null);
      setSize(new Dimension(400, 300));
      setTitle("年月日下拉列表级联");
      // 年的下拉选择框
      cboYear.setFont(new java.awt.Font("Dialog", Font.BOLD, 13));
      cboYear.setBounds(new Rectangle(0, 0, 55, 18));
      // 月的下拉选择框
      cboMonth.setFont(new java.awt.Font("Dialog", Font.BOLD, 13));
      cboMonth.setBounds(new Rectangle(80, 0, 45, 18));
      cboMonth.addItemListener(new DateItemAdapter(this));
//      cboMonth
      // 日的下拉选择框
      cboDay.setFont(new java.awt.Font("Dialog", Font.BOLD, 13));
      cboDay.setBounds(new Rectangle(150, 0, 45, 18));
      // cboDay.setEditable(true);
      // 年的label
      jLabel3.setFont(new java.awt.Font("Dialog", Font.BOLD, 15));
      jLabel3.setText("年");
      jLabel3.setBounds(new Rectangle(60, 0, 20, 20));
      // 月的label
      jLabel2.setFont(new java.awt.Font("Dialog", Font.BOLD, 15));
      jLabel2.setText("月");
      jLabel2.setBounds(new Rectangle(130, 0, 20, 20));
      // 日的label
      jLabel1.setFont(new java.awt.Font("Dialog", Font.BOLD, 15));
      jLabel1.setText("日");
      jLabel1.setBounds(new Rectangle(200, 0, 20, 20));
      
      contentPane.add(cboYear);
      contentPane.add(cboMonth);
      contentPane.add(cboDay);
      contentPane.add(jLabel3);
      contentPane.add(jLabel2);
      contentPane.add(jLabel1);
      
      //添加初始值
      AddInfo();
     }
     
     private void AddInfo() {
      //年下拉选择框
      for (int i = STARTYEAR; i < ENDYEAR; i++) {
       cboYear.addItem("" + i);
      }
      
      //月下拉选择框
      for (int i = 0; i < 12; i++) {
       cboMonth.addItem("" + (i + 1));
      }
      
      //日下拉选择框
      for (int j = 0; j < 31; j++) {
       cboDay.addItem("" + (j + 1));
      }
     }
     public void cboMonth_itemStateChanged(ItemEvent e) {
      
      Object obj = cboMonth.getSelectedItem();// 取得选中月份
      
      if (obj != null) { 
       cboDay.removeAllItems();// 清空日的下拉列表框
       
       int month = Integer.valueOf(obj.toString());
       if (month==5) {//test  JComboBox api combox method setEnabled()
        this.cboDay.setEnabled(false);
    }
       int days = 31;
       if (month == 4 || month == 6 || month == 9 || month == 11) {
        days = 30;
       } else if (month == 2) {
         //取得选中年份
        int year = Integer.parseInt(cboYear.getSelectedItem()
          .toString());
        if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {
         // 是闰年
         days = 29;
        } else {
         // 不是闰年
         days = 28;
        }
       }//if
       
       for (int j = 0; j < days; j++) {
        cboDay.addItem("" + (j + 1));
       }//for
      }//if
     }//if
     
    }//end class

// 事件监听器
class DateItemAdapter implements ItemListener {
 private YearMonthDay adaptee;
 DateItemAdapter(YearMonthDay adaptee) {
  this.adaptee = adaptee;
 }
 public void itemStateChanged(ItemEvent e) {
     if (e.getStateChange()==ItemEvent.SELECTED) {
         System.out.println("was invoked");
         adaptee.cboMonth_itemStateChanged(e);
    }
 }
}

package swing.combox;

public class Test {

     public static void main(String[] args) {
         YearMonthDay testDate = new YearMonthDay();
         testDate.setVisible(true);
         testDate.setBounds(200, 200, 250, 100);

    }
}