用模态的方式打开自定义JDialog，并获取返回值

JFrame的变量名为jf

JDialog的类名为Fff

 btnLoadImage.addMouseListener(new MouseAdapter() {
             @Override
             public void mouseClicked(MouseEvent e) {
                 Fff myff = new Fff();
                 //myff.setModal(false);
                 myff.setModalityType(ModalityType.APPLICATION_MODAL);
                 myff.setVisible(true);

                 //如果是点击确定，则文本框中输入的内容显示出来
                 String strText;
                 int iReturn;

                 iReturn = myff.f_GetCoseType();
                 if (iReturn == 0) {
                     lbImage.setText("选择了取消");
                 }
                 else
                 {
                     strText = myff.f_GetText();
                     lbImage.setText(strText);
                 }

             }
         });

Fff的类

 package bb;

 import java.awt.BorderLayout;
 import java.awt.FlowLayout;

 import javax.swing.JButton;
 import javax.swing.JDialog;
 import javax.swing.JOptionPane;
 import javax.swing.JPanel;
 import javax.swing.border.EmptyBorder;
 import javax.swing.JTextField;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;

 /**
 * @author 作者 E-mail:
 * @version 创建时间：Sep 18, 2017 2:48:29 PM
 * 类说明
 */

 public class Fff extends JDialog {

     private final JPanel contentPanel = new JPanel();
     private JTextField textOut;
     private int iCloseType; //点击确定，该值为1，点击取消，该值为0

     /**
      * Launch the application.
      */
     public static void main(String[] args) {
         try {
             Fff dialog = new Fff();
             dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
             dialog.setVisible(true);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     /**
      * Create the dialog.
      */
     public Fff() {
         iCloseType = 0 ;    //默认是点击取消按钮

         setBounds(100, 100, 450, 300);
         getContentPane().setLayout(new BorderLayout());
         contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
         getContentPane().add(contentPanel, BorderLayout.CENTER);
         contentPanel.setLayout(new BorderLayout(0, 0));
         {
             JPanel panel = new JPanel();
             contentPanel.add(panel);
             panel.setLayout(new BorderLayout(0, 0));
             {
                 textOut = new JTextField();
                 panel.add(textOut, BorderLayout.NORTH);
                 textOut.setColumns(10);
             }
         }
         {
             JPanel buttonPane = new JPanel();
             buttonPane.setLayout(new FlowLayout(FlowLayout.RIGHT));
             getContentPane().add(buttonPane, BorderLayout.SOUTH);
             {
                 JButton okButton = new JButton("OK");
                 okButton.addMouseListener(new MouseAdapter() {
                     @Override
                     public void mouseClicked(MouseEvent e) {
                         //检查用户是否输入了内容
                         if(f_chkInput()) {
                             iCloseType = 1; //点击了确定性按钮
                             dispose();
                         }
                     }
                 });

                 okButton.setActionCommand("OK");
                 buttonPane.add(okButton);
                 getRootPane().setDefaultButton(okButton);
             }
             {
                 JButton cancelButton = new JButton("Cancel");
                 cancelButton.addMouseListener(new MouseAdapter() {
                     @Override
                     public void mouseClicked(MouseEvent e) {
                         iCloseType = 0; //点击了取消按钮
                         dispose();
                     }
                 });
                 cancelButton.setActionCommand("Cancel");
                 buttonPane.add(cancelButton);
             }
         }
     }

     //检查用户是否输入了文本
     public boolean f_chkInput() {
          String strText;
          boolean bRet;
         strText = textOut.getText();
         if ( strText.length()==0 || strText==null) {
             JOptionPane jMsg = new JOptionPane();
             jMsg.showMessageDialog(null, "请输入内容");
             bRet = false;
         }
         else
         {
             bRet = true;
         }

         return bRet;
     }

     public int f_GetCoseType() {
         return iCloseType;
     }
     public String f_GetText() {
         String strOut;
         strOut = textOut.getText();
         return strOut;
     }
 }