想在这个界面下面放个大图的缩略图，应该怎么搞？求教！

Question

import java.sql.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;public class UpdateDemo extends JFrame {    // public class UpdateDemo{
    private String dbURL = "jdbc:mysql://localhost/book?useUnicode=true&characterEncoding=GBK"; // 数据库标识名
    private String user = "root"; // 数据库用户
    private String password = ""; // 数据库用户密码    public UpdateDemo() {
    
        super("添加一本书"); // 调用父类构造函数
        final Frame f=new Frame("添加一本书");
        Container container = getContentPane(); // 得到容器
                
        final JTextField jtf = new JTextField(18); // 实例化地址输入框
        //jtf.setBounds(18, 20, 153, 25);
        final JTextField jtf1 = new JTextField(18);
        final JTextField jtf2 = new JTextField(18);
        final JTextField jtf3 = new JTextField(18);
        final JTextField jtf4 = new JTextField(18);
        final JTextField jtf5 = new JTextField(18);
        final JTextField jtf6 = new JTextField(18);
        final JTextField jtf7 = new JTextField(18);
        
        final JButton jb1 = new JButton("确定"); // 实例化按钮
        final JButton jb2 = new JButton("浏览...");
        
        JLabel jl = new JLabel("书     名：");
        JLabel jl1 = new JLabel("副标题：");
        JLabel jl2 = new JLabel("作     者：");
        JLabel jl3 = new JLabel("国     籍：");
        JLabel jl4 = new JLabel("出版社：");
        JLabel jl5 = new JLabel("价     格：");
        JLabel jl6 = new JLabel("I S B N ：");
        JLabel jl7 = new JLabel("封     面：");
        
        container.setLayout(new FlowLayout()); // 设置布局管理器
        container.add(jl); // 增加组件到容器上
        container.add(jtf);
        container.add(jl1);
        container.add(jtf1);
        container.add(jl2);
        container.add(jtf2);
        container.add(jl3);
        container.add(jtf3);
        container.add(jl4);
        container.add(jtf4);
        container.add(jl5);
        container.add(jtf5);
        container.add(jl6);
        container.add(jtf6);
        container.add(jl7);
        container.add(jtf7);
        container.add(jb2);
        // container.add(jtfUrl1);
        container.add(jb1);
        
        setSize(300, 768); // 设置窗口尺寸
      //距离左上角图标距离100,100
setLocation(0,0);
//设置主键排列方式为靠左
setLayout(new FlowLayout(FlowLayout.LEFT));
//设置主键排列方式为3行2列,水平、垂直间隙为10
//setLayout(new GridLayout(8,2,10,10));
        setVisible(true); // 设置窗口可视
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 关闭窗口时退出程序
               
        jb2.addActionListener(new ActionListener() { 
         public void actionPerformed(ActionEvent ent) {
                try {
                 FileDialog fd=new FileDialog(f,"open file", FileDialog.LOAD);
                 fd.setVisible(true);//替代fd.show();
                 String strFile=fd.getDirectory()+fd.getFile();
                 ImageIcon icon = new ImageIcon(strFile);
                
                 JLabel jlb = new JLabel();
                 scaleImage(icon);
             jlb.setIcon(icon); // 将图片加入
            
             String Str7=fd.getDirectory()+fd.getFile();//取得文件完整路径
             //System.out.println(Str7);
             jtf7.setText(fd.getFile());
             //f.add(jlb);
             add(jlb);
             jlb.setSize(250, 300);
             //jlb.setBounds(0,200,100,200);//设置坐标x，y；宽度，高度
             jlb.setLocation(0,250);
             jlb.setVisible(true);//替代jlb.show();         
            
            
                }catch (Exception ex) {
                    ex.printStackTrace(); // 输出出错信息
                }
         }
        }); 
        
        
        jb1.addActionListener(new ActionListener() { // 按钮事件处理
            public void actionPerformed(ActionEvent ent) {
                try {
                    String Str = jtf.getText(); // 得到图像的URL地址
                    String Str1 = jtf1.getText();
                    String Str2 = jtf2.getText();
                    String Str3 = jtf3.getText();
                    String Str4 = jtf4.getText();
                    String Str5 = jtf5.getText();
                    String Str6 = jtf6.getText();
                    String Str7= jtf7.getText();
                    System.out.println(Str7);
                   // System.out.println(Str1);                        
                    method(Str,Str1,Str2,Str3,Str4,Str5,Str6,Str7);
                } catch (Exception ex) {
                    ex.printStackTrace(); // 输出出错信息
                }
            }
        });       
        
    }
    private  ImageIcon scaleImage(ImageIcon icon) {
     int width = icon.getIconWidth();
     //System.out.print(width);
     int height = icon.getIconHeight();     if (width <= 80 && height <= 80) {
      return icon;
     }
      Image image = icon.getImage();
         image = image.getScaledInstance(80, 80, Image.SCALE_DEFAULT);
     
     return new ImageIcon(image);
     
    }
    public void method(String str,String str1,String str2,String str3,String str4,String str5,String str6,String str7){
        try {
            Class.forName("com.mysql.jdbc.Driver"); // 加载驱动器
            Connection con = DriverManager.getConnection(dbURL, user, password); // 获取连接
            String sqlStr = "select * from user"; // SQL查询语句
            Statement st = con.createStatement(); // 获取PreparedStatement对象
            ResultSet rs = st.executeQuery(sqlStr); // 执行查询
            String id, title, subhead, authors, nationality, publisher, price, isbn; // 查询结果
            // int age;
            System.err.println("更新前数据");
            while (rs.next()) { // 遍历ResultSet
                id = rs.getString("id"); // 获取数据
                title = rs.getString("title");
                subhead = rs.getString("subhead");
                authors = rs.getString("authors");
                nationality = rs.getString("nationality");
                publisher = rs.getString("publisher");
                price = rs.getString("price");
                isbn = rs.getString("isbn");
                /*
                 * System.out.println("id: "+id+"\ttitle:"+title+"\tsubhead:"+subhead
                 * +"\tauthors:"+authors+"\t nationality:"+nationality
                 * +"\tpublisher:"+publisher+"\tprice"+price+"\t isbn"+isbn);
                 * //在控制台输出数据
                 * /*JOptionPane.showMessageDialog(null,"序号: "+id+"\n书名:"
                 * +title+"\n副标题:"+subhead+"\n作者:"+authors+"\n国籍:"+nationality
                 * +"\n出版社:"+publisher+"\n价格"+price+"\nISBN"+isbn);
                 */               
            }
            
            // 插入操作
          //st.executeUpdate("insert into user values(4, '维基经济学', '大规模协作如何改变一切', '唐·泰普斯科特', '加拿大', '中国青年出版社', '30.00', '9787500676911')");            
            sqlStr="insert into user(title,subhead,authors,nationality,publisher,price,isbn,url) values('"+str+"','"+str1+"','"+str2+"','"+str3+"','"+str4+"','"+str5+"','"+str6+"','"+str7+"')";
            st.executeUpdate(sqlStr);          
            
            // 更新操作
            // sqlStr="update user set age=21 where id=\'2\'";
            // st.executeUpdate(sqlStr);            // 删除操作
            // sqlStr="delete from user where name=\'Jinnifier\'";
            // st.executeUpdate(sqlStr);            // 显示修改后结果
            System.err.println("更新后数据");
            sqlStr = "select * from user"; // SQL查询语句
            rs = st.executeQuery(sqlStr); // 执行查询
            while (rs.next()) { // 遍历ResultSet
                id = rs.getString("id"); // 获取数据
                title = rs.getString("title");
                subhead = rs.getString("subhead");
                authors = rs.getString("authors");
                nationality = rs.getString("nationality");
                publisher = rs.getString("publisher");
                price = rs.getString("price");
                isbn = rs.getString("isbn");
                /*
                 * System.out.println("id: "+id+"\ttitle:"+title+"\tsubhead:"+subhead
                 * +"\tauthors:"+authors+"\t nationality:"+nationality
                 * +"\tpublisher:"+publisher+"\tprice"+price+"\t isbn"+isbn);
                 * //在控制台输出数据
                 * JOptionPane.showMessageDialog(null,"序号: "+id+"\t书名:"
                 * +title+"\t副标题:"+subhead+"\t作者:"+authors+"\t 国籍:"+nationality
                 * +"\t出版社:"+publisher+"\t价格"+price+"\t ISBN"+isbn);
                 */
            }
            con.close(); // 关闭连接
        } catch (Exception ex) {
            ex.printStackTrace(); // 输出出错信息
        }
    }
    public static void main(String[] args) {
        new UpdateDemo();        
    }
}请哪位帮忙改下，我只要实现这个功能，有大段改动也无所谓，呵呵！

Answer 1

呵呵，朋友不知道你找的是不是这个？backLabel.setText("<html><body><center><B><h2><font size=5>superet management system</font></h2></B>" +
"<image width='" + backw+ "'height='" + backh + "'src='"
+ ImageLogin.this.getClass().getResource("loginImage.jpg")
+ "'></img></center></body></html>");希望对你有帮助

Answer 2

private JLabel backLabel;
backLabel = new JLabel();

Answer 3

主要是布局的问题，附带了些变量使用的问题，改动不大，自己对比吧。
import java.sql.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;public class UpdateDemo extends JFrame {    // public class UpdateDemo{
    private String dbURL = "jdbc:mysql://localhost/book?useUnicode=true&characterEncoding=GBK"; // 数据库标识名
    private String user = "root"; // 数据库用户
    private String password = ""; // 数据库用户密码
    JLabel jlb = new JLabel();
    JLabel jlbSmall = new JLabel();    public UpdateDemo() {
        
        super("添加一本书"); // 调用父类构造函数
        final Frame f=new Frame("添加一本书");
        Container contentPane = getContentPane(); // 得到容器
        Container container = new Panel();
        contentPane.add(container);
        contentPane.setLayout(null);
        container.setSize(300, 250);
                
        final JTextField jtf = new JTextField(18); // 实例化地址输入框
        //jtf.setBounds(18, 20, 153, 25);
        final JTextField jtf1 = new JTextField(18);
        final JTextField jtf2 = new JTextField(18);
        final JTextField jtf3 = new JTextField(18);
        final JTextField jtf4 = new JTextField(18);
        final JTextField jtf5 = new JTextField(18);
        final JTextField jtf6 = new JTextField(18);
        final JTextField jtf7 = new JTextField(18);
        
        final JButton jb1 = new JButton("确定"); // 实例化按钮
        final JButton browseBtn = new JButton("浏览...");
        
        JLabel jl = new JLabel("书     名：");
        JLabel jl1 = new JLabel("副标题：");
        JLabel jl2 = new JLabel("作     者：");
        JLabel jl3 = new JLabel("国     籍：");
        JLabel jl4 = new JLabel("出版社：");
        JLabel jl5 = new JLabel("价     格：");
        JLabel jl6 = new JLabel("I S B N ：");
        JLabel jl7 = new JLabel("封     面：");
        
        container.setLayout(new FlowLayout()); // 设置布局管理器
        container.add(jl); // 增加组件到容器上
        container.add(jtf);
        container.add(jl1);
        container.add(jtf1);
        container.add(jl2);
        container.add(jtf2);
        container.add(jl3);
        container.add(jtf3);
        container.add(jl4);
        container.add(jtf4);
        container.add(jl5);
        container.add(jtf5);
        container.add(jl6);
        container.add(jtf6);
        container.add(jl7);
        container.add(jtf7);
        container.add(browseBtn);
        // container.add(jtfUrl1);
        container.add(jb1);
        contentPane.add(jlb);
        contentPane.add(jlbSmall);
        
        setSize(300, 768); // 设置窗口尺寸
      //距离左上角图标距离100,100
        setLocation(0,0);
        //设置主键排列方式为靠左
//        setLayout(new FlowLayout(FlowLayout.LEFT));
        //设置主键排列方式为3行2列,水平、垂直间隙为10
        //setLayout(new GridLayout(8,2,10,10));
        setVisible(true); // 设置窗口可视
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 关闭窗口时退出程序
               
        browseBtn.addActionListener(new ActionListener() { 
            public void actionPerformed(ActionEvent ent) {
                try {
                    FileDialog fd=new FileDialog(f,"open file", FileDialog.LOAD);
                    fd.setVisible(true);//替代fd.show();
                    String strFile=fd.getDirectory()+fd.getFile();
                    ImageIcon icon = new ImageIcon(strFile);
                    
//                    scaleImage(icon);
                    jlb.setIcon(icon); // 将图片加入
                    
                    String Str7=fd.getDirectory()+fd.getFile();//取得文件完整路径
                    //System.out.println(Str7);
                    jtf7.setText(fd.getFile());
                    //f.add(jlb);
                    jlb.setSize(250, 300);
                    //jlb.setBounds(0,200,100,200);//设置坐标x，y；宽度，高度
                    jlb.setLocation(0,250);
                    jlb.setVisible(true);//替代jlb.show();                 
                    jlb.invalidate();
                    jlbSmall.setIcon(scaleImage(icon));
                    jlbSmall.setLocation(0, 550);
                    jlbSmall.setSize(80, 80);
                    jlbSmall.setVisible(true);
                    jlbSmall.invalidate();
                }catch (Exception ex) {
                    ex.printStackTrace(); // 输出出错信息
                }
            }
        }); 
        
        
        jb1.addActionListener(new ActionListener() { // 按钮事件处理
            public void actionPerformed(ActionEvent ent) {
                try {
                    String Str = jtf.getText(); // 得到图像的URL地址
                    String Str1 = jtf1.getText();
                    String Str2 = jtf2.getText();
                    String Str3 = jtf3.getText();
                    String Str4 = jtf4.getText();
                    String Str5 = jtf5.getText();
                    String Str6 = jtf6.getText();
                    String Str7= jtf7.getText();
                    System.out.println(Str7);
                   // System.out.println(Str1);                        
                    method(Str,Str1,Str2,Str3,Str4,Str5,Str6,Str7);
                } catch (Exception ex) {
                    ex.printStackTrace(); // 输出出错信息
                }
            }
        });       
        
    }
    private  ImageIcon scaleImage(ImageIcon icon) {
        int width = icon.getIconWidth();
        //System.out.print(width);
        int height = icon.getIconHeight();        if (width <= 80 && height <= 80) {
         return icon;
        }
                Image image = icon.getImage();
               image = image.getScaledInstance(80, 80, Image.SCALE_DEFAULT);
            
        return new ImageIcon(image);
        
       }
    public void method(String str,String str1,String str2,String str3,String str4,String str5,String str6,String str7){
        try {
            Class.forName("com.mysql.jdbc.Driver"); // 加载驱动器
            Connection con = DriverManager.getConnection(dbURL, user, password); // 获取连接
            String sqlStr = "select * from user"; // SQL查询语句
            Statement st = con.createStatement(); // 获取PreparedStatement对象
            ResultSet rs = st.executeQuery(sqlStr); // 执行查询
            String id, title, subhead, authors, nationality, publisher, price, isbn; // 查询结果
            // int age;
            System.err.println("更新前数据");
            while (rs.next()) { // 遍历ResultSet
                id = rs.getString("id"); // 获取数据
                title = rs.getString("title");
                subhead = rs.getString("subhead");
                authors = rs.getString("authors");
                nationality = rs.getString("nationality");
                publisher = rs.getString("publisher");
                price = rs.getString("price");
                isbn = rs.getString("isbn");
                /*
                 * System.out.println("id: "+id+"\ttitle:"+title+"\tsubhead:"+subhead
                 * +"\tauthors:"+authors+"\t nationality:"+nationality
                 * +"\tpublisher:"+publisher+"\tprice"+price+"\t isbn"+isbn);
                 * //在控制台输出数据
                 * /*JOptionPane.showMessageDialog(null,"序号: "+id+"\n书名:"
                 * +title+"\n副标题:"+subhead+"\n作者:"+authors+"\n国籍:"+nationality
                 * +"\n出版社:"+publisher+"\n价格"+price+"\nISBN"+isbn);
                 */               
            }
            
            // 插入操作
          //st.executeUpdate("insert into user values(4, '维基经济学', '大规模协作如何改变一切', '唐·泰普斯科特', '加拿大', '中国青年出版社', '30.00', '9787500676911')");            
            sqlStr="insert into user(title,subhead,authors,nationality,publisher,price,isbn,url) values('"+str+"','"+str1+"','"+str2+"','"+str3+"','"+str4+"','"+str5+"','"+str6+"','"+str7+"')";
            st.executeUpdate(sqlStr);          
            
            // 更新操作
            // sqlStr="update user set age=21 where id=\'2\'";
            // st.executeUpdate(sqlStr);            // 删除操作
            // sqlStr="delete from user where name=\'Jinnifier\'";
            // st.executeUpdate(sqlStr);            // 显示修改后结果
            System.err.println("更新后数据");
            sqlStr = "select * from user"; // SQL查询语句
            rs = st.executeQuery(sqlStr); // 执行查询
            while (rs.next()) { // 遍历ResultSet
                id = rs.getString("id"); // 获取数据
                title = rs.getString("title");
                subhead = rs.getString("subhead");
                authors = rs.getString("authors");
                nationality = rs.getString("nationality");
                publisher = rs.getString("publisher");
                price = rs.getString("price");
                isbn = rs.getString("isbn");
                /*
                 * System.out.println("id: "+id+"\ttitle:"+title+"\tsubhead:"+subhead
                 * +"\tauthors:"+authors+"\t nationality:"+nationality
                 * +"\tpublisher:"+publisher+"\tprice"+price+"\t isbn"+isbn);
                 * //在控制台输出数据
                 * JOptionPane.showMessageDialog(null,"序号: "+id+"\t书名:"
                 * +title+"\t副标题:"+subhead+"\t作者:"+authors+"\t 国籍:"+nationality
                 * +"\t出版社:"+publisher+"\t价格"+price+"\t ISBN"+isbn);
                 */
            }
            con.close(); // 关闭连接
        } catch (Exception ex) {
            ex.printStackTrace(); // 输出出错信息
        }
    }
    public static void main(String[] args) {
        new UpdateDemo();        
    }
}

Answer 4

没必要搞什么图片缩放吧？直接 JLabel.setIcon不行吗？ Label设置多大，图片应该就能相应的缩放为多大