java图形界面里面怎么实现图片缩放

Question

java图形界面里面怎么实现图片缩放，比如我有一个frame里面放了一个label，label上面有张图片，当frame大小改变时让图片一起变，图片原来是将label填满的，

Answer 1

Image image = new ImageIcon("images/set2.jpg").getImage();
image = image.getScaledInstance(300, 180, 0);JLabel label = new JLabel();
label.setBounds(70, 75, 300, 200);
label.setIcon(new ImageIcon(image));

Answer 2

package musicPlatform.client.login;import java.awt.*;
import javax.swing.*;import musicPlatform.client.config.SaveMusicFileDirectory;import testSwing2.UsedToChangeMyFrame;public class SubstituteLoginFrame extends JFrame {
private static final long serialVersionUID = 2022587044957057382L;
private JButton jButton1;// 登录
private JButton jButton2;// 注册
private JLabel jLabel2;// 密码
private JPasswordField jTextField2;// 密码
private JTextField jTextField1;// 用户名
private JLabel jLabel1;// 用户名 public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new SubstituteLoginFrame();
}
});
}
private static void clientConfig() {
String defaultPath = System.getProperty("user.home") + "\\" + "music";
SaveMusicFileDirectory save = new SaveMusicFileDirectory();
save.creatXML(defaultPath);
} public SubstituteLoginFrame() {
super();
autoTest();// 检查服务器
init();
} /**
 * 首次开启客户端时检查连接状态
 */
private void autoTest() {
RespondLoginEnter res = new RespondLoginEnter();
res.initialTestLinkage();
}
public void illegalCallingEntrance() {
SubstituteLoginFrame lf = new SubstituteLoginFrame();
lf.setLocationRelativeTo(null);
lf.setVisible(true);
} public void init() {
Container c = this.getContentPane();
JPanel lowerPanel = new MyPanelk();
c.add(lowerPanel);
GroupLayout lowerPanelLayout = new GroupLayout((JComponent) lowerPanel);
lowerPanel.setLayout(lowerPanelLayout);
lowerPanel.setLocale(new java.util.Locale("zh", "TW"));
// lowerPanel.setPreferredSize(new Dimension(1100, 680));
{
jButton1 = new JButton();
jButton1.setText("注册");
}
{
jButton2 = new JButton();
jButton2.setText("\u767b\u5f55");
}
{
jLabel1 = new JLabel();
jLabel1.setText("\u7528\u6237\u540d");
jLabel1.setFont(new java.awt.Font("微软雅黑", 3, 11));
jLabel1.setForeground(new java.awt.Color(255, 255, 255));
}
{
jLabel2 = new JLabel();
jLabel2.setText("\u5bc6\u7801");
jLabel2.setFont(new java.awt.Font("微软雅黑", 3, 11));
jLabel2.setForeground(new java.awt.Color(255, 255, 255));
}
{
jTextField2 = new JPasswordField();
jTextField2.addFocusListener(new FocusAdapter() {
public void focusGained(FocusEvent evt) {
jTextField2.selectAll();
}
});
}
{
jTextField1 = new JTextField();
jTextField1.addFocusListener(new FocusAdapter() {
public void focusGained(FocusEvent evt) {
jTextField1.selectAll();
}
});
}
lowerPanelLayout.setVerticalGroup(lowerPanelLayout
.createSequentialGroup()
.addContainerGap(63, 63)
.addGroup(
lowerPanelLayout
.createParallelGroup(
GroupLayout.Alignment.BASELINE)
.addComponent(jTextField1,
GroupLayout.Alignment.BASELINE,
GroupLayout.PREFERRED_SIZE, 21,
GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel1,
GroupLayout.Alignment.BASELINE,
GroupLayout.PREFERRED_SIZE,
GroupLayout.PREFERRED_SIZE,
GroupLayout.PREFERRED_SIZE))
.addGap(19)
.addGroup(
lowerPanelLayout
.createParallelGroup(
GroupLayout.Alignment.BASELINE)
.addComponent(jTextField2,
GroupLayout.Alignment.BASELINE,
GroupLayout.PREFERRED_SIZE, 21,
GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2,
GroupLayout.Alignment.BASELINE,
GroupLayout.PREFERRED_SIZE,
GroupLayout.PREFERRED_SIZE,
GroupLayout.PREFERRED_SIZE))
.addGap(29)
.addGroup(
lowerPanelLayout
.createParallelGroup(
GroupLayout.Alignment.BASELINE)
.addComponent(jButton2,
GroupLayout.Alignment.BASELINE,
GroupLayout.PREFERRED_SIZE, 22,
GroupLayout.PREFERRED_SIZE)
.addComponent(jButton1,
GroupLayout.Alignment.BASELINE,
GroupLayout.PREFERRED_SIZE, 22,
GroupLayout.PREFERRED_SIZE))
.addContainerGap(45, 45));
lowerPanelLayout
.setHorizontalGroup(lowerPanelLayout
.createSequentialGroup()
.addContainerGap(108, 108)
.addGroup(
lowerPanelLayout
.createParallelGroup()
.addGroup(
lowerPanelLayout
.createSequentialGroup()
.addGroup(
lowerPanelLayout
.createParallelGroup()
.addComponent(
jLabel1,
GroupLayout.Alignment.LEADING,
GroupLayout.PREFERRED_SIZE,
46,
GroupLayout.PREFERRED_SIZE)
.addGroup(
GroupLayout.Alignment.LEADING,
lowerPanelLayout
.createSequentialGroup()
.addComponent(
jLabel2,
GroupLayout.PREFERRED_SIZE,
26,
GroupLayout.PREFERRED_SIZE)
.addGap(20)))
.addPreferredGap(
LayoutStyle.ComponentPlacement.RELATED,
12,
Short.MAX_VALUE)
.addGroup(
lowerPanelLayout
.createParallelGroup()
.addComponent(
jTextField2,
GroupLayout.Alignment.LEADING,
GroupLayout.PREFERRED_SIZE,
108,
GroupLayout.PREFERRED_SIZE)
.addComponent(
jTextField1,
GroupLayout.Alignment.LEADING,
GroupLayout.PREFERRED_SIZE,
108,
GroupLayout.PREFERRED_SIZE)))
.addGroup(
GroupLayout.Alignment.LEADING,
lowerPanelLayout
.createSequentialGroup()
.addPreferredGap(
jLabel2,
jButton1,
LayoutStyle.ComponentPlacement.INDENT)
.addComponent(jButton1,
0, 67,
Short.MAX_VALUE)
.addGap(17)
.addComponent(
jButton2,
GroupLayout.PREFERRED_SIZE,
70,
GroupLayout.PREFERRED_SIZE)))
.addContainerGap(120, 120)); /**
 * 注册监听
 */
{
jButton1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
// lf.setVisible(false);
// System.out.println("这里可以显示注册窗口了");
SubstituteLoginFrame.this.setVisible(false);
// SubstituteLoginFrame.this.dispose();
RespondLoginEnter res = new RespondLoginEnter();
res.testLinkage();
new LogonJFrame();
InOn inon = new InOn();// 保存本登录窗口对象
inon.backToLogin(SubstituteLoginFrame.this);
}
});
}
/**
 * 登录监听
 */
{
// jButton1.addActionListener(new
// jButton1ActionListener(this));
jButton2.addActionListener(new ActionListener() { // 注册按钮事件
public void actionPerformed(ActionEvent event) { // 事件处理器
String userName = jTextField1.getText();
String password = jTextField2.getText();
// 检查输入合法性
if (ToolString.isInefficacy(userName)
|| ToolString.isInefficacy(password)) {
JOptionPane.showMessageDialog(null, "   用户名和密码不能为空",
"请重新输入", JOptionPane.ERROR_MESSAGE);
return;
}
RespondLoginEnter respondLogin = new RespondLoginEnter();
try {
// 连接服务器
respondLogin.linkage();
// 包装用户名，密码:request=login★userName=a★userPassword=d★
String nameAndPass = ToolString.packageLoginData(
userName, password);
// 发送用户名，密码
respondLogin.sendMessage(nameAndPass);// 发送成功后客户端若等不到服务器数据，界面不响应
// 获得服务器响应 收不到数据的处理？
System.out
.println("开始接收服务器数据：loginsuccess or loginfail！");
String receivedMsg = respondLogin.receiveMsg();
if (receivedMsg == null) {
System.out.println("服务器响应超时！");// 能否显示？？？？？？？？？？？？？？？？？
}
// respondLogin.close(); //
// 需要关闭????????????登錄成功也會關閉????????????????????????????
if (!"loginsuccess".equals(receivedMsg)) {
JOptionPane.showMessageDialog(null, "用户名或密码错误",
"登录失败", JOptionPane.ERROR_MESSAGE);
return;
} else {
// System.out.println("这里开始显示主页并关闭登录窗口");//
// -------------------------------------------------------
SubstituteLoginFrame.this.dispose();
// 登录成功， 显示主页窗口
new UsedToChangeMyFrame();
}
} catch (Exception e) {
e.printStackTrace();
} }
});
} this.setVisible(true);
this.setResizable(false);
String direct = System.getProperty("user.dir")
+ "\\src\\icon\\pro\\key1.gif";
Image img = Toolkit.getDefaultToolkit().getImage(direct);
this.setIconImage(img);
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
this.setLocation(screenSize.width / 2 - 400 / 2,
screenSize.height / 2 - 250 / 2);
this.setTitle("\u97f3\u4e50\u5e73\u53f0");
// this.setSize(new Dimension(1100, 680));
this.setSize(new Dimension(400, 250));
}}class MyPanelk extends JPanel {
/**
 * 
 */
private static final long serialVersionUID = 1L; @Override
public void paintComponent(Graphics g) { // 重绘函数
Graphics2D g2 = (Graphics2D) g;
super.paintComponent(g);
String directory = System.getProperty("user.dir")
+ "\\src\\icon\\pro\\wow2.jpg";
Image img = Toolkit.getDefaultToolkit().getImage(directory);
g2.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this); // 在面板上绘制背景图片
}
}
 

Answer 3

Image的getScaledINnstance(int width, int height, int hints)方法

Answer 4

一句话就是自定义个JPanel，给它加个背景图，再add到JFrame就行了
有用的部分自己挑挑吧  图片路径 src\icon\pro\wow2.jpg
类路径src\musicPlatform\client\login
效果图

Answer 5

JLabel无法自动缩放图片，自己实现一个组件，重写paintComponent方法

Answer 6

final JLabel jlabel = ...;
jlabel.addComponentListener(new ComponentAdapter(){
        @Override public void componentResized(ComponentEvent e){
            ...
        }
    });