甲能夠畫Image爲背景
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import javax.swing.JPanel;
public class BackgroundPane extends JPanel {
private BufferedImage img;
private BufferedImage scaled;
public BackgroundPane() {
}
@Override
public Dimension getPreferredSize() {
return img == null ? super.getPreferredSize() : new Dimension(img.getWidth(), img.getHeight());
}
public void setBackground(BufferedImage value) {
if (value != img) {
this.img = value;
repaint();
}
}
@Override
public void invalidate() {
super.invalidate();
if (getWidth() > img.getWidth() || getHeight() > img.getHeight()) {
scaled = getScaledInstanceToFill(img, getSize());
} else {
scaled = img;
}
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (scaled != null) {
int x = (getWidth() - scaled.getWidth())/2;
int y = (getHeight() - scaled.getHeight())/2;
g.drawImage(scaled, x, y, this);
}
}
public static BufferedImage getScaledInstanceToFill(BufferedImage img, Dimension size) {
double scaleFactor = getScaleFactorToFill(img, size);
return getScaledInstance(img, scaleFactor);
}
public static double getScaleFactorToFill(BufferedImage img, Dimension size) {
double dScale = 1;
if (img != null) {
int imageWidth = img.getWidth();
int imageHeight = img.getHeight();
double dScaleWidth = getScaleFactor(imageWidth, size.width);
double dScaleHeight = getScaleFactor(imageHeight, size.height);
dScale = Math.max(dScaleHeight, dScaleWidth);
}
return dScale;
}
public static double getScaleFactor(int iMasterSize, int iTargetSize) {
double dScale = (double) iTargetSize/(double) iMasterSize;
return dScale;
}
public static BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor) {
return getScaledInstance(img, dScaleFactor, RenderingHints.VALUE_INTERPOLATION_BILINEAR, true);
}
protected static BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor, Object hint, boolean bHighQuality) {
BufferedImage imgScale = img;
int iImageWidth = (int) Math.round(img.getWidth() * dScaleFactor);
int iImageHeight = (int) Math.round(img.getHeight() * dScaleFactor);
if (dScaleFactor <= 1.0d) {
imgScale = getScaledDownInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
} else {
imgScale = getScaledUpInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
}
return imgScale;
}
protected static BufferedImage getScaledDownInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = (img.getTransparency() == Transparency.OPAQUE)
? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
if (targetHeight > 0 || targetWidth > 0) {
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w > targetWidth) {
w /= 2;
if (w < targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h > targetHeight) {
h /= 2;
if (h < targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(Math.max(w, 1), Math.max(h, 1), type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != targetWidth || h != targetHeight);
} else {
ret = new BufferedImage(1, 1, type);
}
return ret;
}
protected static BufferedImage getScaledUpInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w < targetWidth) {
w *= 2;
if (w > targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h < targetHeight) {
h *= 2;
if (h > targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(w, h, type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
tmp = null;
} while (w != targetWidth || h != targetHeight);
return ret;
}
}
製作的使用的JPanel所述面板
BufferedImage backgroundImage = ImageIO.read(...);
BackgroundPane backgroundPane = new BackgroundPane();
backgroundPane.setBackground(backgroundImage);
所述的面板，用背景圖片，帶有標籤和按鈕
backgroundPane.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
backgroundPane.add(new JLabel("This is a label"), gbc);
backgroundPane.add(new JButton("This is a button"), gbc);
記住，大多數部件是由默認的不透明，所以你可能需要使用setOpaque(false)，使之透明（JLabel是一個例外）
在某些時候，你需要將面板添加到基於窗口的類（如JFrame），因爲這是唯一的方式，您可以顯示它們
[有兩個例子，這將回答您的基本問題（http://stackoverflow.com/questions/22162398/how-to- set-a-background-picture-in-jpanel/22162430＃22162430） - 然後你只需要添加你想要展示給那些容器的東西。我會警惕'空'佈局 – MadProgrammer
請仔細閱讀答案，背景圖像的基本功能封裝在'JLabel'或'JPanel'中 - 然後顯示在'JFrame'內 - 因爲你無法顯示一個用戶界面 - 這是不可能的。但是，您可以創建一個[無邊界窗口]（https://docs.oracle.com/javase/tutorial/uiswing/misc/trans_shaped_windows.html），它可以讓您執行[this]（http：// stackoverflow。 COM /問題/ 11703794 /如何對設置的JFrame背景透明 - 丁JPanel的或 - JLabel的背景不透明/ 11705029＃11705029）或 – MadProgrammer
[本]（http://stackoverflow.com/questions/ 13557261 /爲什麼-的圖形 - 不出現功能於JFrame中/ 13557495＃13557495） – MadProgrammer