将JPanel Graphics导出为.png或.gif或.jpg
我正在尝试使用Java开发某种颜料。
我有一个位于JPanel内的JComponent。
我已经可以在该JComponent中绘制线条和矩形。
现在，如何将此图形导出为图像（png，gif，jpg）？
我试过这个：
BufferedImage b = new BufferedImage(1700,1100,BufferedImage.TYPE_INT_RGB); this.print(getGraphics()); try{ImageIO.write(b,"png",new File("test.png"));}catch (Exception e) {} 但这只会创建一个全黑的.png文件。
帮帮我！！！
解决！！！
BufferedImage bi = new BufferedImage(this.getSize().width, this.getSize().height, BufferedImage.TYPE_INT_ARGB); Graphics g = bi.createGraphics(); this.paint(g); //this == JComponent g.dispose(); try{ImageIO.write(bi,"png",new File("test.png"));}catch (Exception e) {}
首先， print()是不正确的方法。 我猜应该工作（尚未测试）是：获取BufferedImage的Graphics（ b.createGraphics() ）并使用该图形对象paint()您的面板/组件。
（例如yourPanel.paint(b.createGraphics()); ）
这是一个演示：
import javax.imageio.ImageIO; import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.image.BufferedImage; import java.io.File; import java.util.ArrayList; import java.util.List; @SuppressWarnings("serial") public class DrawGraph extends JPanel { private static final int PREF_W = 1000; private static final int PREF_H = 800; private static final int BORDER_GAP = 25; private static final int PADDING = 25; private static final Color GRAPH_COLOR = Color.green; private static final Color GRAPH_POINT_COLOR = new Color(100, 100, 100, 180); private static final Color GRID_COLOR = new Color(200, 200, 200, 200); private static final Stroke GRAPH_STROKE = new BasicStroke(3f); private static final int GRAPH_POINT_WIDTH = 4; private static final int Y_HATCH_CNT = 10; private List scores; public DrawGraph(List scores2) { this.scores = scores2; } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D)g; g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); double xScale = ((double) getWidth() - (2 * BORDER_GAP)-PADDING) / (scores.size() - 1); double yScale = ((double) getHeight() - (2 * BORDER_GAP)-PADDING) / (getMaxScore() - getMinScore()); List graphPoints = new ArrayList (); for (int i = 0; i < scores.size(); i++) { int x1 = (int) (i * xScale + BORDER_GAP + PADDING); int y1 = (int) ((getMaxScore() - scores.get(i)) * yScale + BORDER_GAP); graphPoints.add(new Point(x1, y1)); } g2.setColor(Color.WHITE); g2.fillRect(BORDER_GAP + PADDING, BORDER_GAP, getWidth() - (2 * BORDER_GAP) - PADDING, getHeight() - 2 * BORDER_GAP - PADDING); g2.setColor(Color.BLACK); g2.drawLine(BORDER_GAP + PADDING, getHeight() - BORDER_GAP - PADDING, BORDER_GAP + PADDING, BORDER_GAP); g2.drawLine(BORDER_GAP + PADDING, getHeight() - BORDER_GAP - PADDING, getWidth() - BORDER_GAP, getHeight() - BORDER_GAP - PADDING); for (int i = 0; i < Y_HATCH_CNT + 1; i++) { int x0 = BORDER_GAP + PADDING; int x1 = GRAPH_POINT_WIDTH + BORDER_GAP + PADDING; int y0 = getHeight() - ((i * (getHeight() - BORDER_GAP * 2 - PADDING)) / Y_HATCH_CNT + BORDER_GAP + PADDING); int y1 = y0; if (scores.size() > 0) { g2.setColor(GRID_COLOR); g2.drawLine(BORDER_GAP + PADDING + 1 + GRAPH_POINT_WIDTH, y0, getWidth() - BORDER_GAP, y1); g2.setColor(Color.BLACK); String yLabel = ((int) ((getMinScore() + (getMaxScore() - getMinScore()) * ((i * 1.0) / Y_HATCH_CNT)) * 100)) / 100.0 + ""; FontMetrics metrics = g2.getFontMetrics(); int labelWidth = metrics.stringWidth(yLabel); g2.drawString(yLabel, x0 - labelWidth - 5, y0 + (metrics.getHeight() / 2) - 3); } g2.drawLine(x0, y0, x1, y1); } for (int i = 0; i < scores.size(); i++) { if (scores.size() > 1) { int x0 = i * (getWidth() - BORDER_GAP * 2 - PADDING) / (scores.size() - 1) + BORDER_GAP + PADDING; int x1 = x0; int y0 = getHeight() - BORDER_GAP - PADDING; int y1 = y0 - GRAPH_POINT_WIDTH; if ((i % ((int) ((scores.size() / 20.0)) + 1)) == 0) { g2.setColor(GRID_COLOR); g2.drawLine(x0, getHeight() - BORDER_GAP - PADDING - 1 - GRAPH_POINT_WIDTH, x1, BORDER_GAP); g2.setColor(Color.BLACK); String xLabel = i + ""; FontMetrics metrics = g2.getFontMetrics(); int labelWidth = metrics.stringWidth(xLabel); g2.drawString(xLabel, x0 - labelWidth / 2, y0 + metrics.getHeight() + 3); } g2.drawLine(x0, y0, x1, y1); } } Stroke oldStroke = g2.getStroke(); g2.setColor(GRAPH_COLOR); g2.setStroke(GRAPH_STROKE); for (int i = 0; i < graphPoints.size() - 1; i++) { int x1 = graphPoints.get(i).x; int y1 = graphPoints.get(i).y; int x2 = graphPoints.get(i + 1).x; int y2 = graphPoints.get(i + 1).y; g2.drawLine(x1, y1, x2, y2); } g2.setStroke(oldStroke); g2.setColor(GRAPH_POINT_COLOR); for (int i = 0; i < graphPoints.size(); i++) { int x = graphPoints.get(i).x - GRAPH_POINT_WIDTH / 2; int y = graphPoints.get(i).y - GRAPH_POINT_WIDTH / 2;; int ovalW = GRAPH_POINT_WIDTH; int ovalH = GRAPH_POINT_WIDTH; g2.fillOval(x, y, ovalW, ovalH); } } @Override public Dimension getPreferredSize() { return new Dimension(PREF_W, PREF_H); } private double getMinScore() { double minScore = Double.MAX_VALUE; for (Double score : scores) { minScore = Math.min(minScore, score); } return minScore; } private double getMaxScore() { double maxScore = Double.MIN_VALUE; for (Double score : scores) { maxScore = Math.max(maxScore, score); } return maxScore; } public static void createAndShowGui(ArrayList scores, String s) { DrawGraph mainPanel = new DrawGraph(scores); JFrame frame = new JFrame(s); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(mainPanel); frame.getContentPane().add(new JButton(new AbstractAction("Save Image") { @Override public void actionPerformed(ActionEvent e) { mainPanel.saveImage(new File("graph.png")); } }),BorderLayout.SOUTH); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } public void saveImage(File file){ BufferedImage bi = new BufferedImage(this.getSize().width, this.getSize().height, BufferedImage.TYPE_INT_ARGB); Graphics g = bi.createGraphics(); this.paint(g); g.dispose(); try{ ImageIO.write(bi,"png",file); }catch (Exception e) { e.printStackTrace(); } } public static void main(String args[]) { final ArrayList inputValues = new ArrayList (); inputValues.add(1d); inputValues.add(2d); // Read input values from text document and store in ArrayList SwingUtilities.invokeLater(new Runnable() { public void run() { DrawGraph.createAndShowGui(inputValues, "MyGraphTitle"); } }); } }
你可以自己改变它。