设置

感谢您的回复。

自从您告诉我以来，我一直在尝试发短信。从某种意义上说，它仍然不起作用：现在不再抛出该异常，而是出于某种原因创建了空白图像。

所以我从这里出发：

public BarChartGenerator(org.qcri.power.ws.client.Server oServer, ServerStatistics oServerStat, List lVMs, String path) extends Applicationframe {        System.setProperty("java.awt.headless", "true");        boolean headless = GraphicsEnvironment.isHeadless();        System.out.println("Headless: " + headless);        Toolkit tk = Toolkit.getDefaultToolkit();        tk.beep();        // generate dataset        final CategoryDataset dataset = createDataset(lVMs);        setChart(createChart(oServer, oServerStat, lVMs, dataset));        // create PNG of the chart...        setFilename("chart_server"+oServer.getHost()+"_"+System.currentTimeMillis()+".gif");        File fImageFile = new File(path+filename);        try { ChartUtilities.saveChartAsPNG(fImageFile, chart, PowerInterface.CHART_WIDTH, PowerInterface.CHART_HEIGHT);        } catch (Exception e) { e.printStackTrace();        }   }

以下内容（摆脱

extends Applicationframe

public BarChartGenerator(org.qcri.power.ws.client.Server oServer, ServerStatistics oServerStat, List lVMs, String path) {        System.setProperty("java.awt.headless", "true");        boolean headless = GraphicsEnvironment.isHeadless();        System.out.println("Headless: " + headless);        Toolkit tk = Toolkit.getDefaultToolkit();        tk.beep();        // generate dataset        final CategoryDataset dataset = createDataset(lVMs);        setChart(createChart(oServer, oServerStat, lVMs, dataset));        // create PNG of the chart...        setFilename("chart_server"+oServer.getHost()+"_"+System.currentTimeMillis()+".gif");        try { BufferedImage bufferedImage = getChart().createBufferedImage(PowerInterface.CHART_WIDTH, PowerInterface.CHART_HEIGHT); ImageIO.write(bufferedImage, "gif", new FileOutputStream(path+getFilename()));        } catch (Exception e) { e.printStackTrace();        }   }

在日志中，它抱怨

ImageIO.write(bufferedImage, "gif", newFileOutputStream(path+getFilename()));

javax.imageio.IIOException: Can't create output stream!        at javax.imageio.ImageIO.write(ImageIO.java:1560)        at org.qcri.power.util.BarChartGenerator.<init>(BarChartGenerator.java:106)

有什么线索吗？