Java 将blob图像从数据库显示到jlabel中
我试图显示数据库中的图像,该图像存储为longblob。上面写着空指针,我不知道怎么了 该表有两列(用户名、图像)Java 将blob图像从数据库显示到jlabel中,java,mysql,blob,bufferedimage,javax.imageio,Java,Mysql,Blob,Bufferedimage,Javax.imageio,我试图显示数据库中的图像,该图像存储为longblob。上面写着空指针,我不知道怎么了 该表有两列(用户名、图像) 图像=表名, 图像=列名, displayPhoto=JLabel 有人能帮我吗? 提前感谢申请rs.next();在try-and-catch块之前,请将指针移动到数据库中的第一条记录。能否详细说明是哪一部分为您提供了NullPointerException?是ImageIO.read吗?您的图像列是否定义为非空?否则,您应该在尝试读取之前测试null。另外,在尝试显示之前,您应
图像=表名,
图像=列名,
displayPhoto=JLabel
有人能帮我吗?
提前感谢申请rs.next();在try-and-catch块之前,请将指针移动到数据库中的第一条记录。能否详细说明是哪一部分为您提供了
NullPointerException
?是ImageIO.read吗?您的图像
列是否定义为非空
?否则,您应该在尝试读取之前测试null
。另外,在尝试显示之前,您应该测试im
是否为null
,因为ImageIO
无法神奇地将任何类型的blob转换为BufferedImage
。我编辑了文章,包含了错误消息。图像列定义为非空,则数据类型为longblob您希望解决什么问题?NullPoniterException
消失,或者理解为什么ImageIO无法读取blob中的数据?第一个是琐碎的,不适合这样做。第二个部分需要更多的输入(即,遇到NPE时blob的内容是什么?)。如何读取我的blob中的数据(图像)并将其显示到jlabel中
java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:228)
at MyProfile.displayPhoto(MyProfile.java:395)
at MyProfile.<init>(MyProfile.java:195)
at Login.actionPerformed(Login.java:93)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:228)
at MyProfile.displayPhoto(MyProfile.java:395)
at MyProfile.<init>(MyProfile.java:195)
at Login.actionPerformed(Login.java:93)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
try {
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/login", "root", "obierofelix");
stmt = con.createStatement();
rs = stmt.executeQuery("select * from images");
rs.next();
BufferedImage im = ImageIO.read(rs.getBinaryStream("Image"));
BackGroundImage.setIcon(new ImageIcon(im));
} catch (Exception err) {
JOptionPane.showMessageDialog(this, err.getMessage());
}