問題描述

　　將打包好的war部署到linux伺服器上，發現驗證碼部分一直顯示不出來。後來看了日誌：

22-May-2018 18:51:59.813 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in 1838 ms
java.io.IOException: An exception occurred processing [/headBar/makeCertPic.jsp] at line [73]

70:     // 將認證碼存入SESSION
71:     session.setAttribute("certCode"
 
, sRand.toString());
72:     g.dispose();
73:     ImageIO.write(image, "JPEG", response.getOutputStream());
74: %>


Stacktrace:
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:472)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330
 
)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53
 
)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at filter.UserFilter.doFilter(UserFilter.kt:46)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:407)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1376)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)
Caused by: javax.imageio.IIOException: Can't create output stream!
    at javax.imageio.ImageIO.write(ImageIO.java:1574)
    at org.apache.jsp.headBar.makeCertPic_jsp._jspService(makeCertPic_jsp.java:193)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:444)
    ... 28 more
Caused by: javax.imageio.IIOException: Can't create cache file!
    at javax.imageio.ImageIO.createImageOutputStream(ImageIO.java:423)
    at javax.imageio.ImageIO.write(ImageIO.java:1572)
    ... 32 more
Caused by: java.nio.file.NoSuchFileException: /home/wangyu/Android/apache-tomcat-9.0.6/temp/imageio138834226394495527.tmp
    at sun.nio.fs.UnixException.translateToIOException(UnixException.java:86)
    at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
    at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
    at sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:214)
    at java.nio.file.Files.newByteChannel(Files.java:361)
    at java.nio.file.Files.createFile(Files.java:632)
    at java.nio.file.TempFileHelper.create(TempFileHelper.java:138)
    at java.nio.file.TempFileHelper.createTempFile(TempFileHelper.java:161)
    at java.nio.file.Files.createTempFile(Files.java:897)
    at javax.imageio.stream.FileCacheImageOutputStream.<init>(FileCacheImageOutputStream.java:88)
    at com.sun.imageio.spi.OutputStreamImageOutputStreamSpi.createOutputStreamInstance(OutputStreamImageOutputStreamSpi.java:68)
    at javax.imageio.ImageIO.createImageOutputStream(ImageIO.java:419)
    ... 33 more

解決方法

　　主要原因是因為ImageIO需要預設需要有一個資料夾作為緩衝（預設是寫入到tomcat/temp資料夾下），而tomcat預設是不會建立temp資料夾的，所以需要我們手動建立temp資料夾。

其他方法1

　　通過ImageIO.setCacheDirectory(cacheDirectory);設定任意的、存在的快取目錄。

其他方法2

　　ImageIO預設是使用快取目錄，可以通過ImageIO.setUseCache(false)來設定，更改快取策略，不使用檔案目錄快取，使用記憶體快取。

其他方法3

　　不使用ImageIO，換成其它JDK方法。將ImageIO.write(bi, "jpg", os);換成：

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(response.getOutputStream()); 
encoder.encode(image);

附錄

• javax.imageio.IIOException: Can’t create output stream解決方法