java.lang.OutOfMemory错误：

我正在尝试根据从数据库检索的字节创建视频文件。该程序在几个小时前就运行良好。上传大文件后，当我尝试检索它时，它会产生错误java.lang.OutOfMemoryError:

我的代码是：

    conn = prepareConnection();
    StringBuilder sb=new StringBuilder(1024);
    sb.append("select videoname,videoid,videofull from ").append(uname.trim()).append("video");
    String sql=sb.toString();

    stmt = conn.prepareStatement(sql);
    ResultSet rs = stmt.executeQuery();

    while(rs.next()){
         byte[] videoData = rs.getBytes("videofull");       //#57
         int vid=rs.getInt("videoid");
         StringBuilder sb1 = new StringBuilder();
         sb1.append(vid);
         String videoid=sb1.toString();
         String vname=rs.getString("videoname");
         File file=new File("C:/Users/JamesPJ/Documents/skypark/skypark/WebContent/sp/resources/videos/"+vname+""+videoid+".mp4");

        if(file.exists() && !file.isDirectory()){
            continue;
        }
        else
        {
         FileOutputStream output = new FileOutputStream(file);
         IOUtils.write(videoData, output);
         output.close();
        }
       }
    request.setAttribute("uname", uname);
    RequestDispatcher dispatcher = request.getRequestDispatcher("/VideoList");
    if(dispatcher != null) {
        dispatcher.forward(request, response);
    } 

控制台输出为：

Exception in thread "http-bio-8080-exec-3" java.lang.OutOfMemoryError: Java heap space
at oracle.sql.BLOB.getBytes(BLOB.java:217)
at oracle.jdbc.driver.T4CBlobAccessor.getBytes(T4CBlobAccessor.java:462)
at oracle.jdbc.driver.OracleResultSetImpl.getBytes(OracleResultSetImpl.java:716)
at oracle.jdbc.driver.OracleResultSet.getBytes(OracleResultSet.java:402)
at skypark.VideoFileCreator.doGet(VideoFileCreator.java:57)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:487)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
at skypark.VideoStream.processRequest(VideoStream.java:48)
at skypark.VideoStream.doGet(VideoStream.java:64)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:931)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

请任何人告诉我这个错误说明了什么。我需要纠正什么......谢谢......

Here,

byte[] videoData = rs.getBytes("videofull");

您将整个文件内容存储在服务器的内存中。你知道，一个字节byte[]占用 Java 内存的一个字节。如果你有例如只有 500MB 内存而文件超过 500MB，那么你就会得到这个错误。请注意，当 10 个用户同时请求 50MB 的视频文件时，您也会获得它。因此，按照其他答案的建议增加 Java 内存只是一个临时解决方案，并没有经过深思熟虑。

你需要以一种味道来获得它InputStream相反，这样只会在内部分配几个（千）字节作为内存中的流缓冲区，而不是整个文件内容。

InputStream videoData = rs.getBinaryStream("videofull");

并将其写入所需的输出流IOUtils#copy()相反（不要忘记在最后关闭它们！）。

FileOutputStream output = new FileOutputStream(file);
try {
    IOUtils.copy(videoData, output);
} finally {
    IOUtils.closeQuietly(output);
    IOUtils.closeQuietly(videoData);
}