System.setErr() 在 stderr 关闭后不恢复控制台日志记录

Question

我的应用程序使用 System.setErr() to change stderr to a stream which will eventually be closed. Immediately after it's closed I immediately use System.setErr() again to change stderr to a working stream, which goes fine for when my code does something like System.err.println(), but logging with java.util.logging 到控制台（即，到 stderr）不再有效。

Answer 1

为了解决这个问题，我不得不 re-read the logging configuration file and then put back in the console logging handler 自己：

import java.util.logging.ConsoleHandler;
import java.util.logging.Loggger;
import java.util.logging.LogManager;

...

System.setErr(otherStream);

try {
    LogManager.getLogManager().readConfiguration();
}
catch(java.io.IOException e) {
    // ...
}

Logger.getGlobal().addHandler(new ConsoleHandler());

Answer 2

ConsoleHandler 在构造期间捕获对 System.err 的引用。另一种解决方案是替换日志树中的所有 ConsoleHandler。

    LogManager m = LogManager.getLogManager();
    synchronized (m) {
        Enumeration<String> names = m.getLoggerNames();
        while (names.hasMoreElements()) {
            Logger logger = m.getLogger(names.nextElement());
            if (logger != null) {
                for (Handler h : logger.getHandlers()) {
                    if (h.getClass() == ConsoleHandler.class) {
                        logger.removeHandler(h);
                        h.close();
                        logger.addHandler(new ConsoleHandler());
                    }
                }
            }
        }
    }

Answer 3

System.err.println("This is written to stderr");

// this is stderr
PrintStream oldErr = System.err;

try {
    System.setErr(new PrintStream(new File("/path/to/file")));
} catch(Exception e) {
}


System.err.println("This is written to the file");

// note that System.err wouldn't work here because System.err is no longer stderr
// but you preserved stderr in oldErr
try {
    System.setErr(oldErr);
} catch(Exception e) {
}

System.err.println("This is written to stderr again");

System.setErr() 在 stderr 关闭后不恢复控制台日志记录

System.setErr() doesn't restore console logging after stderr closed

java

logging

stderr

java.util.logging