java - log4j将标准输出重定向到DailyRollingFileAppender

我有一个使用log4j的Java应用程序。

配置:

log4j.rootLogger=info, file

log4j.appender.file=org.apache.log4j.DailyRollingFileAppender
log4j.appender.file.File=${user.home}/logs/app.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d [%t] %c %p %m%n

因此，所有日志语句都正确地附加到了文件中，但是我丢失了stdout和stderr。如何将异常堆栈跟踪和sysouts重定向到每日滚动文件？

最佳答案

// I set up a ConsoleAppender in Log4J to format Stdout/Stderr
log4j.rootLogger=DEBUG, CONSOLE
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=[%t] %-5p %c - %m%n


// And I call this StdOutErrLog.tieSystemOutAndErrToLog() on startup

public class StdOutErrLog {

    private static final Logger logger = Logger.getLogger(StdOutErrLog.class);

    public static void tieSystemOutAndErrToLog() {
        System.setOut(createLoggingProxy(System.out));
        System.setErr(createLoggingProxy(System.err));
    }

    public static PrintStream createLoggingProxy(final PrintStream realPrintStream) {
        return new PrintStream(realPrintStream) {
            public void print(final String string) {
                realPrintStream.print(string);
                logger.info(string);
            }
        };
    }
}