log4j 屏蔽掉 System.out

	Logger logger = Logger.getLogger(Log4jTest.class);

	

	public void testSystemout(){

		System.out.println("can print syso");

		logger.info("log4j test");

	}

	public static class LoggerHiddenSystemOutPrintStream extends PrintStream{

		private Logger logger;

		public LoggerHiddenSystemOutPrintStream() {

			super(new ByteArrayOutputStream(0));

			logger = Logger.getLogger(LoggerHiddenSystemOutPrintStream.class);

		}

		

		@Override

		public void println(String x) {

			logger.debug(x);

		}	

		

	}

	@Test

	public void hiddenSys(){

		System.setOut(new LoggerHiddenSystemOutPrintStream());

		testSystemout();

	}

把这段代码放到  一个junit类中，即可测试了。运用log4j  level屏蔽掉  System.out 输出