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