How to verify the Log4j output?

log錯誤是一種錯誤回報的例外處理機制。當功能的測試案例寫完後，就是要開始針對有問題的案例撰寫單元測試。

private StringBuffer mSB;
private StringBufferOutputStream mSBOutputStream;
private WriterAppender testAppender;
 
@Before
public void setUp() throws Exception {
	mSB = new StringBuffer();
	mSBOutputStream =  new StringBufferOutputStream(mSB);
 
	Writer w = new OutputStreamWriter(mSBOutputStream);
	testAppender = new WriterAppender();
	testAppender.setLayout(new PatternLayout(PatternLayout.DEFAULT_CONVERSION_PATTERN));
	testAppender.setName("test");
	testAppender.activateOptions();
	testAppender.setWriter(w);
 
	LogManager.getLogger(TimeWatcherBuilder.class).addAppender(testAppender);
}

@After
public void teardown() throws SchedulerException{
	LogManager.getLogger(TimeWatcherBuilder.class).removeAppender(testAppender);
}

• How to redirect the outputstream or writer to loggers writers?