java - 在字符串变量中获取消息 myLogger.log(e)

Question

我想在字符串变量中获取此方法 myLogger.log(e) 的输出，以便能够使用 Junit 进行测试。

myLogger.log(e);
String s= ????
assertEqual(expected,s);

Answer 1

您可以编写一个写入 StringWriter 的 log4j appender。看看这个帖子：

如何将 log4j 输出读取到网页？

Answer 2

You can add an additional Appender to your Logger. Use a WriterAppender to write to a StringWriter then you change the content of your TextArea to the value of StringWriter#toString()

public static void main(String[] args) {
    Logger logger = Logger.getLogger("logger");
    Layout layout = new PatternLayout();
    StringWriter stringWriter = new StringWriter();
    WriterAppender writerAppender = new WriterAppender(layout, stringWriter);
    logger.addAppender(writerAppender);

    logger.error("test");
    String string = stringWriter.toString();
    System.out.println(string);
  }

as described here.