java - 在记录的消息中逐字打印单引号参数

Question

我正在尝试使用 java.util.logging.Logger.log(Level, String) 方法将一些参数打印到控制台中。但参数总是被逐字打印:

package loggertest;

import java.util.logging.Level;
import java.util.logging.Logger;

public class LoggerTest {
   public static void main(String[] args) {
      final Logger LOGGER = Logger.getLogger(LoggerTest.class.getName());

      LOGGER.log(Level.INFO, "Some info: {0}.", "foo");
      LOGGER.log(Level.INFO, "Some quoted info: '{0}'.", "foo");
   }
}

当我在 Netbeans 中运行此命令时，输出为:

Jan 17, 2017 12:13:43 PM loggertest.LoggerTest main
INFO: Some info: foo.
Jan 17, 2017 12:13:43 PM loggertest.LoggerTest main
INFO: Some quoted info: {0}.

显然，当我们在单引号内使用参数(即 '{0}')时，它们会逐字打印。为什么会发生这种情况以及如何解决这个问题？

Answer 1

出现这个问题的原因是java.text.MessageFormat是 being used .

引用MessageFormat:

Within a String, a pair of single quotes can be used to quote any arbitrary characters except single quotes. For example, pattern string "'{0}'" represents string "{0}", not a FormatElement. A single quote itself must be represented by doubled single quotes '' throughout a String.

所以，解决方法是这样的:

LOGGER.log(Level.INFO, "Some correctly quoted info: ''{0}''.", "foo");

这将打印:

Jan 17, 2017 12:37:58 PM loggertest.LoggerTest main
INFO: Some correctly quoted info: 'foo'.