logging - log4j-2 中的 ConsoleAppender.setWriter 等价物是什么
问题描述
我正在尝试从 log4j-1.2 迁移到 log4j-2
log4j-2 中以下几行的等价物是什么?
import org.apache.log4j.ConsoleAppender;
import org.apache.log4j.Logger;
import org.apache.log4j.PatternLayout;
public static final Logger s_logger = Logger.getLogger(x.class);
ConsoleAppender ca = new ConsoleAppender();
ca.setWriter(new OutputStreamWriter(System.out, "UTF-8"));
ca.setLayout(new PatternLayout("%-5p [%t]: %m%n"));
s_logger.addAppender(ca);
我无法在 Apache 文档中找到答案。
解决方案
在 Log4j2 中,您的代码有两个主要变化:
- Log4j2 分为 API 和实现,因此 an
org.apache.logging.log4j.Logger
不一定是org.apache.logging.log4j.core.Logger
, - 组件是使用构建器模式创建的,没有设置器。
您的代码最接近的等效项使用WriterAppender
:
Logger logger = LogManager.getLogger();
if (logger instanceof org.apache.logging.log4j.core.Logger) {
StringLayout layout = PatternLayout.newBuilder().withPattern("%-5p [%t]: %m%n").build();
OutputStreamWriter writer = new OutputStreamWriter(System.out, StandardCharsets.UTF_8);
Appender appender = WriterAppender.newBuilder().setTarget(writer).setLayout(layout).build();
((org.apache.logging.log4j.core.Logger) logger).addAppender(appender);
}
ConsoleAppender
仅限于使用或System.out
使用System.err
默认系统编码:
Logger logger = LogManager.getLogger();
if (logger instanceof org.apache.logging.log4j.core.Logger) {
StringLayout layout = PatternLayout.newBuilder().withPattern("%-5p [%t]: %m%n").build();
Appender appender = ConsoleAppender.newBuilder().setTarget(Target.SYSTEM_OUT).setLayout(layout).build();
((org.apache.logging.log4j.core.Logger) logger).addAppender(appender);
}
上面的代码示例使用这些导入:
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.StringLayout;
import org.apache.logging.log4j.core.appender.ConsoleAppender;
import org.apache.logging.log4j.core.appender.ConsoleAppender.Target;
import org.apache.logging.log4j.core.appender.WriterAppender;
import org.apache.logging.log4j.core.layout.PatternLayout;