如何配置 log4j2 以记录具有警告级别的"我的异常"错误

Question

如何配置 log4j (v 2( 以使用 WARN 级别记录MyException错误？

请参阅引发 MyException 异常的代码 (rxjava( 示例

return map.get(id).toObservable()
.filter(Objects::nonNull)
.switchIfEmpty(Observable.error(new MyException("Happens")))
.toSingle();

这是由log4j配置捕获的，现在最终达到ERROR级别。

Answer 1

作为参考，我在评论中包含您提供的信息：

我想避免在 rx-flow 中使用 log.error 或 log.warn 的显式逻辑，而是定义可在 logj4 或其他地方配置的异常层次结构，以将哪些异常分别映射到日志级别

下面是一个非常快速的示例，说明如何执行此操作：

package example;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
public class SomeClass {
private static final Logger log = LogManager.getLogger();
//Quick and dirty way to generate a map of exceptions to their log levels. Replace this with whatever method of configuration you prefer.
public static Map<String,String> getExceptionLvlMap(){
Map<String,String> exceptionToLvlMap = new HashMap<>();
exceptionToLvlMap.put("java.io.IOException", "WARN");
exceptionToLvlMap.put("java.lang.NullPointerException", "FATAL");
return exceptionToLvlMap;
}
public static void main(String[] args){
Map<String, String> lvlMap = getExceptionLvlMap();
try {
someOperation();
} catch (IOException e) {
log.log(Level.getLevel(lvlMap.get(e.getClass().getName())), "Something bad happened!", e);
}
try{
anotherOperation();
}catch(Throwable t){
log.log(Level.getLevel(lvlMap.get(t.getClass().getName())), "Something crazy happened!", t);
}
}
public static void someOperation() throws IOException{
throw new IOException("It's an IOException!");
}
public static void anotherOperation(){
String x = null;
//Generate a NPE
x.equals("foo");
}
}

log4j2.xml 配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
</Console>

</Appenders>
<Loggers>
<Root level="debug">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>

输出：

23:24:50.217 [main] WARN  example.SomeClass - Something bad happened!
java.io.IOException: It's an IOException!
at example.SomeClass.someOperation(SomeClass.java:40) ~[classes/:?]
at example.SomeClass.main(SomeClass.java:27) [classes/:?]
23:24:50.221 [main] FATAL example.SomeClass - Something crazy happened!
java.lang.NullPointerException: null
at example.SomeClass.anotherOperation(SomeClass.java:45) ~[classes/:?]
at example.SomeClass.main(SomeClass.java:33) [classes/:?]