我正在尝试在 Android 项目上使用 log4j2 (我正在 Android Studio 上工作)。
为了简化这个问题,我将解释我在一个简单的虚拟项目中所做的事情(我在真实项目中遇到的错误与这个虚拟项目中的错误相同)。
我创建了一个带有主要活动的简单虚拟项目。
我添加了 log4j2 库...
这是等级:
apply plugin: 'com.android.application'
android {
packagingOptions {
exclude 'META-INF/LICENSE'
exclude 'META-INF/NOTICE'
}
compileSdkVersion 21
buildToolsVersion "21.1.2"
defaultConfig {
applicationId "com.example.test20150130"
minSdkVersion 19
targetSdkVersion 21
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:21.0.3'
compile 'com.android.support:support-v4:21.0.3'
compile group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.1'
compile group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.1'
}
我已将 log4j2.xml 缩减为:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="debug">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<ThresholdFilter level="ALL" onMatch="ACCEPT" onMismatch="DENY"/>
<PatternLayout pattern="%m%n" />
</Console>
</Appenders>
<Loggers>
<root level="INFO">
<AppenderRef ref="Console"/>
</root>
<logger name="Queries" level="ALL" additivity="false">
<AppenderRef ref="Console"/>
</logger>
</Loggers>
在活动中,我导入库...
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
但是当我尝试使用它们时......
Logger logger= LogManager.getLogger ("Queries");
logger.error ("It works...");
我在 'Logger logger= LogManager.getLogger ("Queries");' 上遇到错误
01-30 00:49:29.413 1685-1685/com.example.test20150130 E/AndroidRuntime? FATAL EXCEPTION: main
Process: com.example.test20150130, PID: 1685
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test20150130/com.example.test20150130.MainScreenActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at org.apache.logging.log4j.util.ReflectionUtil$PrivateSecurityManager.getCallerClass(ReflectionUtil.java:301)
at org.apache.logging.log4j.util.ReflectionUtil.getCallerClass(ReflectionUtil.java:214)
at org.apache.logging.log4j.util.ReflectionUtil.getCallerClass(ReflectionUtil.java:193)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.getContext(ClassLoaderContextSelector.java:72)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:195)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:41)
at org.apache.logging.log4j.LogManager.getContext(LogManager.java:160)
at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:492)
at com.example.test20150130.MainScreenActivity.delayedHide(MainScreenActivity.java:162)
at com.example.test20150130.MainScreenActivity.onPostCreate(MainScreenActivity.java:129)
at android.app.Instrumentation.callActivityOnPostCreate(Instrumentation.java:1150)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2178)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
我不确定 log4j2.xml 文件应该在哪里,所以我把它放在 \src、\src\main\java\com\example\test20150130 (与主活动相同的目录)、Test20150130\app\ 上build\outputs\apk(与 apk 相同的目录),...
由于错误信息,我在各处尝试了 getLogger:最初在 onCreate 上,然后,我将其放在 onClick 事件上,但我得到了相同的错误。
(当我调试它时,我看到的源与实际执行不符......)
我已经在 Android 项目上使用了 log4j,但我刚刚将 Java EE 项目迁移到 log4j2,并且我想在 Android 项目上执行相同的操作...
log4j2 文档中有关 Android 的信息很少。它只是说有几个模块无法在 Android 上运行(JNDI、JMX...),但没有其他...
也许它内部需要这些模块(JNDI?)...
寻找信息,我创立了这个(https://issues.apache.org/jira/browse/LOG4J2-446?jql=project%20%3D%20LOG4J2%20AND%20text%20~%20android)但我没有找到解决方案......
可以在Android上使用log4j2吗?
预先非常感谢