如果要直接在android工程中使用log4j，是有点问题的，会报如下的错：
11-23 09:44:56.947: D/dalvikvm(1585): GC_FOR_MALLOC freed 3278 objects / 311568 bytes in 31ms
rejecting opcode 0x21 at 0x000a
rejected Lorg/apache/log4j/config/PropertySetter;.getPropertyDescriptor
(Ljava/lang/String;)Ljava/beans/PropertyDescriptor;
Verifier rejected class Lorg/apache/log4j/config/PropertySetter;
Exception Ljava/lang/VerifyError; thrown during Lorg/apache/log4j/LogManager;.
Shutting down VM
threadid=1: thread exiting with uncaught exception (group=0x400259f8)
FATAL EXCEPTION: main
java.lang.ExceptionInInitializerError
at org.slf4j.impl.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:64)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:253)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:265)
...
Caused by: java.lang.VerifyError: org.apache.log4j.config.PropertySetter
at org.apache.log4j.PropertyConfigurator.parseAppender(PropertyConfigurator.java:772)
at org.apache.log4j.PropertyConfigurator.parseCategory(PropertyConfigurator.java:735)
at org.apache.log4j.PropertyConfigurator.configureRootCategory(PropertyConfigurator.java:615)
at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:502)
at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:547)
at org.apache.log4j.helpers.OptionConverter.selectAndConfigure(OptionConverter.java:483)
at org.apache.log4j.LogManager.(LogManager.java:127)
... 20 more
因此，可以另外多下载一个叫android-logging-log4j的项目，地址在：
http://code.google.com/p/android-logging-log4j/downloads/list，注意，原本的log4j还是需要的。
在AndroidManifest.xml中，增加如下设置：
然后在程序中如下使用：