Android 使用log4j

前言：

 如果要直接在android工程中使用log4j，是有點問題的，會報如下的錯：

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，可以另外多下載一個叫android-logging-log4j的項目，地址在：

http://code.google.com/p/android-logging-log4j/downloads/list，注意，原本的log4j還是需要的。

  在AndroidManifest.xml中，增加如下設置：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 

   然后在程序中如下使用：  

package com.android.myapp;   . import java.io.File;    import org.apache.log4j.Level;    import org.apache.log4j.Logger; . import android.app.Application;    import android.os.Environment;    import de.mindpipe.android.logging.log4j.LogConfigurator;  .   public class MyApplication extends Application {        @Override        public void onCreate() {            super.onCreate();            LogConfigurator logConfigurator = new LogConfigurator();            logConfigurator.setFileName(Environment.getExternalStorageDirectory()                    + File.separator + "MyApp" + File.separator + "logs"                    + File.separator + "log4j.txt");            logConfigurator.setRootLevel(Level.DEBUG);            logConfigurator.setLevel("org.apache", Level.ERROR);            logConfigurator.setFilePattern("%d %-5p [%c{2}]-[%L] %m%n");            logConfigurator.setMaxFileSize(1024 * 1024 * 5);            logConfigurator.setImmediateFlush(true);            logConfigurator.configure();            Logger log = Logger.getLogger(MyApplication.class);            log.info("My Application Created");        }    }