Android 如何使用log4j及注意事项

 Android 使用log4j

前言：

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：

<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"); 

    } 

}

现在日志则是以：

Environment.getExternalStorageDirectory() + File.separator + "MyApp" + File.separator + "logs" + File.separator + "log4j.txt
   的方式保存了。其他和log4j的用法差不多了。

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