Android中使用log4j

 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： 
 

Java代码  

1. package com.android.myapp;  
2.    
3. .  
4. import java.io.File;  
5.    
6.   
7. import org.apache.log4j.Level;  
8.    
9.   
10. import org.apache.log4j.Logger;  
11. .  
12. import android.app.Application;  
13.    
14.   
15. import android.os.Environment;  
16.    
17.   
18. import de.mindpipe.android.logging.log4j.LogConfigurator;  
19.  .  
20.    
21. public class MyApplication extends Application {  
22.    
23.   
24.         @Override  
25.    
26.   
27.         public void onCreate() {  
28.    
29.   
30.                 super.onCreate();  
31.    
32.   
33.                 LogConfigurator logConfigurator = new LogConfigurator();  
34.    
35.   
36.                 logConfigurator.setFileName(Environment.getExternalStorageDirectory()  
37.    
38.   
39.                                 + File.separator + "MyApp" + File.separator + "logs"  
40.    
41.   
42.                                 + File.separator + "log4j.txt");  
43.    
44.   
45.                 logConfigurator.setRootLevel(Level.DEBUG);  
46.    
47.   
48.                 logConfigurator.setLevel("org.apache", Level.ERROR);  
49.    
50.   
51.                 logConfigurator.setFilePattern("%d %-5p [%c{2}]-[%L] %m%n");  
52.    
53.   
54.                 logConfigurator.setMaxFileSize(1024 * 1024 * 5);  
55.    
56.   
57.                 logConfigurator.setImmediateFlush(true);  
58.    
59.   
60.                 logConfigurator.configure();  
61.    
62.   
63.                 Logger log = Logger.getLogger(MyApplication.class);  
64.    
65.   
66.                 log.info("My Application Created");  
67.    
68.   
69.         }  
70.    
71.   
72. }  

     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。