#眉標=Maven2、GWT、Log
#大標=從架構師的觀點學開發（3）
#副標=日誌非萬能，但沒有日誌的開發萬萬不能!
#作者=文／圖		盧建州



==<box>===========
設定1：pom.xml

...以上省略...
<properties>
  <gwt.log.version>2.5.3</gwt.log.version>
  <log4j.version>1.2.14</log4j.version>
</properties>

<dependencies>
  <dependency>
    <groupId>com.google.code.gwt-log</groupId>
    <artifactId>gwt-log</artifactId>
    <version>${gwt.log.version}</version>
  </dependency>
  <dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>${log4j.version}</version>
  </dependency>
</dependencies>
...以下省略... 

==<end>==============





==<box>===========
設定2：DemoApp.gwt.xml

...以上省略...
<inherits
 name="com.allen_sauer.gwt.log.gwt-log-DEBUG" />
<set-property
 name="log_RemoteLogger" value="DISABLED" />
<set-property
 name="log_DivLogger" value="ENABLED" />
...以下省略... 
==<end>==============





==<box>===========
設定3：web.xml

<servlet>
  <servlet-name>
    gwt-log-remote-logger-servlet
  </servlet-name>
  <servlet-class>
    com.allen_sauer.gwt.log.server
      .RemoteLoggerServiceImpl
  </servlet-class>
</servlet>

<servlet-mapping>
  <servlet-name>
    gwt-log-remote-logger-servlet
  </servlet-name>
  <url-pattern>
    /demo.gwt.DemoApp/gwt-log
  </url-pattern>
</servlet-mapping> 
==<end>==============






==<box>===========
設定4：log4j.properties
log4j.rootCategory=ERROR, stdout, fileout

# Stdout Logger
log4j.appender.stdout=
  org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=
  org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=
  %d{ISO8601} [%-5p][%c{1}]  %m%n

# Fileout Logger
log4j.appender.fileout=
  org.apache.log4j.DailyRollingFileAppender
log4j.appender.fileout.layout=
  org.apache.log4j.PatternLayout
log4j.appender.fileout.layout.ConversionPattern=
  %d{ISO8601} [%-5p][%c{1}]  %m%n
log4j.appender.fileout.DatePattern=
  .yyyy-MM-dd
log4j.appender.fileout.File=
  trace.log 

==<end>==============






==<box>===========
程式1：Debug與Info應用時機

01 public class LoginManager {
02   public User login(String name, String pwd)
03     throws ManagerException{
04     ...中間省略...
05     try{
06       //取得使用者
07       user = dao.retrieveUser(name);
08       Log.debug("Retrieve User:"+user);
09       //驗證密碼
10       if(!user.getPassword().equals(pwd))
11           throw new ManagerException(
12             "User Password incorrect!!!");
13       Log.info(
14         "User["+
15         user.getName()+
16         "] Login Success~~");
17     }catch(DaoException e){
18       Log.info(
19         "Retrieve User Error:"+
20         e.getMessage());
21       throw new ManagerException(e);
22     }
23     return user;
24   }
25 } 
==<end>==============





==<box>===========
程式2：Warn與Fatal應用時機

01 public class UserDao {
02   ...中間省略...  
03   public User retrieveUser(String name)
04     throws DaoException{
05     ...中間省略...
06     try{
07         //...處理某些資料作業...
08     if(!connectStatus)
09       throw new DaoException(
10         "DataSource Connect Failure");
11     }catch(Exception e){
12       Log.warn(e.getMessage());
13       try{
14         dataSourceReConnect();
15         Log.info(
16           "DataSource ReConnect Success!!");
17         retrieveUser(name);
18       }catch(RuntimeException re){
19         Log.fatal(
20           "System Fatal:"+e.getMessage());
21         throw re;
22       }
23     }
24     ...中間省略...    
25   }
26   
27   private void dataSourceReConnect(){
28     //模擬丟出RuntimeException
29     if(demoFatalFlag)
30       throw
31         new DataSourceFailureException(
32           "DataBase Server Failure~~");
33     else
34       connectStatus = true;
25   }
36 }
==<end>==============





==<box>===========
程式3：Error應用時機

01 public class UserDao {
02   ...中間省略...    
03   public User retrieveUser(String name)
04     throws DaoException{
05     ...中間省略...    
06     try{
07       int[] datas = {0,1,2};
08       int data;
09         if(demoErrorFlag)
10           data = datas[3]; //錯誤索引值
11     }catch(RuntimeException re){
12       Log.error(
13         "get datas["+
14         re.getMessage()+
15         "] fail!!");
16       throw new DaoException(re);
17     }
18     ...中間省略...    
19   }
20   ...中間省略...    
21 }
==<end>==============





===<反灰>=============

----Log1:testHappyPath----
[DEBUG] --Operate:Login Button clicked--
[DEBUG] --Method Execute:service.isValidLogin--
[DEBUG] --Method Execute:manager.login--
[DEBUG] --Method Execute:dao.retrieveUser--
[DEBUG] Retrieve User:demo.gwt.client.model.User
[INFO] User[Name] Login Success~~

----Log2:testPasswordIncorrect----
...中間省略...
[INFO] login fail:User Password incorrect!!!

----Log3:testDataNotFound----
...中間省略...
[INFO] Retrieve User Error:
    UserName= data not found!!
[INFO] login fail:
    DaoException: UserName= data not found!!

----Log4:testThrowWarn----
...中間省略...
[WARN] DataSource Connect Failure
[DEBUG] --Method Execute:dataSourceReConnect--
[INFO] DataSource ReConnect Success!!
[DEBUG] --Method Execute:userDao.retrieveUser--
...中間省略...

----Log5:testThrowError----
[ERROR] get datas[3] fail!!
[INFO] Retrieve User Error:
    java.lang.ArrayIndexOutOfBoundsException: 3
...中間省略...

----Log6:testThrowFatal----
[WARN] DataSource Connect Failure
[DEBUG] --Method Execute:dataSourceReConnect--
[FATAL] System Fatal:DataSource Connect Failure
==<end>==============