69. XPages里的Java日志器

墨蓝 2022-09-18 13:56 160阅读 0赞

在[48. 面向对象的LotusScript（十四）之Log4Dom上][48. _LotusScript_Log4Dom]和[49. 面向对象的LotusScript（十五）之Log4Dom下][49. _LotusScript_Log4Dom]笔者介绍了一个简单实用的日志记录模块，代码用LotusScript写成，在Lotus Notes传统的客户端和web应用程序里都可以使用。在XPages开发里，需要可在SSJS或Java里使用的日志功能。用Java开发时，有很多现成的日志框架，比如Log4J和JDK自带的java.util.logging包。但是这些框架包含日志器层次（logger hierarchy）、过滤器（filter）、记录器（handler）和格式器（formatter）等特性，对于Lotus Notes平台上的开发来说过于复杂。Lotus Notes的环境有特殊性，现成和方便的记录日志的载体就是Notes文档，所以笔者在借鉴了OpenNTF上的[Log4Dom][]项目后，编写了满足典型的Lotus Notes里日志需求的Java类NotesLogger。（与Log4Dom的Java版本比较，NotesLogger放弃了Log4J的可配制记录器的架构，直接将日志写入唯一的载体——指定Notes数据库的文档；更正了bug；简化了使用方法；减少了类的数量；调整了方法的名称和签名。）记录日志的文档使用的表单和视图与LotusScript的Log4Dom一样。下面就是在一个XPage的按钮里分别用xp:eventHandler的action和actionListener属性触发managed bean里的两个测试方法，分成两条日志文档。

<xp:button value="Test eventHandler action" id="button1">
    		<xp:eventHandler event="onclick" submit="true"
    			refreshMode="complete" action="#{bean.testAction}">
    		</xp:eventHandler>
    	</xp:button>
    	<xp:button value="Test eventHandler actionListener" id="button2">
    		<xp:eventHandler event="onclick" submit="true"
    			refreshMode="complete" actionListener="#{bean.testActionListener}">
    		</xp:eventHandler>
    	</xp:button>

注意两处绑定使用的都是表达式语言，并且XPages继承自JSF，分别可以使用action和actionListener/actionListeners绑定两种签名不同的方法。action属性绑定的方法须为managed bean的公开方法，无参数且返回一个字符串；actionListener/actionListeners绑定的方法同样须为公开方法，但接受一个类型为javax.faces.event.ActionEvent的参数且返回类型为void。

public void testActionListener(ActionEvent ae) throws NotesException{
            NotesLogger logger=new NotesLogger(XSPUtil.getSession());
            logger.setLogName("test actionListener from bean");
            logger.info(ae);
            logger.close();
        }
        
        public void testAction() throws NotesException{
            NotesLogger logger=new NotesLogger(XSPUtil.getSession());
            logger.setLogName("test action from bean");
            logger.info("Print message from NotesLogger");
            logger.close();
        }

产生的日志如下：  
 ![SouthEast][]  
 ![SouthEast 1][]  
 ![SouthEast 2][]  
我们还可以稍微再简化一下NotesLogger的调用步骤。在一个managed bean里，很多方法都可能会写日志，我们可以在bean里声明一个logger字段作为共享的日志器，在bean的构造方法里或者利用managed bean的managed property初始化logger变量，如此一来在每个方法写日志时，就可省去创建日志器的环节。  
下面是为此写的faces-config.xml：

<?xml version="1.0" encoding="UTF-8"?>
    <faces-config>
      <managed-bean>
        <managed-bean-name>logger</managed-bean-name>
        <managed-bean-class>starrow.BeanLogger</managed-bean-class>
        <managed-bean-scope>application</managed-bean-scope>
      </managed-bean>
      <managed-bean>
        <managed-bean-name>bean</managed-bean-name>
        <managed-bean-class>starrow.Test</managed-bean-class>
        <managed-bean-scope>session</managed-bean-scope>
        <managed-property>
          <property-name>logger</property-name>
          <value>#{logger}</value>
        </managed-property>
      </managed-bean>
      
      
    </faces-config>

和相应的bean的片段：

private BeanLogger logger;
    
        public void setLogger(BeanLogger logger) {
            this.logger = logger;
        }
        public void test() throws NotesException{
            logger.setLogName("from bean logger");
            logger.debug(1);
            logger.info("text");
            logger.warn(true);
            logger.error(new Date());
            String user=XSPUtil.getSession().getEffectiveUserName();
            logger.info("user: " + user);
            logger.flush();
            logger.close();
        }

产生的日志如下：  
![SouthEast 3][]   
![SouthEast 4][]   
注意上面使用的日志类是BeanLogger，这是为了能将NotesLogger作为managed bean使用而继承自它的一个扩展类。  
最后，我们来看看NotesLogger和BeanLogger的代码。

package starrow;
    
    import lotus.domino.*;
    
    import java.util.*;
    import java.text.SimpleDateFormat;
    
    /**
     * Log to Notes documents
     */
    
    public class NotesLogger {
    
        // built in logging levels
        public static final int LEVEL_DEBUG=5;
        public static final int LEVEL_INFO=4;
        public static final int LEVEL_WARN = 3;
        public static final int LEVEL_ERROR=2;
        public static final int LEVEL_FATAL=1;
        public static final int LEVEL_NONE=0;
    
        protected int logLevel;
        private String logName;
    
        protected String dbPath;
        protected Database logDb;
        private Document logDoc;
        private RichTextItem logItem;
        private boolean written = false;
    
    
        /**
         * @param db A NotesDatabase used for logging
         * @throws NotesException
         */
        public NotesLogger(Database db) throws NotesException{
            logLevel = LEVEL_DEBUG;
            logDb=db;
            if (!logDb.isOpen()){
                if (!logDb.open()){
                    throw new NotesException(NotesError.NOTES_ERR_DATABASE_NOTOPEN, "Cannot open the log database.");
                }
            }
        }
    
        /**
         * @param s notes session
         * @param dbPath path of the log database
         * @throws NotesException
         */
        public NotesLogger(Session s, String dbPath) throws NotesException {
            //Database db=s.getDatabase(null, dbPath);
            this(s.getDatabase(null, dbPath));
        }
    
        /**
         * @param s notes session
         * @throws NotesException
         */
        public NotesLogger(Session s) throws NotesException{
            this(s.getCurrentDatabase());
        }
        
    
        public void setLogLevel(int level) {
            logLevel = level;    
        }
    
        public void setLogName(String name) {
            logName = name;    
        }
    
        public void info(Object message) throws NotesException {
            log(LEVEL_INFO, message);
        }
    
        public void warn(Object message) throws NotesException {
            log(LEVEL_WARN, message);
        }
    
        public void debug(Object message) throws NotesException {
            log(LEVEL_DEBUG, message);
        }
    
        public void error(Object message) throws NotesException {
            log(LEVEL_ERROR, message);
        }
    
        public void fatal(Object message) throws NotesException {
            log(LEVEL_FATAL, message);
        }
    
    
        public void log (int level, Object message) throws NotesException {
            if (level>logLevel) return;
                
            SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd hh:mm:ss aa", Locale.US);
    
            String text = new String();
            Date theCurrentDate = new Date();
            String theDate = dateFormat.format(theCurrentDate);
            String theLevel = new String();
            theLevel = theLevel+getLevelString(level);
    
            //System.out.println("Level :"+level+" - logLevel "+logLevel);    
    
            text = theDate+" ["+theLevel+"]: "+message;
            if (logDoc == null) {
                // create document and a RTF for the log
                logDoc = logDb.createDocument();
                logDoc.replaceItemValue("Form", "log");
                logDoc.replaceItemValue("LogName", logName);
                if (logDb.getParent().isOnServer()){
                    logDoc.replaceItemValue("ScriptRunOn", "Server");
                }else{
                    logDoc.replaceItemValue("ScriptRunOn", "Local");            
                }
                logItem = logDoc.createRichTextItem("logBody");
            }
            // write log entry
            logItem.appendText(text);
            logItem.addNewLine();
    
            written = true;
    
        }
    
        //convert from level numbers into strings
        private String getLevelString(int level) {
    
            String levelString="";
            switch (level) {
            case LEVEL_DEBUG:  levelString="DEBUG" ; break;
    	case LEVEL_INFO:  levelString="INFO" ; break;
    	case LEVEL_WARN:  levelString="WARN" ; break;
    	case LEVEL_ERROR:  levelString="ERROR" ; break;
    	case LEVEL_FATAL:  levelString="FATAL" ; break;
            default : levelString=levelString+"LEVEL "+level; break;
            } // end switch    
    
            return levelString;
        }
    
        /**
         * save the log document
         * @throws NotesException
         */
        public void flush() throws NotesException{
            if (written) {
                logDoc.save();
                written=false;
            }
        }
        
        /**
         * close the log via recycling the underlying resource.
         * @throws NotesException
         */
        public void close() throws NotesException {
            flush();
            logDoc.recycle();
            logDoc=null;
            if (this.dbPath!=""){
                //If the log db is not the current one, recycle it.
                //Even recycling the current db doesn't cause any error.
                this.logDb.recycle();
            }
        }
    }

package starrow;
    
    import starrow.xsp.XSPUtil;
    import lotus.domino.NotesException;
    
    public class BeanLogger extends NotesLogger implements java.io.Serializable{
    
        private static final long serialVersionUID = 1L;
    
        public BeanLogger(String dbPath) throws NotesException {
            super(XSPUtil.getSession());
            this.dbPath=dbPath;
            logLevel = LEVEL_DEBUG;
        }
    
        /**
         * Add a constructor with no parameter for bean creation
         * @throws NotesException
         */
        public BeanLogger() throws NotesException{
            this("");
        }
        
        public void log(int level, Object message) throws NotesException{
            //get the current db freshly        
            if (this.dbPath==""){
                logDb=XSPUtil.getDatabase();
            }else{
                logDb=XSPUtil.getDatabase(this.dbPath);
            }
            super.log(level, message);
        }
    }

BeanLogger里不寻常的一点是在重载的log方法里，获取全新的日志数据库实例，这是因为XPages引擎会频繁地自动清理Java里Lotus Domino对象用到的后端对象（参看[42. Lotus Notes中的垃圾回收之Java][42. Lotus Notes_Java]），BeanLogger用到的日志数据库和文档很快会变成无效状态，调用它会引发以下异常：  
NotesException: Object has been removed or recycled  
    at lotus.domino.local.NotesBase.CheckObject(Unknown Source)  
    at lotus.domino.local.Document.save(Unknown Source)  
    at lotus.domino.local.Document.save(Unknown Source)  
    …

[48. _LotusScript_Log4Dom]: http://blog.csdn.net/starrow/article/details/10045929
[49. _LotusScript_Log4Dom]: http://blog.csdn.net/starrow/article/details/10077905
[Log4Dom]: http://openntf.org/Projects/codebin/codebin.nsf/CodeByDate/BE540FBC95AB8B4C86256DD700207C8A
[SouthEast]: /images/20220828/724aab14d4d24cfb8b279c368884fd58.png
[SouthEast 1]: /images/20220828/e48aa87680564ff1bfba966a3ae87fa3.png
[SouthEast 2]: /images/20220828/2213868d6a8044d583c69243017b96e9.png
[SouthEast 3]: /images/20220828/48c614d6a7ca4b7eaaab6e9e2aeead32.png
[SouthEast 4]: /images/20220828/bd3f15de80f34298b3a9f4a937869045.png
[42. Lotus Notes_Java]: http://blog.csdn.net/starrow/article/details/9427763