一、Logback簡介

Logback是由log4j創(chuàng)始人設(shè)計(jì)的又一個(gè)開源日志組件。logback當(dāng)前分成三個(gè)模塊：logback-core,logback- classic和logback-access。logback-core是其它兩個(gè)模塊的基礎(chǔ)模塊。logback-classic是log4j的一個(gè) 改良版本。此外logback-classic完整實(shí)現(xiàn)SLF4J API使你可以很方便地更換成其它日志系統(tǒng)如log4j或JDK14 Logging。logback-access訪問模塊與Servlet容器集成提供通過Http來訪問日志的功能。

二、編寫背景

很不明白客戶為什么要求將日志信息寫入到數(shù)據(jù)庫中去，還要提供個(gè)頁面給系統(tǒng)使用人員查看相應(yīng)日志。作為一個(gè)業(yè)務(wù)人員真的就能看懂系統(tǒng)日志上報(bào)錯(cuò)信息是啥意思么，個(gè)人深表懷疑。沒辦法，作為一枚屌絲程序猿，需求下來了只能硬著頭皮去開發(fā)。

三、編寫目的

只相信一句話:好記性不如爛筆頭，何況我記性差到前一周寫的代碼到現(xiàn)在竟毫無印象的境地呢。

四、Java日志信息存庫詳細(xì)解決方案

1.開發(fā)環(huán)境說明

Eclipse+Tomcat6+JDK1.6+Oracle+logback1.1

2.Java日志存庫實(shí)現(xiàn)方案

(1)使用logback組件默認(rèn)的DBAppender類實(shí)現(xiàn)

最初需求下來的時(shí)候想著logback應(yīng)該有自己的寫數(shù)據(jù)庫的解決辦法，于是乎結(jié)合源碼及度娘終究還是找到了。在logback-classic-1.1.3.jar的ch/qos/logback/classic/db/script/路徑下找到了Oracle數(shù)據(jù)庫對(duì)應(yīng)的建表語句腳本oracle.sql，其建表語句如下所示:

--Logback: the reliable, generic, fast and flexible logging framework.--Copyright (C) 1999-2010, QOS.ch. All rights reserved.--

--See http://logback.qos.ch/license.html for the applicable licensing--conditions.

--This SQL script creates the required tables by ch.qos.logback.classic.db.DBAppender--

--It is intended for Oracle 9i, 10g and 11g databases. Tested on version 9.2,--10g and 11g.

--The following lines are useful in cleaning any previously existing tables

--drop TRIGGER logging_event_id_seq_trig;--drop SEQUENCE logging_event_id_seq;--drop table logging_event_property;--drop table logging_event_exception;--drop table logging_event;

CREATE SEQUENCE logging_event_id_seq MINVALUE 1 START WITH 1;CREATE TABLElogging_event

(

timestmpNUMBER(20) NOT NULL,

formatted_messageVARCHAR2(4000) NOT NULL,

logger_nameVARCHAR(254) NOT NULL,

level_stringVARCHAR(254) NOT NULL,

thread_nameVARCHAR(254),

reference_flagSMALLINT,

arg0VARCHAR(254),

arg1VARCHAR(254),

arg2VARCHAR(254),

arg3VARCHAR(254),

caller_filenameVARCHAR(254) NOT NULL,

caller_classVARCHAR(254) NOT NULL,

caller_methodVARCHAR(254) NOT NULL,

caller_lineCHAR(4) NOT NULL,

event_idNUMBER(10) PRIMARY KEY);--the / suffix may or may not be needed depending on your SQL Client--Some SQL Clients, e.g. SQuirrel SQL has trouble with the following--trigger creation command, while SQLPlus (the basic SQL Client which--ships with Oracle) has no trouble at all.

CREATE TRIGGERlogging_event_id_seq_trig

BEFOREINSERT ONlogging_eventFOREACH ROWBEGIN

SELECTlogging_event_id_seq.NEXTVALINTO:NEW.event_idFROMDUAL;END;/

CREATE TABLElogging_event_property

(

event_idNUMBER(10) NOT NULL,

mapped_keyVARCHAR2(254) NOT NULL,

mapped_valueVARCHAR2(1024),PRIMARY KEY(event_id, mapped_key),FOREIGN KEY (event_id) REFERENCESlogging_event(event_id)

);CREATE TABLElogging_event_exception

(

event_idNUMBER(10) NOT NULL,

iSMALLINT NOT NULL,

trace_lineVARCHAR2(254) NOT NULL,PRIMARY KEY(event_id, i),FOREIGN KEY (event_id) REFERENCESlogging_event(event_id)

);

該sql腳本共創(chuàng)建了3張表,一個(gè)序列和一個(gè)觸發(fā)器。其中主要日志信息記錄在logging_event中，觸發(fā)器是在logging_event數(shù)據(jù)新增時(shí)，將創(chuàng)建的序列值賦值給logging_event表的event_id。

1)JDBC連接池方式

oracle.jdbc.driver.OracleDriver

jdbc:oracle:thin:@127.0.0.1:1521:orcl

tiger

123456

2) JNDI方式

A.Tomcat服務(wù)器安裝目錄/conf/server.xml配置JNDI信息

B.Spring配置文件applicationContext.xml配置JNDI信息

java:comp/env/jdbc/logging

C.logback.xml文件配置JNDI信息

?xml version="1.0" encoding="UTF-8" ?>

java:comp/env/jdbc/logging

注:對(duì)于JNDI的配置不熟悉的，可以去找度娘幫忙或參考JNDI官方文檔，本文不做細(xì)究。

(2)使用自定義DBAppender類實(shí)現(xiàn)

當(dāng)初按上述的配置輕輕松松實(shí)現(xiàn)了日志信息存庫，但天有不測風(fēng)云，完成后卻被告知客戶那邊任務(wù)觸發(fā)器不安全，禁用觸發(fā)器。得知此消息后心里仿佛有千萬只草泥馬飛奔而過，沒辦法只有繼續(xù)想著怎么去改造了。于是就只能去自定義個(gè)DBAppender了，既然是自定義就干脆把其他兩張表直接刪了，僅使用logging_event表，其表結(jié)構(gòu)如下：

字段名

中文說明

類型

為空

TIMESTMP

記錄時(shí)間

NUMBER(20)

N

FORMATTED_MESSAGE

格式化后的日志信息

CLOB

N

LOGGER_NAME

執(zhí)行記錄請(qǐng)求的logger

VARCHAR2(256)

N

LEVEL_STRING

日志級(jí)別

VARCHAR2(256)

N

THREAD_NAME

日志線程名

VARCHAR2(256)

Y

REFERENCE_FLAG

包含標(biāo)識(shí)：1-MDC或上下文屬性;2-異常;3-均包含

INTEGER

Y

ARG0

參數(shù)1

VARCHAR2(256)

Y

ARG1

參數(shù)2

VARCHAR2(256)

Y

ARG2

參數(shù)3

VARCHAR2(256)

Y

ARG3

參數(shù)4

VARCHAR2(256)

Y

CALLER_FILENAME

文件名

VARCHAR2(256)

N

CALLER_CLASS

類

VARCHAR2(256)

N

CALLER_METHOD

方法名

VARCHAR2(256)

N

CALLER_LINE

行號(hào)

VARCHAR2(256)

N

EVENT_ID

主鍵ID

NUMBER(10)

N

注：這個(gè)表結(jié)構(gòu)與logback提供的默認(rèn)表結(jié)構(gòu)有細(xì)微差別，主要體現(xiàn)在字段類型上，由于FORMATTED_MESSAGE存儲(chǔ)的是詳細(xì)的日志信息，字段類型VARCHAR2(4000)無法存儲(chǔ)大文本信息，所以直接改造成了CLOB類型。

1)自定義DBAppender類(ATSDBAppender.java)

packagecom.hundsun.fund.ats.core.system.loggingevent.dao;importjava.lang.reflect.Method;importjava.sql.Connection;importjava.sql.PreparedStatement;importjava.sql.SQLException;importjava.util.HashMap;importjava.util.Map;import staticch.qos.logback.core.db.DBHelper.closeStatement;import staticch.qos.logback.core.db.DBHelper.closeConnection;importch.qos.logback.classic.db.DBHelper;importch.qos.logback.classic.db.names.DBNameResolver;importch.qos.logback.classic.db.names.DefaultDBNameResolver;importch.qos.logback.classic.spi.CallerData;importch.qos.logback.classic.spi.ILoggingEvent;importch.qos.logback.core.db.DBAppenderBase;public class ATSDBAppender extends DBAppenderBase{protectedString insertSQL;protected static finalMethod GET_GENERATED_KEYS_METHOD;privateDBNameResolver dbNameResolver;static final int TIMESTMP_INDEX = 1;static final int FORMATTED_MESSAGE_INDEX = 2;static final int LOGGER_NAME_INDEX = 3;static final int LEVEL_STRING_INDEX = 4;static final int THREAD_NAME_INDEX = 5;static final int REFERENCE_FLAG_INDEX = 6;static final int ARG0_INDEX = 7;static final int ARG1_INDEX = 8;static final int ARG2_INDEX = 9;static final int ARG3_INDEX = 10;static final int CALLER_FILENAME_INDEX = 11;static final int CALLER_CLASS_INDEX = 12;static final int CALLER_METHOD_INDEX = 13;static final int CALLER_LINE_INDEX = 14;static final int EVENT_ID_INDEX = 15;static final StackTraceElement EMPTY_CALLER_DATA =CallerData.naInstance();static{

Method getGeneratedKeysMethod;try{

getGeneratedKeysMethod= PreparedStatement.class.getMethod("getGeneratedKeys", (Class[]) null);

}catch(Exception ex) {

getGeneratedKeysMethod= null;

}

GET_GENERATED_KEYS_METHOD=getGeneratedKeysMethod;

}public voidsetDbNameResolver(DBNameResolver dbNameResolver) {this.dbNameResolver =dbNameResolver;

}

@Overridepublic voidstart() {if (dbNameResolver == null)

dbNameResolver= newDefaultDBNameResolver();

insertSQL=ATSSQLBuilder.buildInsertSQL(dbNameResolver);super.start();

}public voidappend(ILoggingEvent eventObject) {

Connection connection= null;

PreparedStatement insertStatement= null;try{

connection=connectionSource.getConnection();

connection.setAutoCommit(false);

insertStatement=connection.prepareStatement(getInsertSQL());synchronized (this) {

subAppend(eventObject, connection, insertStatement);

}

connection.commit();

}catch(Throwable sqle) {

addError("problem appending event", sqle);

}finally{

closeStatement(insertStatement);

closeConnection(connection);

}

}

@Overrideprotected void subAppend(ILoggingEvent event, Connection connection,PreparedStatement insertStatement) throwsThrowable {

bindLoggingEventWithInsertStatement(insertStatement, event);

bindLoggingEventArgumentsWithPreparedStatement(insertStatement, event.getArgumentArray());

bindCallerDataWithPreparedStatement(insertStatement, event.getCallerData());int updateCount =insertStatement.executeUpdate();if (updateCount != 1) {

addWarn("Failed to insert loggingEvent");

}

}protected voidsecondarySubAppend(ILoggingEvent event,

Connection connection,long eventId) throwsThrowable {

}voidbindLoggingEventWithInsertStatement(PreparedStatement stmt,

ILoggingEvent event)throwsSQLException {stmt.setLong(TIMESTMP_INDEX, event.getTimeStamp());

stmt.setString(FORMATTED_MESSAGE_INDEX, event.getFormattedMessage());

stmt.setString(LOGGER_NAME_INDEX, event.getLoggerName());

stmt.setString(LEVEL_STRING_INDEX, event.getLevel().toString());

stmt.setString(THREAD_NAME_INDEX, event.getThreadName());

stmt.setShort(REFERENCE_FLAG_INDEX, DBHelper.computeReferenceMask(event));

}voidbindLoggingEventArgumentsWithPreparedStatement(PreparedStatement stmt,

Object[] argArray)throwsSQLException {int arrayLen = argArray != null ? argArray.length : 0;for(int i = 0; i < arrayLen && i < 4; i++) {

stmt.setString(ARG0_INDEX+i, asStringTruncatedTo254(argArray[i]));

}if(arrayLen < 4) {for(int i = arrayLen; i < 4; i++) {

stmt.setString(ARG0_INDEX+i, null);

}

}

}

String asStringTruncatedTo254(Object o) {

String s= null;if(o != null) {

s=o.toString();

}if(s == null) {return null;

}if(s.length() <= 254) {returns;

}else{return s.substring(0, 254);

}

}voidbindCallerDataWithPreparedStatement(PreparedStatement stmt,

StackTraceElement[] callerDataArray)throwsSQLException {

StackTraceElement caller=extractFirstCaller(callerDataArray);

stmt.setString(CALLER_FILENAME_INDEX, caller.getFileName());

stmt.setString(CALLER_CLASS_INDEX, caller.getClassName());

stmt.setString(CALLER_METHOD_INDEX, caller.getMethodName());

stmt.setString(CALLER_LINE_INDEX, Integer.toString(caller.getLineNumber()));

}privateStackTraceElement extractFirstCaller(StackTraceElement[] callerDataArray) {

StackTraceElement caller=EMPTY_CALLER_DATA;if(hasAtLeastOneNonNullElement(callerDataArray))

caller= callerDataArray[0];returncaller;

}private booleanhasAtLeastOneNonNullElement(StackTraceElement[] callerDataArray) {return callerDataArray != null && callerDataArray.length > 0 && callerDataArray[0] != null;

}

MapmergePropertyMaps(ILoggingEvent event) {

Map mergedMap = new HashMap();

Map loggerContextMap =event.getLoggerContextVO().getPropertyMap();

Map mdcMap =event.getMDCPropertyMap();if (loggerContextMap != null) {

mergedMap.putAll(loggerContextMap);

}if (mdcMap != null) {

mergedMap.putAll(mdcMap);

}returnmergedMap;

}

@OverrideprotectedMethod getGeneratedKeysMethod() {returnGET_GENERATED_KEYS_METHOD;

}

@OverrideprotectedString getInsertSQL() {returninsertSQL;

}

}

2)自定義SQLBuilder類(ATSSQLBuilder.java)

packagecom.hundsun.fund.ats.core.system.loggingevent.dao;importch.qos.logback.classic.db.names.ColumnName;importch.qos.logback.classic.db.names.DBNameResolver;importch.qos.logback.classic.db.names.TableName;public classATSSQLBuilder {staticString buildInsertSQL(DBNameResolver dbNameResolver) {

StringBuilder sqlBuilder= new StringBuilder("INSERT INTO ");

sqlBuilder.append(dbNameResolver.getTableName(TableName.LOGGING_EVENT)).append(" (");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.TIMESTMP)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.FORMATTED_MESSAGE)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.LOGGER_NAME)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.LEVEL_STRING)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.THREAD_NAME)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.REFERENCE_FLAG)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.ARG0)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.ARG1)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.ARG2)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.ARG3)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.CALLER_FILENAME)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.CALLER_CLASS)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.CALLER_METHOD)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.CALLER_LINE)).append(", ");

sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.EVENT_ID)).append(") ");

sqlBuilder.append("VALUES (?, ?, ? ,?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,LOGGING_EVENT_ID_SEQ.nextval)");returnsqlBuilder.toString();

}

}

注：類中LOGGING_EVENT_ID_SEQ序列需自行創(chuàng)建，logback默認(rèn)建表語句中有該序列的創(chuàng)建語句，直接拿來使用即可。

3)logback.xml配置

此時(shí)JDBC與JNDI方式配置只需要將原name為DB的appender標(biāo)簽class屬性的值指向自定義DBAppender即可,其他配置不變，下述代碼為JDBC配置示例:

oracle.jdbc.driver.OracleDriver

jdbc:oracle:thin:@127.0.0.1:1521:orcl

tiger

123456

(3)測試類的編寫

packagecom.hundsun.fund.ats.modules.server.test;importorg.slf4j.Logger;importorg.slf4j.LoggerFactory;public classLogbackTest {public static voidmain(String[] args) {//dblog為logback.xml中l(wèi)ogger標(biāo)簽name屬性的值

Logger logger= LoggerFactory.getLogger("dblog");

logger.debug("DEBUG級(jí)別信息");

logger.warn("WARN級(jí)別信息");

logger.info("INFO級(jí)別信息");

logger.error("ERROR級(jí)別信息");

}

}

五、總結(jié)

文中涉及到的Logback日志信息存庫的處理只是在源代碼的基礎(chǔ)上做了點(diǎn)小小的改動(dòng)而已，并非完整地介紹該組件的功能。想要全面學(xué)習(xí)Logback日志組件，請(qǐng)參考官方提供的源碼和相應(yīng)的API幫助文檔。

總結(jié)

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