Logback输出日志到自定义MySQL数据库（重写DBAppender）
目录
前言：需求
1 项目总览
2 原始logback输出日志至MySQL数据库配置
3 源码解析
3.1 names
3.2 script
3.3 DBAppender
3.3.1 数据格式化方法
3.3.2 数据插入以及入口方法
3.4 SQLBuilder
3.4 其他
4 重写源码
4.1 数据库表设计
4.2 数据库插入语句生成
4.3 数据格式化
4.4 修改后代码 （MyDBAppender.java）
4.5 运行测试
5 总结
附：
前言：需求
在一个系统开发过程中，日志系统和测试系统必不可少，在整个开发流程中扮演着及其重要的角色。在现有的主流日志框架中，有log4j,slf4j和logback等，本着买新不买旧的原则，在系统中采用了logback＋slf4j的日志框架。
在配置过程中，可以实现日志实时格式化显示在console中，也可以分时间分大小记录到文件中。因为项目中需要将日志实时记录到MySQL数据库中，查找了很多资料，遇到很多问题，基本都在配置文件中倒下。
以下，将分享两种记录日志至MySQL数据库中的方式，其一是根据logback原始配置，其二是自定义数据库表，记录日志。
1 项目总览
2 原始logback输出日志至MySQL数据库配置
com.mysql.cj.jdbc.Driver
jdbc:mysql://127.0.0.1:3306/log?serverTimezone=UTC
root
z111111
此上代码段，为输出日志到MySQL数据库中的配置，其中
logback-text.xml 配置文件源码如下：
${CONSOLE_LOG_PATTERN}
com.mysql.cj.jdbc.Driver
jdbc:mysql://127.0.0.1:3306/log?serverTimezone=UTC
root
z111111
MySQL数据库表创建脚本在 ch.qos.logback.classic.db.scrip 包下，选择mysql.sql 内容如下，运行并创建数据库表：
BEGIN;
DROP TABLE IF EXISTS logging_event_property;
DROP TABLE IF EXISTS logging_event_exception;
DROP TABLE IF EXISTS logging_event;
COMMIT;
BEGIN;
CREATE TABLE logging_event
(
timestmp BIGINT NOT NULL,
formatted_message TEXT NOT NULL,
logger_name VARCHAR(254) NOT NULL,
level_string VARCHAR(254) NOT NULL,
thread_name VARCHAR(254),
reference_flag SMALLINT,
arg0 VARCHAR(254),
arg1 VARCHAR(254),
arg2 VARCHAR(254),
arg3 VARCHAR(254),
caller_filename VARCHAR(254) NOT NULL,
caller_class VARCHAR(254) NOT NULL,
caller_method VARCHAR(254) NOT NULL,
caller_line CHAR(4) NOT NULL,
event_id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY
);
COMMIT;
BEGIN;
CREATE TABLE logging_event_property
(
event_id BIGINT NOT NULL,
mapped_key VARCHAR(254) NOT NULL,
mapped_value TEXT,
PRIMARY KEY(event_id, mapped_key),
FOREIGN KEY (event_id) REFERENCES logging_event(event_id)
);
COMMIT;
BEGIN;
CREATE TABLE logging_event_exception
(
event_id BIGINT NOT NULL,
i SMALLINT NOT NULL,
trace_line VARCHAR(254) NOT NULL,
PRIMARY KEY(event_id, i),
FOREIGN KEY (event_id) REFERENCES logging_event(event_id)
);
COMMIT;测试类如下：
public class BlogAction {
private static Logger logger = LoggerFactory.getLogger(BlogAction.class);
public static void main(String[] args) {
for(int i = 0 ; i < 3 ; i++){
logger.info("logback So"+i);
logger.error("logback Down");
logger.debug("debug");
}
logger.info("logback So44");
}
}运行后，控制台显示如下
数据库中数据如下所示
3 源码解析
在上面第一条试验后，我们发现，在实际项目开发中，项目日志并不需要很多内容，如此繁多的表项反而会耽误我们阅读查看的时间和效率，于是在考虑到实际需要，我想着能不能将数据库表自定义，仅保留下一部分重要信息，以便阅读。
在此之前，反复查看 logback 中 ch.qos.logback.classic.db 包下的所有源代码，结构如下图：
在db包下，有names 、script 、和DBAppender 、DBHelper 、SQLBuilder文件，下面分别介绍其作用：
3.1 names
此包下含有几个文件，包含枚举类和一些方法，总结来说就是，这几个文件的作用为，规定数据库表名和数据库表中各个表项的名字，在枚举类ColumnName中包含三个表中各个表项的名字
package ch.qos.logback.classic.db.names;
public enum ColumnName {
EVENT_ID,
TIMESTMP, FORMATTED_MESSAGE, LOGGER_NAME, LEVEL_STRING, THREAD_NAME, REFERENCE_FLAG, ARG0, ARG1, ARG2, ARG3, CALLER_FILENAME, CALLER_CLASS, CALLER_METHOD, CALLER_LINE,
// MDC
MAPPED_KEY, MAPPED_VALUE,
I, TRACE_LINE;
}
在枚举类TableName中包含三个表的名字
/**
* @author Tomasz Nurkiewicz
* @since 0.9.19
*/
public enum TableName {
LOGGING_EVENT, LOGGING_EVENT_PROPERTY, LOGGING_EVENT_EXCEPTION
}
其余的类中包含一些必须的方法，例如将枚举类中数据转换为小写字母的表名等方法。
3.2 script
此包下包含的所有文件为SQL脚本，对应不同的数据库，有不同的数据库表创建脚本。
3.3 DBAppender
此类，为重点，其继承自 DBAppenderBase
package ch.qos.logback.classic.db;
import static ch.qos.logback.core.db.DBHelper.closeStatement;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import ch.qos.logback.classic.db.names.DBNameResolver;
import ch.qos.logback.classic.db.names.DefaultDBNameResolver;
import ch.qos.logback.classic.spi.*;
import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.db.DBAppenderBase;
/**
* The DBAppender inserts logging events into three database tables in a format
* independent of the Java programming language.
*
* For more information about this appender, please refer to the online manual
* at http://logback.qos.ch/manual/appenders.html#DBAppender
*
* @author Ceki Gülcü
* @author Ray DeCampo
* @author Sébastien Pennec
*/
public class DBAppender extends DBAppenderBase {
protected String insertPropertiesSQL;
protected String insertExceptionSQL;
protected String insertSQL;
protected static final Method GET_GENERATED_KEYS_METHOD;
private DBNameResolver 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 {
// PreparedStatement.getGeneratedKeys() method was added in JDK 1.4
Method getGeneratedKeysMethod;
try {
// the
getGeneratedKeysMethod = PreparedStatement.class.getMethod("getGeneratedKeys", (Class[]) null);
} catch (Exception ex) {
getGeneratedKeysMethod = null;
}
GET_GENERATED_KEYS_METHOD = getGeneratedKeysMethod;
}
public void setDbNameResolver(DBNameResolver dbNameResolver) {
this.dbNameResolver = dbNameResolver;
}
@Override
public void start() {
if (dbNameResolver == null)
dbNameResolver = new DefaultDBNameResolver();
insertExceptionSQL = SQLBuilder.buildInsertExceptionSQL(dbNameResolver);
insertPropertiesSQL = SQLBuilder.buildInsertPropertiesSQL(dbNameResolver);
insertSQL = SQLBuilder.buildInsertSQL(dbNameResolver);
super.start();
}
@Override
protected void subAppend(ILoggingEvent event, Connection connection, PreparedStatement insertStatement) throws Throwable {
bindLoggingEventWithInsertStatement(insertStatement, event);
bindLoggingEventArgumentsWithPreparedStatement(insertStatement, event.getArgumentArray());
// This is expensive... should we do it every time?
bindCallerDataWithPreparedStatement(insertStatement, event.getCallerData());
int updateCount = insertStatement.executeUpdate();
if (updateCount != 1) {
addWarn("Failed to insert loggingEvent");
}
}
protected void secondarySubAppend(ILoggingEvent event, Connection connection, long eventId) throws Throwable {
Map mergedMap = mergePropertyMaps(event);
insertProperties(mergedMap, connection, eventId);
if (event.getThrowableProxy() != null) {
insertThrowable(event.getThrowableProxy(), connection, eventId);
}
}
void bindLoggingEventWithInsertStatement(PreparedStatement stmt, ILoggingEvent event) throws SQLException {
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));
}
void bindLoggingEventArgumentsWithPreparedStatement(PreparedStatement stmt, Object[] argArray) throws SQLException {
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) {
return s;
} else {
return s.substring(0, 254);
}
}
void bindCallerDataWithPreparedStatement(PreparedStatement stmt, StackTraceElement[] callerDataArray) throws SQLException {
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()));
}
private StackTraceElement extractFirstCaller(StackTraceElement[] callerDataArray) {
StackTraceElement caller = EMPTY_CALLER_DATA;
if (hasAtLeastOneNonNullElement(callerDataArray))
caller = callerDataArray[0];
return caller;
}
private boolean hasAtLeastOneNonNullElement(StackTraceElement[] callerDataArray) {
return callerDataArray != null && callerDataArray.length > 0 && callerDataArray[0] != null;
}
Map mergePropertyMaps(ILoggingEvent event) {
Map mergedMap = new HashMap();
// we add the context properties first, then the event properties, since
// we consider that event-specific properties should have priority over
// context-wide properties.
Map loggerContextMap = event.getLoggerContextVO().getPropertyMap();
Map mdcMap = event.getMDCPropertyMap();
if (loggerContextMap != null) {
mergedMap.putAll(loggerContextMap);
}
if (mdcMap != null) {
mergedMap.putAll(mdcMap);
}
return mergedMap;
}
@Override
protected Method getGeneratedKeysMethod() {
return GET_GENERATED_KEYS_METHOD;
}
@Override
protected String getInsertSQL() {
return insertSQL;
}
protected void insertProperties(Map mergedMap, Connection connection, long eventId) throws SQLException {
Set propertiesKeys = mergedMap.keySet();
if (propertiesKeys.size() > 0) {
PreparedStatement insertPropertiesStatement = null;
try {
insertPropertiesStatement = connection.prepareStatement(insertPropertiesSQL);
for (String key : propertiesKeys) {
String value = mergedMap.get(key);
insertPropertiesStatement.setLong(1, eventId);
insertPropertiesStatement.setString(2, key);
insertPropertiesStatement.setString(3, value);
if (cnxSupportsBatchUpdates) {
insertPropertiesStatement.addBatch();
} else {
insertPropertiesStatement.execute();
}
}
if (cnxSupportsBatchUpdates) {
insertPropertiesStatement.executeBatch();
}
} finally {
closeStatement(insertPropertiesStatement);
}
}
}
/**
* Add an exception statement either as a batch or execute immediately if
* batch updates are not supported.
*/
void updateExceptionStatement(PreparedStatement exceptionStatement, String txt, short i, long eventId) throws SQLException {
exceptionStatement.setLong(1, eventId);
exceptionStatement.setShort(2, i);
exceptionStatement.setString(3, txt);
if (cnxSupportsBatchUpdates) {
exceptionStatement.addBatch();
} else {
exceptionStatement.execute();
}
}
short buildExceptionStatement(IThrowableProxy tp, short baseIndex, PreparedStatement insertExceptionStatement, long eventId) throws SQLException {
StringBuilder buf = new StringBuilder();
ThrowableProxyUtil.subjoinFirstLine(buf, tp);
updateExceptionStatement(insertExceptionStatement, buf.toString(), baseIndex++, eventId);
int commonFrames = tp.getCommonFrames();
StackTraceElementProxy[] stepArray = tp.getStackTraceElementProxyArray();
for (int i = 0; i < stepArray.length - commonFrames; i++) {
StringBuilder sb = new StringBuilder();
sb.append(CoreConstants.TAB);
ThrowableProxyUtil.subjoinSTEP(sb, stepArray[i]);
updateExceptionStatement(insertExceptionStatement, sb.toString(), baseIndex++, eventId);
}
if (commonFrames > 0) {
StringBuilder sb = new StringBuilder();
sb.append(CoreConstants.TAB).append("... ").append(commonFrames).append(" common frames omitted");
updateExceptionStatement(insertExceptionStatement, sb.toString(), baseIndex++, eventId);
}
return baseIndex;
}
protected void insertThrowable(IThrowableProxy tp, Connection connection, long eventId) throws SQLException {
PreparedStatement exceptionStatement = null;
try {
exceptionStatement = connection.prepareStatement(insertExceptionSQL);
short baseIndex = 0;
while (tp != null) {
baseIndex = buildExceptionStatement(tp, baseIndex, exceptionStatement, eventId);
tp = tp.getCause();
}
if (cnxSupportsBatchUpdates) {
exceptionStatement.executeBatch();
}
} finally {
closeStatement(exceptionStatement);
}
}
}
因为方法较多，所以我将几个重要的方法单独提出来讲解
3.3.1 数据格式化方法
首先，查找对应数据库插入的方法：
void bindLoggingEventWithInsertStatement(PreparedStatement stmt, ILoggingEvent event) throws SQLException {
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));
}
void bindCallerDataWithPreparedStatement(PreparedStatement stmt, StackTraceElement[] callerDataArray) throws SQLException {
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()));
}上两个方法，则是将日志所有的参数，格式化为数据库对应的格式，根据类的开始几行数据，如以下
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;
可以很明显找到这个关键的方法之一，这也为我们后面重写此类的重点。
3.3.2 数据插入以及入口方法
我们上面找到格式化数据的方法，下面则将查找插入数据库的具体操作实现方法，不难看出，我们找到以下方法内容：
@Override
public void start() {
if (dbNameResolver == null)
dbNameResolver = new DefaultDBNameResolver();
insertExceptionSQL = SQLBuilder.buildInsertExceptionSQL(dbNameResolver);
insertPropertiesSQL = SQLBuilder.buildInsertPropertiesSQL(dbNameResolver);
insertSQL = SQLBuilder.buildInsertSQL(dbNameResolver);
super.start();
}
@Override
protected void subAppend(ILoggingEvent event, Connection connection, PreparedStatement insertStatement) throws Throwable {
bindLoggingEventWithInsertStatement(insertStatement, event);
bindLoggingEventArgumentsWithPreparedStatement(insertStatement, event.getArgumentArray());
// This is expensive... should we do it every time?
bindCallerDataWithPreparedStatement(insertStatement, event.getCallerData());
int updateCount = insertStatement.executeUpdate();
if (updateCount != 1) {
addWarn("Failed to insert loggingEvent");
}
}以上只是插入logging_event这个表内数据的方法，还有其他两个表，其插入方法在类中，可以自行查找。
不难看出，我们找到了此类中的关键方法，了解这两个方法后，有助于我们自己实现自定义DBAppender。
3.4 SQLBuilder
在上一个类中，找到了插入数据库的具体实现方法，那么还有插入数据库的SQL语句没有查到，于是在这个类SQLBuilder中，便集成了三个表的数据插入语句的格式化。具体内容如下：
/**
* Logback: the reliable, generic, fast and flexible logging framework.
* Copyright (C) 1999-2015, QOS.ch. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation.
*/
package ch.qos.logback.classic.db;
import ch.qos.logback.classic.db.names.*;
/**
* @author Tomasz Nurkiewicz
* @since 2010-03-16
*/
public class SQLBuilder {
static String buildInsertPropertiesSQL(DBNameResolver dbNameResolver) {
StringBuilder sqlBuilder = new StringBuilder("INSERT INTO ");
sqlBuilder.append(dbNameResolver.getTableName(TableName.LOGGING_EVENT_PROPERTY)).append(" (");
sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.EVENT_ID)).append(", ");
sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.MAPPED_KEY)).append(", ");
sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.MAPPED_VALUE)).append(") ");
sqlBuilder.append("VALUES (?, ?, ?)");
return sqlBuilder.toString();
}
static String buildInsertExceptionSQL(DBNameResolver dbNameResolver) {
StringBuilder sqlBuilder = new StringBuilder("INSERT INTO ");
sqlBuilder.append(dbNameResolver.getTableName(TableName.LOGGING_EVENT_EXCEPTION)).append(" (");
sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.EVENT_ID)).append(", ");
sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.I)).append(", ");
sqlBuilder.append(dbNameResolver.getColumnName(ColumnName.TRACE_LINE)).append(") ");
sqlBuilder.append("VALUES (?, ?, ?)");
return sqlBuilder.toString();
}
static String 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("VALUES (?, ?, ? ,?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)");
return sqlBuilder.toString();
}
}
由上不难看出其作用，生成具体的SQL语句，用于数据插入。
3.4 其他
此包内还有几个其他的类没有讲解，因为其对我们自定义重写的作用不大，就不多赘述了。
4 重写源码
由以上源码的解析过程，我们熟悉了其工作方式和具体实现方法，以下，将开始重写源码的过程。
4.1 数据库表设计
在之前我们说过，原配置的数据库表有很多我们并不需要的信息，于是，将数据库表中不需要的表项删除，删除不需要的表，只留下一个logging_event表的内容，并加以修改。其SQL脚本如下：
BEGIN;
DROP TABLE IF EXISTS log_record;
COMMIT;
BEGIN;
CREATE TABLE log_record
(
id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
time DATETIME(6) NOT NULL,
message TEXT NOT NULL,
level_string VARCHAR(254) NOT NULL,
logger_name VARCHAR(254) NOT NULL,
thread_name VARCHAR(254),
reference_flag SMALLINT,
caller_filename VARCHAR(254) NOT NULL,
caller_class VARCHAR(254) NOT NULL,
caller_method VARCHAR(254) NOT NULL,
caller_line CHAR(4) NOT NULL
);
COMMIT;由以上表得知，只留下时间和日志具体位置和信息，同时删除其余两个表。
其中，原数据表中时间的格式为Long型，不便于阅读，本文将时间改为DATETIME形式，方便查询和操作。
4.2 数据库插入语句生成
因为我们只需要管理一个数据库表，本着简洁的原则，我们将names包下面的所有文件全部删除，将SQLBuilder 文件中简化为一个方法，放在MyDBAppender.java 中，方法代码如下:
private static String buildInsertSQL() {
return "INSERT INTO log_record " +
"(time, message, level_string, logger_name, thread_name," +
"caller_filename, caller_class, caller_method, caller_line)"+
"VALUES (?, ?, ? ,?, ?, ?, ?, ?, ?)";
}是不是简洁了很多，可以根据自己定义的数据库表自行修改。
4.3 数据格式化
因为我们对数据库表的修改只是删除某些表项，其具体数据格式化方法本质没变，代码如下：
private static final int TIME_INDEX = 1;
private static final int MESSAGE_INDEX = 2;
private static final int LEVEL_STRING_INDEX = 3;
private static final int LOGGER_NAME_INDEX = 4;
private static final int THREAD_NAME_INDEX = 5;
private static final int CALLER_FILENAME_INDEX = 6;
private static final int CALLER_CLASS_INDEX = 7;
private static final int CALLER_METHOD_INDEX = 8;
private static final int CALLER_LINE_INDEX = 9;
private void bindLoggingEventWithInsertStatement(PreparedStatement stmt, ILoggingEvent event) throws SQLException {
stmt.setTimestamp(TIME_INDEX, new Timestamp(event.getTimeStamp()));
stmt.setString(MESSAGE_INDEX, event.getFormattedMessage());
stmt.setString(LEVEL_STRING_INDEX, event.getLevel().toString());
stmt.setString(LOGGER_NAME_INDEX, event.getLoggerName());
stmt.setString(THREAD_NAME_INDEX, event.getThreadName());
}
private void bindCallerDataWithPreparedStatement(PreparedStatement stmt, StackTraceElement[] callerDataArray) throws SQLException {
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()));
}4.4 修改后代码 （MyDBAppender.java）
package com.ahdy.logtest.config;
import ch.qos.logback.classic.spi.*;
import ch.qos.logback.core.db.DBAppenderBase;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* @Description:
* @Author: Rocty
* @Date: 2019-06-18 16:22
* @Version: 1.0
*/
public class MyDBAppender extends DBAppenderBase {
private String insertSQL;
private static final Method GET_GENERATED_KEYS_METHOD;
private static final int TIME_INDEX = 1;
private static final int MESSAGE_INDEX = 2;
private static final int LEVEL_STRING_INDEX = 3;
private static final int LOGGER_NAME_INDEX = 4;
private static final int THREAD_NAME_INDEX = 5;
private static final int CALLER_FILENAME_INDEX = 6;
private static final int CALLER_CLASS_INDEX = 7;
private static final int CALLER_METHOD_INDEX = 8;
private static final int CALLER_LINE_INDEX = 9;
private static final StackTraceElement EMPTY_CALLER_DATA = CallerData.naInstance();
static {
// PreparedStatement.getGeneratedKeys() method was added in JDK 1.4
Method getGeneratedKeysMethod;
try {
// the
getGeneratedKeysMethod = PreparedStatement.class.getMethod("getGeneratedKeys", (Class[]) null);
} catch (Exception ex) {
getGeneratedKeysMethod = null;
}
GET_GENERATED_KEYS_METHOD = getGeneratedKeysMethod;
}
@Override
public void start() {
insertSQL = buildInsertSQL();
super.start();
}
private static String buildInsertSQL() {
return "INSERT INTO log_record " +
"(time, message, logger_name, level_string, thread_name," +
"caller_filename, caller_class, caller_method, caller_line)"+
"VALUES (?, ?, ? ,?, ?, ?, ?, ?, ?)";
}
private void bindLoggingEventWithInsertStatement(PreparedStatement stmt, ILoggingEvent event) throws SQLException {
stmt.setTimestamp(TIME_INDEX, new Timestamp(event.getTimeStamp()));
stmt.setString(MESSAGE_INDEX, event.getFormattedMessage());
stmt.setString(LEVEL_STRING_INDEX, event.getLevel().toString());
stmt.setString(LOGGER_NAME_INDEX, event.getLoggerName());
stmt.setString(THREAD_NAME_INDEX, event.getThreadName());
}
private void bindCallerDataWithPreparedStatement(PreparedStatement stmt, StackTraceElement[] callerDataArray) throws SQLException {
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()));
}
@Override
protected void subAppend(ILoggingEvent event, Connection connection, PreparedStatement insertStatement) throws Throwable {
bindLoggingEventWithInsertStatement(insertStatement, event);
// This is expensive... should we do it every time?
bindCallerDataWithPreparedStatement(insertStatement, event.getCallerData());
int updateCount = insertStatement.executeUpdate();
if (updateCount != 1) {
addWarn("Failed to insert loggingEvent");
}
}
private StackTraceElement extractFirstCaller(StackTraceElement[] callerDataArray) {
StackTraceElement caller = EMPTY_CALLER_DATA;
if (hasAtLeastOneNonNullElement(callerDataArray))
caller = callerDataArray[0];
return caller;
}
private boolean hasAtLeastOneNonNullElement(StackTraceElement[] callerDataArray) {
return callerDataArray != null && callerDataArray.length > 0 && callerDataArray[0] != null;
}
@Override
protected Method getGeneratedKeysMethod() {
return GET_GENERATED_KEYS_METHOD;
}
@Override
protected String getInsertSQL() {
return insertSQL;
}
protected void secondarySubAppend(ILoggingEvent event, Connection connection, long eventId) throws Throwable {
}
}
4.5 运行测试
首先，修改logback-test.xml 中的
其次，原测试文件 BlogAction.java不变，运行后控制台输出一致，数据库中数据如下图示：
至此，可以看到数据完全插入数据库中，完全实现自定义功能。结束。
5 总结
在写这个日志模块的过程中，查了很多资料，几乎所有的文章都是千篇一律，仅有几个重写DBApepender的文章也很不清晰，无法学习。
在实在找不到资料的情况下，阅读学习源码，并重写方法实现自定义功能。一切教程文章，都比不上阅读源码来的实在，为此，写上这么一篇文章，将logback中配置的源码讲解一些，如有不清晰，还请多多包涵。在码农中，还是新人，尚在学习中。