Logback 日志持久化

Logback是log4j的增强版，比log4j更具灵活，其提供了将日志输出到数据库的功能，本文将介绍如何将指定的日志输出到mysql中。

一、自定义log标志

由于Logback原生的配置会将所有的日志信息输出到mysql数据表中，故需要自定义标志，继承AbstractMatcherFilter，过滤掉无标志的日志：

1、自定义标志过滤器

public class LogbackMarkerFilter extends AbstractMatcherFilter<ILoggingEvent> {

    private Marker markerToMatch = null;

    @Override
    public void start() {
        if (null != this.markerToMatch) {
            super.start();
        } else {
            addError(" no MARKER yet !");
        }
    }

    @Override
    public FilterReply decide(ILoggingEvent event) {
        Marker marker = event.getMarker();
        if (!isStarted()) {
            return FilterReply.NEUTRAL;
        }
        if (null == marker) {
            return onMismatch;
        }
        if (markerToMatch.contains(marker)) {
            return onMatch;
        }
        return onMismatch;
    }

    public void setMarker(String markerStr) {
        if (null != markerStr) {
            markerToMatch = MarkerFactory.getMarker(markerStr);
        }
    }
}

2、logback-spring.xml 相关配置文件

<!-- 读取配置文件中参数 -->
<springProperty scope="context" name="driverClass" source="spring.datasource.driver-class-name"/>
<springProperty scope="context" name="url" source="spring.datasource.url"/>
<springProperty scope="context" name="username" source="spring.datasource.username"/>
<springProperty scope="context" name="password" source="spring.datasource.password"/>
<springProperty scope="context" name="logFilePath" source="logging.path"/>
<springProperty scope="context" name="maxHistory" source="logging.maxHistory"/>

<!-- 数据库日志记录 -->
<appender name="DB_APPENDER" class="ch.qos.logback.classic.db.DBAppender">
　　<filter class="com.cenobitor.logging.filter.LogbackMarkerFilter">
    　　　<!-- 自定义标志 -->
    　　　<marker>DB</marker>
    　　　<onMatch>ACCEPT</onMatch>
    　　　<onMismatch>DENY</onMismatch>
    </filter>
　　<!-- 配置数据源 springboot默认情况会开启光连接池 -->
　　<connectionSource class="ch.qos.logback.core.db.DriverManagerConnectionSource">
        <driverClass>${driverClass}</driverClass>
        <url>${url}</url>
        <user>${username}</user>
        <password>${password}</password>
    </connectionSource>
</appender>

<!-- 异步日志记录 -->
<appender name="ASYNC_APPENDER" class="ch.qos.logback.classic.AsyncAppender">
　　<appender-ref ref="DB_APPENDER" />
　　<includeCallerData>true</includeCallerData>
</appender>

        <!-- 日志输出级别 -->
<root level="${LOG_LEVEL}">
　　<appender-ref ref="ASYNC_APPENDER" />
</root>

经配置，其需要建三张数据表，分别为日志信息、异常信息、属性信息，其建表语句如下：

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;

二、自定义输出日志

由于Logback原生要求建三张表，如何指定指输出一种信息，及自定义日志内容，而异常、属性信息不输出？

通过查看DBAppender发现，插入数据方法，此处只需重写DBAppender，即继承DBAppenderBase<ILoggingEvent>，删除掉异常、属性信息插入的相关方法即可实现只输出指定日志到指定表，而其它信息将不会输出到数据库中，代码如下：

public class LogDBAppender extends DBAppenderBase<ILoggingEvent> {

    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();
        insertSQL = 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<String, String> 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<String, String> mergePropertyMaps(ILoggingEvent event) {
        Map<String, String> mergedMap = new HashMap<String, String>();
        // 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<String, String> loggerContextMap = event.getLoggerContextVO().getPropertyMap();
        Map<String, String> 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;
    }


    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();
    }
}

现在只需将配置中引用的DBAppender：

<appender name="DB_APPENDER" class="ch.qos.logback.classic.db.DBAppender">

更改为自己重写的类：

<appender name="DB_APPENDER" class="com.cenobitor.logging.db.LogDBAppender">

表logging_event_property、表logging_event_exception将可删除，至此基本的配置已完成，可以畅快的使用了。

三、使用

log.info(MarkerFactory.getMarker("DB"), "logback!");

即可异步将该日志输出到数据库中。