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log4j写数据库存在单引号问题
项目中要求把日志信息写到文件的同时也把其写入数据库中, log4j.properties版本log4j-1.2.17, 配置如下
log4j.rootLogger=INFO,wjc,wjf,wjj#commonlog4j.appender.wjc.Encoding=GB2312log4j.appender.wjc=org.apache.log4j.ConsoleAppenderlog4j.appender.wjc.layout=org.apache.log4j.PatternLayoutlog4j.appender.wjc.layout.ConversionPattern=%d %5p (%F:%L) - %m%nlog4j.appender.wjf.Encoding=GB2312log4j.appender.wjf=org.apache.log4j.DailyRollingFileAppenderlog4j.appender.wjf.Append=truelog4j.appender.wjf.File.DatePattern=‘.‘yyyy-MM-ddlog4j.appender.wjf.File=${catalina.base}/logs/jin.loglog4j.appender.wjf.layout=org.apache.log4j.PatternLayoutlog4j.appender.wjf.layout.ConversionPattern=%d{yyyy-MM-dd HH\:mm\:ss } %t %p -%m%nlog4j.appender.wjj.Threshold=WARNlog4j.appender.wjj=com.common.component.syslog.Log4JdbcAppenderlog4j.appender.wjj.layout=org.apache.log4j.PatternLayoutlog4j.appender.wjj.sql=insert into cp_syslog(log_time, log_level, location, message) values (‘%d{yyyyMMddHHmmss }‘, ‘%-5p‘, ‘%C,%L‘, ‘%m‘)#speciallog4j.logger.org.apache.cxf=WARN在代码中调用log.warn("abcd");等就可以把信息写入数据库了.错误日志:
log4j:ERROR Failed to excute sql
com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘classes/spring/spring‘‘)‘ at line 1
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:936)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2870)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1665)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3170)
at com.mysql.jdbc.Statement.executeUpdate(Statement.java:1316)
at com.mysql.jdbc.Statement.executeUpdate(Statement.java:1235)
at com.joysim.common.component.syslog.Log4JdbcAppender.execute(Log4JdbcAppender.java:52)
at org.apache.log4j.jdbc.JDBCAppender.flushBuffer(JDBCAppender.java:289)
at org.apache.log4j.jdbc.JDBCAppender.append(JDBCAppender.java:186)
at org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:251)
经调试发现要执行的sql语句里面包含了单引号，而我们知道要插入数据库中单引号是要进行转义处理的.
从错误信息中跟进发现sql是在JDBCAppender.flushBuffer()方法中进行了处理, 源码如下:
public void flushBuffer() { //Do the actual logging removes.ensureCapacity(buffer.size()); for (Iterator i = buffer.iterator(); i.hasNext();) { LoggingEvent logEvent = (LoggingEvent)i.next(); try { String sql = getLogStatement(logEvent); execute(sql); } catch (SQLException e) { errorHandler.error("Failed to excute sql", e, ErrorCode.FLUSH_FAILURE); } finally { removes.add(logEvent); } }
打印发现是getLogStatement(logEvent)对sql进行了处理, 该方法的代码如下:
/** * By default getLogStatement sends the event to the required Layout object. * The layout will format the given pattern into a workable SQL string. * * Overriding this provides direct access to the LoggingEvent * when constructing the logging statement. * */ protected String getLogStatement(LoggingEvent event) { return getLayout().format(event); }
搜索setLayout()方法, 发现是在setSql(String s)方法中进行了赋值, 该方法代码如下:
public void setSql(String s) { sqlStatement = s; if (getLayout() == null) { this.setLayout(new PatternLayout(s)); } else { ((PatternLayout)getLayout()).setConversionPattern(s); } }
该方法的意思就是如果log4j配置文件没有为jdbcAppender配置patterLayout, 那么会默认指定一个PatternLayout对象给jdbcAppender. 接下来就看一下PatternLayout的format方法, 代码如下:
/** Produces a formatted string as specified by the conversion pattern. */ public String format(LoggingEvent event) { // Reset working stringbuffer if(sbuf.capacity() > MAX_CAPACITY) { sbuf = new StringBuffer(BUF_SIZE); } else { sbuf.setLength(0); } PatternConverter c = head; while(c != null) { c.format(sbuf, event); c = c.next; } return sbuf.toString(); }
head在其构造方法中进行了赋值, 代码如下:
public PatternLayout(String pattern) { this.pattern = pattern; head = createPatternParser((pattern == null) ? DEFAULT_CONVERSION_PATTERN : pattern).parse(); }
或是在setConversionPattern方法中进行赋值
public void setConversionPattern(String conversionPattern) { pattern = conversionPattern; head = createPatternParser(conversionPattern).parse(); }
从上面的代码中可以看到在JDBCAppender的setSql方法中对上述两方法进行了调用.
执行parse(),
public org.apache.log4j.helpers.PatternConverter parse() { return new BridgePatternConverter(pattern); }构造方法 public BridgePatternConverter( final String pattern) { next = null; handlesExceptions = false; List converters = new ArrayList(); List fields = new ArrayList(); Map converterRegistry = null; PatternParser.parse( pattern, converters, fields, converterRegistry, PatternParser.getPatternLayoutRules()); patternConverters = new LoggingEventPatternConverter[converters.size()]; patternFields = new FormattingInfo[converters.size()]; int i = 0; Iterator converterIter = converters.iterator(); Iterator fieldIter = fields.iterator(); while (converterIter.hasNext()) { Object converter = converterIter.next(); if (converter instanceof LoggingEventPatternConverter) { patternConverters[i] = (LoggingEventPatternConverter) converter; handlesExceptions |= patternConverters[i].handlesThrowable(); } else { patternConverters[i] = new org.apache.log4j.pattern.LiteralPatternConverter(""); } if (fieldIter.hasNext()) { patternFields[i] = (FormattingInfo) fieldIter.next(); } else { patternFields[i] = FormattingInfo.getDefault(); } i++; } }解析public static void parse( final String pattern, final List patternConverters, final List formattingInfos, final Map converterRegistry, final Map rules) { if (pattern == null) { throw new NullPointerException("pattern"); } StringBuffer currentLiteral = new StringBuffer(32); int patternLength = pattern.length(); int state = LITERAL_STATE; char c; int i = 0; FormattingInfo formattingInfo = FormattingInfo.getDefault(); while (i < patternLength) { c = pattern.charAt(i++); switch (state) { case LITERAL_STATE: // In literal state, the last char is always a literal. if (i == patternLength) { currentLiteral.append(c); continue; } if (c == ESCAPE_CHAR) { // peek at the next char. switch (pattern.charAt(i)) { case ESCAPE_CHAR: currentLiteral.append(c); i++; // move pointer break; default: if (currentLiteral.length() != 0) { patternConverters.add( new LiteralPatternConverter(currentLiteral.toString())); formattingInfos.add(FormattingInfo.getDefault()); } currentLiteral.setLength(0); currentLiteral.append(c); // append % state = CONVERTER_STATE; formattingInfo = FormattingInfo.getDefault(); } } else { currentLiteral.append(c); } break; case CONVERTER_STATE: currentLiteral.append(c); switch (c) { case ‘-‘: formattingInfo = new FormattingInfo( true, formattingInfo.getMinLength(), formattingInfo.getMaxLength()); break; case ‘.‘: state = DOT_STATE; break; default: if ((c >= ‘0‘) && (c <= ‘9‘)) { formattingInfo = new FormattingInfo( formattingInfo.isLeftAligned(), c - ‘0‘, formattingInfo.getMaxLength()); state = MIN_STATE; } else { i = finalizeConverter( c, pattern, i, currentLiteral, formattingInfo, converterRegistry, rules, patternConverters, formattingInfos); // Next pattern is assumed to be a literal. state = LITERAL_STATE; formattingInfo = FormattingInfo.getDefault(); currentLiteral.setLength(0); } } // switch break; case MIN_STATE: currentLiteral.append(c); if ((c >= ‘0‘) && (c <= ‘9‘)) { formattingInfo = new FormattingInfo( formattingInfo.isLeftAligned(), (formattingInfo.getMinLength() * 10) + (c - ‘0‘), formattingInfo.getMaxLength()); } else if (c == ‘.‘) { state = DOT_STATE; } else { i = finalizeConverter( c, pattern, i, currentLiteral, formattingInfo, converterRegistry, rules, patternConverters, formattingInfos); state = LITERAL_STATE; formattingInfo = FormattingInfo.getDefault(); currentLiteral.setLength(0); } break; case DOT_STATE: currentLiteral.append(c); if ((c >= ‘0‘) && (c <= ‘9‘)) { formattingInfo = new FormattingInfo( formattingInfo.isLeftAligned(), formattingInfo.getMinLength(), c - ‘0‘); state = MAX_STATE; } else { LogLog.error( "Error occured in position " + i + ".\n Was expecting digit, instead got char \"" + c + "\"."); state = LITERAL_STATE; } break; case MAX_STATE: currentLiteral.append(c); if ((c >= ‘0‘) && (c <= ‘9‘)) { formattingInfo = new FormattingInfo( formattingInfo.isLeftAligned(), formattingInfo.getMinLength(), (formattingInfo.getMaxLength() * 10) + (c - ‘0‘)); } else { i = finalizeConverter( c, pattern, i, currentLiteral, formattingInfo, converterRegistry, rules, patternConverters, formattingInfos); state = LITERAL_STATE; formattingInfo = FormattingInfo.getDefault(); currentLiteral.setLength(0); } break; } // switch } // while if (currentLiteral.length() != 0) { patternConverters.add( new LiteralPatternConverter(currentLiteral.toString())); formattingInfos.add(FormattingInfo.getDefault()); } }
代码较长, 大概的意思就是把log4j配置文件中的sql语句, insert into cp_syslog(log_time, log_level, location, message) values (‘%d{yyyyMMddHHmmss }‘, ‘%-5p‘, ‘%C,%L‘, ‘%m‘), 中的p, c, l, m等都转成PatternConverter, 并返回第一个PatternConverter, 说到底就是一个链表, 而this.head是这个链表的头元素. 现在主要就是关注各个PatternConverter的format方法,
static { // We set the global rules in the static initializer of PatternParser class Map rules = new HashMap(17); rules.put("c", LoggerPatternConverter.class); rules.put("logger", LoggerPatternConverter.class); rules.put("C", ClassNamePatternConverter.class); rules.put("class", ClassNamePatternConverter.class); rules.put("d", DatePatternConverter.class); rules.put("date", DatePatternConverter.class); rules.put("F", FileLocationPatternConverter.class); rules.put("file", FileLocationPatternConverter.class); rules.put("l", FullLocationPatternConverter.class); rules.put("L", LineLocationPatternConverter.class); rules.put("line", LineLocationPatternConverter.class); rules.put("m", MessagePatternConverter.class); rules.put("message", MessagePatternConverter.class); rules.put("n", LineSeparatorPatternConverter.class); rules.put("M", MethodLocationPatternConverter.class); rules.put("method", MethodLocationPatternConverter.class); rules.put("p", LevelPatternConverter.class); rules.put("level", LevelPatternConverter.class); rules.put("r", RelativeTimePatternConverter.class); rules.put("relative", RelativeTimePatternConverter.class); rules.put("t", ThreadPatternConverter.class); rules.put("thread", ThreadPatternConverter.class); rules.put("x", NDCPatternConverter.class); rules.put("ndc", NDCPatternConverter.class); rules.put("X", PropertiesPatternConverter.class); rules.put("properties", PropertiesPatternConverter.class); rules.put("sn", SequenceNumberPatternConverter.class); rules.put("sequenceNumber", SequenceNumberPatternConverter.class); rules.put("throwable", ThrowableInformationPatternConverter.class); PATTERN_LAYOUT_RULES = new ReadOnlyMap(rules); Map fnameRules = new HashMap(4); fnameRules.put("d", FileDatePatternConverter.class); fnameRules.put("date", FileDatePatternConverter.class); fnameRules.put("i", IntegerPatternConverter.class); fnameRules.put("index", IntegerPatternConverter.class); FILENAME_PATTERN_RULES = new ReadOnlyMap(fnameRules); }
MessagePatternConverter的format方法如下:
public void format(final LoggingEvent event, final StringBuffer toAppendTo) { toAppendTo.append(event.getRenderedMessage()); }
MyLoggingEvent类中有getThreadName和getRenderedMessage两个方法
很奇怪, 跟踪到这里发现源码中是有对单引号进行处理的, 可是为什么还会出现问题呢
ThreadPatternConverter 的format方法如下:
public void format(final LoggingEvent event, final StringBuffer toAppendTo) { toAppendTo.append(event.getThreadName()); }
我们可以在event.getThreadName()和event.getRenderedMessage()方法返回前对单引号进行替换, 因此我们可以写一个类扩展LoggingEvent, 重写LoggingEvent的getRenderedMessage和getThreadName方法, 代码如下:
public class MyLoggingEvent extends LoggingEvent { /** */ private static final long serialVersionUID = -3499094864944744184L; public MyLoggingEvent(String fqnOfCategoryClass, Category logger, Priority level, Object message, Throwable throwable) { super(fqnOfCategoryClass, logger, level, message, throwable); } public String getThreadName() { String thrdName = super.getThreadName(); if (thrdName.indexOf("‘") != -1) { thrdName = thrdName.replaceAll("‘", "‘‘"); } return thrdName; } public String getRenderedMessage() { String msg = super.getRenderedMessage(); if (msg.indexOf("‘") != -1) { msg = msg.replaceAll("‘", "‘‘"); } return msg; }}
最后在我们log4j配置文件中指定的Log4JdbcAppender处理类中, 覆写JDBCAppender的getLogStatement方法, 让程序执行我们重写的MyLoggingEvent类中的相应方法, 代码如下:
public class Log4JdbcAppender extends JDBCAppender { private JdbcSupport jdbcSupport; @Override protected void closeConnection(Connection conn) { try { if (conn != null && !conn.isClosed()) conn.close(); } catch (SQLException e) { errorHandler.error("Error closing connection", e, ErrorCode.GENERIC_FAILURE); } } @Override protected Connection getConnection() throws SQLException { if (jdbcSupport == null) { jdbcSupport = SpringUtils.getBean(JdbcSupport.class, "jdbcSupport"); } return jdbcSupport == null ? null : jdbcSupport.getJt().getDataSource().getConnection(); } @Override protected void execute(String sql) throws SQLException { Connection conn = getConnection(); if (conn != null) { Statement stmt = null; try { stmt = conn.createStatement(); stmt.executeUpdate(sql); } catch (SQLException e) { if (stmt != null) stmt.close(); throw e; } stmt.close(); closeConnection(conn); } } @Override protected String getLogStatement(LoggingEvent event) { String fqnOfCategoryClass=event.fqnOfCategoryClass; Category logger=event.getLogger(); Priority level=event.getLevel(); Object message=event.getMessage(); Throwable throwable=null; MyLoggingEvent bEvent=new MyLoggingEvent(fqnOfCategoryClass,logger,level,message,throwable); return super.getLogStatement(bEvent); }}
大功告成, 日志成功插入到数据库
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