想要得到自己钟意的日志输出，必须了解PatternLayout的配置。可以理解成c或java的String Format,只是format中的参数按照ConversionPattern的约定由log4j来填充。各个参数的含义如下表：
来自官网手册 http://logging.apache.org/log4j/2.x/manual/layouts.html#PatternLayout
也可以参考《Log4j输出格式控制--log4j的PatternLayout参数含义》 这篇博文，相对比较简短。
| Conversion Pattern | Description | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| c{precision} logger{precision} |
Outputs the name of the logger that published the logging event. The logger conversion specifier can be optionally followed by precision specifier, which consists of a decimal integer, or a pattern starting with a decimal integer. When the precision specifier is an integer value, it reduces the size of the logger name. If the number is positive, the layout prints the corresponding number of rightmost logger name components. If negative, the layout removes the corresponding number of leftmost logger name components. If the precision contains any non-integer characters, then the layout abbreviates the name based on the pattern. If the precision integer is less than one, the layout still prints the right-most token in full. By default, the layout prints the logger name in full.
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| C{precision} class{precision} |
Outputs the fully qualified class name of the caller issuing the logging request. This conversion specifier can be optionally followed by precision specifier, that follows the same rules as the logger name converter. Generating the class name of the caller (location information) is an expensive operation and may impact performance. Use with caution. |
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| d{pattern} date{pattern} |
Outputs the date of the logging event. The date conversion specifier may be followed by a set of braces containing a date and time pattern string per SimpleDateFormat . The predefined formats are DEFAULT, ABSOLUTE, COMPACT, DATE, ISO8601, and ISO8601_BASIC. You can also use a set of braces containing a time zone id per java.util.TimeZone.getTimeZone. If no date format specifier is given then the DEFAULT format is used.
%d{UNIX} outputs the UNIX time in seconds. %d{UNIX_MILLIS} outputs the UNIX time in milliseconds. The UNIX time is the difference, in seconds for UNIX and in milliseconds for UNIX_MILLIS, between the current time and midnight, January 1, 1970 UTC. While the time unit is milliseconds, the granularity depends on the operating system (Windows). This is an efficient way to output the event time because only a conversion from long to String takes place, there is no Date formatting involved. |
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| enc{pattern} encode{pattern} |
Encodes special characters such as '\n' and HTML characters to help prevent log forging and some XSS attacks that could occur when displaying logs in a web browser. Anytime user provided data is logged, this can provide a safeguard. A typical usage would encode the message %enc{%m} but user input could come from other locations as well, such as the MDC %enc{%mdc{key}} The replaced characters are:
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| equals{pattern}{test}{substitution} equalsIgnoreCase{pattern}{test}{substitution} |
Replaces occurrences of 'test', a string, with its replacement 'substitution' in the string resulting from evaluation of the pattern. For example, "%equals{[%marker]}{[]}{}" will replace '[]' strings produces by events without markers with an empty string. The pattern can be arbitrarily complex and in particular can contain multiple conversion keywords. |
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| ex|exception|throwable {["none" |"full" |depth |"short" |"short.className" |"short.fileName" |"short.lineNumber" |"short.methodName" |"short.message" |"short.localizedMessage"]} |
Outputs the Throwable trace bound to the LoggingEvent, by default this will output the full trace as one would normally find with a call to Throwable.printStackTrace(). You can follow the throwable conversion word with an option in the form %throwable{option}. %throwable{short} outputs the first line of the Throwable. %throwable{short.className} outputs the name of the class where the exception occurred. %throwable{short.methodName} outputs the method name where the exception occurred. %throwable{short.fileName} outputs the name of the class where the exception occurred. %throwable{short.lineNumber} outputs the line number where the exception occurred. %throwable{short.message} outputs the message. %throwable{short.localizedMessage} outputs the localized message. %throwable{n} outputs the first n lines of the stack trace. Specifying %throwable{none} or %throwable{0} suppresses output of the exception. |
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| F file |
Outputs the file name where the logging request was issued. Generating the file information (location information) is an expensive operation and may impact performance. Use with caution. |
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| highlight{pattern}{style} | Adds ANSI colors to the result of the enclosed pattern based on the current event's logging level. The default colors for each level are:
The color names are ANSI names defined in the AnsiEscape class. The color and attribute names and are standard, but the exact shade, hue, or value. Color table
You can use the default colors with: %highlight{%d [%t] %-5level: %msg%n%throwable} You can override the default colors in the optional {style} option. For example: %highlight{%d [%t] %-5level: %msg%n%throwable}{FATAL=white, ERROR=red, WARN=blue, INFO=black, DEBUG=green, TRACE=blue} You can highlight only the a portion of the log event: %d [%t] %highlight{%-5level: %msg%n%throwable} You can style one part of the message and highlight the rest the log event: %style{%d [%t]}{black} %highlight{%-5level: %msg%n%throwable} You can also use the STYLE key to use a predefined group of colors: %highlight{%d [%t] %-5level: %msg%n%throwable}{STYLE=Logback} The STYLE value can be one of:
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| K{key} map{key} MAP{key} |
Outputs the entries in a MapMessage, if one is present in the event. The K conversion character can be followed by the key for the map placed between braces, as in%K{clientNumber} where clientNumber is the key. The value in the Map corresponding to the key will be output. If no additional sub-option is specified, then the entire contents of the Map key value pair set is output using a format {{key1,val1},{key2,val2}} |
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| l location |
Outputs location information of the caller which generated the logging event. The location information depends on the JVM implementation but usually consists of the fully qualified name of the calling method followed by the callers source the file name and line number between parentheses. Generating location information is an expensive operation and may impact performance. Use with caution. |
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| L line |
Outputs the line number from where the logging request was issued. Generating line number information (location information) is an expensive operation and may impact performance. Use with caution. |
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| m{nolookups}{ansi} msg{nolookups}{ansi} message{nolookups}{ansi} |
Outputs the application supplied message associated with the logging event. Add {ansi} to render messages with ANSI escape codes (requires JAnsi.) The default syntax for embedded ANSI codes is:
For example, to render the message "Hello" in green, use:
To render the message "Hello" in bold and red, use:
You can also define custom style names in the configuration with the syntax:
For example:
The call site can look like this:
Use {nolookups} to log messages like "${date:YYYY-MM-dd}" without using any lookups. Normally calling logger.info("Try ${date:YYYY-MM-dd}") would replace the date template ${date:YYYY-MM-dd} with an actual date. Using nolookups disables this feature and logs the message string untouched. |
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| M method |
Outputs the method name where the logging request was issued. Generating the method name of the caller (location information) is an expensive operation and may impact performance. Use with caution. |
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| marker | The full name of the marker, including parents, if one is present. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| markerSimpleName | The simple name of the marker (not including parents), if one is present. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| maxLen maxLength |
Outputs the result of evaluating the pattern and truncating the result. If the length is greater than 20, then the output will contain a trailing ellipsis. If the provided length is invalid, a default value of 100 is used. Example syntax: %maxLen{%p: %c{1} - %m%notEmpty{ =>%ex{short}}}{160} will be limited to 160 characters with a trailing ellipsis. Another example: %maxLen{%m}{20}will be limited to 20 characters and no trailing ellipsis. |
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| n | Outputs the platform dependent line separator character or characters. This conversion character offers practically the same performance as using non-portable line separator strings such as "\n", or "\r\n". Thus, it is the preferred way of specifying a line separator. |
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| N nano |
Outputs the result of System.nanoTime() at the time the log event was created. |
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| variablesNotEmpty{pattern} varsNotEmpty{pattern} notEmpty{pattern} |
Outputs the result of evaluating the pattern if and only if all variables in the pattern are not empty. For example: %notEmpty{[%marker]} |
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| p|level{level=label, level=label, ...}p|level{length=n}p|level{lowerCase=true|false} | Outputs the level of the logging event. You provide a level name map in the form "level=value, level=value" where level is the name of the Level and value is the value that should be displayed instead of the name of the Level. For example: %level{WARN=Warning, DEBUG=Debug, ERROR=Error, TRACE=Trace, INFO=Info} Alternatively, for the compact-minded: %level{WARN=W, DEBUG=D, ERROR=E, TRACE=T, INFO=I} More succinctly, for the same result as above, you can define the length of the level label: %level{length=1} If the length is greater than a level name length, the layout uses the normal level name. You can combine the two kinds of options: %level{ERROR=Error, length=2} This give you the Error level name and all other level names of length 2. Finally, you can output lower-case level names (the default is upper-case): %level{lowerCase=true} |
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| r relative |
Outputs the number of milliseconds elapsed since the JVM was started until the creation of the logging event. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| replace{pattern}{regex}{substitution} | Replaces occurrences of 'regex', a regular expression, with its replacement 'substitution' in the string resulting from evaluation of the pattern. For example, "%replace(%msg}{\s}{}" will remove all spaces contained in the event message. The pattern can be arbitrarily complex and in particular can contain multiple conversion keywords. For instance, "%replace{%logger %msg}{\.}{/}" will replace all dots in the logger or the message of the event with a forward slash. |
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| rEx["none"|"short"|"full"|depth],[filters(packages)} rException["none"|"short"|"full"|depth],[filters(packages)} rThrowable["none"|"short"|"full"|depth],[filters(packages)} |
The same as the %throwable conversion word but the stack trace is printed starting with the first exception that was thrown followed by each subsequent wrapping exception. The throwable conversion word can be followed by an option in the form %rEx{short} which will only output the first line of the Throwable or %rEx{n} where the first n lines of the stacktrace will be printed. The conversion word can also be followed by "filters(packages)" where packages is a list of package names that should be suppressed from stack traces. Specifying %rEx{none} or %rEx{0} will suppress printing of the exception. |
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| sn sequenceNumber |
Includes a sequence number that will be incremented in every event. The counter is a static variable so will only be unique within applications that share the same converter Class object. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| style{pattern}{ANSI style} | Uses ANSI escape sequences to style the result of the enclosed pattern. The style can consist of a comma separated list of style names from the following table.
For example: %style{%d{ISO8601}}{black} %style{[%t]}{blue} %style{%-5level:}{yellow} %style{%msg%n%throwable}{green} You can also combine styles: %d %highlight{%p} %style{%logger}{bright,cyan} %C{1.} %msg%n You can also use % with a color like %black, %blue, %cyan, and so on. For example: %black{%d{ISO8601}} %blue{[%t]} %yellow{%-5level:} %green{%msg%n%throwable} |
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| T tid threadId |
Outputs the ID of the thread that generated the logging event. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| t tn thread threadName |
Outputs the name of the thread that generated the logging event. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| tp threadPriority |
Outputs the priority of the thread that generated the logging event. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| x NDC |
Outputs the Thread Context Stack (also known as the Nested Diagnostic Context or NDC) associated with the thread that generated the logging event. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| X{key[,key2...]} mdc{key[,key2...]} MDC{key[,key2...]} |
Outputs the Thread Context Map (also known as the Mapped Diagnostic Context or MDC) associated with the thread that generated the logging event. The X conversion character can be followed by one or more keys for the map placed between braces, as in %X{clientNumber} where clientNumber is the key. The value in the MDC corresponding to the key will be output. If a list of keys are provided, such as %X{name, number}, then each key that is present in the ThreadContext will be output using the format {name=val1, number=val2}. The key/value pairs will be printed in the order they appear in the list. If no sub-options are specified then the entire contents of the MDC key value pair set is output using a format {key1=val1, key2=val2}. The key/value pairs will be printed in sorted order. See the ThreadContext class for more details. |
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| u{"RANDOM" | "TIME"} uuid |
Includes either a random or a time-based UUID. The time-based UUID is a Type 1 UUID that can generate up to 10,000 unique ids per millisecond, will use the MAC address of each host, and to try to insure uniqueness across multiple JVMs and/or ClassLoaders on the same host a random number between 0 and 16,384 will be associated with each instance of the UUID generator Class and included in each time-based UUID generated. Because time-based UUIDs contain the MAC address and timestamp they should be used with care as they can cause a security vulnerability. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| xEx|xException|xThrowable { ["none"|"short"|"full"|depth] [,filters(package,package,...)] } {ansi( Key=Value,Value,... Key=Value,Value,... ...) } |
The same as the %throwable conversion word but also includes class packaging information. At the end of each stack element of the exception, a string containing the name of the jar file that contains the class or the directory the class is located in and the "Implementation-Version" as found in that jar's manifest will be added. If the information is uncertain, then the class packaging data will be preceded by a tilde, i.e. the '~' character. The throwable conversion word can be followed by an option in the form %xEx{short} which will only output the first line of the Throwable or %xEx{n} where the first n lines of the stacktrace will be printed. The conversion word can also be followed by "filters(packages)" where packages is a comma-sepaarted list of package names that should be suppressed from stack traces. Specifying %xEx{none} or %xEx{0} will suppress printing of the exception. The ansi option renders stack traces with ANSI escapes code using the JAnsi library. Use {ansi} to use the default color mapping. You can specify your own mappings withkey=value pairs. The keys are:
The values are names from JAnsi's Code class like blue, bg_red, and so on (Log4j ignores case.) The special key StyleMapName can be set to one of the following prefedined maps: Spock, Kirk. |
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| % | The sequence %% outputs a single percent sign. |