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本文主要研究一下logback的ThresholdFilter
ThresholdFilter
ch/qos/logback/classic/filter/ThresholdFilter.java
代码语言：javascript复制public class ThresholdFilter extends Filter<ILoggingEvent> {
Level level;
@Override
public FilterReply decide(ILoggingEvent event) {
if (!isStarted()) {
return FilterReply.NEUTRAL;
}
if (event.getLevel().isGreaterOrEqual(level)) {
return FilterReply.NEUTRAL;
} else {
return FilterReply.DENY;
}
}
public void setLevel(String level) {
this.level = Level.toLevel(level);
}
public void start() {
if (this.level != null) {
super.start();
}
}
}ThresholdFilter继承了Filter，其decide方法从ILoggingEvent获取level，若该level大于等于指定的level则返回NEUTRAL，否则返回DENY
isGreaterOrEqual
ch/qos/logback/classic/Level.java
代码语言：javascript复制public final class Level implements java.io.Serializable {
private static final long serialVersionUID = -814092767334282137L;
public static final int OFF_INT = Integer.MAX_VALUE;
public static final int ERROR_INT = 40000;
public static final int WARN_INT = 30000;
public static final int INFO_INT = 20000;
public static final int DEBUG_INT = 10000;
public static final int TRACE_INT = 5000;
public static final int ALL_INT = Integer.MIN_VALUE;
/**
* The <code>OFF</code> is used to turn off logging.
*/
public static final Level OFF = new Level(OFF_INT, "OFF");
/**
* The <code>ERROR</code> level designates error events which may or not be
* fatal to the application.
*/
public static final Level ERROR = new Level(ERROR_INT, "ERROR");
/**
* The <code>WARN</code> level designates potentially harmful situations.
*/
public static final Level WARN = new Level(WARN_INT, "WARN");
/**
* The <code>INFO</code> level designates informational messages highlighting
* overall progress of the application.
*/
public static final Level INFO = new Level(INFO_INT, "INFO");
/**
* The <code>DEBUG</code> level designates informational events of lower
* importance.
*/
public static final Level DEBUG = new Level(DEBUG_INT, "DEBUG");
/**
* The <code>TRACE</code> level designates informational events of very low
* importance.
*/
public static final Level TRACE = new Level(TRACE_INT, "TRACE");
/**
* The <code>ALL</code> is used to turn on all logging.
*/
public static final Level ALL = new Level(ALL_INT, "ALL");
public final int levelInt;
public final String levelStr;
/**
* Instantiate a Level object.
*/
private Level(int levelInt, String levelStr) {
this.levelInt = levelInt;
this.levelStr = levelStr;
}
/**
* Returns <code>true</code> if this Level has a higher or equal Level than the
* Level passed as argument, <code>false</code> otherwise.
*/
public boolean isGreaterOrEqual(Level r) {
return levelInt >= r.levelInt;
}
//......
} Level定义了OFF(
Integer.MAX_VALUE)、ERROR(40000)、WARN(30000)、INFO(20000)、DEBUG(10000)、TRACE(5000)、ALL(Integer.MIN_VALUE)这几个level，其int值依次减小。isGreaterOrEqual方法则是根据levelInt值来判断。
示例
代码语言：javascript复制 <appender name="FILE_INFO"
class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>infoLog.log</file>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<fileNamePattern>infoLogs.%d{yyyy-MM-dd}.log</fileNamePattern>
<maxHistory>30</maxHistory>
<totalSizeCap>3GB</totalSizeCap>
</rollingPolicy>
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<level>INFO</level>
</filter>
<encoder>
<pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n
</pattern>
</encoder>
</appender>这里对FILE_INFO添加了ThresholdFilter，只有级别大于等于INFO的才打印
小结
logback的ThresholdFilter继承了Filter，其decide方法从ILoggingEvent获取level，若该level大于等于指定的level则返回NEUTRAL，否则返回DENY。Level定义了OFF(Integer.MAX_VALUE)、ERROR(40000)、WARN(30000)、INFO(20000)、DEBUG(10000)、TRACE(5000)、ALL(Integer.MIN_VALUE)这几个level，其int值依次减小。isGreaterOrEqual方法则是根据levelInt值来判断。
