Tomcat中日志组件

Tomcat日志组件

AccessLog接口

public interface AccessLog {
public void log(Request request, Response response, long time);
}


AccessLogAdapter

public class AccessLogAdapter implements AccessLog {
private AccessLog[] logs;
// 构造函数
public AccessLogAdapter(AccessLog log) {
Objects.requireNonNull(log);
logs = new AccessLog[] { log };
}
// 添加新的 访问日志 AccessLog
public void add(AccessLog log) {
Objects.requireNonNull(log);
AccessLog newArray[] = Arrays.copyOf(logs, logs.length + 1);
newArray[newArray.length - 1] = log;
logs = newArray;
}
// AccessLog 接口中的 log 方法，循环操作
@Override
public void log(Request request, Response response, long time) {
for (AccessLog log: logs) {
log.log(request, response, time);
}
}
}


Tomcat中日志

​默认在 server.xml 中配置了 AccessLogValve 。

<!-- server.xml Host 节点 -->
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
suffix=".txt"
prefix="localhost_access_log"
pattern="%h %l %u %t &quot;%r&quot; %s %b" />
<!--
className=org.apache.catalina.valves.AccessLogValve
directory=logs 存储位置
prefix 文件前缀
suffix 文件后缀
pattern 输出格式
-->


@Override
public void log(CharArrayWriter message) {
System.out.println("log");
rotate(); /* In case something external rotated the file instead */
if (checkExists) {
synchronized (this) {
if (currentLogFile != null && !currentLogFile.exists()) {
try {
close(false);
} catch (Throwable e) {
ExceptionUtils.handleThrowable(e);
log.info(sm.getString("accessLogValve.closeFail"), e);
} /* Make sure date is correct */
dateStamp = fileDateFormatter.format(
new Date(System.currentTimeMillis())); open();
}
}
} // Log this message
try {
synchronized(this) {
if (writer != null) {
message.writeTo(writer);
writer.println("");
if (!buffered) {
writer.flush();
}
}
}
} catch (IOException ioe) {
log.warn(sm.getString(
"accessLogValve.writeFail", message.toString()), ioe);
}
}


调用过程

// ContainerBase
@Override
public void logAccess(Request request, Response response, long time,
boolean useDefault) {
boolean logged = false;
// 获取 注册的 日志组件
AccessLog accessLog = getAccessLog();
if (accessLog != null) {
// 调用 适配器 log 方法
accessLog.log(request, response, time);
logged = true;
}
if (getParent() != null) {
getParent().logAccess(request, response, time,
(useDefault && !logged));
}
}@Override
public AccessLog getAccessLog() {
// 默认 false
if (accessLogScanComplete) {
return accessLog;
}
// AccessLog 适配器
AccessLogAdapter adapter = null;
// 获取所有注册的 阀门 Valve
Valve valves[] = getPipeline().getValves();
for (Valve valve : valves) {
// 判断 Valve 的类型
if (valve instanceof AccessLog) {
if (adapter == null) {
adapter = new AccessLogAdapter((AccessLog) valve);
} else {
adapter.add((AccessLog) valve);
}
}
}
if (adapter != null) {
accessLog = adapter;
}
accessLogScanComplete = true;
return accessLog;
}


自定义 AccessLog

在 server.xml 中 ,配置 Valve ，在解析 server.xml 会自动注册。

public class WswAccessLogValve extends AbstractAccessLogValve { @Override
protected void log(CharArrayWriter message) {
System.out.println("access log");
}
}
// message
// ||
// VV
// 0:0:0:0:0:0:0:1 - - [08/Dec/2018:23:47:07 +0800] "GET /tomcat/ HTTP/1.1" 200 139


<!-- server.xml Host 节点 -->
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" suffix=".txt"
prefix="localhost_access_log"
pattern="%h %l %u %t &quot;%r&quot; %s %b" /><Valve className="org.apache.catalina.valves.WswAccessLogValve"/>


log // AccessLogValve 中输出
access log// WswAccessLogValve 中输出