log4j MDC实现日志追踪
MDC 中包含的可以被同一线程中执行的代码所访问内容。当前线程的子线程会继承其父线程中的 MDC 的内容。记录日志时，只需要从 MDC 中获取所需的信息即可。
作用：
使用MDC来记录日志，可以规范多开发下日志格式。
1、新建线程处理类 ThreadContext
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
public class ThreadContext {
private final static ThreadLocal<Map<String, Object>> CTX_HOLDER = new ThreadLocal<Map<String, Object>>();
static {
CTX_HOLDER.set(new HashMap<String, Object>());
}
private final static String TRACE_ID_KEY = "traceId";
private final static String SESSION_KEY = "token";
private final static String VISITOR_ID_KEY = "userId";
private final static String VISITOR_NAME_KEY = "userName";
private static final String CLIENT_IP_KEY = "clientIp";
public final static void putContext(String key, Object value) {
Map<String, Object> ctx = CTX_HOLDER.get();
if (ctx == null) {
return;
}
ctx.put(key, value);
}
@SuppressWarnings("unchecked")
public final static <T extends Object> T getContext(String key) {
Map<String, Object> ctx = CTX_HOLDER.get();
if (ctx == null) {
return null;
}
return (T) ctx.get(key);
}
public final static Map<String, Object> getContext() {
Map<String, Object> ctx = CTX_HOLDER.get();
if (ctx == null) {
return null;
}
return ctx;
}
public final static void remove(String key) {
Map<String, Object> ctx = CTX_HOLDER.get();
if (ctx != null) {
ctx.remove(key);
}
}
public final static boolean contains(String key) {
Map<String, Object> ctx = CTX_HOLDER.get();
if (ctx != null) {
return ctx.containsKey(key);
}
return false;
}
public final static void clean() {
CTX_HOLDER.remove();
}
public final static void init() {
CTX_HOLDER.set(new HashMap<String, Object>());
}
public final static void putTraceId(String traceId) {
putContext(TRACE_ID_KEY, traceId);
}
public final static String getTraceId() {
return getContext(TRACE_ID_KEY);
}
public final static void putUserId(Integer userId) {
putContext(VISITOR_ID_KEY, userId);
}
public final static int getUserId() {
Integer val = getContext(VISITOR_ID_KEY);
return val == null ? 0 : val;
}
public final static void putUserName(String userName) {
putContext(VISITOR_NAME_KEY, userName);
}
public final static String getUserName() {
return Optional.ofNullable(getContext(VISITOR_NAME_KEY))
.map(name -> String.valueOf(name))
.orElse("");
}
public static final String getClientIp() {
return getContext(CLIENT_IP_KEY);
}
public static final void putClientIp(String ip) {
putContext(CLIENT_IP_KEY, ip);
}
public static void putSessionId(String token) {
putContext(SESSION_KEY, token);
}
public static String getSessionId(String token) {
return getContext(SESSION_KEY);
}
public final static void removeSessionId() {
remove(SESSION_KEY);
}
}
2、添加工具类TraceUtil
import java.util.UUID;
import org.slf4j.MDC;
import ThreadContext;
public class TraceUtil {
public static void traceStart() {
ThreadContext.init();
String traceId = generateTraceId();
MDC.put('traceId', traceId);
ThreadContext.putTraceId(traceId);
}
public static void traceEnd() {
MDC.clear();
ThreadContext.clean();
}
private static String generateTraceId() {
return UUID.randomUUID().toString();
}
}3、添加ContextFilter
对于每个请求随机生成RequestID并放入MDC
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.web.filter.OncePerRequestFilter;
import com.pingan.manpan.common.util.TraceUtil;
import com.pingan.manpan.user.dto.ThreadContext;
import com.pingan.manpan.web.common.surpport.IpUtils;
//@Order 标记组件的加载顺序
@Order(Ordered.HIGHEST_PRECEDENCE)
public class ContextFilter extends OncePerRequestFilter {
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
FilterChain filterChain) throws ServletException, IOException {
try {
ThreadContext.putClientIp(IpUtils.getClientIp(request));
TraceUtil.traceStart();
filterChain.doFilter(request, response);
} finally {
TraceUtil.traceEnd();
}
}
}4、在webConfiguriation注册filter
@Bean
public FilterRegistrationBean requestContextRepositoryFilterRegistrationBean() {
FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
filterRegistrationBean.setFilter(new ContextFilter());
filterRegistrationBean.addUrlPatterns("
@WebFilter(filterName = "Log4j2Filter", urlPatterns = "/*", initParams = {@WebInitParam(name = "DESCRIPTION", value = "这是Log4j2Filter过滤器")})
public class Log4j2Filter implements Filter {
private String description;
public static final String TRACE_ID = "traceID";
private static final Logger logger = LoggerFactory.getLogger(Log4j2Filter.class);
@Override
public void init(FilterConfig filterConfig) throws ServletException {
description = filterConfig.getInitParameter("DESCRIPTION");
System.out.println("过滤器初始化:"+ description);
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
throws IOException,ServletException {
HttpServletRequest req = (HttpServletRequest) servletRequest;
HttpServletResponse resp = (HttpServletResponse) servletResponse;
// 生成一个随机数给到前端
String traceId = UUID.randomUUID().toString().replace("-", "");
// 随机数放到此线程的上下文中，可以在每条日志前加入。具体看下面log4j2.xml
ThreadContext.put(TRACE_ID, traceId);
// 随机数放到Header中，在Response Headers中可查看到此数据
resp.addHeader(TRACE_ID, traceId);
filterChain.doFilter(req, resp);
ThreadContext.clearAll();
}
@Override
public void destroy() {
System.out.println("过滤器，被销毁："+ description);
}
}
log4j2.xml <PatternLayout pattern="[traceID:%X{traceID}]-[%d{yyyy-MM-dd HH:mm:ss:SSS}]-[%t]-[%p]-[%l]-%m%n"/>
<?xml version="1.0" encoding="UTF-8"?>
<!--设置log4j2的自身log级别为warn-->
<!--日志级别以及优先级排序: OFF > FATAL > ERROR > WARN > INFO > DEBUG > TRACE > ALL -->
<!--Configuration后面的status，这个用于设置log4j2自身内部的信息输出，可以不设置,当设置成trace时，你会看到log4j2内部各种详细输出-->
<!--monitorInterval：Log4j能够自动检测修改配置 文件和重新配置本身，设置间隔秒数-->
<configuration status="warn" monitorInterval="30">
<!--全局参数-->
<Properties>
<Property name="logPath">logs</Property>
</Properties>
<!--先定义所有的appender-->
<appenders>
<!--这个输出控制台的配置-->
<console name="Console" target="SYSTEM_OUT">
<!-- traceID:就是在过滤器中生成的随机数 -->
<PatternLayout pattern="[traceID:%X{traceID}]-[%d{yyyy-MM-dd HH:mm:ss:SSS}]-[%t]-[%p]-[%l]-%m%n"/>
</console>
</appenders>
<!--然后定义logger，只有定义了logger并引入的appender，appender才会生效-->
<loggers>
<!--过滤掉spring和mybatis的一些无用的debug信息-->
<logger name="org.springframework" level="INFO"></logger>
<logger name="org.mybatis" level="INFO"></logger>
<logger name="com.zaxxer" level="WARN"></logger>
<!-- com.generator开发/测试环境用DEBUG,并用控制台输出即可 -->
<logger name="com.generator" level="DEBUG" additivity="false">
<appender-ref ref="Console"/>
</logger>
<!-- 未指定的包都按此 level 打印日志 -->
<root level="DEBUG">
<appender-ref ref="Console"/>
</root>
</loggers>
</configuration>以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程网。
