springCloud微服务系列——链路跟踪第五篇——mybatis链路跟踪器

向右看齐 2022-05-16 22:43 230阅读 0赞

**目录**

一、简介

二、思路

interceptor的创建源码分析

spring上下文之外获得bean

三、示例代码

--------------------

# 一、简介 #

这篇文章总结mybatis链路跟踪器的实现

# 二、思路 #

拦截的话用mybatis自带的interceptor就可以了，这里有一点需要注意。mybatis的interceptor是没办法注入到spring中的。

## interceptor的创建源码分析 ##

mybatis的interceptor是通过反射构建出来的，是在启动的时候通过XMLConfigBuilder类解析ml文件，然后根据类名调用classLoader加载进来，再通过反射实例化的。因此不可能作为bean让spring管理。

private void pluginElement(XNode parent) throws Exception {
        if (parent != null) {
          for (XNode child : parent.getChildren()) {
            String interceptor = child.getStringAttribute("interceptor");
            Properties properties = child.getChildrenAsProperties();
            Interceptor interceptorInstance = (Interceptor) resolveClass(interceptor).newInstance();
            interceptorInstance.setProperties(properties);
            configuration.addInterceptor(interceptorInstance);
          }
        }
      }

## spring上下文之外获得bean ##

由于interceptor无法注入，那么我们想要使用spring管理的bean或者配置信息怎么办，我们可以通过写一个方法类，该类注册成spring的bean，然后再将需要的bean或属性注入到它的静态成员变量中。

举个例子

public class ProfileContext {
    	
    	public static String profile;
    
    	public void setProfile(String profile) {
    		ProfileContext.profile = profile;
    	}
    	
    }

@Configuration
    public class TrackerAutoConfiguration {
    
        @Value("${spring.profiles.active:default}")
    	private String profile;
    
        @Bean
    	public ProfileContext profileContext() throws IOException {
    		 ProfileContext profileHelper = new ProfileContext();
    		 profileHelper.setProfile(profile);
    		 return profileHelper;
    	}
    
    }

# 三、示例代码 #

@Slf4j
 @Intercepts({
 	@Signature(type = Executor.class, args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}, method = "query"),
 	@Signature(type = Executor.class, args = {MappedStatement.class, Object.class}, method = "update")
 })
 public class MybatisTracker extends GenericTracker implements Interceptor {
 	
 	private static String MAPPER_SEPARATOR = "Dao.";
 	private static String JDBC_PREFIX = "jdbc:";
 	
 	public MybatisTracker() {
 		super();
 	}
 	
 	/** 
 	* Title: 
 	* Description: 
 	* @param traceClient 
 	*/ 
 	public MybatisTracker(TraceClient traceClient) {
 		super(traceClient);
 	}
 
 	/* (non-Javadoc) 
 	 * Title: intercept 
 	 * Description: 
 	 * @param arg0
 	 * @return
 	 * @throws Throwable 
 	 * @see org.apache.ibatis.plugin.Interceptor#intercept(org.apache.ibatis.plugin.Invocation) 
 	 */
 	@Override
 	public Object intercept(Invocation invocation) throws Throwable {
 		
 		log.info("mybatis tracker");
 		
 		TraceHolder traceHolder = new TraceHolder();
 		Object result = null;
 		
 		try {
 			
 			Gson gson = new Gson();
 			
 			if(traceClient == null)
 				traceClient = getTraceClient();
 			
 		 String sqlId = "";
 		 Object parameter = null;
 		 MappedStatement mappedStatement = null;
 		 BoundSql boundSql = null;
 		 Configuration configuration = null;
 		 String jdbcUrl = "";
 		 
 			Object[] args = invocation.getArgs();
 		 for(Object arg : args) {
 		 	if(arg != null) {
 		 		if(arg instanceof MappedStatement) {
 		 			mappedStatement = (MappedStatement) arg;
 		 			sqlId = mappedStatement.getId();
 		 		}
 		 		else if(!(arg instanceof RowBounds) && !(arg instanceof ResultHandler)) {
 		 			parameter = arg;
 		 		}
 		 	}
 		 }
 
 		 if(mappedStatement !=null && parameter != null) {
 		 	 boundSql = mappedStatement.getBoundSql(parameter);
 		 	 configuration = mappedStatement.getConfiguration();
 		 }
 		 
 		 String methodName = sqlId.substring(sqlId.indexOf(MAPPER_SEPARATOR)+MAPPER_SEPARATOR.length());
 		 String serviceName = sqlId.substring(0, sqlId.lastIndexOf("."));
 		 
 		 String requestParam = boundSql.getSql();
 		 
 		 if(parameter != null) {
 		 	requestParam = requestParam + "|" + gson.toJson(parameter);
 		 }
 		 
 		 traceHolder.setProfile(getProfile());
 		 traceHolder.setRpcType(RpcTypeEnum.DB.name());
 			traceHolder.setServiceCategory("mybatis");
 			traceHolder.setServiceName(serviceName);
 			traceHolder.setMethodName(methodName);
 			traceHolder.setRequestParam(requestParam);
 			
 			preHandle(traceHolder);
 			result = invocation.proceed();
 			
 			if(configuration != null) {
 				DataSource dataSource = configuration.getEnvironment().getDataSource();
 		 	 if(dataSource instanceof DruidDataSource) {
 		 		 jdbcUrl = ((DruidDataSource) dataSource).getUrl();
 		 	 }
 			}
 			String serviceHost = jdbcUrl.substring(jdbcUrl.indexOf(JDBC_PREFIX)+JDBC_PREFIX.length(), jdbcUrl.indexOf("?"));
 			
 			traceHolder.getEntity().setServiceHost(serviceHost);
 			
 			traceHolder.getEntity().setResponseInfo(result.toString());
 			postHandle(traceHolder);
 			
 		} catch(Exception e) {
 			log.error(e.getMessage(), e);
 			exceptionHandle(traceHolder, e);
 		} 
 		
 		return result;
 		
 	}
 
 	/* (non-Javadoc) 
 	 * Title: plugin 
 	 * Description: 
 	 * @param arg0
 	 * @return 
 	 * @see org.apache.ibatis.plugin.Interceptor#plugin(java.lang.Object) 
 	 */
 	@Override
 	public Object plugin(Object target) {
 		return Plugin.wrap(target, this);
 	}
 
 	/* (non-Javadoc) 
 	 * Title: setProperties 
 	 * Description: 
 	 * @param arg0 
 	 * @see org.apache.ibatis.plugin.Interceptor#setProperties(java.util.Properties) 
 	 */
 	@Override
 	public void setProperties(Properties properties) {
 		
 	}
 	
 	public String getProfile() {
 		log.warn("默认实现方法");
 		return null;
 	}
 	
 	public TraceClient getTraceClient() {
 		log.warn("默认实现方法");
 		return null;
 	}
 
 }

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