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歡迎跳轉到本文原文閱讀：https://honeypps.com/java/mybatis-sql-interceptor/

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主要功能：通過log4j配置mybatis的打印，只能輸出到控制臺，而并非真正能夠實現sql的獲取，本文主要通過攔截器實現sql的攔截，進而對sql進行相應的操作。

起因：因項目需要，服務器要配成雙機熱備，那么數據庫（這里采用的是MySQL）也是雙機的，這就牽涉到數據庫同步的問題，由于某種原因（這就不透露了）不能采用MySQL自身的同步機制，采用原先C/S系統的同步機制進行同步。

實現方式：mybatis與主數據庫正常交互，通過攔截器攔截sql并通過webservice將sql發送到C/S系統的同步模塊，進而同步備數據庫。

主要代碼：

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package com.shr.dao;import java.text.DateFormat; import java.util.Date; import java.util.List; import java.util.Locale; import java.util.Properties;import java.util.concurrent.ConcurrentLinkedDeque; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit;import org.apache.log4j.Logger;import javax.inject.Inject; import javax.inject.Named;import org.apache.ibatis.executor.Executor; import org.apache.ibatis.mapping.BoundSql; import org.apache.ibatis.mapping.MappedStatement; import org.apache.ibatis.mapping.ParameterMapping; import org.apache.ibatis.plugin.Interceptor; import org.apache.ibatis.plugin.Intercepts; import org.apache.ibatis.plugin.Invocation; import org.apache.ibatis.plugin.Plugin; import org.apache.ibatis.plugin.Signature; import org.apache.ibatis.reflection.MetaObject; import org.apache.ibatis.session.Configuration; import org.apache.ibatis.session.ResultHandler; import org.apache.ibatis.session.RowBounds; import org.apache.ibatis.type.TypeHandlerRegistry;@Intercepts({@Signature(type = Executor.class, method = "update", args = { MappedStatement.class, Object.class }),@Signature(type = Executor.class, method = "query", args = { MappedStatement.class, Object.class,RowBounds.class, ResultHandler.class }) }) public class MyBatisSQLInterceptor implements Interceptor {private Logger logger = Logger.getLogger(MyBatisSQLInterceptor.class.getSimpleName());@SuppressWarnings("unused")private Properties properties;private ConcurrentLinkedDeque<String> list = new ConcurrentLinkedDeque<String>(); // @Inject // @Named("soapClient") // private SoapClient soapClient;public MyBatisSQLInterceptor(){ExecutorService exec = Executors.newSingleThreadExecutor();exec.execute(new Thread(){public void run(){while(true){if(list.isEmpty() == false){String sql = list.pollFirst();logger.info("[SEND WS: ["+sql+"]]");//與WebService交互}try {TimeUnit.MILLISECONDS.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}}}});exec.shutdown();}public Object intercept(Invocation invocation) throws Throwable {MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];Object parameter = null;if (invocation.getArgs().length > 1) {parameter = invocation.getArgs()[1];}BoundSql boundSql = mappedStatement.getBoundSql(parameter);Configuration configuration = mappedStatement.getConfiguration();Object returnValue = null;returnValue = invocation.proceed();showSql(configuration, boundSql);return returnValue;}private String getParameterValue(Object obj) {String value = null;if (obj instanceof String) {value = "'" + obj.toString() + "'";} else if (obj instanceof Date) {DateFormat formatter = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.CHINA);value = "'" + formatter.format(obj) + "'"; // System.out.println(value);} else {if (obj != null) {value = obj.toString();} else {value = "";}}return value;}public String showSql(Configuration configuration, BoundSql boundSql) {Object parameterObject = boundSql.getParameterObject();List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();String sql = boundSql.getSql().replaceAll("[\\s]+", " ");if (parameterMappings.size() > 0 && parameterObject != null) {TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {sql = sql.replaceFirst("\\?", getParameterValue(parameterObject));} else {MetaObject metaObject = configuration.newMetaObject(parameterObject);for (ParameterMapping parameterMapping : parameterMappings) {String propertyName = parameterMapping.getProperty();if (metaObject.hasGetter(propertyName)) {Object obj = metaObject.getValue(propertyName);sql = sql.replaceFirst("\\?", getParameterValue(obj));} else if (boundSql.hasAdditionalParameter(propertyName)) {Object obj = boundSql.getAdditionalParameter(propertyName);sql = sql.replaceFirst("\\?", getParameterValue(obj));}}}}logger.info(sql);if(sql.startsWith("select") == false){list.add(sql);}return sql;}public Object plugin(Object target) {return Plugin.wrap(target, this);}public void setProperties(Properties properties0) {this.properties = properties0;} }

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歡迎支持筆者新作：《深入理解Kafka:核心設計與實踐原理》和《RabbitMQ實戰指南》，同時歡迎關注筆者的微信公眾號：朱小廝的博客。

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歡迎跳轉到本文原文閱讀：https://honeypps.com/java/mybatis-sql-interceptor/

超強干貨來襲 云風專訪：近40年碼齡，通宵達旦的技術人生

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