springboot+mybatis拦截器不生效问题分析 springboot+mybatis拦截器不生效问

【springboot+mybatis拦截器不生效问题分析】一、环境信息
SpringBoot:2.3.6.RELEASE
Mybatis-plus:3.3.1
二、碰到问题
今天因业务系统功能需要，使用mybatis的拦截器对ORACLE的数据库会话进行用户当前语言环境设置(NLS_LANGUAGE),碰到拦截器代码不生效的问题，特此记录下来，方便将来查阅。
三、代码如下：
1、在Mybatis的@Configuration相关代码添加如下代码（自动注入到拦截器链）：

/** * 更改会话状态 * * @return */ @Bean public AlterSessionInterceptor alterSessionInterceptor() { return new AlterSessionInterceptor(); }

2、拦截器代码（拦截StatementHandler的prepare方法，取到Connection执行ALTER SESSION的语句）：
/**

更改会话解析器
*
@since 2021/7/14
*/

@Slf4j
@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class})})
public class AlterSessionInterceptor implements Interceptor {

@Override public Object intercept(Invocation invocation) throws Throwable { Object[] args = invocation.getArgs(); Connection connection = (Connection) args[0]; if ("Oracle".equalsIgnoreCase(connection.getMetaData().getDatabaseProductName())) { Statement statement = null; try { statement = connection.createStatement(); String locale = RequestHelper.getCurrentLocale(); if ("en_GB".equalsIgnoreCase(locale)) { statement.execute("ALTER SESSION SET NLS_LANGUAGE='AMERICAN'"); } else { statement.execute("ALTER SESSION SET NLS_LANGUAGE='SIMPLIFIED CHINESE'"); } } finally { statement.close(); } } return invocation.proceed(); }

}
在运行调试时发现代码无法执行到拦截逻辑，经过参考分页插件代码，发现需要重载以下方法（代码默认是只要实现intercept这个接口，但是实际上需要多加以下插件的处理逻辑才可以，才会启用Plugin的Proxy）：

@Override public Object plugin(Object target) { if (target instanceof StatementHandler) { return Plugin.wrap(target, this); } return target; }

最终拦截器代码如下：
/**

更改会话解析器
*
@since 2021/7/14
*/

@Slf4j
@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class})})
public class AlterSessionInterceptor implements Interceptor {

@Override public Object intercept(Invocation invocation) throws Throwable { Object[] args = invocation.getArgs(); Connection connection = (Connection) args[0]; if ("Oracle".equalsIgnoreCase(connection.getMetaData().getDatabaseProductName())) { Statement statement = null; try { statement = connection.createStatement(); String locale = RequestHelper.getCurrentLocale(); if ("en_GB".equalsIgnoreCase(locale)) { statement.execute("ALTER SESSION SET NLS_LANGUAGE='AMERICAN'"); } else { statement.execute("ALTER SESSION SET NLS_LANGUAGE='SIMPLIFIED CHINESE'"); } } finally { statement.close(); } } return invocation.proceed(); }@Override public Object plugin(Object target) { if (target instanceof StatementHandler) { return Plugin.wrap(target, this); } return target; }@Override public void setProperties(Properties properties) { // to do nothing }

}