如何显示Spring和MyBatis的SQL错误？

Question

我有使用--debug在调试器中运行的以下代码，但不会打印出任何SQL错误。 它会静默失败，并带有异常，并从servlet请求返回。

    System.out.println("sourceMapper = " + sourceMapper);
    Source source = sourceMapper.findByHost(host);
    System.out.println("source = " + source);

这是输出

2018-05-11 13:47:58.080  INFO 29392 --- [nio-8080-exec-2] c.s.shorturl.apis.ShortUrlApiController  : Method name: doUrlRequest() user agent is = curl/7.59.0
sourceMapper = org.apache.ibatis.binding.MapperProxy@30a1e904
2018-05-11 13:47:58.359  INFO 29392 --- [nio-8080-exec-2] o.s.b.f.xml.XmlBeanDefinitionReader      : Loading XML bean definitions from class path resource [org/springframework/jdbc/support/sql-error-codes.xml]
2018-05-11 13:47:58.489  INFO 29392 --- [nio-8080-exec-2] o.s.jdbc.support.SQLErrorCodesFactory    : SQLErrorCodes loaded: [DB2, Derby, H2, HSQL, Informix, MS-SQL, MySQL, Oracle, PostgreSQL, Sybase, Hana]
2018-05-11 13:47:58.541 DEBUG 29392 --- [nio-8080-exec-2] o.s.b.w.f.OrderedRequestContextFilter    : Cleared thread-bound request context: org.apache.catalina.connector.RequestFacade@645ec595

如何打印遇到的SQL错误？ 还是找出失败的原因以及异常是什么？

MyBatis 3.4.5，MyBatis Spring 1.3.1，MyBatis Spring Boot自动配置1.3.1，MyBatis Spring Boot Starter 1.3.1，Spring Boot 1.5.6

Answer 1

您可以在代码周围添加try/catch并记录捕获的异常：

try {
    System.out.println("sourceMapper = " + sourceMapper);
    Source source = sourceMapper.findByHost(host);
    System.out.println("source = " + source);
} catch (Exception e) {
    // log using slf4j's Logger
    logger.error("An exception caught", e);
    // or print it to standard output
    e.printStackTrace();
}

某个地方应该有一个Logger实例（可能在同一类中）：

private final Logger logger = LoggerFactory.getLogger(this.getClass());