spring boot集成mybatis（druid线程池）

摘要: spring boot，mybatis，druid

###我的github代码示例
https://github.com/jiahaos/spring-boot-mybatis.git
###Druid是什么？有什么作用？
Druid首先是一个数据库连接池，但它不仅仅是一个数据库连接池，它还包含一个ProxyDriver，一系列内置的JDBC组件库，一个SQL Parser。
###Druid支持哪些数据库？
Druid支持所有JDBC兼容的数据库，包括Oracle、MySql、Derby、Postgresql、SQL Server、H2等等。

Druid针对Oracle和MySql做了特别优化，比如Oracle的PS Cache内存占用优化，MySql的ping检测优化。
###为什么说Druid是“最好的数据库连接池”?体现在哪些方面？这是如何实现的？
阿里巴巴是一个重度使用关系数据库的公司，我们在生产环境中大量的使用Druid，通过长期在极高负载的生产环境中实际使用、修改和完善，让Druid逐步发展成最好的数据库连接池。Druid在监控、可扩展性、稳定性和性能方面都有明显的优势。
###配置源码
###1、监控ServletRegistrationBean

@Slf4j
@Configuration
public class DruidAdminConfiguration {

@Bean
public ServletRegistrationBean druidServlet() {
ServletRegistrationBean reg = new ServletRegistrationBean();
reg.setServlet(new StatViewServlet());
reg.addUrlMappings("/druid/*");
//reg.addInitParameter("allow", "127.0.0.1");
//reg.addInitParameter("deny","");
reg.addInitParameter("loginUsername", "paicheya");
reg.addInitParameter("loginPassword", "PaiCheYaDev");
return reg;
}

@Bean
public FilterRegistrationBean filterRegistrationBean() {
FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
filterRegistrationBean.setFilter(new WebStatFilter());
filterRegistrationBean.addUrlPatterns("/*");
filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
return filterRegistrationBean;
}

}

###2、DruidDataSource bean

@Slf4j
@Configuration
public class DruidDatabaseConfiguration {

@Autowired
private Environment environment;

@Bean
public DruidDataSource dataSource() throws PropertyVetoException {
String url = environment.getProperty("spring.datasource.url");
String username = environment.getProperty("spring.datasource.username");
String password = environment.getProperty("spring.datasource.password");
String driverClassName = environment.getProperty("spring.datasource.driver-class-name");

if (url == null || "".equals(url)) {
return null;
}

DruidDataSource druidDataSource = new DruidDataSource();
druidDataSource.setDriverClassName(driverClassName);
druidDataSource.setUrl(url);
druidDataSource.setUsername(username);
druidDataSource.setPassword(password);

druidDataSource.setMaxActive(30);
druidDataSource.setMinIdle(5);
druidDataSource.setInitialSize(5);
druidDataSource.setTestWhileIdle(true);
druidDataSource.setTestOnBorrow(true);
druidDataSource.setValidationQuery("select 1");
druidDataSource.setValidationQueryTimeout(3600);

try {
// druidDataSource.setFilters("stat, wall");
druidDataSource.setFilters("stat");
} catch (SQLException e) {
log.warn("设置Druid的Filters错误。", e);
}
return druidDataSource;
}

}

###3、mybatis 配置类

@Configuration
@ConditionalOnExpression("'${fortress.mybatis.enabled}'=='true'")
public class MyBatisDataSourceConfig {

@Autowired
private DataSource dataSource;

@Bean
public DataSourceTransactionManager transactionManager() {
return new DataSourceTransactionManager(dataSource);
}

@Bean
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
sessionFactory.setDataSource(dataSource);
sessionFactory.setMapperLocations(resolver.getResources("classpath:mapper/*.xml"));

PageHelper pageHelper = new PageHelper();
Properties properties = new Properties();
properties.setProperty("reasonable", "true");
properties.setProperty("supportMethodsArguments", "true");
properties.setProperty("returnPageInfo", "check");
properties.setProperty("params", "count=countSql");
pageHelper.setProperties(properties);
sessionFactory.setPlugins(new Interceptor[]{pageHelper});

return sessionFactory.getObject();
}
}

####（1）@ConditionalOnExpression("'${fortress.mybatis.enabled}'=='true'")，此配置为动态加载配置。配置文件中配置true则加载该配置
####（2）sessionFactory.setMapperLocations(resolver.getResources("classpath:mapper/*.xml"));，此配置为为加载xml文件。
###4、加载原理
MyBatisDataSourceConfig 中加载sqlSessionFactory的参数DataSource 来自spring默认配置。如果在代码中重写 dataSourceBean则加载传入重写的source。如DruidDatabaseConfiguration的dataSourceBean方法。

###4、附赠xml配置方式，加上sql动态监控方式
引用他人博客：https://my.oschina.net/wangmengjun/blog/788386