spring boot starter开发
作为公司的技术保障部，一直承担着技术方向的把控，最近公司准备全面转入spring boot的开发。所以我们部门也一直在调研相关的技术知识点；
使用springboot开发应用已经有一段时间了，我们都沉醉于它简洁的配置和平滑的上手曲线。
在springboot的开发中，starter是一个核心的配置，只需要引入对应模块的starter，然后在application.properties中引入对应的配置项，就可以开发业务逻辑了。
这一切都归功于springboot的自动配置的能力。
本文会从一个mybatis与spring boot结合的starter开始学习，该框架是我们提供出来，需要使用mybatis的团队只需要引入这个starter的jar包即可使用
新建原型项目
完整的pom.xml如下
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>cn.caijiajia</groupId>
<artifactId>springboot-parent</artifactId>
<version>1.0.0.RELEASE</version>
</parent>
<groupId>cn.caijiajia</groupId>
<artifactId>mybatis-starter</artifactId>
<version>${project.release.version}</version>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>cn.caijiajia</groupId>
<artifactId>framework-starter</artifactId>
<version>${project.release.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jdbc</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
</dependency>
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
</dependencies>
</project>
开发阶段
1.配置类 DatabaseAutoConfiguration DbProperties
@EnableConfigurationProperties({DbProperties.class})
public class DatabaseAutoConfiguration
implements BeanDefinitionRegistryPostProcessor, EnvironmentAware {
private static Logger log = LoggerFactory.getLogger(DatabaseAutoConfiguration.class);
private Environment environment;
@Override
public void setEnvironment(Environment environment) {
this.environment = environment;
}
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
}
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
DbProperties dbProperties = ConfigUtil.getDbConfig(environment, DbProperties.PROPERTY_PREFIX,
DbProperties.class);
// TODO 检查参数
if (dbProperties.getDatabase() == null && dbProperties.getDatabases() != null && dbProperties
.getDatabases().size() == 1) {
dbProperties.setDatabase(dbProperties.getDatabases().get(0));
}
initAllDataAccessBean(dbProperties, registry);
}
protected void initAllDataAccessBean(DbProperties dbProperties, BeanDefinitionRegistry registry) {
// 单数据源
if (dbProperties.getDatabase() != null) {
initDataAccessBean(dbProperties.getDatabase(), null, registry);
}
// 多数据源
else if (dbProperties.getDatabases() != null && dbProperties.getDatabases().size() > 0) {
for (int i = 0; i < dbProperties.getDatabases().size(); i++) {
initDataAccessBean(dbProperties.getDatabases().get(i), i, registry);
}
}
}
/**
* 注册一个datasource的所有bean 信息
*
* @param databaseConfig
* @param index
* @param registry
*/
protected void initDataAccessBean(DatabaseConfig databaseConfig, Integer index, BeanDefinitionRegistry registry) {
DataSourceConfig dataSourceConfig = databaseConfig.getDataSource();
TransactionConfig transactionConfig = databaseConfig.getTransaction();
MyBatisConfig myBatisConfig = databaseConfig.getMybatis();
LogConfig logConfig = databaseConfig.getLog();
// 给与默认 dataSource bean id: dataSource${index}
if (StringUtils.isEmpty(dataSourceConfig.getName())) {
if (index == null) {
dataSourceConfig.setName("dataSource");
} else {
dataSourceConfig.setName("dataSource" + index);
}
}
// 注册datasource
registry.registerBeanDefinition(dataSourceConfig
.getName(), getTomcatJdbcDataSourceBeanDefinition(dataSourceConfig, logConfig));
// 注册事务
if (transactionConfig != null && transactionConfig.isEnable()) {
if (index == null) {
registry.registerBeanDefinition("transactionManager", getTransactionManagerBeanDefinition(dataSourceConfig));
} else {
registry.registerBeanDefinition("transactionManager" + index, getTransactionManagerBeanDefinition(dataSourceConfig));
}
}
// 注册mybatis
if (myBatisConfig != null) {
final String sqlSessionFactoryBeanName = "sqlSessionFactory" + dataSourceConfig.getName();
registry.registerBeanDefinition(sqlSessionFactoryBeanName, getSqlSessionFactoryBeanDefinition(myBatisConfig, dataSourceConfig));
registry.registerBeanDefinition("mapperScannerConfigurer" + dataSourceConfig
.getName(), getMapperScannerConfigurerBeanDefinition(myBatisConfig, sqlSessionFactoryBeanName));
// 给与默认 dataSource bean id: sqlSession${index}
if (StringUtils.isEmpty(myBatisConfig.getSqlSessionBeanName())) {
if (index == null) {
myBatisConfig.setSqlSessionBeanName("sqlSession");
} else {
myBatisConfig.setSqlSessionBeanName("sqlSession" + index);
}
}
registry.registerBeanDefinition(myBatisConfig
.getSqlSessionBeanName(), getSqlSessionBeanDefinition(sqlSessionFactoryBeanName));
}
}
/**
* 获取 tomcat jdbc datasource bean 定义
*
* @param dataSourceConfig
* @return
*/
protected AbstractBeanDefinition getTomcatJdbcDataSourceBeanDefinition(DataSourceConfig dataSourceConfig, LogConfig logConfig) {
if (dataSourceConfig.getMinIdle() == null) {
dataSourceConfig.setMinIdle(dataSourceConfig.getInitialSize());
}
if (dataSourceConfig.getMaxIdle() == null) {
dataSourceConfig.setMaxIdle(dataSourceConfig.getMaxActive());
}
BeanDefinitionBuilder definitionBuilder = BeanDefinitionBuilder
.rootBeanDefinition("org.apache.tomcat.jdbc.pool.DataSource");
definitionBuilder.setDestroyMethodName("close");
// add filter
definitionBuilder
.addPropertyValue("jdbcInterceptors", "cn.caijiajia.framework.db.log.TomcatJdbcLogFilter(slowLogOn=" + logConfig
.isSlowSqlOn() + ",slowSqlThreshold=" + logConfig.getSlowSqlThreshold() + ")");
// if not set, use default value in jdbc driver
if (dataSourceConfig.getDefaultAutoCommit() != null) {
definitionBuilder
.addPropertyValue("defaultAutoCommit", dataSourceConfig.getDefaultAutoCommit());
}
if (dataSourceConfig.getDefaultReadOnly() != null) {
definitionBuilder
.addPropertyValue("defaultReadOnly", dataSourceConfig.getDefaultReadOnly());
}
if (dataSourceConfig.getDefaultTransactionIsolation() != null) {
definitionBuilder
.addPropertyValue("defaultTransactionIsolation", dataSourceConfig.getDefaultTransactionIsolation());
}
definitionBuilder.addPropertyValue("url", dataSourceConfig.getUrl());
definitionBuilder.addPropertyValue("username", dataSourceConfig.getUsername());
definitionBuilder.addPropertyValue("password", dataSourceConfig.getPassword());
definitionBuilder.addPropertyValue("driverClassName", dataSourceConfig.getDriverClassName());
// 配置初始化大小、最小、最大
definitionBuilder.addPropertyValue("initialSize", dataSourceConfig.getInitialSize());
definitionBuilder.addPropertyValue("minIdle", dataSourceConfig.getMinIdle());
definitionBuilder.addPropertyValue("maxActive", dataSourceConfig.getMaxActive());
definitionBuilder.addPropertyValue("maxIdle", dataSourceConfig.getMaxIdle());
// 配置获取连接等待超时的时间
definitionBuilder.addPropertyValue("maxWait", dataSourceConfig.getMaxWait());
// 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫
definitionBuilder
.addPropertyValue("timeBetweenEvictionRunsMillis", dataSourceConfig.getTimeBetweenEvictionRunsMillis());
// 配置一个连接在池中最小生存的时间，单位是毫秒
definitionBuilder
.addPropertyValue("minEvictableIdleTimeMillis", dataSourceConfig.getMinEvictableIdleTimeMillis());
definitionBuilder.addPropertyValue("validationQuery", "select 1");
definitionBuilder.addPropertyValue("testOnConnect", dataSourceConfig.isTestOnConnect());
definitionBuilder.addPropertyValue("testWhileIdle", dataSourceConfig.isTestWhileIdle());
definitionBuilder.addPropertyValue("testOnBorrow", dataSourceConfig.isTestOnBorrow());
definitionBuilder.addPropertyValue("testOnReturn", dataSourceConfig.isTestOnReturn());
definitionBuilder.addPropertyValue("removeAbandoned", dataSourceConfig.isRemoveAbandoned());
definitionBuilder.addPropertyValue("removeAbandonedTimeout", dataSourceConfig.getRemoveAbandonedTimeout());
AbstractBeanDefinition bd = definitionBuilder.getRawBeanDefinition();
bd.setScope(BeanDefinition.SCOPE_SINGLETON);
return bd;
}
/**
* 获取mybaits SqlSessionFactory bean 定义
*
* @param dataSourceConfig
* @return
*/
protected AbstractBeanDefinition getSqlSessionFactoryBeanDefinition(MyBatisConfig myBatisConfig, DataSourceConfig dataSourceConfig) {
BeanDefinitionBuilder definitionBuilder = BeanDefinitionBuilder
.rootBeanDefinition(org.mybatis.spring.SqlSessionFactoryBean.class);
definitionBuilder.addPropertyReference("dataSource", dataSourceConfig.getName());
PageInterceptor pageInterceptor = new PageInterceptor();
if (myBatisConfig.getPage().isSupportMethodsArguments()) {
Properties pageInterceptorProperties = new Properties();
pageInterceptorProperties.setProperty("supportMethodsArguments", "true");
pageInterceptorProperties.setProperty("params", "pageNum=pageNum;pageSize=pageSize");
pageInterceptor.setProperties(pageInterceptorProperties);
}
definitionBuilder
.addPropertyValue("plugins", new Interceptor[]{new LogInfoInterceptor(), pageInterceptor});
AbstractBeanDefinition bd = definitionBuilder.getRawBeanDefinition();
bd.setScope(BeanDefinition.SCOPE_SINGLETON);
return bd;
}
/**
* 获取mybaits MapperScannerConfigurer bean 定义
*
* @param myBatisConfig
* @param sqlSessionFactoryBeanName
* @return
*/
protected AbstractBeanDefinition getMapperScannerConfigurerBeanDefinition(MyBatisConfig myBatisConfig, String sqlSessionFactoryBeanName) {
BeanDefinitionBuilder definitionBuilder = BeanDefinitionBuilder
.rootBeanDefinition(org.mybatis.spring.mapper.MapperScannerConfigurer.class);
definitionBuilder
.addPropertyValue("sqlSessionFactoryBeanName", sqlSessionFactoryBeanName);
definitionBuilder.addPropertyValue("basePackage", myBatisConfig.getBasePackage());
AbstractBeanDefinition bd = definitionBuilder.getRawBeanDefinition();
bd.setScope(BeanDefinition.SCOPE_SINGLETON);
return bd;
}
/**
* 获取mybaits SqlSessionTemplate bean 定义
*
* @param sqlSessionFactoryBeanName
* @return
*/
protected AbstractBeanDefinition getSqlSessionBeanDefinition(String sqlSessionFactoryBeanName) {
BeanDefinitionBuilder definitionBuilder = BeanDefinitionBuilder
.rootBeanDefinition(org.mybatis.spring.SqlSessionTemplate.class);
definitionBuilder.addConstructorArgReference(sqlSessionFactoryBeanName);
AbstractBeanDefinition bd = definitionBuilder.getRawBeanDefinition();
bd.setScope(BeanDefinition.SCOPE_SINGLETON);
return bd;
}
/**
* 获取 DataSourceTransactionManager bean定义
*
* @param dataSourceConfig
* @return
*/
protected AbstractBeanDefinition getTransactionManagerBeanDefinition(DataSourceConfig dataSourceConfig) {
BeanDefinitionBuilder definitionBuilder = BeanDefinitionBuilder
.genericBeanDefinition(DataSourceTransactionManager.class);
definitionBuilder.addConstructorArgReference(dataSourceConfig.getName());
AbstractBeanDefinition bd = definitionBuilder.getRawBeanDefinition();
bd.setScope(BeanDefinition.SCOPE_SINGLETON);
return bd;
}
}
@ConfigurationProperties(prefix = DbProperties.PROPERTY_PREFIX)
public class DbProperties {
public final static String PROPERTY_PREFIX = "caijiajia.db";
private DatabaseConfig database;
private List<DatabaseConfig> databases = new ArrayList();
public DatabaseConfig getDatabase() {
return database;
}
public void setDatabase(DatabaseConfig database) {
this.database = database;
}
public List<DatabaseConfig> getDatabases() {
return databases;
}
public void setDatabases(List<DatabaseConfig> databases) {
this.databases = databases;
}
}
这是两段核心配置类，其它还有一些pojo类，这里就不写出来了
自定义spring.factories
自定义spring.factories的步骤很简单，只需要在src/main/resource目录下创建META-INF目录,并在该目录下添加文件spring.factories，文件内容为：
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ cn.caijiajia.framework.db.autoconfigure.DatabaseAutoConfiguration
到这里通过spring boot的自动装配原理实现了配置类的自动装配
一个简单的starter创造就完成了
