Spring boot 随笔 1 DatasourceInitializer

0. 为啥感觉升级了 win11 之后，电脑像是刚买回来的，很快

这篇加餐完全是一个意外：时隔两年半，再看 Springboot-quartz-starter 集成实现的时候，不知道为啥我的h2 在应用启动的时候，不能自动创建quartz相关的schema。后面看了 springboot 的文档，据说是可以做到的，AI也是这么说的。

没办法，只能看 QuartzAutoConfiguration 源码了。于是乎，就有了这么个好活

没办法，就当是一个支线任务了

1. AbstractScriptDatabaseInitializer

下面是熟悉的，阉割后的 源码

package org.springframework.boot.sql.init;/*** Base class for an {@link InitializingBean} that performs SQL database initialization* using schema (DDL) and data (DML) scripts.** @author Andy Wilkinson* @since 2.5.0*/
public abstract class AbstractScriptDatabaseInitializer implements ResourceLoaderAware, InitializingBean {// 构造入参配置private final DatabaseInitializationSettings settings;private volatile ResourceLoader resourceLoader;@Overridepublic void afterPropertiesSet() throws Exception {// 初始化后，就执行逻辑了initializeDatabase();}/*** Initializes the database by applying schema and data scripts.* @return {@code true} if one or more scripts were applied to the database, otherwise* {@code false}*/public boolean initializeDatabase() {ScriptLocationResolver locationResolver = new ScriptLocationResolver(this.resourceLoader);// 先后执行 schema, data 的脚本boolean initialized = applySchemaScripts(locationResolver);return applyDataScripts(locationResolver) || initialized;}// 真正执行脚本前，会走这个判断，决定是否要执行脚本private boolean isEnabled() {if (this.settings.getMode() == DatabaseInitializationMode.NEVER) {return false;}return this.settings.getMode() == DatabaseInitializationMode.ALWAYS || isEmbeddedDatabase();}/*** Returns whether the database that is to be initialized is embedded.* @return {@code true} if the database is embedded, otherwise {@code false}* @since 2.5.1*/protected boolean isEmbeddedDatabase() {throw new IllegalStateException("Database initialization mode is '" + this.settings.getMode() + "' and database type is unknown");}private boolean applySchemaScripts(ScriptLocationResolver locationResolver) {return applyScripts(this.settings.getSchemaLocations(), "schema", locationResolver);}private boolean applyDataScripts(ScriptLocationResolver locationResolver) {return applyScripts(this.settings.getDataLocations(), "data", locationResolver);}private boolean applyScripts(List<String> locations, String type, ScriptLocationResolver locationResolver) {List<Resource> scripts = getScripts(locations, type, locationResolver);if (!scripts.isEmpty() && isEnabled()) {runScripts(scripts);return true;}return false;}// 根据配置的 路径的字符串 -> spring.Resource 类型private List<Resource> getScripts(List<String> locations, String type, ScriptLocationResolver locationResolver) {if (CollectionUtils.isEmpty(locations)) {return Collections.emptyList();}List<Resource> resources = new ArrayList<>();for (String location : locations) {for (Resource resource : doGetResources(location, locationResolver)) {if (resource.exists()) {resources.add(resource);}}}return resources;}private List<Resource> doGetResources(String location, ScriptLocationResolver locationResolver) {return locationResolver.resolve(location);}private void runScripts(List<Resource> resources) {runScripts(resources, this.settings.isContinueOnError(), this.settings.getSeparator(),this.settings.getEncoding());}protected abstract void runScripts(List<Resource> resources, boolean continueOnError, String separator,Charset encoding);private static class ScriptLocationResolver {private final ResourcePatternResolver resourcePatternResolver;private List<Resource> resolve(String location) throws IOException {// ...}}}

再看几个它的实现类，加载上配置类，基本上，可以知道它的使用方法了

2. 吾のDemo

始于测试类

package org.pajamas.spring.boot;import org.junit.jupiter.api.Disabled;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.pajamas.example.starter.core.entity.AlbumEntity;
import org.pajamas.example.starter.core.repo.AlbumRepo;
import org.pajamas.example.test.AbstractApplicationTest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Import;
import org.springframework.test.context.TestPropertySource;import java.util.List;/*** @author william* @since 2024/5/30*/
@DisplayName("what the interesting component")
@TestPropertySource(properties = {"spring.application.name=service-example-test",// 屏蔽 liquibase 的干扰 "spring.liquibase.enabled=false"
})
@Import(ExampleDatabaseInitializer.class)
public class DatabaseInitializerTest extends AbstractApplicationTest {// 其实就，一个 jpa 实体类的 repository@AutowiredAlbumRepo repo;// @Disabled@DisplayName("execute DDL, DML automatically, as App startup")@Testpublic void t0() throws Exception {// 预期的结果：启动启动时，自动创建表，并插入一条记录List<AlbumEntity> all = this.repo.findAll();printErr(all);}
}

既然是测试，就走简单的方式，注册这个bean

package org.pajamas.spring.boot;import org.springframework.boot.autoconfigure.sql.init.SqlDataSourceScriptDatabaseInitializer;
import org.springframework.boot.autoconfigure.sql.init.SqlInitializationProperties;
import org.springframework.boot.sql.init.DatabaseInitializationMode;import java.util.Collections;import javax.sql.DataSource;/*** @author william* @since 2024/5/30*/
public class ExampleDatabaseInitializer extends SqlDataSourceScriptDatabaseInitializer {public ExampleDatabaseInitializer(DataSource dataSource) {super(dataSource, getProperty());}private static SqlInitializationProperties getProperty() {SqlInitializationProperties properties = new SqlInitializationProperties();properties.setSchemaLocations(Collections.singletonList("classpath:sql/schema.sql"));properties.setDataLocations(Collections.singletonList("classpath:sql/data.sql"));properties.setMode(DatabaseInitializationMode.ALWAYS);properties.setContinueOnError(false);return properties;}
}

schema.sql

CREATE TABLE IF NOT EXISTS `t_album`
(`id`             bigint NOT NULL AUTO_INCREMENT,`album_name`     varchar(32)                                                  DEFAULT NULL COMMENT 'album name',`album_year`     int                                                          DEFAULT NULL COMMENT 'album publish year',`create_date`    timestamp NULL DEFAULT NULL,`create_user_id` bigint                                                       DEFAULT NULL,`update_date`    timestamp NULL DEFAULT NULL,`update_user_id` bigint                                                       DEFAULT NULL,`ver`            int    NOT NULL                                              DEFAULT '0',`del`            bigint NOT NULL                                              DEFAULT '0',PRIMARY KEY (`id`),UNIQUE KEY `uni_album_id_del` (`id`,`del`)
) COMMENT='album table';CREATE TABLE IF NOT EXISTS `t_artist`
(`id`             bigint NOT NULL AUTO_INCREMENT,`artist_name`    varchar(32)                                                  DEFAULT NULL COMMENT 'artist name',`artist_from`    varchar(32)                                                  DEFAULT NULL COMMENT 'shorten of country name',`create_date`    timestamp NULL DEFAULT NULL,`create_user_id` bigint                                                       DEFAULT NULL,`update_date`    timestamp NULL DEFAULT NULL,`update_user_id` bigint                                                       DEFAULT NULL,`ver`            int    NOT NULL                                              DEFAULT '0',`del`            bigint NOT NULL                                              DEFAULT '0',PRIMARY KEY (`id`),UNIQUE KEY `uni_artist_id_del` (`id`,`del`)
) COMMENT='artist table';

data.sql

insert into`t_album`
(`album_name`,`album_year`,`create_user_id`,`update_user_id`
)
values
('Boomerang',2023,1023,1023
);

3. 话说回来：为甚么，我的h2没有自动创建quartz的schema

这是springboot.Quartz的实现

接下来，源码启动…

package org.springframework.boot.jdbc.init;/*** {@link InitializingBean} that performs {@link DataSource} initialization using schema* (DDL) and data (DML) scripts.** @author Andy Wilkinson* @since 2.5.0*/
public class DataSourceScriptDatabaseInitializer extends AbstractScriptDatabaseInitializer {@Overrideprotected boolean isEmbeddedDatabase() {try {// step into ..return EmbeddedDatabaseConnection.isEmbedded(this.dataSource);}catch (Exception ex) {logger.debug("Could not determine if datasource is embedded", ex);return false;}}
}----------// org.springframework.boot.jdbc.EmbeddedDatabaseConnection/*** Convenience method to determine if a given data source represents an embedded* database type.* @param dataSource the data source to interrogate* @return true if the data source is one of the embedded types*/public static boolean isEmbedded(DataSource dataSource) {try {return new JdbcTemplate(dataSource)// step into ....execute(new IsEmbedded());}catch (DataAccessException ex) {// Could not connect, which means it's not embeddedreturn false;}}----------// org.springframework.boot.jdbc.EmbeddedDatabaseConnection.IsEmbedded@Overridepublic Boolean doInConnection(Connection connection) throws SQLException, DataAccessException {DatabaseMetaData metaData = connection.getMetaData();String productName = metaData.getDatabaseProductName();if (productName == null) {return false;}productName = productName.toUpperCase(Locale.ENGLISH);// step into ...EmbeddedDatabaseConnection[] candidates = EmbeddedDatabaseConnection.values();for (EmbeddedDatabaseConnection candidate : candidates) {if (candidate != NONE && productName.contains(candidate.getType().name())) {// 根据jdbc.url判断是不是一个 嵌入式数据库String url = metaData.getURL();return (url == null || candidate.isEmbeddedUrl(url));}}return false;}------------public enum EmbeddedDatabaseConnection {// H2 判断是否为嵌入式数据的依据/*** H2 Database Connection.*/H2(EmbeddedDatabaseType.H2, DatabaseDriver.H2.getDriverClassName(),"jdbc:h2:mem:%s;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE", (url) -> url.contains(":h2:mem")),}

破案：我的h2 使用默认的 file(xxx.mv.db) 存储，默认配置下(DatabaseInitializationMode.EMBEDDED), 只有内存（嵌入式）的数据库会开启这个特性。

• 要么配置 DatabaseInitializationMode.ALWAYS
• 要么使用内存数据库

Anyway, h2支持好多种连接方式，新版本h2, 默认的file模式，采用mv的storeEngine 支持MVCC。所以说，对于quartz这种依赖行锁的要求，也是支持的。

4. 话又说回去… 这个东西对项目的意义是什么

• 可以试下这个：如果你有一个连接数据库的测试环境，或者你的程序很简单，又或者 有特殊的xp（内存数据库）
• 专门数据库的版本控制工具：你的程序比较复杂，或者 本身就需要数据库的版本控制工具（如 Liquibase），运行在严肃的生产环境