H2依赖

<dependency><groupId>com.h2database</groupId><artifactId>h2</artifactId><version>2.1.214</version>
</dependency>

持久化配置

SpringBoot版本是2.3.12.RELEASE，下面有些配置看SpringBoot版本的，比如spring.datasource.schema是这个版本以下的，spring.sql.init.data是更高版本的

./dbfile 是把持久文件生成到程序启动路径下，你也可以自定义其他路径

# 数据源配置
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.schema=classpath:db/h2-schema.sql
spring.datasource.url=jdbc:h2:file:./dbfile
spring.datasource.username=root
spring.datasource.password=root
# 下面是控制台的配置
spring.h2.console.enabled=true
spring.h2.console.path=/h2-console

H2 url的含义

先看以下两个常量，代表url开头与后半段，后半段的类型有mem内存模式、file本地文件模式、tcp|ssl远程模式，含义如下（参考http://www.h2database.com/html/features.html#embedded_databases）

Topic	URL Format and Examples
Embedded (local) connection	jdbc:h2:[file:][] jdbc:h2:~/test jdbc:h2:file:/data/sample jdbc:h2:file:C:/data/sample (Windows only)
In-memory (private)	jdbc:h2:mem:
In-memory (named)	jdbc:h2:mem: jdbc:h2:mem:test_mem
Server mode (remote connections) using TCP/IP	jdbc:h2:tcp://[:]/[] jdbc:h2:tcp://localhost/~/test jdbc:h2:tcp://dbserv:8084/~/sample jdbc:h2:tcp://localhost/mem:test
Server mode (remote connections) using TLS	jdbc:h2:ssl://[:]/[] jdbc:h2:ssl://localhost:8085/~/sample;

org.h2.engine.Constants

	/*** The database URL prefix of this database.*/public static final String START_URL = "jdbc:h2:";/*** The database URL format in simplified Backus-Naur form.*/public static final String URL_FORMAT = START_URL +"{ {.|mem:}[name] | [file:]fileName | " +"{tcp|ssl}:[//]server[:port][,server2[:port]]/name }[;key=value...]";

去驱动里查看，ConnectionInfo里把url截取，然后判断类型，当是file时，把持久化标识persistent标位了true，后续数据库启动和运行都会用到这个标识判断是否持久化

org.h2.engine.ConnectionInfo

	/*** Create a connection info object.** @param u the database URL (must start with jdbc:h2:)* @param info the connection properties or {@code null}* @param user the user name or {@code null}* @param password*            the password as {@code String} or {@code char[]}, or*            {@code null}*/public ConnectionInfo(String u, Properties info, String user, Object password) {u = remapURL(u);originalURL = url = u;if (!u.startsWith(Constants.START_URL)) {throw getFormatException();}if (info != null) {readProperties(info);}if (user != null) {prop.put("USER", user);}if (password != null) {prop.put("PASSWORD", password);}readSettingsFromURL();Object timeZoneName = prop.remove("TIME ZONE");if (timeZoneName != null) {timeZone = TimeZoneProvider.ofId(timeZoneName.toString());}setUserName(removeProperty("USER", ""));name = url.substring(Constants.START_URL.length());parseName();convertPasswords();String recoverTest = removeProperty("RECOVER_TEST", null);if (recoverTest != null) {FilePathRec.register();try {Utils.callStaticMethod("org.h2.store.RecoverTester.init", recoverTest);} catch (Exception e) {throw DbException.convert(e);}name = "rec:" + name;}}	private void parseName() {if (".".equals(name)) {name = "mem:";}if (name.startsWith("tcp:")) {remote = true;name = name.substring("tcp:".length());} else if (name.startsWith("ssl:")) {remote = true;ssl = true;name = name.substring("ssl:".length());} else if (name.startsWith("mem:")) {persistent = false;if ("mem:".equals(name)) {unnamed = true;}} else if (name.startsWith("file:")) {name = name.substring("file:".length());persistent = true;} else {persistent = true;}if (persistent && !remote) {name = IOUtils.nameSeparatorsToNative(name);}}