深入理解r2dbc在mysql中的使用

简介

mysql应该是我们在日常工作中使用到的一个非常普遍的数据库，虽然mysql现在是oracle公司的，但是它是开源的，市场占有率还是非常高的。

今天我们将会介绍r2dbc在mysql中的使用。

r2dbc-mysql的maven依赖

要想使用r2dbc-mysql，我们需要添加如下的maven依赖：

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< dependency >    < groupId >dev.miku</ groupId >    < artifactId >r2dbc-mysql</ artifactId >    < version >0.8.2.RELEASE</ version > </ dependency >

当然，如果你想使用snapshot版本的话，可以这样：

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< dependency >    < groupId >dev.miku</ groupId >    < artifactId >r2dbc-mysql</ artifactId >    < version >${r2dbc-mysql.version}.BUILD-SNAPSHOT</ version > </ dependency >   < repository >    < id >sonatype-snapshots</ id >    < name >SonaType Snapshots</ name >    < url > https://oss.sonatype.org/content/repositories/snapshots </ url >    < snapshots >      < enabled >true</ enabled >    </ snapshots > </ repository >

创建connectionFactory

创建connectionFactory的代码实际上使用的r2dbc的标准接口，所以和之前讲到的h2的创建代码基本上是一样的：

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// Notice: the query string must be URL encoded ConnectionFactory connectionFactory = ConnectionFactories.get(    "r2dbcs: mysql://root:database-password-in-here@127.0.0.1:3306/r2dbc? " +    "zeroDate=use_round&" +    "sslMode=verify_identity&" +    "useServerPrepareStatement=true&" +    "tlsVersion=TLSv1.3%2CTLSv1.2%2CTLSv1.1&" +    "sslCa=%2Fpath%2Fto%2Fmysql%2Fca.pem&" +    "sslKey=%2Fpath%2Fto%2Fmysql%2Fclient-key.pem&" +    "sslCert=%2Fpath%2Fto%2Fmysql%2Fclient-cert.pem&" +    "sslKeyPassword=key-pem-password-in-here" )   // Creating a Mono using Project Reactor Mono<Connection> connectionMono = Mono.from(connectionFactory.create());

不同的是ConnectionFactories传入的参数不同。

我们也支持unix domain socket的格式：

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// Minimum configuration for unix domain socket ConnectionFactory connectionFactory = ConnectionFactories.get( "r2dbc: mysql://root@unix?unixSocket=%2Fpath%2Fto%2Fmysql.sock " )   Mono<Connection> connectionMono = Mono.from(connectionFactory.create());

同样的，我们也支持从ConnectionFactoryOptions中创建ConnectionFactory：

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ConnectionFactoryOptions options = ConnectionFactoryOptions.builder()    .option(DRIVER, "mysql" )    .option(HOST, "127.0.0.1" )    .option(USER, "root" )    .option(PORT, 3306 ) // optional, default 3306    .option(PASSWORD, "database-password-in-here" ) // optional, default null, null means has no password    .option(DATABASE, "r2dbc" ) // optional, default null, null means not specifying the database    .option(CONNECT_TIMEOUT, Duration.ofSeconds( 3 )) // optional, default null, null means no timeout    .option(SSL, true ) // optional, default sslMode is "preferred", it will be ignore if sslMode is set    .option(Option.valueOf( "sslMode" ), "verify_identity" ) // optional, default "preferred"    .option(Option.valueOf( "sslCa" ), "/path/to/mysql/ca.pem" ) // required when sslMode is verify_ca or verify_identity, default null, null means has no server CA cert    .option(Option.valueOf( "sslCert" ), "/path/to/mysql/client-cert.pem" ) // optional, default null, null means has no client cert    .option(Option.valueOf( "sslKey" ), "/path/to/mysql/client-key.pem" ) // optional, default null, null means has no client key    .option(Option.valueOf( "sslKeyPassword" ), "key-pem-password-in-here" ) // optional, default null, null means has no password for client key (i.e. "sslKey")    .option(Option.valueOf( "tlsVersion" ), "TLSv1.3,TLSv1.2,TLSv1.1" ) // optional, default is auto-selected by the server    .option(Option.valueOf( "sslHostnameVerifier" ), "com.example.demo.MyVerifier" ) // optional, default is null, null means use standard verifier    .option(Option.valueOf( "sslContextBuilderCustomizer" ), "com.example.demo.MyCustomizer" ) // optional, default is no-op customizer    .option(Option.valueOf( "zeroDate" ), "use_null" ) // optional, default "use_null"    .option(Option.valueOf( "useServerPrepareStatement" ), true ) // optional, default false    .option(Option.valueOf( "tcpKeepAlive" ), true ) // optional, default false    .option(Option.valueOf( "tcpNoDelay" ), true ) // optional, default false    .option(Option.valueOf( "autodetectExtensions" ), false ) // optional, default false    .build(); ConnectionFactory connectionFactory = ConnectionFactories.get(options);   // Creating a Mono using Project Reactor Mono<Connection> connectionMono = Mono.from(connectionFactory.create());

或者下面的unix domain socket格式：

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// Minimum configuration for unix domain socket ConnectionFactoryOptions options = ConnectionFactoryOptions.builder()    .option(DRIVER, "mysql" )    .option(Option.valueOf( "unixSocket" ), "/path/to/mysql.sock" )    .option(USER, "root" )    .build(); ConnectionFactory connectionFactory = ConnectionFactories.get(options);   Mono<Connection> connectionMono = Mono.from(connectionFactory.create());

使用MySqlConnectionFactory创建connection

上面的例子中，我们使用的是通用的r2dbc api来创建connection，同样的，我们也可以使用特有的MySqlConnectionFactory来创建connection：

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MySqlConnectionConfiguration configuration = MySqlConnectionConfiguration.builder()    .host( "127.0.0.1" )    .user( "root" )    .port( 3306 ) // optional, default 3306    .password( "database-password-in-here" ) // optional, default null, null means has no password    .database( "r2dbc" ) // optional, default null, null means not specifying the database    .serverZoneId(ZoneId.of( "Continent/City" )) // optional, default null, null means query server time zone when connection init    .connectTimeout(Duration.ofSeconds( 3 )) // optional, default null, null means no timeout    .sslMode(SslMode.VERIFY_IDENTITY) // optional, default SslMode.PREFERRED    .sslCa( "/path/to/mysql/ca.pem" ) // required when sslMode is VERIFY_CA or VERIFY_IDENTITY, default null, null means has no server CA cert    .sslCert( "/path/to/mysql/client-cert.pem" ) // optional, default has no client SSL certificate    .sslKey( "/path/to/mysql/client-key.pem" ) // optional, default has no client SSL key    .sslKeyPassword( "key-pem-password-in-here" ) // optional, default has no client SSL key password    .tlsVersion(TlsVersions.TLS1_3, TlsVersions.TLS1_2, TlsVersions.TLS1_1) // optional, default is auto-selected by the server    .sslHostnameVerifier(MyVerifier.INSTANCE) // optional, default is null, null means use standard verifier    .sslContextBuilderCustomizer(MyCustomizer.INSTANCE) // optional, default is no-op customizer    .zeroDateOption(ZeroDateOption.USE_NULL) // optional, default ZeroDateOption.USE_NULL    .useServerPrepareStatement() // Use server-preparing statements, default use client-preparing statements    .tcpKeepAlive( true ) // optional, controls TCP Keep Alive, default is false    .tcpNoDelay( true ) // optional, controls TCP No Delay, default is false    .autodetectExtensions( false ) // optional, controls extension auto-detect, default is true    .extendWith(MyExtension.INSTANCE) // optional, manual extend an extension into extensions, default using auto-detect    .build(); ConnectionFactory connectionFactory = MySqlConnectionFactory.from(configuration);   // Creating a Mono using Project Reactor Mono<Connection> connectionMono = Mono.from(connectionFactory.create());

或者下面的unix domain socket方式：

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// Minimum configuration for unix domain socket MySqlConnectionConfiguration configuration = MySqlConnectionConfiguration.builder()    .unixSocket( "/path/to/mysql.sock" )    .user( "root" )    .build(); ConnectionFactory connectionFactory = MySqlConnectionFactory.from(configuration);   Mono<Connection> connectionMono = Mono.from(connectionFactory.create());

执行statement

首先看一个简单的不带参数的statement:

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2	connection.createStatement( "INSERT INTO `person` (`first_name`, `last_name`) VALUES ('who', 'how')" )    .execute(); // return a Publisher include one Result

然后看一个带参数的statement:

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connection.createStatement( "INSERT INTO `person` (`birth`, `nickname`, `show_name`) VALUES (?, ?name, ?name)" )    .bind( 0 , LocalDateTime.of( 2019 , 6 , 25 , 12 , 12 , 12 ))    .bind( "name" , "Some one" ) // Not one-to-one binding, call twice of native index-bindings, or call once of name-bindings.    .add()    .bind( 0 , LocalDateTime.of( 2009 , 6 , 25 , 12 , 12 , 12 ))    .bind( 1 , "My Nickname" )    .bind( 2 , "Naming show" )    .returnGeneratedValues( "generated_id" )    .execute(); // return a Publisher include two Results.

注意，如果参数是null的话，可以使用bindNull来进行null值的绑定。

接下来我们看一个批量执行的操作：

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connection.createBatch()    .add( "INSERT INTO `person` (`first_name`, `last_name`) VALUES ('who', 'how')" )    .add( "UPDATE `earth` SET `count` = `count` + 1 WHERE `id` = 'human'" )    .execute(); // return a Publisher include two Results.

执行事务

我们看一个执行事务的例子：

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connection.beginTransaction()    .then(Mono.from(connection.createStatement( "INSERT INTO `person` (`first_name`, `last_name`) VALUES ('who', 'how')" ).execute()))    .flatMap(Result::getRowsUpdated)    .thenMany(connection.createStatement( "INSERT INTO `person` (`birth`, `nickname`, `show_name`) VALUES (?, ?name, ?name)" )      .bind( 0 , LocalDateTime.of( 2019 , 6 , 25 , 12 , 12 , 12 ))      .bind( "name" , "Some one" )      .add()      .bind( 0 , LocalDateTime.of( 2009 , 6 , 25 , 12 , 12 , 12 ))      .bind( 1 , "My Nickname" )      .bind( 2 , "Naming show" )      .returnGeneratedValues( "generated_id" )      .execute())    .flatMap(Result::getRowsUpdated)    .then(connection.commitTransaction());

使用线程池

为了提升数据库的执行效率，减少建立连接的开销，一般数据库连接都会有连接池的概念，同样的r2dbc也有一个叫做r2dbc-pool的连接池。

r2dbc-pool的依赖：

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< dependency >   < groupId >io.r2dbc</ groupId >   < artifactId >r2dbc-pool</ artifactId >   < version >${version}</ version > </ dependency >

如果你想使用snapshot版本，也可以这样指定：

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< dependency >   < groupId >io.r2dbc</ groupId >   < artifactId >r2dbc-pool</ artifactId >   < version >${version}.BUILD-SNAPSHOT</ version > </ dependency >   < repository >   < id >spring-libs-snapshot</ id >   < name >Spring Snapshot Repository</ name >   < url > https://repo.spring.io/libs-snapshot </ url > </ repository >

看一下怎么指定数据库连接池：

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2 3	ConnectionFactory connectionFactory = ConnectionFactories.get( "r2dbc:pool:<my-driver>://<host>:<port>/<database>[?maxIdleTime=PT60S[&…]" );   Publisher<? extends Connection> connectionPublisher = connectionFactory.create();

可以看到，我们只需要在连接URL上面添加pool这个driver即可。

同样的，我们也可以通过ConnectionFactoryOptions来创建：

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ConnectionFactory connectionFactory = ConnectionFactories.get(ConnectionFactoryOptions.builder()    .option(DRIVER, "pool" )    .option(PROTOCOL, "postgresql" ) // driver identifier, PROTOCOL is delegated as DRIVER by the pool.    .option(HOST, "…" )    .option(PORT, "…" )    .option(USER, "…" )    .option(PASSWORD, "…" )    .option(DATABASE, "…" )    .build());   Publisher<? extends Connection> connectionPublisher = connectionFactory.create();   // Alternative: Creating a Mono using Project Reactor Mono<Connection> connectionMono = Mono.from(connectionFactory.create());

最后， 你也可以直接通过创建ConnectionPoolConfiguration来使用线程池：

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ConnectionFactory connectionFactory = …;   ConnectionPoolConfiguration configuration = ConnectionPoolConfiguration.builder(connectionFactory)    .maxIdleTime(Duration.ofMillis( 1000 ))    .maxSize( 20 )    .build();   ConnectionPool pool = new ConnectionPool(configuration);     Mono<Connection> connectionMono = pool.create();   // later   Connection connection = …; Mono<Void> release = connection.close(); // released the connection back to the pool   // application shutdown pool.dispose();

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原文链接：https://blog.csdn.net/superfjj/article/details/109919239