简介
mysql应该是咱们在日常工作中应用到的一个十分广泛的数据库，尽管mysql当初是oracle公司的，然而它是开源的，市场占有率还是十分高的。
明天咱们将会介绍r2dbc在mysql中的应用。
r2dbc-mysql的maven依赖
要想应用r2dbc-mysql，咱们须要增加如下的maven依赖：
<dependency> <groupId>dev.miku</groupId> <artifactId>r2dbc-mysql</artifactId> <version>0.8.2.RELEASE</version></dependency>当然，如果你想应用snapshot版本的话，能够这样：
<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>创立connectionFactory
创立connectionFactory的代码实际上应用的r2dbc的标准接口，所以和之前讲到的h2的创立代码基本上是一样的：
// Notice: the query string must be URL encodedConnectionFactory 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 ReactorMono<Connection> connectionMono = Mono.from(connectionFactory.create());不同的是ConnectionFactories传入的参数不同。
咱们也反对unix domain socket的格局：
// Minimum configuration for unix domain socketConnectionFactory connectionFactory = ConnectionFactories.get("r2dbc:mysql://root@unix?unixSocket=%2Fpath%2Fto%2Fmysql.sock")Mono<Connection> connectionMono = Mono.from(connectionFactory.create());同样的，咱们也反对从ConnectionFactoryOptions中创立ConnectionFactory：
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 ReactorMono<Connection> connectionMono = Mono.from(connectionFactory.create());或者上面的unix domain socket格局：
// Minimum configuration for unix domain socketConnectionFactoryOptions 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());应用MySqlConnectionFactory创立connection
下面的例子中，咱们应用的是通用的r2dbc api来创立connection，同样的，咱们也能够应用特有的MySqlConnectionFactory来创立connection：
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 ReactorMono<Connection> connectionMono = Mono.from(connectionFactory.create());或者上面的unix domain socket形式：
// Minimum configuration for unix domain socketMySqlConnectionConfiguration 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
首先看一个简略的不带参数的statement:
connection.createStatement("INSERT INTO `person` (`first_name`, `last_name`) VALUES ('who', 'how')") .execute(); // return a Publisher include one Result而后看一个带参数的statement:
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.留神，如果参数是null的话，能够应用bindNull来进行null值的绑定。
接下来咱们看一个批量执行的操作：
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
咱们看一个执行事务的例子：
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());应用线程池
为了晋升数据库的执行效率，缩小建设连贯的开销，个别数据库连贯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：
<dependency> <groupId>io.r2dbc</groupId> <artifactId>r2dbc-pool</artifactId> <version>${version}</version></dependency>如果你想应用snapshot版本，也能够这样指定：
<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：
ConnectionFactory connectionFactory = ConnectionFactories.get("r2dbc:pool:<my-driver>://<host>:<port>/<database>[?maxIdleTime=PT60S[&…]");Publisher<? extends Connection> connectionPublisher = connectionFactory.create();能够看到，咱们只须要在连贯URL下面增加pool这个driver即可。
同样的，咱们也能够通过ConnectionFactoryOptions来创立：
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 ReactorMono<Connection> connectionMono = Mono.from(connectionFactory.create());最初， 你也能够间接通过创立ConnectionPoolConfiguration来应用线程池：
ConnectionFactory connectionFactory = …;ConnectionPoolConfiguration configuration = ConnectionPoolConfiguration.builder(connectionFactory) .maxIdleTime(Duration.ofMillis(1000)) .maxSize(20) .build();ConnectionPool pool = new ConnectionPool(configuration); Mono<Connection> connectionMono = pool.create();// laterConnection connection = …;Mono<Void> release = connection.close(); // released the connection back to the pool// application shutdownpool.dispose();本文作者：flydean程序那些事本文链接：http://www.flydean.com/r2dbc-mysql-in-depth/
本文起源：flydean的博客
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