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簡介

mysql應該是我們在日常工作中使用到的一個非常普遍的數據庫，雖然mysql現在是oracle公司的，但是它是開源的，市場占有率還是非常高的。

今天我們將會介紹r2dbc在mysql中的使用。

r2dbc-mysql的maven依賴

要想使用r2dbc-mysql，我們需要添加如下的maven依賴：

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

當然，如果你想使用snapshot版本的話，可以這樣：

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>

創建connectionFactory

創建connectionFactory的代碼實際上使用的r2dbc的標準接口，所以和之前講到的h2的創建代碼基本上是一樣的：

// 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
MonoConnection> connectionMono = Mono.from(connectionFactory.create());

不同的是ConnectionFactories傳入的參數不同。

我們也支持unix domain socket的格式：

// Minimum configuration for unix domain socket
ConnectionFactory connectionFactory = ConnectionFactories.get("r2dbc:mysql://root@unix?unixSocket=%2Fpath%2Fto%2Fmysql.sock")

MonoConnection> connectionMono = Mono.from(connectionFactory.create());

同樣的，我們也支持從ConnectionFactoryOptions中創建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 Reactor
MonoConnection> connectionMono = Mono.from(connectionFactory.create());

或者下面的unix domain socket格式：

// 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);

MonoConnection> connectionMono = Mono.from(connectionFactory.create());

使用MySqlConnectionFactory創建connection

上面的例子中，我們使用的是通用的r2dbc api來創建connection，同樣的，我們也可以使用特有的MySqlConnectionFactory來創建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 Reactor
MonoConnection> connectionMono = Mono.from(connectionFactory.create());

或者下面的unix domain socket方式：

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

MonoConnection> connectionMono = Mono.from(connectionFactory.create());

執行statement

首先看一個簡單的不帶參數的statement:

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

然后看一個帶參數的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.

注意，如果參數是null的話，可以使用bindNull來進行null值的綁定。

接下來我們看一個批量執行的操作：

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.

執行事務

我們看一個執行事務的例子：

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());

使用線程池

為了提升數據庫的執行效率，減少建立連接的開銷，一般數據庫連接都會有連接池的概念，同樣的r2dbc也有一個叫做r2dbc-pool的連接池。

r2dbc-pool的依賴：

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

如果你想使用snapshot版本，也可以這樣指定：

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>

看一下怎么指定數據庫連接池：

ConnectionFactory connectionFactory = ConnectionFactories.get("r2dbc:pool:my-driver>://host>:port>/database>[?maxIdleTime=PT60S[…]");

Publisher? extends Connection> connectionPublisher = connectionFactory.create();

可以看到，我們只需要在連接URL上面添加pool這個driver即可。

同樣的，我們也可以通過ConnectionFactoryOptions來創建：

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
MonoConnection> connectionMono = Mono.from(connectionFactory.create());

最后，你也可以直接通過創建ConnectionPoolConfiguration來使用線程池：

ConnectionFactory connectionFactory = …;

ConnectionPoolConfiguration configuration = ConnectionPoolConfiguration.builder(connectionFactory)
  .maxIdleTime(Duration.ofMillis(1000))
  .maxSize(20)
  .build();

ConnectionPool pool = new ConnectionPool(configuration);
 

MonoConnection> connectionMono = pool.create();

// later

Connection connection = …;
MonoVoid> release = connection.close(); // released the connection back to the pool

// application shutdown
pool.dispose();

到此這篇關于深入理解r2dbc在mysql中的使用的文章就介紹到這了,更多相關mysql r2dbc 內容請搜索腳本之家以前的文章或繼續瀏覽下面的相關文章希望大家以后多多支持腳本之家！

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