深入理解r2dbc-mysql

客官°小女子只卖身不卖艺 2022-12-23 03:25 107阅读 0赞

### 文章目录 ###

*  简介
 *  r2dbc-mysql的maven依赖
 *  创建connectionFactory
 *  使用MySqlConnectionFactory创建connection
 *  执行statement
 *  执行事务
 *  使用线程池

# 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：

<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：

<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：

// 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：

// 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：

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：

// 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：

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：

// 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:

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:

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：

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：

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：

<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：

<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();

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：

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：

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();

> 本文作者：flydean程序那些事
> 
> 本文链接：[http://www.flydean.com/r2dbc-mysql-in-depth/][http_www.flydean.com_r2dbc-mysql-in-depth]
> 
> 本文来源：flydean的博客
> 
> 欢迎关注我的公众号:「程序那些事」最通俗的解读，最深刻的干货，最简洁的教程，众多你不知道的小技巧等你来发现！

[http_www.flydean.com_r2dbc-mysql-in-depth]: http://www.flydean.com/r2dbc-mysql-in-depth/