（024）Spring Boot之配置数据源

　　springboot整合了一些数据源，在org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration类中可以查看。

　　1.4.0.RELEASE版本中整合了4个，默认是：tomcat-jdbc，如下：

 　　2.0.4.RELEASE版本中整合了5个，默认是：Hikari，如下：

 　　以2.0.4.RELEASE版本为例讲解怎样配置数据源，数据库采用mysql。

（1）采用默认数据源。需要添加以下依赖：

<dependency>
　　<groupId>org.springframework.boot</groupId>
　　<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
　　<groupId>mysql</groupId>
　　<artifactId>mysql-connector-java</artifactId>
</dependency>

　　pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.edu.spring</groupId>
    <artifactId>springboot_web</artifactId>
    <version>1.0.0</version>

    <name>springboot_web</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>
    <parent> 
        <groupId>org.springframework.boot</groupId> 
        <artifactId>spring-boot-starter-parent</artifactId> 
        <version>2.0.4.RELEASE</version> 
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

</project>

　　application.properties中添加如下配置：

spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3309/springboot
spring.datasource.username=root
spring.datasource.password=123456

　　App.java

package com.edu.spring.springboot;

import java.sql.Connection;
import java.sql.DatabaseMetaData;

import javax.sql.DataSource;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class App    
{ 
    public static void main(String[] args) throws Exception{
        ConfigurableApplicationContext context=SpringApplication.run(App.class, args); 
        DataSource ds=context.getBean(DataSource.class);
        System.out.println("-----------------------------------------------");
        System.out.println(ds.getClass().getName());//获取数据源
        Connection conn=ds.getConnection();
        DatabaseMetaData databaseMetaData=conn.getMetaData();
        System.out.println(databaseMetaData.getUserName());//获取用户名
        System.out.println(databaseMetaData.getURL());//获取URL
        System.out.println(conn.getCatalog());//获取数据库名
        System.out.println("-----------------------------------------------");

        context.close();
    }
} 

　　运行结果如下：

 （2）指定一个已经整合的数据源，tomcat-jdbc的数据源

　　第一种方法：在starter-jdbc依赖中排除默认添加的HikariCP，然后添加tomcat-jdbc依赖，如下：

<dependency>
　　<groupId>org.springframework.boot</groupId>
　　<artifactId>spring-boot-starter-jdbc</artifactId>
　　<exclusions>
　　　　<exclusion>
　　　　　　<groupId>com.zaxxer</groupId>
　　　　　　<artifactId>HikariCP</artifactId>
　　　　</exclusion>
　　</exclusions>
</dependency>
<dependency>
　　<groupId>org.apache.tomcat</groupId>
　　<artifactId>tomcat-jdbc</artifactId>
</dependency>

　　pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.edu.spring</groupId>
    <artifactId>springboot_web</artifactId>
    <version>1.0.0</version>

    <name>springboot_web</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>
    <parent> 
        <groupId>org.springframework.boot</groupId> 
        <artifactId>spring-boot-starter-parent</artifactId> 
        <version>2.0.4.RELEASE</version> 
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>com.zaxxer</groupId>
                    <artifactId>HikariCP</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
             <groupId>org.apache.tomcat</groupId>
               <artifactId>tomcat-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

</project>

　　运行结果如下：

 　　第二种方法：添加tomcat-jdbc依赖，在application.properties文件中指定数据源：

spring.datasource.type=org.apache.tomcat.jdbc.pool.DataSource

<dependency>
　　<groupId>org.apache.tomcat</groupId>
　　<artifactId>tomcat-jdbc</artifactId>
</dependency>

　　application.properties

spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3309/springboot
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.type=org.apache.tomcat.jdbc.pool.DataSource

　　pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.edu.spring</groupId>
    <artifactId>springboot_web</artifactId>
    <version>1.0.0</version>

    <name>springboot_web</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>
    <parent> 
        <groupId>org.springframework.boot</groupId> 
        <artifactId>spring-boot-starter-parent</artifactId> 
        <version>2.0.4.RELEASE</version> 
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
　　            <groupId>org.apache.tomcat</groupId>
　　            <artifactId>tomcat-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

</project>

　　运行结果如下：

 （3）自定义一个数据源DruidDataSource，先添加依赖，再装配成bean，springboot首先会用自定义的

<dependency>
　　<groupId>com.alibaba</groupId>
　　<artifactId>druid</artifactId>
　　<version>1.0.25</version>
</dependency>

　　pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.edu.spring</groupId>
    <artifactId>springboot_web</artifactId>
    <version>1.0.0</version>

    <name>springboot_web</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>
    <parent> 
        <groupId>org.springframework.boot</groupId> 
        <artifactId>spring-boot-starter-parent</artifactId> 
        <version>2.0.4.RELEASE</version> 
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.25</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

</project>

　　application.properties

spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3309/springboot
spring.datasource.username=root
spring.datasource.password=123456

　　DBConfiguration.java

package com.edu.spring.springboot;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.core.env.Environment;

import com.alibaba.druid.pool.DruidDataSource;

@SpringBootConfiguration
public class DBConfiguration {

    @Autowired
    private Environment environment;
    
    @Bean
    public DataSource createDateSource(){
        DruidDataSource dataSource=new DruidDataSource();
        dataSource.setDriverClassName(environment.getProperty("spring.datasource.driverClassName"));
        dataSource.setUrl(environment.getProperty("spring.datasource.url"));
        dataSource.setUsername(environment.getProperty("spring.datasource.username"));
        dataSource.setPassword(environment.getProperty("spring.datasource.password"));
        return dataSource;
    }
}

　　运行结果如下：