【SpringBoot】SpringBoot 配置JDBC数据源（十二）

　　本例介绍SpringBoot与数据源的使用

JDBC

　　1、新建一个项目SpringBoot Web项目，引入JDBC相关jar包。SpringBoot版本是：2.1.8.RELEASE，pom文件如下：

<?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.test</groupId>
    <artifactId>test-springboot-jdbc</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
    </parent>

    <properties>

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

        <!-- mysql -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.12</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

    </dependencies>


    <!-- SpringBoot打包插件，可以将代码打包成一个可执行的jar包 -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

　　2、配置数据源

spring:
  datasource:
    username: admin
    password: 123456
    url: jdbc:mysql://127.0.0.1:3306/test
    driver-class-name: com.mysql.jdbc.Driver

　　3、编辑测试JDBC代码，如下：

package com.test.springboot;

import com.mysql.jdbc.Driver;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.test.context.junit4.SpringRunner;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

@RunWith(SpringRunner.class)
@SpringBootTest
public class TestApplication {

    @Autowired
    private DataSource dataSource;
    
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Test
    public void context() throws SQLException {
        System.out.println("========");
        System.out.println("dataSource ====" + dataSource);

        Connection connection = dataSource.getConnection();
        System.out.println("connecttion ====" + connection);

        List<Map<String, Object>> maps = jdbcTemplate.queryForList("select * from user");
        System.out.println(maps);
    }

}

　　4、测试： 

　　　　

　　　　效果: 默认是用com.zaxxer.hikari.HikariDataSource作为数据源; 数据源的相关配置都在DataSourceProperties里面;

 数据自动配置原理

　　通过参考org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration类，可以看到自动配置内容

　　1、参考DataSourceConfiguration，根据配置创建数据源，默认使用HikariDataSource连接池;可以使用 spring.datasource.type指定自定义的数据源类型;

　　2、SpringBoot默认可以支持：

　　　　org.apache.tomcat.jdbc.pool.DataSource、HikariDataSource、BasicDataSource

　　3、自定义数据源类型

/**
 * Generic DataSource configuration.
 */
@Configuration
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type")
static class Generic {

    @Bean
    public DataSource dataSource(DataSourceProperties properties) {

        //使用DataSourceBuilder创建数据源，利用反射创建响应type的数据源，并且绑定相关属性
        return properties.initializeDataSourceBuilder().build();
    }

}

　　4、操作数据库:自动配置了JdbcTemplate操作数据库

整合Druid数据源

　　1、引入druid数据源依赖

<!--引入druid数据源-->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.8</version>
</dependency>

　　2、编辑Druid数据源配置类

package com.test.springboot.config;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

@Configuration
public class DruidConfig {

    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource druid(){
       return  new DruidDataSource();
    }

    //配置Druid的监控
    //1、配置一个管理后台的Servlet
    @Bean
    public ServletRegistrationBean statViewServlet(){
        ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
        Map<String,String> initParams = new HashMap<>();

        // 后台用户名
        initParams.put("loginUsername","admin");
        // 后台密码
        initParams.put("loginPassword","123456");
        //默认就是允许所有访问
        initParams.put("allow","");
        // 拒接访问
        initParams.put("deny","192.168.1.3");

        bean.setInitParameters(initParams);
        return bean;
    }


    //2、配置一个web监控的filter
    @Bean
    public FilterRegistrationBean webStatFilter(){
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.setFilter(new WebStatFilter());

        Map<String,String> initParams = new HashMap<>();
        initParams.put("exclusions","*.js,*.css,*.png,*.jpg,/druid/*");

        bean.setInitParameters(initParams);

        bean.setUrlPatterns(Arrays.asList("/*"));

        return  bean;
    }
}

　　3、启动web项目。浏览器输入地址：http://localhost:8080/druid/，进行访问