016-Spring Boot JDBC

一、数据源装配

通过查看代码可知，默认已装配了数据源和JdbcTemplate

System.out.println(context.getBean(DataSource.class));
System.out.println(context.getBean(JdbcTemplate.class));

1.1、环境搭建

主要是pom引用：spring-boot-starter-jdbc、增加数据库驱动

<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.lhx.spring</groupId>
    <artifactId>springboot-web</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springboot-web</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>1.5.9.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
    </dependencies>
</project>

查看spring-boot-autoconfigure-1.5.9.RELEASE.jar包下的org.springframework.boot.autoconfigure.jdbc下的DataSourceProperties其实所有的都是类似的配置

@ConfigurationProperties(prefix = "spring.datasource")
public class DataSourceProperties
        implements BeanClassLoaderAware, EnvironmentAware, InitializingBean {

可以看到默认读取spring.datasource开头的配置。

1.2、配置

spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/springboot
spring.datasource.username=root
spring.datasource.password=root

1.3、使用

    public static void main(String[] args) throws SQLException {
        ConfigurableApplicationContext context = SpringApplication.run(App.class, args);
        dataSource = context.getBean(DataSource.class);

        Connection connection = dataSource.getConnection();
        System.out.println(connection.getCatalog());
    }

二、JdbcTemplate

在配置好基本配置后，JdbcTemplate就可以使用了

@Repository
public class ProductDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    public void addProdcut(String value) {
        String sql = "insert into product(pname) values('" + value + "')";
        jdbcTemplate.execute(sql);
    }
}

调用

public class App {

    public static void main(String[] args) throws SQLException {
        ConfigurableApplicationContext context = SpringApplication.run(App.class, args);

        context.getBean(ProductDao.class).addProdcut("mp3");
        connection.close();
    }
}

三、切换数据源

System.out.println(context.getBean(DataSource.class));

查看到使用的是默认提供的：org.apache.tomcat.jdbc.pool.DataSource数据源

方式一、排除添加切换

1》排除掉tomcat-jdbc

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

2》添加新的数据源

        <dependency>
            <groupId>com.zaxxer</groupId>
            <artifactId>HikariCP</artifactId>
        </dependency>

方式二、type配置数据源切换

3.2.1、原理查看

查看spring-boot-autoconfigure-1.5.9.RELEASE.jar包下的org.springframework.boot.autoconfigure.jdbc下的DataSourceProperties的配置

使用type指定【private Class<? extends DataSource> type;】在application.properties中

spring.datasource.type=com.zaxxer.hikari.HikariDataSource

默认支持以下几种数据源类型，查看spring-boot-autoconfigure-1.5.9.RELEASE.jar包下的org.springframework.boot.autoconfigure.jdbc下的DataSourceAutoConfiguration

DataSourceConfiguration.Tomcat.class
DataSourceConfiguration.Hikari.class
DataSourceConfiguration.Dbcp.class
DataSourceConfiguration.Dbcp2.class
DataSourceConfiguration.Generic.class

3.2.2、具体步骤

1》添加对应数据源pom

        <dependency>
            <groupId>com.zaxxer</groupId>
            <artifactId>HikariCP</artifactId>
        </dependency>

2》使用配置

spring.datasource.type=com.zaxxer.hikari.HikariDataSource

3.3、配置自定义数据源

1》添加POM依赖

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.6</version>
        </dependency>

2》、增加DBConfiguration配置类

package com.lhx.spring.springboot_web;

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 env;

    @Bean
    public DataSource createDataSource() {
        DruidDataSource source = new DruidDataSource();
        source.setUrl(env.getProperty("spring.datasource.url"));
        source.setUsername(env.getProperty("spring.datasource.username"));
        source.setPassword(env.getProperty("spring.datasource.password"));
        source.setDriverClassName(env.getProperty("spring.datasource.driverClassName"));
        return source;
    }
}

四、事务

4.1、配置开启

1、在入口app增加注解

@EnableTransactionManagement

2、在需要事务的公有方法上添加注解

@Transactional

示例

    @Transactional
    public void addProdcutBatch(String... names) throws Exception {
        for (String name : names) {
            String sql = "insert into product(pname) values('" + name + "')";
            jdbcTemplate.execute(sql);
            if ("".equals("")) {
                throw new NullPointerException();
            }
        }
    }

注意：spring事务，默认支持运行时异常，即RunTimeException，非运行时异常不会回滚

4.2、设置针对哪些异常使用事务

默认是运行时

设置所有异常

@Transactional(rollbackFor=Exception.class)

设置哪些异常不回滚

@Transactional(noRollbackFor=NullPointerException.class)

注意点：

1、要想使用事务生效，被调用的方法必须有Transactional 注解，对于内部调用方法有无注解无影响

2、需要数据库支持事务。