SpingBoot與數據訪問(一)JDBC方式、整合Druid

1.JDBC

我們首先使用JDBC連接數據庫

1.1 導入Maven座標

我們首先導入JDBC與mysql依賴

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

1.2 配置文件

接下來我們配置數據庫連接相關參數

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

1.3 測試

	@Autowired
	DataSource dataSource;

	@Test
	public void contextLoads() throws SQLException {

		System.out.println(dataSource);
		System.out.println(dataSource.getConnection());

	}

可以看到springBoot是默認使用org.apache.tomcat.jdbc.pool.DataSource作爲數據源

1.4 配置原理

接下來我們看一下他是如何生效的,看一下JDBC相關自動配置類DataSourceConfiguration

abstract class DataSourceConfiguration {

	@SuppressWarnings("unchecked")
	protected static <T> T createDataSource(DataSourceProperties properties,
			Class<? extends DataSource> type) {
		return (T) properties.initializeDataSourceBuilder().type(type).build();
	}

	/**
	 * Tomcat Pool DataSource configuration.
	 */
	@ConditionalOnClass(org.apache.tomcat.jdbc.pool.DataSource.class)
	@ConditionalOnMissingBean(DataSource.class)
	@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.tomcat.jdbc.pool.DataSource", matchIfMissing = true)
	static class Tomcat {

		@Bean
		@ConfigurationProperties(prefix = "spring.datasource.tomcat")
		public org.apache.tomcat.jdbc.pool.DataSource dataSource(
				DataSourceProperties properties) {
			org.apache.tomcat.jdbc.pool.DataSource dataSource = createDataSource(
					properties, org.apache.tomcat.jdbc.pool.DataSource.class);
			DatabaseDriver databaseDriver = DatabaseDriver
					.fromJdbcUrl(properties.determineUrl());
			String validationQuery = databaseDriver.getValidationQuery();
			if (validationQuery != null) {
				dataSource.setTestOnBorrow(true);
				dataSource.setValidationQuery(validationQuery);
			}
			return dataSource;
		}

	}

可以看到createDataSource方法傳入DataSourceProperties，而我們配置文件中spring.datasource 自動綁定到DataSourceProperties

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

	private ClassLoader classLoader;

	private Environment environment;

接下來我們可以從DataSourceConfiguration 中看到我們默認使用org.apache.tomcat.jdbc.pool.DataSource 作爲數據源，並且可以使用spring.datasource.type 指定數據源

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

		@Bean
		public DataSource dataSource(DataSourceProperties properties) {
			return properties.initializeDataSourceBuilder().build();
		}

	}

接着看DataSourceConfiguration 中其他數據源配置

當我們沒有導入相關依賴相關數據源是不生效的@ConditionalOnClass，因此這就是爲什麼我們再配置文件中配置spring.datasource 前綴可以生效並且數據源默認是tomcat數據源的原因。

並且springBoot也幫我們自動配置了JdbcTemplate 可以操作數據庫

	@Autowired
	JdbcTemplate jdbcTemplate;

	@Test
	public void query() throws Exception{
		List<Map<String, Object>> mapList = jdbcTemplate.queryForList("select * from emb_t_dictBusType");
		System.out.println(mapList);
	}

1.5 DataSourceInitializer

接下來我們看一下DataSourceInitializer 這個類

class DataSourceInitializer implements ApplicationListener<DataSourceInitializedEvent> {

	@PostConstruct
	public void init() {
		if (!this.properties.isInitialize()) {
			logger.debug("Initialization disabled (not running DDL scripts)");
			return;
		}
		if (this.applicationContext.getBeanNamesForType(DataSource.class, false,
				false).length > 0) {
			this.dataSource = this.applicationContext.getBean(DataSource.class);
		}
		if (this.dataSource == null) {
			logger.debug("No DataSource found so not initializing");
			return;
		}
		runSchemaScripts();
	}

	private void runSchemaScripts() {
		List<Resource> scripts = getScripts("spring.datasource.schema",
				this.properties.getSchema(), "schema");
		if (!scripts.isEmpty()) {
			String username = this.properties.getSchemaUsername();
			String password = this.properties.getSchemaPassword();
			runScripts(scripts, username, password);
			try {
				this.applicationContext
						.publishEvent(new DataSourceInitializedEvent(this.dataSource));
				// The listener might not be registered yet, so don't rely on it.
				if (!this.initialized) {
					runDataScripts();
					this.initialized = true;
				}
			}
			catch (IllegalStateException ex) {
				logger.warn("Could not send event to complete DataSource initialization ("
						+ ex.getMessage() + ")");
			}
		}
	}

	@Override
	public void onApplicationEvent(DataSourceInitializedEvent event) {
		if (!this.properties.isInitialize()) {
			logger.debug("Initialization disabled (not running data scripts)");
			return;
		}
		// NOTE the event can happen more than once and
		// the event datasource is not used here
		if (!this.initialized) {
			runDataScripts();
			this.initialized = true;
		}
	}

	private void runDataScripts() {
		List<Resource> scripts = getScripts("spring.datasource.data",
				this.properties.getData(), "data");
		String username = this.properties.getDataUsername();
		String password = this.properties.getDataPassword();
		runScripts(scripts, username, password);
	}
	private List<Resource> getScripts(String propertyName, List<String> resources,
			String fallback) {
		if (resources != null) {
			return getResources(propertyName, resources, true);
		}
		String platform = this.properties.getPlatform();
		List<String> fallbackResources = new ArrayList<String>();
		fallbackResources.add("classpath*:" + fallback + "-" + platform + ".sql");
		fallbackResources.add("classpath*:" + fallback + ".sql");
		return getResources(propertyName, fallbackResources, false);
	}

我們看一下runDataScripts 與runSchemaScripts方法我們可以總結如下
也就是說我們在容器啓動的時候，可以在類路徑下加上一下sql文件，他們會自動執行裏面的語句
作用：

runSchemaScripts();運行建表語句；
runDataScripts();運行插入數據的sql語句；
默認只需要將文件命名爲：

schema-*.sql、data-*.sql
默認規則：schema.sql，schema-all.sql；

可以使用   
	schema:
      - classpath:department.sql
      指定位置

如：spring.datasource.schema=classPath:data.sql

2 整合Druid數據源

我們前面說了可以使用spring.datasource.type 指定數據源，下面我們來整合Druid數據源
首先我們加上Maven 座標

		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid</artifactId>
			<version>1.1.9</version>
		</dependency>

然後在我們的配置文件中增加如下配置

spring.datasource.type=com.alibaba.druid.pool.DruidDataSource

#最大活躍數
spring.datasource.maxActive: 20
#初始化數量
spring.datasource.initialSize: 1
#最大連接等待超時時間
spring.datasource.maxWait: 60000
#打開PSCache，並且指定每個連接PSCache的大小
spring.datasource.poolPreparedStatements: true
spring.datasource.maxPoolPreparedStatementPerConnectionSize: 20
#通過connectionProperties屬性來打開mergeSql功能；慢SQL記錄
#connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
spring.datasource.minIdle: 1
spring.datasource.timeBetweenEvictionRunsMillis: 60000
spring.datasource.minEvictableIdleTimeMillis: 300000
spring.datasource.validationQuery: select 1 from dual
spring.datasource.testWhileIdle: true
spring.datasource.testOnBorrow: false
spring.datasource.testOnReturn: false
#配置監控統計攔截的filters，去掉後監控界面sql將無法統計,'wall'用於防火牆
filters: stat, wall, log4j

爲了使相關屬性可以映射到我們的DruidDataSource上,我們增加一個配置類

@Configuration
public class DruidConfig {

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


    //配置Druid的監控
    //1、配置一個管理後臺的Servlet
    @Bean
    public ServletRegistrationBean statViewServlet(){
        ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
        Map<String,String> initParams = new HashMap<>();

        initParams.put("loginUsername","admin");
        initParams.put("loginPassword","123456");
        initParams.put("allow","");//默認就是允許所有訪問
        initParams.put("deny","192.168.15.21");

        bean.setInitParameters(initParams);
        return bean;
    }


    //2、配置一個web監控的filter
    @Bean
    public FilterRegistrationBean webStatFilter(){
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.setFilter(new WebStatFilter());

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

        bean.setInitParameters(initParams);

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

        return  bean;
    }

}

我們再打印出我們的數據源就已經是Druid的數據源了

SpingBoot與數據訪問(一)JDBC方式、整合Druid

1.JDBC

1.1 導入Maven座標

1.2 配置文件

1.3 測試

1.4 配置原理

1.5 DataSourceInitializer

2 整合Druid數據源

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