SpingBoot与数据访问(一)JDBC方式、整合Druid
1.JDBC
我们首先使用JDBC连接数据库
1.1 导入Maven坐标
我们首先导入JDBC与mysql依赖
<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
接下来我们配置数据库连接相关参数
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 测试
@Autowired
DataSource dataSource;
@Test
public void contextLoads() throws SQLException {
System.out.println(dataSource);
System.out.println(dataSource.getConnection());
}
可以看到springBoot是默认使用org.apache.tomcat.jdbc.pool.DataSource
作为数据源
1.4 配置原理
接下来我们看一下他是如何生效的,看一下JDBC相关自动配置类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方法传入DataSourceProperties,而我们配置文件中spring.datasource
自动绑定到DataSourceProperties
@ConfigurationProperties(prefix = "spring.datasource")
public class DataSourceProperties
implements BeanClassLoaderAware, EnvironmentAware, InitializingBean {
private ClassLoader classLoader;
private Environment environment;
接下来我们可以从DataSourceConfiguration
中看到 我们默认使用org.apache.tomcat.jdbc.pool.DataSource
作为数据源,并且可以使用spring.datasource.type
指定数据源
/**
* 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
中其他数据源配置
当我们没有导入相关依赖 相关数据源是不生效的@ConditionalOnClass
,因此这就是为什么我们再配置文件中配置spring.datasource
前缀可以生效并且数据源默认是tomcat数据源的原因。
并且springBoot也帮我们自动配置了JdbcTemplate
可以操作数据库
@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
接下来我们看一下DataSourceInitializer
这个类
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);
}
我们看一下runDataScripts
与runSchemaScripts
方法 我们可以总结如下
也就是说我们在容器启动的时候,可以在类路径下加上一下sql文件,他们会自动执行里面的语句
作用:
- runSchemaScripts();运行建表语句;
- runDataScripts();运行插入数据的sql语句;
默认只需要将文件命名为:
schema-*.sql、data-*.sql
默认规则: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数据源
我们前面说了 可以使用spring.datasource.type
指定数据源,下面我们来整合Druid数据源
首先我们加上Maven 坐标
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.9</version>
</dependency>
然后在我们的配置文件中增加如下配置
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
#最大活跃数
spring.datasource.maxActive: 20
#初始化数量
spring.datasource.initialSize: 1
#最大连接等待超时时间
spring.datasource.maxWait: 60000
#打开PSCache,并且指定每个连接PSCache的大小
spring.datasource.poolPreparedStatements: true
spring.datasource.maxPoolPreparedStatementPerConnectionSize: 20
#通过connectionProperties属性来打开mergeSql功能;慢SQL记录
#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
#配置监控统计拦截的filters,去掉后监控界面sql将无法统计,'wall'用于防火墙
filters: stat, wall, log4j
为了使相关属性可以映射到我们的DruidDataSource上,我们增加一个配置类
@Configuration
public class DruidConfig {
@ConfigurationProperties(prefix="spring.datasource")
@Bean
public DataSource dataSource(){
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<>();
initParams.put("loginUsername","admin");
initParams.put("loginPassword","123456");
initParams.put("allow","");//默认就是允许所有访问
initParams.put("deny","192.168.15.21");
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,/druid/*");
bean.setInitParameters(initParams);
bean.setUrlPatterns(Arrays.asList("/*"));
return bean;
}
}
我们再打印出我们的数据源就已经是Druid的数据源了