SpringBoot数据访问和自动配置原理

一、SpringBoot数据库访问

　　1、导入依赖

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 3          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 4     <modelVersion>4.0.0</modelVersion>
 5     <parent>
 6         <groupId>org.springframework.boot</groupId>
 7         <artifactId>spring-boot-starter-parent</artifactId>
 8         <version>2.2.6.RELEASE</version>
 9         <relativePath/> <!-- lookup parent from repository -->
10     </parent>
11     <groupId>com.lxy</groupId>
12     <artifactId>springboot-05-data</artifactId>
13     <version>0.0.1-SNAPSHOT</version>
14     <name>springboot-05-data</name>
15     <description>Demo project for Spring Boot</description>
16 
17     <properties>
18         <java.version>1.8</java.version>
19     </properties>
20 
21     <dependencies>
22 
23         <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
24         <dependency>
25             <groupId>com.alibaba</groupId>
26             <artifactId>druid</artifactId>
27             <version>1.1.21</version>
28         </dependency>
29 
30         <!--log4j-->
31         <dependency>
32             <groupId>log4j</groupId>
33             <artifactId>log4j</artifactId>
34             <version>1.2.17</version>
35         </dependency>
36 
37         <!--web-->
38         <dependency>
39             <groupId>org.springframework.boot</groupId>
40             <artifactId>spring-boot-starter-web</artifactId>
41         </dependency>
42 
43         <!--jdbc-->
44         <dependency>
45             <groupId>org.springframework.boot</groupId>
46             <artifactId>spring-boot-starter-jdbc</artifactId>
47         </dependency>
48 
49         <!--mybatis-->
50         <dependency>
51             <groupId>org.mybatis.spring.boot</groupId>
52             <artifactId>mybatis-spring-boot-starter</artifactId>
53             <version>2.1.2</version>
54         </dependency>
55 
56         <dependency>
57             <groupId>mysql</groupId>
58             <artifactId>mysql-connector-java</artifactId>
59             <scope>runtime</scope>
60         </dependency>
61         <dependency>
62             <groupId>org.springframework.boot</groupId>
63             <artifactId>spring-boot-starter-test</artifactId>
64             <scope>test</scope>
65             <exclusions>
66                 <exclusion>
67                     <groupId>org.junit.vintage</groupId>
68                     <artifactId>junit-vintage-engine</artifactId>
69                 </exclusion>
70             </exclusions>
71         </dependency>
72     </dependencies>
73 
74     <build>
75         <plugins>
76             <plugin>
77                 <groupId>org.springframework.boot</groupId>
78                 <artifactId>spring-boot-maven-plugin</artifactId>
79             </plugin>
80         </plugins>
81     </build>
82 
83 </project>

　　　　2、配置application.yml文件中关于数据源的参数

 1 spring:
 2   datasource:
 3     username: root
 4     password: mysql
 5     url: jdbc:mysql://localhost:3306/mybatis?&useUnicode=true&characterEncoding=UTF8&serverTimezone=GMT%2B8&useSSL=false
 6     driver-class-name: com.mysql.cj.jdbc.Driver
 7     type: com.alibaba.druid.pool.DruidDataSource
 8 
 9 
10     #Spring Boot 默认是不注入这些属性值的，需要自己绑定
11     #druid 数据源专有配置
12     initialSize: 5
13     minIdle: 5
14     maxActive: 20
15     maxWait: 60000
16     timeBetweenEvictionRunsMillis: 60000
17     minEvictableIdleTimeMillis: 300000
18     validationQuery: SELECT 1 FROM DUAL
19     testWhileIdle: true
20     testOnBorrow: false
21     testOnReturn: false
22     poolPreparedStatements: true
23 
24     #配置监控统计拦截的filters，stat:监控统计、log4j：日志记录、wall：防御sql注入
25     #如果允许时报错  java.lang.ClassNotFoundException: org.apache.log4j.Priority
26     #则导入 log4j 依赖即可，Maven 地址：https://mvnrepository.com/artifact/log4j/log4j
27     filters: stat,wall,log4j
28     maxPoolPreparedStatementPerConnectionSize: 20
29     useGlobalDataSourceStat: true
30     connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

二、自动配置原理

　　1、参考 DataSourceConfiguration 根据配置创建数据源。默认使用 HikariDataSource 数据源

　　2、SpringBoot默认还可以支持：org.apache.tomcat.jdbc.pool.DataSource.class、org.apache.commons.dbcp2.BasicDataSource.class数据源

　　3、自定义数据源类型

 1 /**
 2      * Generic DataSource configuration.
 3      */
 4     @Configuration(proxyBeanMethods = false)
 5     @ConditionalOnMissingBean(DataSource.class)
 6     @ConditionalOnProperty(name = "spring.datasource.type")
 7     static class Generic {
 8 
 9         @Bean
10         DataSource dataSource(DataSourceProperties properties) {
11　　　　　　　　　// 使用DataSourceBuilder创建数据源，利用反射创建相应type的数据源，并绑定相关属性
12             return properties.initializeDataSourceBuilder().build();
13         }
14     }

　　4、DataSourceInitiallizer：ApplicationListener

　　　　作用：在运行期间创建表

　　　　配置规则：把相应的.sql文件放入resource/sql文件夹下即可

1 spring:
2   datasource:
3     initialization-mode: always
4     schema:
5       - classpath:sql/department.sql
6       - classpath:sql/employee.sql

三、配置Druid数据源

　　1、添加依赖

 1         <!--druid -->
 2         <dependency>
 3             <groupId>com.alibaba</groupId>
 4             <artifactId>druid</artifactId>
 5             <version>1.1.21</version>
 6         </dependency>
 7 
 8         <!--log4j-->
 9         <dependency>
10             <groupId>log4j</groupId>
11             <artifactId>log4j</artifactId>
12             <version>1.2.17</version>
13         </dependency>

　 2、在application.yml中配置druid参数同上一、2

　　3、配置druidController

 1 package com.lxy.config;
 2 
 3 import com.alibaba.druid.pool.DruidDataSource;
 4 import com.alibaba.druid.support.http.StatViewServlet;
 5 import com.alibaba.druid.support.http.WebStatFilter;
 6 import org.springframework.boot.context.properties.ConfigurationProperties;
 7 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 8 import org.springframework.boot.web.servlet.ServletRegistrationBean;
 9 import org.springframework.context.annotation.Bean;
10 import org.springframework.context.annotation.Configuration;
11 
12 
13 import javax.sql.DataSource;
14 import java.util.Arrays;
15 import java.util.HashMap;
16 import java.util.Map;
17 
18 @Configuration
19 public class DruidConfig {
20     @ConfigurationProperties(prefix = "spring.datasource")
21     @Bean
22     public DataSource druid(){
23         return new DruidDataSource();
24     }
25     //配置Druid的监控
26     //1、配置一个管理后台的Servlet
27     @Bean
28     public ServletRegistrationBean statViewServlet(){
29         ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(),
30                 "/druid/*");
31         Map<String,String> initParams = new HashMap<>();
32         initParams.put("loginUsername","admin");
33         initParams.put("loginPassword","123456");
34         initParams.put("allow","");//默认就是允许所有访问
35         initParams.put("deny","192.168.15.21");
36         bean.setInitParameters(initParams);
37         return bean;
38     }
39 
40     //2、配置一个web监控的filter
41     @Bean
42     public FilterRegistrationBean webStatFilter(){
43         FilterRegistrationBean bean = new FilterRegistrationBean();
44         bean.setFilter(new WebStatFilter());
45         Map<String,String> initParams = new HashMap<>();
46         initParams.put("exclusions","*.js,*.css,/druid/*");
47         bean.setInitParameters(initParams);
48         bean.setUrlPatterns(Arrays.asList("/*"));
49         return bean;
50     }
51 }

SpringBoot数据访问和自动配置原理

一、SpringBoot数据库访问

1、导入依赖

2、配置application.yml文件中关于数据源的参数

二、自动配置原理

三、配置Druid数据源

1、添加依赖

2、在application.yml中配置druid参数 同上一、2

3、配置druidController

　　1、导入依赖

　　　　2、配置application.yml文件中关于数据源的参数

　　1、添加依赖

　 2、在application.yml中配置druid参数同上一、2

　　3、配置druidController