SpringBoot之数据库连接

SpringBoot之数据库连接

1.整合JDBC

1. 编写配置文件，数据库连接信息

2. 测试连接信息

• 自动注入DataSource

• 获取数据库连接

• SpringBoot中已经配置好了模板Bean：xxxxTemplate ，可以直接使用eg：jdbcTemplate，redisTemplate

• 关闭连接

3. 编写dao层

• 自动注入JdbcTemplate

• 使用JdbcTemplate增删改查

• 返回数据

2.整合Druid数据源

只需要在配置文件数据源上添加type即可

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
​
    #SpringBoot默认是不配置这些属性值的，需要自己绑定
    #druid 数据源专有配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictable IdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
​
    #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
    #如果允许时报错 java.lang.ClassNotFoundException:org.apache.log4j.Priority
    #则导入log4j 依赖即可,Maven地址：https://mvnrepository.com/artifact/log4j/log4j
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

Druid的强大之处

//Druid强大之处
@Configuration
public class DruidConfig {
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource druidDataSource(){
        return new DruidDataSource();
    }
    //后台监控
    @Bean
    public ServletRegistrationBean statViewServlet(){
        ServletRegistrationBean<StatViewServlet> bean = 
                new ServletRegistrationBean<>(new StatViewServlet(),"/druid/*");
        //后台需要登录，设置账户密码
        HashMap<String,String> initParameters = new HashMap<>();
        initParameters.put("loginUsername","admin");//key是固定
        initParameters.put("loginPassword","123456");
        //允许谁可以访问
        initParameters.put("allow","");
        //initParameters.put("lele","192.168.112.112") 禁止谁访问
        //设置初始化参数
        bean.setInitParameters(initParameters);
        return bean;
    }
    @Bean
    public FilterRegistrationBean webStatFilter(){
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.setFilter(new WebStatFilter());
        //可以过滤哪些请求
        HashMap<String,String> initParameters = new HashMap<>();
        //哪些可以不用过滤
        initParameters.put("exclusions","*.css,*.js,/druid/*");
        bean.setInitParameters(initParameters);
        return bean;
    }
}

3.整合Mybatis

0. 建表，实体类

use school
create table user(
    id int(10) auto_increment,
    name varchar(20) not null default '匿名',
    password varchar(20) not null default '123456',
    primary key (id)
)ENGINE=InnoDB default charset =utf8
​
insert into user(name) values("张三"),("李四"),("王五"),("赵六"),("田七"),("吴九")

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    Integer id;
    String name;
    String password;
}

1. 导入依赖mybatis-spring-boot-starter

 <dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.2.0</version>
</dependency>

2. 配置文件application.yml

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver

3. mybatis配置 写Mapper

@Mapper
@Repository
public interface UserMapper {
    List<User> queryAll();
}

4. 写mapper.xml,在resources/mybatis/mapper目录下

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//ibatis.apache.org//DTD Mapper 3.0//EN"
        "http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">
​
<mapper namespace="com.lele.mapper.UserMapper">
    <!--resultType: 返回类型,写别名，需要在配置文件配置别名     -->
    <select id="queryAll" resultType="User">
        SELECT * FROM user
    </select>
</mapper>

resultType: 返回类型,写别名，需要在配置文件配置别名application.yml

#整合mybatis
mybatis:
  type-aliases-package: com.lele.pojo
  mapper-locations: classpath:mybatis/mapper/*.xml

5. 业务层调用dao层

@RestController
public class UserController {
    @Autowired
    UserMapper userMapper;
     @RequestMapping("/list")
     public List<User> queryAll(){
        return userMapper.queryAll();
     }
}