springboot访问数据

springboot数据访问

jdbc 访问

1.添加数据访问依赖包。

2.添加配置：

spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.url=jdbc:mysql://192.168.85.132:3306/book
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

默认使用org.apache.tomcat.jdbc.pool.DataSource作为数据源

自定义数据源配置：

spring.datasource.initialSize=5
spring.datasource.maxWait=20

@Configuration
public class MyDruidConfig {
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DruidDataSource druid(){
        return new DruidDataSource();
    }
}

配置数据源监控：

package com.tree.springbootspringdata.config;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.ServletRegistration;
import javax.sql.DataSource;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

@Configuration
public class MyDruidConfig {
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DruidDataSource druid(){
        return new DruidDataSource();
    }

    //配置druid监控
    //1. 配置一个管理后台servle
    @Bean
    public ServletRegistrationBean staViewServlet(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
        Map<String,String> initParam =new HashMap<String,String>();
        initParam.put("loginUsername","admin");
        initParam.put("loginPassword","123456");
        initParam.put("allow",""); //默认是允许所有访问
        initParam.put("deny","192.168.85.44");

        servletRegistrationBean.setInitParameters(initParam);
        return servletRegistrationBean;
    }
    //2. 配置一个监控filtre
    @Bean
    public FilterRegistrationBean webStatFilter(){
        FilterRegistrationBean filterRegistrationBean=new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new WebStatFilter());
        Map<String,String> initParam =new HashMap<String,String>();
        initParam.put("exclusions","*.js,*.css,/druid/*");

        filterRegistrationBean.setInitParameters(initParam);
        filterRegistrationBean.setUrlPatterns(Arrays.asList("/*"));
        return filterRegistrationBean;
    }
}

:http://localhost:8080/book/druid/index.html 监控数据源

使用mybatis访问数据

配置：mybatis.xml xxxMapper.xml

mybatis.config-location=classpath:mybatis/mybatis-config.xml
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
添加映射文件

使用dao层接时，记得加上@Mapper 注解或者在spingboot启动类上加@MapperScan

使用JPA访问数据即spring data

JPA：ORM（对象关系映射）

@Entity //放置在实体类上，用来告诉Jpa这是一个实体类(和数据表映射的类)

@Table(name=“tb_user”) //指定和和哪个数据表对应，可以忽略参数，如果省略，默认表明就是类名

@Id // 这是主键

@GeneratedValue(strategy=GenerationType.IDENTITY) //自增主键

@Cloumn(name=“lastName”,length=50) // 和表对应的一个属性

如果省略，则列明就会是属性名

编写一个Dao接口来操作实体类对应的数据表(Repository)

//用于继承JpaRepository来操作数据库
public interface UserRepository extend JpaRepository<User,Integer>(){}

spring:
	jpa:
	  hibernate：
	  	ddl-auto: update # 更新或者创建数据表
	  	show-sql: true   # 控制台显示sql