Spring Boot系列笔记--数据访问

 
  
   
  
 一、JDBC 
 SpringBoot使用JDBC只需导入相应依赖<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
 
将sqlName.sql放入resources文件夹内，再在application.yml中配置必要属性，classpath:后没有空格spring:
  datasource:
    username: root
    password: password
    url: jdbc:mysql://ip address:3306/database
    driver-class-name: com.mysql.cj.jdbc.Driver
    # 需要执行的建表语句，
    schema:
      - calsspath:sqlName.sql
	#Spring Boot2.x 必须添加 initialization-mode配置才会执行建表语句
	initialization-mode: always
 
这样即可将DataSource默认数据源放入容器中
 
 二、整合Druid数据源 
 在application.yml中配置Druid数据源spring:
  datasource:
#   数据源基本配置
    username: root
    password: password
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://ip address:3306/database
    type: com.alibaba.druid.pool.DruidDataSource
#   数据源其他配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
#   配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙  
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true  
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500
 
需要写一个配置类package com.atguigu.springboot.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.sql.DataSource;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

@Configuration
public class DruidConfig {
      
      
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource druid(){
      
      
        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", "123");
        initParams.put("allow","");//默认就是允许所有访问
        initParams.put("deny","ip address");
        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;
    }
}
 
访问http://localhost:8080/druid/login.html会进入一个监控页面
 
 三、整合Mybatis 
 1. 使用注解配置相关类 
 创建数据库、表、JavaBean以及配置数据源相关属性
创建操作数据库的mapper类@Mapper
public interface DepartmentMapper {
      
      

    @Select("select * from department where id=#{id}")
    public Department getDeptById(Integer id);

    @Delete("delete from department where id=#{id}")
    public int deleteDeptById(Integer id);

    @Options(useGeneratedKeys = true,keyProperty = "id")
    @Insert("insert into department(departmentName) values(#{departmentName})")
    public int insertDept(Department department);

    @Update("update department set departmentName=#{departmentName} where id=#{id}")
    public int updateDept(Department department);
}
 
自定义Mybatis的配置规则@Configuration
public class MybatisConfig {
      
      

    @Bean
    public ConfigurationCustomizer customizer(){
      
      
        return new ConfigurationCustomizer() {
      
      
            @Override
            public void customize(org.apache.ibatis.session.Configuration configuration) {
      
      
            	//驼峰命名
                configuration.setMapUnderscoreToCamelCase(true);
            }
        };
    }
}
 
当mapper数量过多，配置@Mapper注解麻烦，使用@MapperScan批量扫描所有的Mapper接口@MapperScan(value = "com.atguigu.springboot.mapper")
@SpringBootApplication
public class SpringBoot06DataMybatisApplication {
      
      

	public static void main(String[] args) {
      
      
		SpringApplication.run(SpringBoot06DataMybatisApplication.class, args);
	}
}
 
 
 2. 使用配置文件 
 在application.yml中添加配置mybatis:
  config-location: classpath:mybatis/mybatis-config.xml #指定全局配置文件的位置
  mapper-locations: classpath:mybatis/mapper/*.xml  #指定sql映射文件的位置
 
SQL映射文件<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.atguigu.springboot.mapper.EmployeeMapper">
    <select id="getEmpById" resultType="com.atguigu.springboot.bean.Employee">
        select * from employee where id = #{id}
  </select>
</mapper>
 
全局配置文件<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
    	<!--驼峰命名-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>
 
 
 四、整合SpringData JPA 
 编写一个bean，和数据表进行映射//使用JPA注解配置映射关系
@Entity //告诉JPA这是一个实体类（和数据表映射的类）
@Table(name = "tbl_user") //@Table来指定和哪个数据表对应;如果省略默认表名就是user；
public class User {
      
      
    @Id //这是一个主键
    @GeneratedValue(strategy = GenerationType.IDENTITY)//自增主键
    private Integer id;
    @Column(name = "last_name",length = 50) //这是和数据表对应的一个列
    private String lastName;
    @Column //省略默认列名就是属性名
    private String email;
}    
 
编写一个Dao接口来操作实体类对应的数据表（Repository）//继承JpaRepository来完成对数据库的操作
public interface UserRepository extends JpaRepository<User,Integer> {
      
      
}
 
基本的配置JpaPropertiesspring:  
 jpa:
    hibernate:
#     更新或者创建数据表结构
      ddl-auto: update
#    控制台显示SQL
    show-sql: true
 
 
一、JDBC

二、整合Druid数据源

三、整合Mybatis

1. 使用注解配置相关类

2. 使用配置文件

四、整合SpringData JPA

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