SpringBoot(六) SpirngBoot与Mysql关系型数据库

pom.xml文件的配置

<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>

写配置文件

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

spring:
  datasource:
    username: root
    password: Welcome_1
    url: jdbc:mysql://192.168.179.131:3306/jdbc
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
#    schema:
#      - classpath:department.sql
server:
  port: 9000

自定义数据源DRUID

spring-boot-starter-jdbc 默认使用tomcat-jdbc数据源，如果你想使用其他的数据源，比如这里使用了阿里巴巴的数据池管理,你应该额外添加以下依赖：

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.0.19</version>
</dependency>

编写java测试链接代码

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
    //destroy-method="close"的作用是当数据库连接不使用的时候,就把该连接重新放到数据池中,方便下次使用调用.
    @Bean(destroyMethod =  "close")
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl(env.getProperty("spring.datasource.url"));
        dataSource.setUsername(env.getProperty("spring.datasource.username"));//用户名
        dataSource.setPassword(env.getProperty("spring.datasource.password"));//密码
        dataSource.setDriverClassName(env.getProperty("spring.datasource.driver-class-name"));
        dataSource.setInitialSize(2);//初始化时建立物理连接的个数
        dataSource.setMaxActive(20);//最大连接池数量
        dataSource.setMinIdle(0);//最小连接池数量
        dataSource.setMaxWait(60000);//获取连接时最大等待时间，单位毫秒。
        dataSource.setValidationQuery("SELECT 1");//用来检测连接是否有效的sql
        dataSource.setTestOnBorrow(false);//申请连接时执行validationQuery检测连接是否有效
        dataSource.setTestWhileIdle(true);//建议配置为true，不影响性能，并且保证安全性。
        dataSource.setPoolPreparedStatements(false);//是否缓存preparedStatement，也就是PSCache
        return dataSource;
    }
}

spring:
  datasource:
    username: root
    password: Welcome_1
    url: jdbc:mysql://192.168.179.131:3306/jdbc
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
    # 初始化大小，最小，最大  
    initialSize: 5
    minIdle: 5
    maxActive: 20
    # 配置获取连接等待超时的时间  
    maxWait: 60000
    # 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 
    timeBetweenEvictionRunsMillis: 60000
    # 配置一个连接在池中最小生存的时间，单位是毫秒 
    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,去掉监控界面sql无法统计，‘wall’用于防火墙
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    userGlobalDataSourceStat: true
    # 通过connectProperties属性来打开mergeSql功能；慢SQL记录  
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500
#    schema:
#      - classpath:department.sql
server:
  port: 9000

编写测试代码

@Repository
public class LearnDaoImpl  implements LearnDao{
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public int add(LearnResouce learnResouce) {
        return jdbcTemplate.update("insert into learn_resource(author, title,url) values(?, ?, ?)",learnResouce.getAuthor(),learnResouce.getTitle(),learnResouce.getUrl());
    }
    @Override
    public Page queryLearnResouceList(Map<String,Object> params) {
        StringBuffer sql =new StringBuffer();
        sql.append("select * from learn_resource where 1=1");
        if(!StringUtil.isNull((String)params.get("author"))){
            sql.append(" and author like '%").append((String)params.get("author")).append("%'");
        }
        if(!StringUtil.isNull((String)params.get("title"))){
            sql.append(" and title like '%").append((String)params.get("title")).append("%'");
        }
        Page page = new Page(sql.toString(), Integer.parseInt(params.get("page").toString()), Integer.parseInt(params.get("rows").toString()), jdbcTemplate);
        return page;
    }
}

@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
    @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");
        bean.setInitParameters(initParams);
        return bean;
    }
    //2、配置监控的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：localhost:8080/druid/login.html　　　　　　　　　　　　　　　　　

以上是使用JDBCTemptlate模板，可以参考API文档    JdbcTemplate

SpringBoot整合Mybatis

1.使用注解的方式

• 　导入依赖

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.9</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

• 导入配置文件中关于Druid的配置
• 创建数据表
• 创建数据库对应的JavaBean，以及getter和setter方法
• 在配置文件中修改驼峰命名开启 ,不写配置文件就写配置类

mybatis:
  configuration:
    map-underscore-to-camel-case: true

• 数据库中以下划线分割，而javabean中以驼峰命名。解决办法

public class MyBatisConfig {

    @Bean
    public ConfigurationCustomizer configurationCustomizer(){

        return new ConfigurationCustomizer() {
            @Override
            public void customize(Configuration configuration) {
                configuration.setMapUnderscoreToCamelCase(true);
            }
        };
    }
}

• 使用注解方式导入mapper

@MapperScan(value = "com.test.testMapper")

• 编写测试类（@component注解不添加也没事，只是不加service那边引入mapper的时候会有错误提示，也就是红线，但不影响程序的运行）

@Component
@Mapper
public interface DepartmentMapper {

    @Insert("insert into department(dept_name) value(#{deptName})")
    public int insertDept(Department department);

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

    @Update("update department set dept_Name=#{deptName} where id=#{id}")
    public int updateDept(Department department);

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

}

配置文件的方式整合Mybatis（xml方式）

• 新建mybatis的配置文件。

<?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>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

• 新建mapper接口及其方法。

public interface EmployeeMapper {

    public Employee getEmpById(Integer id);

    public void insetEmp(Employee employee);
}

• 新建Employee的mapper.xml的映射文件

<?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.wdjr.springboot.mapper.EmployeeMapper">
    <select id="getEmpById" resultType="com.wdjr.springboot.bean.Employee">
      select * from employee where id=#{id}
   </select>

    <insert id="insetEmp">
        INSERT  INTO employee(last_name,email,gender,d_id) VALUES (#{lastName},#{email},#{gender},#{dId})
    </insert>
</mapper>

• 修改application.yml配置文件

mybatis:
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/*.xml

• 编写controller类进行测试。更多的mybatis使用查询官方文档。mybatis官方中文参考文档

PageHelper分页插件

• 导入pom.xml

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper</artifactId>
    <version>x.x.x</version>
</dependency>

• 例子

//2. use static method startPage
PageHelper.startPage(1, 10);
List<Country> list = countryMapper.selectIf(1);

//3. use static method offsetPage
PageHelper.offsetPage(1, 10);
List<Country> list = countryMapper.selectIf(1);

//4. method parameters
public interface CountryMapper {
    List<Country> selectByPageNumSize(
            @Param("user") User user,
            @Param("pageNum") int pageNum, 
            @Param("pageSize") int pageSize);
}
//config supportMethodsArguments=true
List<Country> list = countryMapper.selectByPageNumSize(user, 1, 10);

分页插件PageHelper项目地址： https://github.com/pagehelper/Mybatis-PageHelper

具体使用实例：https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/en/HowToUse.md