浅谈Spring之用纯注解方式整合Dbutils

要想使用纯注解开发，还需了解以下几个注解

1. @Configuration：相当于

   applicationContext.xml

   ，将此类作为xml配置文件
2. @ComponentScan：相当于

   <context:component-scan base-package=""/>

   开启包扫描
3. @PropertySource：相当于

   <context:property-placeholder location=""/>

   ,导入外部配置文件
4. @Bean：将第三方类（对象）交给ioc容器，让他去为需要的地方注入此对象
5. @Import：相当于

   <import resource=""/>

   引入另一个xml配置

Spring配置类

@Configuration // applicationContext.xml
@ComponentScan(value = "com.lepeng") // <context:component-scan base-package=""/>
@PropertySource("classpath:jdbc.properties")// <context:property-placeholder location=""/>
public class SpringConfig {

    @Value("${jdbc.driver}")
    private String driverClassName;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String username;
    @Value("${jdbc.password}")
    private String password;

    // 创建连接池（第三方对象）
    @Bean("dataSource")
    public DataSource dataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        druidDataSource.setDriverClassName(driverClassName);
        druidDataSource.setUrl(url);
        druidDataSource.setUsername(username);
        druidDataSource.setPassword(password);
        return druidDataSource;
    }

    // 创建queryRunner（第三方对象）
    @Bean("queryRunner")
    public QueryRunner queryRunner(DataSource dataSource) { //方法形参位置，会自动从ioc容器获取对象实例，完成注入
        QueryRunner queryRunner = new QueryRunner(dataSource);
        return queryRunner;
    }
}
           

这个类也就对应我们编写的xml配置文件：

<!--开启注解组件扫描-->
    <context:component-scan base-package="com.lepeng"/>

    <!--导入外部的properties配置文件-->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!--创建连接池-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driver}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>

    <!--创建queryRunner-->
    <bean id="queryRunner" class="org.apache.commons.dbutils.QueryRunner">
        <constructor-arg name="ds" ref="dataSource"></constructor-arg>
    </bean>
           

实体类

public class Account {
    private int id;
    private String name;
    private double money;
    //自动生成set和get方法  toString方法
}

           

dao层

@Repository
public class AccountDaoImpl implements AccountDao {

    //简单的jdbc封装对象，比mybatis框架更轻量级    //参数是连接池对象
    //QueryRunner queryRunner = new QueryRunner(DataSourceUtil.getDataSource());

    //声明一个操作数据库的CRUD对象
    @Autowired
    private QueryRunner queryRunner;

    public List<Account> findAll() throws SQLException {
        return queryRunner.query("SELECT * FROM account", new BeanListHandler<Account>(Account.class));
    }
}
           

service层

@Service
public class AccountServiceImpl implements AccountService {

    //声明dao对象
    @Autowired
    private AccountDao accountDao;

    public List<Account> findAll() throws SQLException {
        return accountDao.findAll();
    }
}
           

测试类

public class AccountTest {

    @Test
    public void test01() throws Exception {
        // 加载配置文件，初始化spring环境（ioc容器）
        // ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        ApplicationContext app = new AnnotationConfigApplicationContext(SpringConfig.class);

        // 获得指定类型对象实例
        AccountService accountService = app.getBean(AccountService.class);
        // 测试
        List<Account> list = accountService.findAll();
        for (Account account : list) {
            System.out.println(account);
        }
    }
}