Spring IOC 註解式配置實戰筆記

專案目標

從零構建「用戶註冊登入」專案，逐步整合 Spring IOC、MyBatis、SpringMVC、事務、緩存、Security 等核心技術棧。本篇聚焦純 Java 配置（零 XML）的 IOC 容器啟動與組件掃描策略。

環境準備

Maven 核心依賴

<properties>
    <spring.version>4.3.1.RELEASE</spring.version>
</properties>

<dependencies>
    <!-- Spring Core -->
    <dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${spring.version}</version></dependency>
    <dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>${spring.version}</version></dependency>
    <dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>${spring.version}</version></dependency>
    <dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>${spring.version}</version></dependency>
    
    <!-- MyBatis -->
    <dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.4.1</version></dependency>
    <dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>1.3.0</version></dependency>
    
    <!-- DB -->
    <dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>6.0.3</version></dependency>
    <dependency><groupId>c3p0</groupId><artifactId>c3p0</artifactId><version>0.9.1.2</version></dependency>
    
    <!-- Validation -->
    <dependency><groupId>javax.validation</groupId><artifactId>validation-api</artifactId><version>1.1.0.Final</version></dependency>
    <dependency><groupId>org.hibernate</groupId><artifactId>hibernate-validator</artifactId><version>5.2.4.Final</version></dependency>
</dependencies>

核心配置類

1. 根容器配置

@Configuration
@ComponentScan(
    basePackages = "com.everSeeker",
    excludeFilters = @ComponentScan.Filter(
        type = FilterType.CUSTOM, 
        value = RootConfig.WebPackage.class  // 排除 Web 層組件
    )
)
@ImportResource("classpath:spring-mybatis.xml")  // 保留 MyBatis XML 配置
public class RootConfig {
    
    // 自定義過濾器：排除 com.everSeeker.web 包
    public static class WebPackage extends RegexPatternTypeFilter {
        public WebPackage() {
            super(Pattern.compile("com\\.everSeeker\\.web"));
        }
    }
}

2. Web 容器配置

@Configuration
@EnableWebMvc
@ComponentScan("com.everSeeker.web")
public class WebConfig implements WebMvcConfigurer {
    
    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");
        resolver.setExposeContextBeansAsAttributes(true);
        return resolver;
    }
    
    @Bean
    public MultipartResolver multipartResolver() throws IOException {
        return new StandardServletMultipartResolver();  // Servlet 3.0+ 標準上傳解析
    }
    
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();  // 靜態資源由預設 Servlet 處理
    }
}

3. Servlet 容器初始化器

public class WebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{RootConfig.class};  // 根容器：Service、DAO、DataSource
    }
    
    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{WebConfig.class};   // Web 容器：Controller、ViewResolver
    }
    
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};  // DispatcherServlet 映射根路徑
    }
    
    @Override
    protected void customizeRegistration(Dynamic registration) {
        // 檔案上傳限制：單檔 2MB、總請求 4MB、臨時目錄 /tmp/uploads
        registration.setMultipartConfig(new MultipartConfigElement(
            "/tmp/uploads", 2_097_152, 4_194_304, 0));
    }
}

MyBatis 整合

保留 spring-mybatis.xml 統一管理 DataSource、SqlSessionFactory、Mapper 掃描、事務管理器，避免 Java 配置過於冗長。

關鍵 XML 片段

<context:property-placeholder location="classpath:db.properties"/>

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
    <property name="driverClass" value="${db.mysql.driverClass}"/>
    <property name="jdbcUrl" value="${db.mysql.jdbcUrl}"/>
    <property name="user" value="${db.mysql.user}"/>
    <property name="password" value="${db.mysql.password}"/>
    <!-- 連線池參數略 -->
</bean>

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="configLocation" value="classpath:mybatis.xml"/>
    <property name="mapperLocations" value="classpath*:mapper/*Mapper.xml"/>
</bean>

<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.everSeeker.dao"/>
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
</bean>

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
</bean>

<tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true"/>

實體與 DAO 範例

// User.java
public class User {
    @Size(min=32, max=32) private String id;
    @Size(min=1, max=32) private String username;
    @NotEmpty @Size(max=32) private String password;
    @NotEmpty @Email private String email;
    @Size(min=11, max=11) private String cellphone;
    private long regDate;
    // 建構子、Getter/Setter、toString 略
}

// UserDao.java
@Repository
public interface UserDao {
    void addUser(User user);
    User getUserByUsername(String username);
}

// UserMapper.xml
<mapper namespace="com.everSeeker.dao.UserDao">
    <insert id="addUser" parameterType="User">
        INSERT INTO user(id, username, password, email, cellphone, regDate)
        VALUES(#{id}, #{username}, #{password}, #{email}, #{cellphone}, #{regDate})
    </insert>
    <select id="getUserByUsername" resultType="User">
        SELECT * FROM user WHERE username=#{username}
    </select>
</mapper>

關鍵註解對照表

總結

純 Java 配置優勢：類型安全、IDE 重構友善、條件化裝配靈活（@Conditional）。實務中常採「Java 配置核心基礎設施 + XML 配置持久層」混合策略，兼顧可維護性與 MyBatis 的 XML 映射優勢。