Spring ioc 完全注解

基于注解、配置类方式整合三层架构组件

三层架构案例，模拟查询全部学生（学生表）信息

数据库准备

sql 复制代码

create database studb;

use studb;

CREATE TABLE students (
  id INT PRIMARY KEY,
  name VARCHAR(50) NOT NULL,
  gender VARCHAR(10) NOT NULL,
  age INT,
  class VARCHAR(50)
);

INSERT INTO students (id, name, gender, age, class)
VALUES
  (1, '张三', '男', 20, '高中一班'),
  (2, '李四', '男', 19, '高中二班'),
  (3, '王五', '女', 18, '高中一班'),
  (4, '赵六', '女', 20, '高中三班'),
  (5, '刘七', '男', 19, '高中二班'),
  (6, '陈八', '女', 18, '高中一班'),
  (7, '杨九', '男', 20, '高中三班'),
  (8, '吴十', '男', 19, '高中二班');

项目创建

项目的目录文件夹

Maven 依赖导入

xml 复制代码

<!-- pom.xml -->
<dependencies>
      <!--spring context依赖-->
      <!--当你引入 SpringContext 依赖之后，表示将 Spring 的基础依赖引入了-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context</artifactId>
          <version>6.0.6</version>
      </dependency>
      <!-- 数据库驱动和连接池-->
      <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>8.0.25</version>
      </dependency>
      <dependency>
          <groupId>com.alibaba</groupId>
          <artifactId>druid</artifactId>
          <version>1.2.8</version>
      </dependency>
      <dependency>
            <groupId>jakarta.annotation</groupId>
            <artifactId>jakarta.annotation-api</artifactId>
            <version>2.1.1</version>
       </dependency>
      <!-- spring-jdbc -->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-jdbc</artifactId>
          <version>6.0.6</version>
      </dependency>
</dependencies>

写完依赖后需要刷新

右侧 Maven 面板
点击 Sync Project
下载依赖

配置 JDBCProperties 数据库连接信息

在 resources 下创建 jdbc.properties 文件

properties 复制代码

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/studb?useSSL=false&serverTimezone=UTC&characterEncoding=utf8
jdbc.username=root
jdbc.password=XXX

配置项	作用
jdbc.driver	数据库驱动类
jdbc.url	数据库连接地址
jdbc.username	数据库用户名
jdbc.password	数据库密码

实体类准备

java 复制代码

package com.study.java;

public class Student {
    private Integer id;
    private String name;
    private String gender;
    private Integer age;
    private String classes;

    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public String getClasses() {
        return classes;
    }
    public void setClasses(String classes) {
        this.classes = classes;
    }
    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", age=" + age +
                ", classes='" + classes + '\'' +
                '}';
    }
}

三层架构搭建和实现

Controller

java 复制代码

@Controller
public class StudentController {
    @Autowired
    private StudentService studentService; // 注入 service

    public void  findAll(){
        List<Student> studentList =  studentService.findAll();
        System.out.println("studentList = " + studentList);
    }
}

Service

java 复制代码

// StudentService 接口
public interface StudentService {
    /**
     * 查询全部学员业务
     * @return
     */
    List<Student> findAll();
}

java 复制代码

// 实现类 StudentServiceImpl
@Service
public class StudentServiceImpl  implements StudentService {
    @Autowired
    private StudentDao studentDao;
    /**
     * 查询全部学员业务
     * @return
     */
    @Override
    public List<Student> findAll() {
        List<Student> studentList =  studentDao.queryAll();
        return studentList;
    }
}

java 复制代码

// 接口
public interface StudentDao {
    /**
     * 查询全部学生数据
     * @return
     */
    List<Student> queryAll();
}

java 复制代码

// 实现类
@Repository
public class StudentDaoImpl implements StudentDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    /**
     * 查询全部学生数据
     * @return
     */
    @Override
    public List<Student> queryAll() {
        String sql = "select id , name , age , gender , class as classes from students ;";
        /*
          query可以返回集合!
          BeanPropertyRowMapper就是封装好RowMapper的实现,要求属性名和列名相同即可
         */
        List<Student> studentList = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Student.class));
        return studentList;
    }
}

三层架构 IOC 配置类

上述操作配置好了类的结构吗，现在需要做 IOC 配置，否则上面声明的类没办法加入到 IOC 容器中。

java 复制代码

// IOC 配置类
@Configuration // 配置类，规定要加这个
@ComponentScan(basePackages = "com.study.java") // 扫描包，将包里面的内容加到 IOC
@PropertySource("classpath:jdbc.properties") // 引入外部配置文件
public class JavaConfig {
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.driver}")
    private String driver;
    @Value("${jdbc.username}")
    private String username;
    @Value("${jdbc.password}")
    private String password;

    @Bean(destroyMethod = "close")
    public DruidDataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl(url);
        dataSource.setDriverClassName(driver);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return dataSource;
    }

    @Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
    @Bean
    public JdbcTemplate jdbcTemplate(DataSource dataSource) {
        JdbcTemplate jdbcTemplate = new JdbcTemplate();
        jdbcTemplate.setDataSource(dataSource);
        return jdbcTemplate;
    }
}

测试

java 复制代码

// 测试类
public class SpringIocTest {
    @Test
    public void test () {
        // 创建 IOC 容器
        AnnotationConfigApplicationContext applicationContext =
                new AnnotationConfigApplicationContext(JavaConfig.class);
        StudentController studentController = applicationContext.getBean(StudentController.class);
        // 调用 Controller 的方法，模拟调用接口
        studentController.findAll();
    }
}

注意如果 @Test 没有生效，则需要安装 junit

xml 复制代码

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13.2</version>
    <scope>test</scope>
</dependency>