Spring_xml方式开发

1. spring核心配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
    <!-- 读取占位符配置文件，和mybatis的一样  -->
    <context:property-placeholder location="classpath:db.properties" />
    
    <!-- apache的连接池依赖类，pom里配置引入commons-dbcp -->
    <!-- 这里需要占位符配置url、username、password -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${db.driver}" />
        <property name="url" value="${db.url}" />
        <property name="username" value="${db.username}" />
        <property name="password" value="${db.password}" />
    </bean>
    
    <!-- spring提供的jdbc template方便dao层编写，pom引入依赖spring-jdbc -->
    <!-- 这里需要注入上面生成好的数据库连接池dataSource -->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    
    <!-- 自己编写的持久层，内置一个叫template的属性（必须要有setter） -->
    <!-- 往属性template注入上面生成好的jdbcTemplate -->
    <bean id="userDao" class="dao.daoXmlImpl">
        <property name="template" ref="jdbcTemplate"></property>
    </bean>
    
    <!-- 自己编写的业务层，内置一个叫dao的属性（必须要有setter） -->
    <!-- 往属性dao注入上面生成好的userDao -->
    <bean id="userService" class="service.xmlImpl">
        <property name="dao" ref="userDao"></property>
    </bean>

</beans>

2.POJO类

public class User {
    private int id;

    private String username;

    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", address=" + address + "]";
    }

    private String address;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

3. dao类

public class daoXmlImpl implements userDao {

    private JdbcTemplate template;

    // 留一个dao的setter让Spring帮忙注入jdbcTemplate
    public void setTemplate(JdbcTemplate template) {
        this.template = template;
    }

    @Override
    public User getUserById(int id) {
        // 业务SQL
        String sql = "SELECT * FROM user WHERE id = ?";
        // 参数数组
        Object[] args = { id };
        // 使用jdbcTemplate来查询数据库
        return template.queryForObject(sql, args, new RowMapper<User>() {

            @Override
            public User mapRow(ResultSet rs, int rowNum) throws SQLException {
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("username"));
                user.setAddress(rs.getString("address"));
                return user;
            }
        });
    }
}

4.service类

public class xmlImpl implements userService{
    
    private userDao dao;

    // 留一个dao的setter让Spring帮忙注入userDao
    public void setDao(userDao dao) {
        this.dao = dao;
    }

    @Override
    public User findUser(int id) {
        return dao.getUserById(id);
    }
}

5.使用类（这里用servlet）

public class userView extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        // 获取参数
        String id = request.getParameter("id");
        
        // 获取Spring IOC容器
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

        // 通过Spring IOC容器获取 service bean
        userService service = context.getBean(userService.class);

        // 调用service的方法，获取user
        User user = service.findUser(Integer.parseInt(id));

        // 响应，打印user
        response.setContentType("application/json;charset=utf-8");
        response.getWriter().print(user);
    }
}