Spring访问数据层——jdbctemplate

项目结构

从入口TestCustomerService开始

public class TestCustomerService {

    @Test
    public void testDemo() {
        ApplicationContext context = 
                new ClassPathXmlApplicationContext("Spring-JdbcTemplate.xml");
        CustomerService service = (CustomerService) context.getBean("CustomerService");
//      service.insert(new Customer(5,"fuck",20));
        Customer findCustomer = service.findByCustomerId(4);

        System.out.println(findCustomer.getId());
        System.out.println(findCustomer.getName());
        System.out.println(findCustomer.getAge());

    }

}

Spring的核心配置文件

<?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:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"> 

    <!--配置c3p0连接池  -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
     <!-- 注入属性值 -->
     <property name="driverClass" value="com.mysql.jdbc.Driver" ></property>
     <property name="jdbcUrl" value="jdbc:mysql:///spring_jdbc"></property>
     <property name="user" value="root"></property>
     <property name="password" value="shengri"></property>
     </bean>

      <!-- 创建Jdbctemplate对象 -->
     <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
     <!-- 把dataSource传递到jdbctemplate中 -->
        <property name="dataSource" ref="dataSource"></property>
     </bean>


     <bean id="CustomerDao" class="dao.JdbcTemplateCustomerDao">
     <!-- 注入jdbctemplate对象 -->
            <property name="jdbcTemplate" ref="jdbcTemplate">
            </property>
     </bean>

     <bean id="CustomerService" class="Service.CustomerService">
            <property name="CustomerDao" ref="CustomerDao">
            </property>
     </bean>

</beans> 

比较简单，就是各种属性的注入，c3p0连接池需要学习，另外注解方式！？需要实现

CustomerService业务层

public class CustomerService {
    private CustomerDao customerDao;

    public void setCustomerDao(CustomerDao customerDao) {
        this.customerDao = customerDao;
    }

    public void insert(Customer customer) {
        customerDao.insert(customer);
        System.out.println("Insert done");
    }

    public Customer findByCustomerId(int custId) {
        return customerDao.findByCustomerId(custId);
    } 

}

这里不涉及对于Dao层的代码，全是核心代码，即插入，寻找

CustomerDao层

• 接口

public interface CustomerDao {
    public void insert(Customer customer);
    public Customer findByCustomerId(int custId);
}

• 实现

public class JdbcTemplateCustomerDao implements CustomerDao {

    private JdbcTemplate jdbcTemplate;

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    @Override
    public void insert(Customer customer) {
        String sql = "insert into CUSTOMER (CUST_ID, NAME, AGE) values(?,?,?)";
        jdbcTemplate.update(sql,customer.getId(),customer.getName(),customer.getAge());


    }

    @Override
    public Customer findByCustomerId(int custId) {
        String sql = "SELECT * FROM CUSTOMER WHERE CUST_ID = ?";
        Customer customer = jdbcTemplate.queryForObject(sql, new MyRowMapper(), custId);

        return customer;
    }

}

从这里可以看出jdbctemplate和JDBC的表面上的区别，即对于sql的封装预编译有所不同，Jdbctemplate更加简洁，此处还需深究

工具类

import java.sql.ResultSet;
import java.sql.SQLException;
public class MyRowMapper implements RowMapper<Customer> {

    @Override
    public Customer mapRow(ResultSet rs, int arg1) throws SQLException {
        int CustId = rs.getInt("CUST_ID"); 
        String Name= rs.getString("NAME"); 
        int Age = rs.getInt("AGE");

        Customer customer = new Customer(CustId,Name,Age);

        return customer;
    }

}

关于这个工具类也需要深究，还有结果集的问题
印象中hibernate不需要这一步，即对于对象的封装这一步也用hibernate帮我们完成，这一步就是hibernate 持久层（即hibernate会探知对象的变化）？？？这部分也需要在思考~

问题：部署在JUNIT是可以的
但是部署在TOMCAT上面就会报错

警告: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property ‘source’ to ‘org.eclipse.jst.jee.server:spring_jdbctemplate’ did not find a matching property.

查了许多资料，觉得这篇文章比较靠谱，意思就是
tomcat服务器启动，当其加载一个web应用时，会先去eclipse的workspace下的Servers工程下的server.xml文件寻找元素，再查找conf\Catalina\localhost下的.xml文件的元素，那么就会因为出现重复的Context元素而报警告。但是他的解决方法依旧没有解决这个问题。未完待续