Spring4.x学习笔记——JdbcTemplate基础操作

一、相关概念

spring是一个一站式的框架，对不同持久层的技术都进行了封装（处理数据库技术，基本的crud操作即增删改查），如JDBC、Hibermate、MaBatis、JPA等。

二、spring对JDBC的封装使用步骤大体如下：

• 导入jar包 spring-jdbc、spring-tx
• 创建DriveManagerDataSource对象，对数据库进行配置
  
  • className
  • url
  • username
  • password
• 创建JdbcTemplate对象
  
  • 注入dataSource对象
• 调用JdbcTemplate封装的方法进行sql操作
  
  • update(String sql , Object…arr) //增删改
  • queryForObject(String sql , RowMapper rowMapper , Object…arr); //查询，单个值或对象
  • query(String sql , RowMapper rowMapper , Object…arr); //查询 ，list
  • 查询方法的形参需要一个实现RowMapper接口的类，对数据进行封装，详见以下实例

三、利用spring的jdbcTemplate实现简单的sql操作实例

1、创建工程，引入相关jar包

2、创建spring配置文件并写必要约束

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

3、建表、配置数据库及jdbcTemplate

• 创建一个简单的book表
  
• 创建DataSource.properties

#DataSource.properities

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/spring_jdbc_template_test?characterEncoding=UTF-8&useOldAliasMetadataBehavior=true
username=root
password=123456

• spring配置：

<!-- 扫描包下的所有注解 -->
    <context:component-scan base-package="com.jdbctemplate.book"></context:component-scan>

    <context:property-placeholder location="resource/DataSource.properties"></context:property-placeholder>
    <!-- 创建DataSource对象 -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driverClassName}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>
    <!-- 创建JdbcTemplate对象 -->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <constructor-arg name="dataSource" ref="dataSource"></constructor-arg>
    </bean>

4、创建Book实例类，保存从数据库取出的数据

public class Book {
    private String name;
    private float prive;
    public Book() {
        super();
    }
    public Book(String name, float prive) {
        super();
        this.name = name;
        this.prive = prive;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public float getPrive() {
        return prive;
    }
    public void setPrive(float prive) {
        this.prive = prive;
    }

    @Override
    public String toString() {
        return "Book [name=" + name + ", prive=" + prive +  "]";
    }
}

4、写dao层接口

public interface BookDao {
    /**
     * 添加图书
     * @param name
     * @param price
     * @return
     */
    public int addBook(String name , float price);
    /**
     * 删除图书
     * @param name
     * @return
     */
    public int delBook(String name);
    /**
     * 修改价格
     * @param name
     * @param price
     * @return
     */
    public int updateBook(String name,float price);
    /**
     * 返回所有Book信息
     * @return
     */
    public List<Book> getAllBook();
    /**
     * 返回指定书名的图书信息
     * @param name
     * @return
     */
    public Book getBook(String name);
    /**
     * 返回指定书名的价格
     * @param name
     * @return
     */
    public float getPrice(String name);
}

5、写BookDao的实现类，并配置

public class BookDaoImpl implements BookDao{
    // jdbc模板
    @Resource(name="jdbcTemplate")
    private  JdbcTemplate jdbcTemplate;
    public int addBook(String name, float price) {
        return jdbcTemplate.update("insert into book value(?,?)",name,price);
    }

    public int delBook(String name) {
        return jdbcTemplate.update("delete from book where name=?",name);
    }

    public int updateBook(String name, float price) {
        return jdbcTemplate.update("update book set price=? where name=?",price,name);
    }

    public List<Book> getAllBook() {
        return jdbcTemplate.query("select * from book", new BookRowMapper());
    }

    public Book getBook(String name) {
        return jdbcTemplate.queryForObject("select * from book where name=?", new BookRowMapper(),name);
    }

    public float getPrice(String name) {
        return jdbcTemplate.queryForObject("select price from book where name=?", Float.class);
    }

    private class BookRowMapper implements RowMapper<Book>{
        @Override
        public Book mapRow(ResultSet re, int arg1) throws SQLException {
            return new Book(re.getString("name"),re.getShort("price"));
        }

    }
}

<bean id="bookDaoImpl" class="com.jdbctemplate.book.dao.impl.BookDaoImpl"></bean>

6、写BookService类

public class BookService {
    @Resource(name="bookDaoImpl")
    private BookDaoImpl bookDaoImpl;
    public List<Book> getAll() {
        return bookDaoImpl.getAllBook();
    }
    public Book get(String name) {
        return bookDaoImpl.getBook(name);
    }
    public float getPrice(String name) {
        return bookDaoImpl.getPrice(name);
    }
    public int add(String name,float price) {
        return bookDaoImpl.addBook(name, price);
    }
    public int delet(String name) {
        return bookDaoImpl.delBook(name);
    }
}

    <!-- 创建BookService对象 -->
    <bean id="bookService" class="com.jdbctemplate.book.service.BookService"></bean>

7、写测试类

public class Test {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("resource/spring.xml");
        BookService bookService = (BookService) context.getBean("bookService");
        bookService.add("数学", 23.5F);
        bookService.add("语文", 20.5F);
        System.out.println(bookService.getAll());
    }
}

四、在过程中@Resource无法使用解决

在过程中注解@Resource无法使用，import javax.annotation.Resource;也一直红线无法引入，改变JDK版本后奇怪的就好了，但项目中没有错误，项目上总有个红叉。解决：右键项目–properties–project Facets–java对于的版本改统一即可