使用Spring连接MySql数据库

一、首先安装Mysql数据库，之后，创建数据库及表：

安装之后，输入mysql -u root -p，之后再输入对应的密码，打开mysql的控制台；
创建数据库mydb，create database mydb;
切换到mydb数据库下，use mydb；
创建数据表user， create table user (id int auto_increment, name varchar(20), primary key(id));
使用show tables查看是否创建成功。

二、创建Maven项目：

New Project，选择Maven，一路next即可创建；

在pom.xml中加入需要的jar包：

<dependencies>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.38</version>
    </dependency>

    <dependency>
        <groupId>commons-pool</groupId>
        <artifactId>commons-pool</artifactId>
        <version>1.6</version>
    </dependency>

    <dependency>
        <groupId>commons-dbcp</groupId>
        <artifactId>commons-dbcp</artifactId>
        <version>1.4</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.2.6.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>4.2.6.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>4.2.6.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>

</dependencies>

在resources文件夹下创建一个beans.xml文件（这个文件夹的是资源文件）；

打开Spring的说明文档，点击打开链接，找到The IoC container一节中的Container Overview小节，点开Configuration metadata，复制一份，拷贝到beans.xml中：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd">

  <bean id="..." class="...">
    <!-- collaborators and configuration for this bean go here -->
  </bean>

  <bean id="..." class="...">
    <!-- collaborators and configuration for this bean go here -->
  </bean>

  <!-- more bean definitions go here -->

</beans>

打开Spring的说明文档，点击打开链接，还是在The IoC container一节中的Container Overview小节下，找到Annotation-based container configuration小节，复制其xml头，添加以下绿色部分，添加context标签：

<?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">

   <context:annotation-config/>

</beans>

找到Spring说明文档的The IoC container一节中的Container Overview下，Dependencies小节，点击打开Dependencies and configuration in detail，可以看到mysql的配置方式，将其拷贝到beans.xml中：

<bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

<!-- results in a setDriverClassName(String) call -->
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mydb"/>
<property name="username" value="root"/>
<property name="password" value="masterkaoli"/>
</bean>

在src/main/java文件夹下创建today包，在today包下创建dao、impl和model文件夹，在dao文件夹下创建接口UserDAO：
```
package today.dao;

import today.model.User;

public interface UserDAO {
    public void save(User user);
}
```

在impl创建类UserDaoImpl：

package today.impl;

import org.springframework.stereotype.Component;
import today.dao.UserDAO;
import today.model.User;

import javax.annotation.Resource;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

@Component
public class UserDaoImpl implements UserDAO {
    private DataSource dataSource;

    //使用接口save来保存user的数据
    public void save(User user) {
        Connection connection = null;
        try {
            connection = dataSource.getConnection();
            connection.createStatement().executeUpdate(
                    "insert into user values("+ user.getId()
                            +",'"+ user.getUsername() +"')");
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public DataSource getDataSource() {
        return dataSource;
    }

    //使用setter注入myDataSource
    @Resource(name = "myDataSource")
    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }
}

在model创建类User：

package today.model;

public class User{
    private int id;
    private String username;

    public User(int id, String username) {
        this.id = id;
        this.username = username;
    }

    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;
    }
}

运行结果

使用Spring连接MySql数据库

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