spring boot整合mybatis使用c3p0数据源连接mysql

刚刚接触springboot，对很多东西都不熟悉，例如，它的注解方式，他的配置方式等；听说它很牛逼，所以就尝试着去学习。在基本熟悉springboot的第一个程序之后。想到当时spring整合mybatis时使用了数据源连接数据库，所以自己也想尝试使用c3p0连接数据库。所以就有了以下的内容：

首先第一步，创建maven项目导入包：

pom.xml

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.1.RELEASE</version>
</parent>

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

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<version>1.4.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>1.4.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.33</version>
</dependency>
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
</dependency>
</dependencies>

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

应用服务类

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan(value="com.myk.spring.t3")//扫描mapper包
@EnableAutoConfiguration//自动载入应用程序所需的所有Bean，当使用Exclude这个属性时，是禁止自动配置某个类
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}

配置文件内容（配置数据库）

datasource:
url: jdbc:mysql://ip:port/databaseName
driver-class: com.mysql.jdbc.Driver
username: ***
password: ***

准备无误，尝试启用应用服务，没有报错即可继续

配置数据源，尝试很多方法，自己注入是不可能的，所以，我就想到spring的配置，尝试按照那样的方式去配置，所以，

DataSourceConfig.java

import javax.sql.DataSource;

import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import com.mchange.v2.c3p0.ComboPooledDataSource;

@Configuration
public class DataSourceConfig {

@Bean(name="dataSource")
@Qualifier(value="dataSource")//限定描述符除了能根据名字进行注入，但能进行更细粒度的控制如何选择候选者
@Primary//用@Primary区分主数据源
@ConfigurationProperties(prefix="c3p0.primary")//指定配置文件中，前缀为c3p0的属性值
public DataSource dataSource(){
return DataSourceBuilder.create().type(ComboPooledDataSource.class).build();//创建数据源
}
/**
*返回sqlSessionFactory
*/
@Bean
public SqlSessionFactoryBean sqlSessionFactoryBean(){
SqlSessionFactoryBean sqlSessionFactory = new SqlSessionFactoryBean();
sqlSessionFactory.setDataSource(dataSource());
return sqlSessionFactory;
}
}

也许会有疑问，为什么这里只需要一个sqlSessionFactory，这个具体要去熟悉spring整合mybatis。还有看看底层就明白了

这样就可以自动装配了。

数据源都准备好了，尝试连接数据库吧

编辑接口

ExamPleMapper.java

import java.util.List;

public interface ExamPleMapper {
public List<Users> getUsers();
}

编辑Mapper xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.*.ExamPleMapper">
<select id="getUsers" resultType="com.*.Users">
select * from users
</select>
</mapper>

编辑实体类，因为要将结果反射到bean类中

Users.java

public class Users {
private int userid;
private String username;

@Override
public String toString() {
return "Users [userid=" + userid + ", username=" + username + "]";
}

public int getUserid() {
return userid;
}

public void setUserid(int userid) {
this.userid = userid;
}

public String getUsername() {
return username;
}

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

public Users(int userid, String username) {
super();
this.userid = userid;
this.username = username;
}

public Users() {
super();
// TODO Auto-generated constructor stub
}

}

编辑实现

Example2.java

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping(value="/example2")//映射
public class Example2 {
@Autowired
public ExamPleMapper examPleMapper;

@ResponseBody
@RequestMapping(value="/gu")
public List<Users> getUsers(){
return examPleMapper.getUsers();
}
}

输入地址：http://localhost:8080/example2/gu

页面显示结果：

[{“userid”:1,”username”:”as”},{“userid”:2,”username”:”we”},{“userid”:3,”username”:”zx”}]