springboot整合多数据源(一)

首先整合springboot+jap（为例）

新建工程springbootdata引入所需的pom依赖

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.2.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

java/resources目录下新建application.properties文件配置数据源

spring.datasource.url=jdbc:mysql://localhost:3306/my-first
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

然后新建对应的实体类entity

package com.lwq.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity(name = "users")
public class User {
    @Id
    @GeneratedValue
    private Integer id;
    @Column
    private String name;
    @Column
    private Integer age;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    
}

新建dao

package com.lwq.dao;

import org.springframework.data.jpa.repository.JpaRepository;

import com.lwq.entity.User;

public interface UserDao extends JpaRepository<User, Integer> {
}

本文省略service
创建启动类

package com.lwq;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@ComponentScan(basePackages = { "com.lwq" })
@EnableJpaRepositories(basePackages = "com.lwq.dao")
@EnableAutoConfiguration
@EntityScan(basePackages = "com.lwq.entity")
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }

}

创建访问类

package com.lwq.controller;

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

import com.lwq.dao.UserDao;
import com.lwq.entity.User;

@RestController
public class TestController {

    @Autowired
    private UserDao userDao;
    
    @RequestMapping("/index")
    public String index(Integer id) {
        User findUser = userDao.findOne(id);
        System.out.println(findUser.getName());
        return "success";
    } 
}

启动项目访问即刻
注意:启动项目如果报错java.math.BigInteger cannot be cast to java.lang.Long问题，原因如下：
在连接数据库进行查询数据时，大家可能会遇见这样一个问题：java.math.BigInteger cannot be cast to ``java.lang.Long，然后去检查代码中的类型为Long，接着检查数据表中字段的类型为bigint，按道理类型是匹``配的啊，那么问题到底出现在哪儿呢？

如果出现以上问题，大家就应该注意了，是不是数据库版本与mysql-connector.jar包的版本不兼容造成的。本人用的是Mysql8.0.12免安装版本，出现问题时的jar包版本为5.1.26，更换为5.1.47后解决了该问题。希望能够帮助到遇到这类问题的朋友。
到此，整合JPA完毕。