如何使用 SpringBoot 使用 Spring Data JPA 和 MYSQas DB 创建一个简单的 CRUD 应用程序？

Question

我正在尝试使用 Spring Boot 版本 1.4.4 创建一个简单的虚拟应用程序。 这是我的pom.xml 的样子：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.bootstrap</groupId>
<artifactId>bootstrap</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>tsqln</name>
<description>Demo project for Spring Boot</description>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.4.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

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

我的应用程序类看起来像：

package com.bootstrap;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class TsqlnApplication {

    public static void main(String[] args) {
        SpringApplication.run(TsqlnApplication.class, args);
    }
}

我的 application.properties 看起来像：

spring.jpa.hibernate.ddl-auto=create
spring.datasource.url=jdbc:mysql://localhost:3306/lostandfound
spring.datasource.username=root
spring.datasource.password=root

但是当我运行应用程序时，我收到以下错误说明：

*****************************
APPLICATION FAILED TO START
***************************
Description:
Parameter 0 of constructor in org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration required a bean of type 'javax.sql.DataSource' that could not be found.
    - Bean method 'dataSource' not loaded because @ConditionalOnClass did not find required class 'org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType'
    - Bean method 'dataSource' not loaded because @ConditionalOnClass did not find required class 'org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType'
Action:
Consider revisiting the conditions above or defining a bean of type 'javax.sql.DataSource' in your configuration.
2017-01-29 17:32:44.645 ERROR 4316 --- [           main] o.s.test.context.TestContextManager      : Caught exception while allowing TestExecutionListener [org.springframework.test.context.web.ServletTestExecutionListener@516be40f] to prepare test instance [com.bootstrap.TsqlnApplicationTests@9573b3b]**

我的项目目录结构是：

但是，上面的应用程序使用相同的方法与 SpringBoot 版本 1.3 一起工作。有什么建议可以让它与 1.4.4 版一起使用吗？

Answer 1

在你的 application.properties 添加这一行

spring.datasource.url = jdbc:mysql://localhost:3306/yourdatabase
# Username and password
spring.datasource.username = root
spring.datasource.password = 
# Show or not log for each sql query
spring.jpa.show-sql = true
spring.jpa.hibernate.ddl-auto = create
# Naming strategy
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy
# Allows Hibernate to generate SQL optimized for a particular DBMS
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

Answer 2

确保您的 mysql-connector 在运行时确实存在于类路径中（如果您使用的是 Tomcat，那么它应该在 lib 文件夹中）。

如果你没有它，在你的 pom.xml 中添加一个编译依赖

<dependency>
 <groupId>mysql</groupId>
 <artifactId>mysql-connector-java</artifactId>
 <version>5.1.36</version>
</dependency>

另外你在application.properties 中忘记了这一行：

spring.datasource.driver-class-name=com.mysql.jdbc.Driver

Answer 3

您可以通过创建自己的数据源 bean 来恢复该行为：

@Bean
public DataSource dataSource() {
    return DataSourceBuilder
        .create()
        .username("")
        .password("")
        .url("")
        .driverClassName("")
        .build();
}