问题背景 #

我搭建了一个可与SQL Server交互的Spring Boot REST CRUD服务，支持POST、GET请求及响应，但运行项目时始终触发Bean创建相关的异常。以下是我的配置和异常详情：

application.properties 配置 #

server.port=9004
spring.datasource.url=jdbc:sqlserver://localhost/1433;databaseName=test1
spring.datasource.username=sa
spring.datasource.password=*****
spring.datasource.driverClassName=com.microsoft.sqlserver.jdbc.SQLServerDriver
spring.jpa.show-sql=true
spring.jpa.hibernate.dialect=org.hibernate.dialect.SQLServer2014Dialect
spring.jpa.hibernate.ddl-auto =ddl-auto

pom.xml 内容 #

<properties>
  <maven.compiler.source>1.8</maven.compiler.source>
  <maven.compiler.target>1.8</maven.compiler.target>
</properties>
<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.3.6.RELEASE</version>
</parent>
<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-rest</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
  </dependency>
  <dependency>
    <groupId>com.microsoft.sqlserver</groupId>
    <artifactId>sqljdbc4</artifactId>
    <version>4.0</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
  </dependency>
</dependencies>
<build>
  <plugins>
    <plugin>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-maven-plugin</artifactId>
    </plugin>
  </plugins>
</build>
</project>

启动异常信息 #

Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.boot.autoconfigure.web.HttpMessageConverters org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.messageConverters; nested exception is and: with name 'mappingJackson2HttpMessageConverter' defined in class path resource [org/springframework/boot/autoconfigure/web/JacksonHttpMessageConvertersConfiguration$MappingJackson2HttpMessageConverterConfiguration.class]: Unsatisfied dependency expressed through constructor argument with index 0 of type [com.fasterxml.jackson.databind.ObjectMapper]: Error creating bean with name 'objectMapper' defined in class path resource [org/springframework/boot/autoconfigure/data/rest/SpringBootRepositoryRestMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.fasterxml.jackson.databind.ObjectMapper]: Factory method 'objectMapper' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'config' defined in class path resource [org/springframework/boot/autoconfigure/data/rest/SpringBootRepositoryRestMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.rest.core.config.RepositoryRestConfiguration]: Factory method 'config' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'resourceMappings' defined in class path resource [org/springframework/boot/autoconfigure/data/rest/SpringBootRepositoryRestMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is

解决方案 #

我帮你梳理了几个关键修改点，应该能解决这个启动异常：

1. 修复application.properties中的配置错误 #

• 修正ddl-auto值：你写的spring.jpa.hibernate.ddl-auto =ddl-auto是无效的，合法值包括create、create-drop、update、validate、none，推荐用update（保留数据并更新表结构）：

  spring.jpa.hibernate.ddl-auto=update
  

• 修正SQL Server连接URL：端口应该用冒号分隔，不是斜杠，正确格式：

  spring.datasource.url=jdbc:sqlserver://localhost:1433;databaseName=test1
  

2. 升级Spring Boot版本（核心修复） #

你用的1.3.6.RELEASE版本太老旧，和spring-boot-starter-data-rest的Jackson组件兼容性问题是这次异常的主要原因。建议升级到和Java 8兼容的稳定版本，比如1.5.22.RELEASE：

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.5.22.RELEASE</version>
</parent>

3. 替换SQL Server驱动依赖 #

旧的sqljdbc4驱动对新SQL Server版本支持有限，换成微软官方维护的mssql-jdbc驱动，适配Java 8的版本选6.4.0.jre8：

<dependency>
  <groupId>com.microsoft.sqlserver</groupId>
  <artifactId>mssql-jdbc</artifactId>
  <version>6.4.0.jre8</version>
</dependency>

4. 调整Tomcat依赖作用域 #

spring-boot-starter-tomcat的provided作用域会导致本地运行时缺失Tomcat相关类，如果你是本地直接启动应用，要么去掉scope属性，要么直接删除这个依赖（因为spring-boot-starter-data-rest已经包含了Tomcat）：

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>

5. 检查实体类配置 #

最后确认你的JPA实体类是否正确添加了@Entity、@Id等注解，保证Hibernate能正确映射到SQL Server的表结构。

按以上步骤修改后，重新启动项目，应该就能正常运行了。

内容的提问来源于stack exchange，提问作者Sagitarius