记录 Spring Boot2 启动报错The bean ‘beanNameViewResolver‘, defined in class path resource 解决过程

绝地灬酷狼 2023-02-28 05:23 14阅读 0赞

在必问里面回答一个网友的问题：[https://biwen.csdn.net/question/4664][https_biwen.csdn.net_question_4664]

# 一、问题现象 #

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>  
> 
> Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
> 
> 2020-07-19 10:47:22.557 ERROR 7412 --- \[      main\] o.s.b.d.LoggingFailureAnalysisReporter  :
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> \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*
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> APPLICATION FAILED TO START
> 
> \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*
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> Description:
> 
> The bean 'beanNameViewResolver', defined in class path resource \[cn/afterturn/easypoi/configuration/EasyPoiAutoConfiguration.class\], could not be registered. A bean with that name has already been defined in class path resource \[org/springframework/boot/autoconfigure/web/servlet/error/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class\] and overriding is disabled.
> 
> Action:
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> Consider renaming one of the beans or enabling overriding by setting **spring.main.allow-bean-definition-overriding=true**

上面错误已经提示我们在application.ym/application.properties添加如下配置就可以解决。  
**spring.main.allow-bean-definition-overriding=true**  
spring.main.allow-bean-definition-overriding设置为true，表示后发现的bean会覆盖之前相同名称的bean。  
**但是添加这个配置无效，启动仍然提示上面错误。**

# 二、问题分析和原因 #

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## 1、怀疑**spring没有读取到spring.main.allow-bean-definition-overriding** ##

> **把这个参数spring.main.allow-bean-definition-overriding放到启动参数里面，然后启动看看:**
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> ![20200721143448860.png][]
> 
> **然后启动spring boot报错信息，数据源配置错误：**Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
> 
> ![format_png][]
> 
> 这已经说明spring已经正确读取到**spring.main.allow-bean-definition-overriding**。初步怀疑spring没有读取带application.yml 配置。

## **2、debug数据源配置信息** ##

> **1)、在启动参数添加spring.datasource.url**
> 
> ![format_png 1][]
> 
> **2)、同时断点debug数据源配置，**
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> ![format_png 2][]
> 
> 可以看到数据源配置信息，在启动参数里面**spring.datasource.url**可以读到，但**spring.datasource.username**和**spring.datasource.password**没有读取到。
> 
>  
> 
> ![format_png 3][]
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> **明确问题原因：spring无法读取application.yml配置。**
> 
>  
> 
> 由于没有注意springboot启动的提示信息:**No active profile set**, 但在application.yml已经指明sprin.profiles.active=test. **这就已经说明了spring没有正确读取到application.yml配置。**
> 
> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hndWlzdQ_size_16_color_FFFFFF_t_70][]
> 
>

## **3、分析无法读取application.yml文件的原因** ##

> **1）springboot编译后默认把application.yml文件是放在target/classes目录下。**
> 
> **查看编译后的目录结构,** 结果**application.yml是在**BOOT-INF/classes目录下，导致在idea启动时候，spring无法正常读取到application.yml.
> 
> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hndWlzdQ_size_16_color_FFFFFF_t_70 1][]  
>  
> 
> **2）、最后检查maven编译设置，原来是在pom.xm指定了编译路径。**
> 
> ![format_png 4][]

# 三、问题解决 #

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**注释掉这些信息就可以在IDEA下正常启动：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hndWlzdQ_size_16_color_FFFFFF_t_70 2][]

> spring boot使用spring-boot maven插件打包，会把resource的文件放到BOOT-INF\\classes下。所以不必设置编译resources项。
> 
> 解压打包后![20200721143012626.png][] 的jar包就可以看到resources的源文件都在BOOT-INF\\classes目录下。
> 
> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hndWlzdQ_size_16_color_FFFFFF_t_70 3][]
> 
>

[https_biwen.csdn.net_question_4664]: https://biwen.csdn.net/question/4664
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