初學spring boot踩過的坑
一、搭建spring boot環境
maven工程
pom文件內容
|
<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"> <version>0.0.1-SNAPSHOT</version> <parent> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> </dependency> <dependency> <groupId>MySQL</groupId> <artifactId>mysql-connector-Java</artifactId> <version>5.0.8</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.0.9</version> </dependency> <dependency> <groupId>org.antlr</groupId> <artifactId>antlr4-runtime</artifactId> <version>4.1</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <optional>true</optional><!-- optional=true,依賴不會傳遞，該項目依賴devtools；之後依賴myboot項目的項目如果想要使用devtools，需要重新引入 --> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> <scope>provided</scope> </dependency> </dependencies> <!-- <build> <plugins> java編譯插件 <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.2</version> <configuration> <source>1.7</source> <target>1.7</target> <encoding>UTF-8</encoding> </configuration> </plugin> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <configuration> <port>8080</port> <path>/</path> <url>http://192.168.25.135:8080/manager/text</url> 用戶名 <username>tomcat</username> 密碼 <password>tomcat</password> </configuration> </plugin> </plugins> </build> --> </project> |
項目目錄結構
其中springTest類是spring boot內部tomcat啟動時要運行的類
其中內容如下
| package com.qm; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.EnableAutoConfiguration; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.boot.web.servlet.ServletComponentScan; import org.springframework.data.jpa.repository.config.EnableJpaRepositories; import com.qm.controller.UserController; @SpringBootApplication public class SpringTest { public static void main(String[] args) { SpringApplication.run(SpringTest.class, args); } } |
Application類的作用是外部服務器啟動spring boot所要做的一些事。內容如下
|
package com.qm;
|
application.properties文件內容如下
|
server.port=8080 //熱部署，需要提供的路徑 |
踩過的坑
坑一，
一開始以為文件目錄，可以隨便放，經過坑一的教訓，才知道代碼文件存放有一定的順序
如上項目結構圖，其中springtest類和application類一定要放在最外面的包裏，如com.qm 當啟動spring boot時，它會去加載com.qm包及其子包下的所有類，
當你不按順序時，[email protected]，會報以下錯誤
Description:
Field userService in com.qm.controller.UserController required a bean of type ‘com.qm.service.UserService‘ that could not be found.
Action:
Consider defining a bean of type ‘com.qm.service.UserService‘ in your configuration.
,即bean找不到。，這是應該註意代碼順序。
坑二
補齊坑一後，在service層的接口繼承jpa，然後在controller層使用註入的service方法會報以下錯誤
Error creating bean with name ‘dataController‘: Unsatisfied dependency expressed through field ‘personRepository‘; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘personRepository‘: Invocation of init method failed; nested exception is org.springframework.data.mapping.PropertyReferenceException: No property auto found for type Person!
這是因為hibernate版本的問題，
只要加上
<dependency>
<groupId>org.antlr</groupId>
<artifactId>antlr4-runtime</artifactId>
<version>4.1</version>
這個依賴即可
添加之後，若maven倉庫中有該jar包，最好刪掉，編譯時重新下載
若spring boot正常啟動，而地址欄訪問不到controller,則此時應該註意，spring boot啟動時，未掃描到controller類，
在spring boot入口類上再添加一個註解
@ComponentScan("要掃描的包名")
以上就是我在學spring boot時遇到過得一些坑。
初學spring boot踩過的坑