创建 bean 时抛出名称异常时出错

问题描述

我是 Spring Boot 的新手，我正在尝试做一个教程，但出现以下错误：

Error creating bean with name 'employeeController': Unsatisfied dependency expressed through field 'employeeDao';

Error creating bean with name 'employeeDao': Unsatisfied dependency expressed through field 'jdbcTemplate';

我能够创建数据库，甚至向其中添加一行，但随后程序开始抛出上述异常。会是什么呢？我已经一遍又一遍地检查了教程，我找不到我犯错的地方

员工类

package com.tutorial.demo;

public class Employee {
    private long id;
    private String firstName,lastName;

    public Employee(long id,String firstName,String lastName) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }
}

员工控制器

package com.tutorial.demo;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class EmployeeController {

    @Autowired
    public EmployeeDao employeeDao;

    @PostMapping(path = "/addEmployee")
    public @ResponseBody
    String addEmployee(@RequestParam String firstName,@RequestParam String lastName) {
        employeeDao.addEmployee(firstName,lastName);
        return "Saved Employee";
    }

    @GetMapping(path = "/getAllEmployees")
    public @ResponseBody
    Iterable getAllEmployees() {
        return employeeDao.getAllEmployees();
    }
}

员工道

package com.tutorial.demo;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;

import java.sql.ResultSet;
import java.sql.sqlException;
import java.util.List;

@Repository

public class EmployeeDao {

    @Autowired
    JdbcTemplate jdbcTemplate;

    public List getAllEmployees() {
        return jdbcTemplate.query("SELECT * FROM EMPLOYEE",new EmployeeRowMapper());
    }

    public void addEmployee(final String firstName,String lastName) {
        jdbcTemplate.update("INSERT INTO EMPLOYEE (FirsT_NAME,LAST_NAME) VALUES (?,?)",firstName,lastName);
    }

    private static final class EmployeeRowMapper implements RowMapper {

        @Override
        public Employee mapRow(final ResultSet rs,final int rowNum) throws sqlException {
            Employee employee = new Employee(rs.getLong("ID"),rs.getString("FirsT_NAME"),rs.getString("LAST_NAME"));
            return employee;
        }
    }
}

POM

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.tutorial</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Tutorial</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>15</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.liquibase</groupId>
            <artifactId>liquibase-core</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>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
    </dependencies>

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

</project>

application.properties

spring.datasource.url=jdbc:MysqL://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=*****
spring.datasource.driver-class-name=com.MysqL.jdbc.Driver
spring.jpa.database-platform=org.hibernate.dialect.MysqL5InnoDBDialect

完全错误

rror starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-02-25 20:01:30.461 ERROR 1936 --- [           main] o.s.boot.SpringApplication               : Application run Failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'employeeController': Unsatisfied dependency expressed through field 'employeeDao'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'employeeDao': Unsatisfied dependency expressed through field 'jdbcTemplate'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'liquibase' defined in class path resource [org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfiguration$LiquibaseConfiguration.class]: Invocation of init method Failed; nested exception is java.lang.classCastException: class java.time.LocalDateTime cannot be cast to class java.lang.String (java.time.LocalDateTime and java.lang.String are in module java.base of loader 'bootstrap')
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:660) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessproperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.populateBean(AbstractAutowireCapablebeanfactory.java:1413) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.doCreateBean(AbstractAutowireCapablebeanfactory.java:601) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.createBean(AbstractAutowireCapablebeanfactory.java:524) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.lambda$doGetBean$0(Abstractbeanfactory.java:335) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.doGetBean(Abstractbeanfactory.java:333) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.getBean(Abstractbeanfactory.java:208) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultListablebeanfactory.preInstantiateSingletons(DefaultListablebeanfactory.java:944) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.context.support.AbstractApplicationContext.finishbeanfactoryInitialization(AbstractApplicationContext.java:917) ~[spring-context-5.3.4.jar:5.3.4]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:582) ~[spring-context-5.3.4.jar:5.3.4]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:767) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1311) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1300) ~[spring-boot-2.4.3.jar:2.4.3]
    at com.tutorial.demo.TutorialApplication.main(TutorialApplication.java:10) ~[classes/:na]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'employeeDao': Unsatisfied dependency expressed through field 'jdbcTemplate'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'liquibase' defined in class path resource [org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfiguration$LiquibaseConfiguration.class]: Invocation of init method Failed; nested exception is java.lang.classCastException: class java.time.LocalDateTime cannot be cast to class java.lang.String (java.time.LocalDateTime and java.lang.String are in module java.base of loader 'bootstrap')
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:660) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessproperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.populateBean(AbstractAutowireCapablebeanfactory.java:1413) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.doCreateBean(AbstractAutowireCapablebeanfactory.java:601) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.createBean(AbstractAutowireCapablebeanfactory.java:524) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.lambda$doGetBean$0(Abstractbeanfactory.java:335) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.doGetBean(Abstractbeanfactory.java:333) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.getBean(Abstractbeanfactory.java:208) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultListablebeanfactory.doResolveDependency(DefaultListablebeanfactory.java:1380) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultListablebeanfactory.resolveDependency(DefaultListablebeanfactory.java:1300) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:657) ~[spring-beans-5.3.4.jar:5.3.4]
    ... 21 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'liquibase' defined in class path resource [org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfiguration$LiquibaseConfiguration.class]: Invocation of init method Failed; nested exception is java.lang.classCastException: class java.time.LocalDateTime cannot be cast to class java.lang.String (java.time.LocalDateTime and java.lang.String are in module java.base of loader 'bootstrap')
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.initializeBean(AbstractAutowireCapablebeanfactory.java:1786) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.doCreateBean(AbstractAutowireCapablebeanfactory.java:602) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.createBean(AbstractAutowireCapablebeanfactory.java:524) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.lambda$doGetBean$0(Abstractbeanfactory.java:335) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.doGetBean(Abstractbeanfactory.java:333) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.getBean(Abstractbeanfactory.java:208) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.doGetBean(Abstractbeanfactory.java:322) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.Abstractbeanfactory.getBean(Abstractbeanfactory.java:208) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultListablebeanfactory.doResolveDependency(DefaultListablebeanfactory.java:1380) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultListablebeanfactory.resolveDependency(DefaultListablebeanfactory.java:1300) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:657) ~[spring-beans-5.3.4.jar:5.3.4]
    ... 35 common frames omitted
Caused by: java.lang.classCastException: class java.time.LocalDateTime cannot be cast to class java.lang.String (java.time.LocalDateTime and java.lang.String are in module java.base of loader 'bootstrap')
    at liquibase.changelog.StandardChangeLogHistoryService.getRanChangeSets(StandardChangeLogHistoryService.java:328) ~[liquibase-core-3.10.3.jar:na]
    at liquibase.changelog.AbstractChangeLogHistoryService.upgradeChecksums(AbstractChangeLogHistoryService.java:66) ~[liquibase-core-3.10.3.jar:na]
    at liquibase.changelog.StandardChangeLogHistoryService.upgradeChecksums(StandardChangeLogHistoryService.java:297) ~[liquibase-core-3.10.3.jar:na]
    at liquibase.Liquibase.checkLiquibaseTables(Liquibase.java:1174) ~[liquibase-core-3.10.3.jar:na]
    at liquibase.Liquibase.update(Liquibase.java:192) ~[liquibase-core-3.10.3.jar:na]
    at liquibase.Liquibase.update(Liquibase.java:178) ~[liquibase-core-3.10.3.jar:na]
    at liquibase.integration.spring.SpringLiquibase.performUpdate(SpringLiquibase.java:368) ~[liquibase-core-3.10.3.jar:na]
    at liquibase.integration.spring.SpringLiquibase.afterPropertiesSet(SpringLiquibase.java:316) ~[liquibase-core-3.10.3.jar:na]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.invokeInitMethods(AbstractAutowireCapablebeanfactory.java:1845) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.initializeBean(AbstractAutowireCapablebeanfactory.java:1782) ~[spring-beans-5.3.4.jar:5.3.4]
    ... 47 common frames omitted

解决方法

这是 Liquibase（用于管理数据库架构更改的库）中的一个错误：https://github.com/liquibase/liquibase/issues/1639

如果您不需要 Liquibase，只需删除依赖项：

<dependency>
    <groupId>org.liquibase</groupId>
    <artifactId>liquibase-core</artifactId>
</dependency>

或者升级 Liquibase（最好）或使用 mysql 驱动程序版本

我相信如果你升级你正在使用的 Spring Boot 版本，它也可以解决这个问题。