java的jdbc驱动问题 Cannot load driver class: com.mysql.cj.jdbc.Driver

总体描述

 java出现Error creating bean with name 'blockController': Unsatisfied dependency expressed through field 'blockService'问题，后续有Cannot load driver class: com.mysql.cj.jdbc.Driver

我的工程目录结构

本人主要代码

pom.xml

<?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.example</groupId>
	<artifactId>ssmdemo01</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>ssmdemo01</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.1.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>
	
	<!-- 处理一些请求日志,或者对某些方法进行一些监控,如果出现例外情况应该进行怎么样的处理 -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-aop</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</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>


		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>1.1.1</version>
		</dependency>
		 
		  <!-- thymeleaf模板引擎 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>
		
		<!-- 热启动配置 -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<optional>true</optional>
		</dependency>	
		
		
		<dependency>
	        <groupId>org.apache.tomcat.embed</groupId>
	        <artifactId>tomcat-embed-jasper</artifactId>
	        <scope>provided</scope>
		</dependency>
		<dependency>
	        <groupId>javax.servlet</groupId>
	        <artifactId>jstl</artifactId>
	        <scope>runtime</scope> 
		</dependency>
		<dependency>  
		   	<groupId>javax.servlet</groupId>  
		   	<artifactId>javax.servlet-api</artifactId>  
		</dependency> 

	</dependencies>
	

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				
				<configuration>
                    <fork>true</fork><!-- fork:如果没有该配置，这个devtools不会起作用，即应用不会restart -->
                </configuration>
			</plugin>
		</plugins>
	</build>
</project>

application.properties

 前端框架thymeleaf映射
spring.thymeleaf.prefix=classpath:/templates/
server.servlet.session.timeout=10
server.tomcat.uri-encoding=UTF-8

#spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.suffix=.html
spring.thymeleaf.mode=HTML5
spring.thymeleaf.encoding=UTF-8
#spring.thymeleaf.servlet.content-type=text/html  

#数据库
 # ?serverTimezone=GMT，去除时区异常
spring.datasource.url = jdbc:mysql://localhost:3306/agriculture_test?serverTimezone=GMT%2B8
spring.datasource.username = root
spring.datasource.password = rs651616
#jdbc驱动的全限定类名，默认根据URL自动检测
spring.datasource.driver-class-name = com.mysql.cj.jdbc.Driver
#配置连接池同时能维持的最大连接数
spring.datasource.tomcat.max-active = 200

### 空闲时间，idle连接池中的最大连接数
spring.datasource.tomcat.max-idle = 10
### idle连接池中的最小空闲连接数
spring.datasource.tomcat.min-idle = 5

##连接池在等待返回连接时，最长等待时间再抛出异常
spring.datasource.tomcat.max-wait = 10000
## 在连接池启动时要建立的连接数
spring.datasource.tomcat.initial-size = 5

Block.java

package com.example.demo.dao;

public class Block {

	private String id;
	private String name;
	private String type;
	private String coord;
	private String property;
	
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getType() {
		return type;
	}
	public void setType(String type) {

BlockService.java

package com.example.demo.service;

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

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

import com.example.demo.dao.Block;

@Service
public class BlockService {

	@Autowired
	private JdbcTemplate jdbcTemplate;
	
	public List<Block> getList(){
		
		String sql = "SELECT * FROM base_block";
		return (List<Block>) jdbcTemplate.query(sql, new RowMapper<Block>(){

			@Override
			public Block mapRow(ResultSet rs, int rowNum) throws SQLException {
				// TODO Auto-generated method stub
				Block block = new Block();
				block.setId(rs.getString("id"));
				block.setName(rs.getString("name"));
				block.setType(rs.getString("type"));
				block.setCoord(rs.getString("coord"));
				block.setProperty(rs.getString("property"));
				return block;
			}
		});
	}
//	public Block findById(String i) {
//		// TODO Auto-generated method stub
//		
//		return null;
//	}
	
}

BlockController.java

package com.example.demo.controller;

import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.example.demo.dao.Block;
import com.example.demo.service.BlockService;


@RestController
@RequestMapping("/block")
public class BlockController {
	
	private static final Logger logger= LoggerFactory.getLogger(BlockController.class);
	
	@Autowired
	private BlockService  blockService;
	
	@RequestMapping("/datalist")
	public List<Block> getBlocks(){
		logger.info("从数据库读取Bolckdata集合");
		return blockService.getList();
		}
}

出现的问题

Caused by: java.lang.IllegalStateException: Cannot load driver class: com.mysql.cj.jdbc.Driver 
	at org.springframework.util.Assert.state(Assert.java:94) ~[spring-core-5.0.5.RELEASE.jar:5.0.5.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceProperties.determineDriverClassName(DataSourceProperties.java:224) ~[spring-boot-autoconfigure-2.0.1.RELEASE.jar:2.0.1.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceProperties.initializeDataSourceBuilder(DataSourceProperties.java:176) ~[spring-boot-autoconfigure-2.0.1.RELEASE.jar:2.0.1.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration.createDataSource(DataSourceConfiguration.java:43) ~[spring-boot-autoconfigure-2.0.1.RELEASE.jar:2.0.1.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Hikari.dataSource(DataSourceConfiguration.java:81) ~[spring-boot-autoconfigure-2.0.1.RELEASE.jar:2.0.1.RELEASE]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
	... 73 common frames omitted

解决方案

开始一直以为是我的controller或service类写错了，仔细看完错误最后发现是 Cannot load driver class: com.mysql.cj.jdbc.Driver，百度后逐个试，发现是jdbc驱动的原因

#jdbc驱动的全限定类名，默认根据URL自动检测
spring.datasource.driver-class-name = com.mysql.cj.jdbc.Driver

查到这个链接，由于mysql驱动版本比较低（5及以下），不支持com.mysql.cj.jdbc.Driver驱动，故使用较低版本驱动即可！com.mysql.jdbc.Driver，修改后可以运行了，

具体版本对应详情参考。
修改后就可以了。

2019年10月14日