Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/util/ClassUtils 异常：Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/util/ClassUtils缺少org.springframework.core包<!-- https://mvnrepository.com/artifact/org.springframework/org.springframework.core --> <dependency> <groupId>org.springframework</groupId> <artifactId>org.springframework.core</artifactId> <version>2.5.6.SEC01</version> </dependency> 

-bash: /etc/profile: line 11: syntax error near unexpected token `$'{\r'' 'bash: /etc/profile: line 使用source命令不能生效使用cat -v /etc/profile检查，发现里面大量的Windows下的换行符:解决方法：#cd /etc #dos2unix profile使用dos2unix profile将profile文件从Windows格式文件转换为Unix、Linux格式，然后在执行source profile使之生效查看#echo $PATH 

Caused by: java.lang.NoClassDefFoundError: org/mybatis/logging/LoggerFactory 原有依赖： <!-- mybatis-plus --> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.1.2</version> </dependency> <!--mysql--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.46</version> </dependency>异常问题：org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [com/baomidou/mybatisplus/autoconfigure/MybatisPlusAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.ibatis.session.SqlSessionFactory]: Factory method 'sqlSessionFactory' threw exception; nested exception is java.lang.NoClassDefFoundError: org/mybatis/logging/LoggerFactory at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:627) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:607) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1288) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1127) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:538) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:846) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:863) ~[spring-context-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546) ~[spring-context-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.1.RELEASE.jar:2.1.1.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.1.RELEASE.jar:2.1.1.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.1.RELEASE.jar:2.1.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.1.RELEASE.jar:2.1.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.1.RELEASE.jar:2.1.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.1.RELEASE.jar:2.1.1.RELEASE] at com.comet.CometAdminApplication.main(CometAdminApplication.java:11) [classes/:na] Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.ibatis.session.SqlSessionFactory]: Factory method 'sqlSessionFactory' threw exception; nested exception is java.lang.NoClassDefFoundError: org/mybatis/logging/LoggerFactory at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:622) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] ... 19 common frames omitted Caused by: java.lang.NoClassDefFoundError: org/mybatis/logging/LoggerFactory at com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean.<clinit>(MybatisSqlSessionFactoryBean.java:97) ~[mybatis-plus-extension-3.1.2.jar:3.1.2] at com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration.sqlSessionFactory(MybatisPlusAutoConfiguration.java:142) ~[mybatis-plus-boot-starter-3.1.2.jar:3.1.2] at com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration$$EnhancerBySpringCGLIB$$84052ef9.CGLIB$sqlSessionFactory$1(<generated>) ~[mybatis-plus-boot-starter-3.1.2.jar:3.1.2] at com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration$$EnhancerBySpringCGLIB$$84052ef9$$FastClassBySpringCGLIB$$264ba30b.invoke(<generated>) ~[mybatis-plus-boot-starter-3.1.2.jar:3.1.2] at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.1.3.RELEASE.jar:5.1.3.RELEASE] at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) ~[spring-context-5.1.3.RELEASE.jar:5.1.3.RELEASE] at com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration$$EnhancerBySpringCGLIB$$84052ef9.sqlSessionFactory(<generated>) ~[mybatis-plus-boot-starter-3.1.2.jar:3.1.2] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131] at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.1.3.RELEASE.jar:5.1.3.RELEASE] ... 20 common frames omitted Caused by: java.lang.ClassNotFoundException: org.mybatis.logging.LoggerFactory at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_131] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_131] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[na:1.8.0_131] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_131] ... 32 common frames omitted添加依赖： <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-extension</artifactId> <version>3.1.2</version> </dependency>    

Caused by: java.sql.SQLException: Value '0000-00-00 00:00:00' can not be represented as java.sql.Tim 异常问题：Caused by: java.sql.SQLException: Value '0000-00-00 00:00:00' can not be represented as java.sql.Timestamp原因：经过排查，发现数据表中有记录的time字段（属性为timestamp）其值为：“0000-00-00 00:00:00”或者是查询时该字段为null，在装换时间格式时出现此异常经过查询资料发现 “0000-00-00 00:00:00”在mysql中是作为一个特殊值存在的但 java.sql.Date 将其视为 不合法的值 格式不正确，所以才会报上面的错误；解决办法：在jdbc的url加上 zeroDateTimeBehavior参数：datasource.url=jdbc:mysql://localhost:3306/hunter?useUnicode=true&characterEncoding=utf8 &zeroDateTimeBehavior=convertToNullzeroDateTimeBehaviorzeroDateTimeBehavior=round是为了指定MySql中的DateTime字段默认值查询时的处理方式；默认是抛出异常，对于值为0000-00-00 00:00:00（默认值）的纪录，采用两种配置，会返回不同的结果：设置zeroDateTimeBehavior=round，返回值为 0001-01-01 00:00:00.0设置zeroDateTimeBehavior=convertToNull ，返回值为 null 

java.lang.NoSuchMethodError: org.springframework.boot.builder.SpringApplicationBuilder. ([Ljava 搭建spring cloud,启动时报错：java.lang.NoSuchMethodError: org.springframework.boot.builder.SpringApplicationBuilder.<init>([Ljava/lang/Object;)V这个是版本兼容原因 <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.1.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent>改： <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> 

java.sql.SQLException: Parameter index out of range (1 > number of parameters, which is 0). java.sql.SQLException: Parameter index out of range (1 > number of parameters, which is 0).原因如下：@Select("select count(*) from pro_mac where id like'%#{val}%' or mac like'%#{val}%'")在where id like'%#{val}%' or mac like'%#{val}%'"中#{val}是带‘’的，显示结果可能为where id like'%‘123’%' ​​​​​​​所以改为${val}就好了@Select("select count(*) from pro_mac where id like'%${val}%' or mac like'%${val}%'") 

java.sql.SQLException: null, message from server: "Host 'xxx.xxx.xxx.xxx' is not allowed to connect 其实道理很简单，也就是说，远程的机器B不允许机器A访问他的数据库。一：打开mysql控制台#use mysql; #show tables;  二：输入#select host from user; #update user set host ='%' where user ='root'; 三：使用 service 启动#service mysqld restart 然后再访问就没有问题了

java.lang.NoClassDefFoundError: com/sun/image/codec/jpeg/JPEGCodec 图片压缩在windows下正常，linux服务器报java.lang.NoClassDefFoundError: com/sun/image/codec/jpeg/JPEGCodec本地开发，jre里有这个包，所以不会报错但是在新的 jdk 版本中，这个类不推荐使用了，使用 ImageIO.write 方法替代// JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(fos); // encoder.encode(image); ImageIO.write(image, "jpg", fos); 

java.lang.IllegalStateException: Failed to load property source from location 'classpath:/applicatio 异常问题：java.lang.IllegalStateException: Failed to load property source from location 'classpath:/application.yml' 可能是application.yml文件内容格式或层级的问题

redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketTimeoutException: connect ti  redis连接报错：redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketTimeoutException: connect timed out开启防火墙（systemctl start firewalld）1.使用命令  firewall-cmd --state查看防火墙状态。得到结果是running或者not running2.在running 状态下，向firewall 添加需要开放的端口命令为 firewall-cmd --permanent --zone=public --add-port=6379/tcp //永久的添加该端口。去掉--permanent则表示临时。4.firewall-cmd --reload //加载配置，使得修改有效。5.使用命令 firewall-cmd --permanent --zone=public --list-ports //查看开启的端口，出现6379/tcp这开启正确 在redis客户端输入：config set protected-mode "no"再测试：@Test     public void test(){         Jedis jedis = new Jedis("192.168.***.***" , 6379);         jedis.set("key2", "aaaaaa");         String key2 = jedis.get("key2");         System.out.println("获取到的key2为:"+key2);         jedis.close();     }