Tag Archives: java

[Solved] Linux java -jar Start Project Error: Unsupported major.minor version 52.0

The error information is as follows:

Caused by inconsistent JDK environment

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/springframework/boot/loader/JarLauncher : Unsupported major.minor version 52.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

Solution:

First, download the appropriate JDK on the Linux server. I have re downloaded JDK1.8, and the original 1.7 has been installed

Start command:

To find the installation directory of JDK, start the project through the corresponding version of JDK

  nohup /usr/local/jdk8/bin/java -jar -Dspring.profiles.active=test read.jar &

[Solved] defineClass Error: java.lang.NoClassDefFoundError: Illegal:

The defineclass() method actually converts byte bytes into class objects

I always thought that the problem in the above picture was that the path could not be found, so I kept changing various paths. As a result, it was wrong to try. As a result, I looked at a blog and directly passed the empty parameters. I took a try attitude. I found that it was right and did not report an error. Suddenly, I found that alas, how can it be empty, Click the converted class to see the data, and then assign the value to the parameter according to that

Just change the ASM/asmhelloworld parameter to asm.asmhelloworld.

Done!

Solution to communication link failure with error in idea startup project

Problem description 

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Solution

Option 1   Tomcat VM configuration parameters: – DJava. Net. Preferipv4stack = true

Option 2   ① Nginx configuring agent MySQL:

    ② Modify database connection: spring. Datasource. Url = JDBC: mysql://localhost:9999/demo?characterEncoding=utf8

Reference from:

https://blog.csdn.net/baidu_21349635/article/details/121032229
https://adong.blog.csdn.net/article/details/111501253

Ureport opens the report files Error: baseMapper [How to Solve]

Initial exception

org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class com.cdw.common.core.model.Resp] with preset Content-Type 'text/json;charset=UTF-8'

Solution:

Set ↓

resp.setContentType("text/json");

Change to ↓

resp.setContentType("application/json");

Then another exception occurs


java.lang.IllegalStateException: getOutputStream() has already been called for this response

Solution:

Set ↓

this.writeObjectToJson(resp, this.reportProviders);

Change to ↓

this.writeObjectToJson(resp, JSONObject.toJSON(this.reportProviders));

Full screenshot after modification:

Namenode startup error: outofmemoryerror: Java heap space

1. Find problems

Phenomenon: restart the Hadoop cluster, and the namenode reports an error and cannot be started.

Error reported:

2. Analyze problems

         As soon as you see the word “outofmemoryerror: Java heap space” in the error report, it should be the problem of JVM related parameters. Go to the hadoop-env.sh configuration file when. The configuration file settings are as follows:

export HADOOP_NAMENODE_OPTS="-Dhadoop.security.logger=${HADOOP_SECURITY_LOGGER:-INFO,RFAS} -Dhdfs.audit.logger=${HDFS_AUDIT_LOGGER:-INFO,NullAppender} $HADOOP_NAMENODE_OPTS" 
export HADOOP_DATANODE_OPTS="-Dhadoop.security.logger=ERROR,RFAS $HADOOP_DATANODE_OPTS"

         It can be seen from the above that the size of heap memory is not set in the parameter.

         The default heap memory size of roles (namenode, secondarynamenode, datanode) in the HDFS cluster is 1000m

3. Problem solving

         Change the parameters to the following, start the cluster again, and the start is successful.

export HADOOP_NAMENODE_OPTS="-Xms4096m -Xmx4096m -Dhadoop.security.logger=${HADOOP_SECURITY_LOGGER:-INFO,RFAS} -Dhdfs.audit.logger=${HDFS_AUDIT_LOGGER:-INFO,NullAppender} $HADOOP_NAMENODE_OPTS" 
export HADOOP_SECONDARYNAMENODE_OPTS="-Xms4096m -Xmx4096m -Dhadoop.security.logger=${HADOOP_SECURITY_LOGGER:-INFO,RFAS} -Dhdfs.audit.logger=${HDFS_AUDIT_LOGGER:-INFO,NullAppender} $HADOOP_NAMENODE_OPTS" 
export HADOOP_DATANODE_OPTS="-Xms2048M -Xmx2048M -Dhadoop.security.logger=ERROR,RFAS -Xmx4096m $HADOOP_DATANODE_OPTS"

Parameter Description:

        – Xmx4096m   Maximum heap memory available

        – Xms4096m   Initial heap memory

Reference: HDFS memory configuration – flowers are not fully opened * months are not round – blog Park

Redis Stand-alone Builds a Master-slave Copy Error [How to Solve]

Premise: connect Huawei ECS purchased by individuals on the xshell platform, install redis, and build a master-slave replication architecture on a single machine

Problem: after the setup is completed, start the slave node. The slave node Ping the master node succeeds, but the master status is displayed as down, and the background log prompts that the connection times out. As shown below:

Solution:

1. Check the configuration of the slave node: is replicaof correct.

It should be configured as the IP of Linux and the redis port of the master node

2. Check whether the master node is configured with a password. If so, the slave node also needs to be configured with a password

3. Check whether the Ping configuration of the primary node configures a single non own IP. If so, comment it out or change it to 0.0.0.0

4. Check whether the firewall is on. There are two types of firewalls

1. Iptables firewall

View firewall service iptables status     If this firewall is not installed, the query will fail.

Stop firewall   service iptables stop

Turn on the firewall   service iptables start

service iptables restart   service iptables restart

Permanently turn off the firewall   chkconfig iptables off

Restart firewall after permanent shutdown   chkconfig iptables on

2.Firewall firewall

View firewall service status   systemctl status firewalld

Turn off firewall   service firewalld stop

View firewall rules   firewall-cmd --list-all

Permanently open 80 ports   firewall-cmd --permanent --add-port=80/tcp

service iptables restart  firewall-cmd --reload (restart after modifying firewall configuration)

4. After I tried the above, I still reported the same error. Finally, I found that the IP configuration of my slave node replicaof was wrong. I mistakenly thought that the IP connected to xshell was the Linux IP I should configure. Who knows, I actually need to use my local IP 127.0.0.1

[Solved] Mailsslsocketfactory error: Cannot find declaration to go to

1. Status. The 1.6.2 jar package is configured in Maven

The solution is to try to add Maven dependency again and replace the invalid jar package version

Finally, create the Lib package manually, copy the downloaded jar package to this directory, and then add it to the library. Add as library is successful

You have 77 PMD violations maven error [How to Solve]

Maven compilation exception

Failed to execute goal org.apache.maven.plugins:
maven-pmd-plugin:3.8:check (default) 
on project xxx: You have 133 PMD violations.

Reason: PMD verification is added to Maven to judge whether your code complies with the specification. If it does not comply with the specification, an error will be reported when Maven compiles

Solution: how can this specification be removed? Just execute the following command, which can ignore the PMD check

mvn clean install -Dpmd.skip=true -Dcheckstyle.skip=true

Of course, when Maven compiles, there will be unit test execution, so how to ignore unit test execution?Just execute the following command

mvn clean install -Dmaven.test.skip=true

Therefore, as long as you want to ignore it, you can execute a command directly behind it
in a word:

In order to be compatible with errors, the following methods can be performed:

mvn clean install -Dpmd.skip=true -Dcheckstyle.skip=true -Dmaven.test.skip=true

[Solved] org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot 

09:06:12.163 [http-nio-9207-exec-6] ERROR c.s.p.c.GlobalExceptionHandler - [exceptionHandler,90] - 发生其他异常，原因是；{}
org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token
 at [Source: (PushbackInputStream); line: 1, column: 2] (through reference chain: java.lang.Object[][0])
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:285)
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:243)
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:205)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:158)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:131)
	at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
	at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:167)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at com.signature.pc.config.HttpServletRequestReplacedFilter.doFilter(HttpServletRequestReplacedFilter.java:35)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:888)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token
 at [Source: (PushbackInputStream); line: 1, column: 2] (through reference chain: java.lang.Object[][0])
	at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
	at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1468)
	at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1242)
	at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1148)
	at com.fasterxml.jackson.databind.deser.std.StdDeserializer._parseString(StdDeserializer.java:615)
	at com.fasterxml.jackson.databind.deser.std.StringArrayDeserializer.deserialize(StringArrayDeserializer.java:157)
	at com.fasterxml.jackson.databind.deser.std.StringArrayDeserializer.deserialize(StringArrayDeserializer.java:21)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4526)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3521)
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:274)
	... 58 common frames omitted

Interface input parameter format:

Front end parameter transfer format

[{"id":"26a0eac8-edb1-43be-9869-4f7c45c0693a"},
{"id":"E3ECF542585749B996EC0C13907E7D94"}]

.
.
.
the problem is obvious. The format of the value passed by the front end is incorrect. What we need is an array of string type, while the data passed by the front end is object type data.

The front-end transmission parameter is changed to:

[
    "30lkbc2b-1c80-46c3-857e-e934e9842c08",
    "E3ECF542585749B996EC0C13907E7D94"
]

That’s it

[Solved] BeanCreationException: Error creating bean with name ‘configurationPropertiesBeans‘

Created a SpringBoot project, used SpringCloud, and then started the project and reported an error:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘configurationPropertiesBeans’ defined in class path resource [org/springframework/cloud/autoconfigure/ConfigurationPropertiesRebinderAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.context.properties.ConfigurationPropertiesBeans]: Factory method ‘configurationPropertiesBeans’ threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/boot/context/properties/ConfigurationBeanFactoryMetadata


It is found that the version of SpringBoot is inconsistent with the version of SpringCloud
Corresponding to the modified version


   <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/>
    </parent>
             <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version></version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>