Author Archives: Robins

Invalid vs modification project properties

The last few days I have been puzzled by how my VS2015 always changes project attributes or file attributes. If I want to change from ANSCII to UNICODE, turn off GS protection, SDL check, or change a CPP attribute (excluded from generation), it doesn’t work, and I have reinstalled VS2015 again.
 
It had been torturing me for days, and then I didn’t do much about it, until I suddenly found out why, alas.
 
For this reason, the 32-bit and 64-bit platforms must be matched with Debug and Release versions!!
 


 
 
 

Spring failed to commit the transaction

In the project, Spring JPA and Spring JDBC were used, but in the actual use, it was found that transactions in Spring JDBC were not committed, and the handling methods were mainly as follows

    ensure that transactions are enabled in the project 
@EnableTransactionManagement
    ensure that the transaction annotation

is added on the method

@Transactional

These two points have been added in the system, but still not effective, see the spring jpa document found is, indeed, support for jpa transactions and JDBC transaction https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/orm/jpa/JpaTransactionManager.html , On the debug the Jpa's transaction processing mainly in the JpaTransactionManager. DoBegin , the execution will determine whether using JDBC transaction;

the system specifies JpaTransactionManager but does not specify jpaDialect. If not specified, it defaults to DefaultJpaDialect, while DefaultJpaDialect does not handle 0 JdbcConnection1. Therefore, the JDBC transaction could not be committed, and the solution was relatively simple. Manually specify jpaDialect as HibernateJpaDialect;

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" primary="true">
  <property name="entityManagerFactory" ref="entityManagerFactory"/> 
  <property name="jpaDialect">
    <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"></bean> 
  </property>
 </bean>

The function and usage of argc and argv in C language

In C programming, you often see the following main function declaration:

int main(int argc, char *argv[])

So what are argc and Argv [] for?
Where argc is the number of arguments entered externally and argv[] is the string array of arguments. This may not be obvious to you, but let’s take a look at an example of the C file argtest.c shown below

#include <stdio.h>
 
int main(int argc, char *argv[])
{
	printf("argc is %d\n",argc);
	for(int i=0;i<argc;i++)
	{
		printf("argv[%d] is: %s\n",i,argv[i]);	
	}
	
	return 0;
}

These lines of code are simple, first printing the value of argc, then printing out the string of all argv[] arrays.
Use the following command to compile the C file

gcc argtest.c -o argtest

After compiling to produce the executable file argtest, execute the following command

./argtest

The output result of the program is

argc is 1
argv[0] is: ./argtest

This indicates that when the program is executed, only one parameter is entered, and this parameter is the command executing the program.
Execute the following command

./argtest 1234 abcd

The output result of the program is

argc is 3
argv[0] is: ./argtest
argv[1] is: 1234
argv[2] is: abcd

This indicates that the program entered three arguments, and that the last two space-separated strings of the command were passed to the main function.
Through argc and Argv [] we can pass arguments to the program by command.

CentOS Yum error: cannot retrieve repository metadata (repomd.xml) for repository:

An error is always reported when using Yum Install again after installing Gitlab. The error code is as follows:

Error: Cannot retrieve repository metadata (repomd.xml) for repository: gitlab_gitlab-ce. Please verify its path and try again

the solution is as follows:

A. open/etc/yum. Repos. D/XXXXX. Repo, for this example is the/etc/yum. Repost. D/XXX. ‘
b. Change the term ‘enabled=1’ in [XXX] to ‘enabled=0
‘

As indicated in the code above, my error is gitlab_gitlab-CE, so the enabled=0 in gitlab_gitlab-ce-repo’s [gitlab_gitlab-CE]

[root@web1 ~]# cd /etc/yum.repos.d
[root@web1 yum.repos.d]# vim gitlab_gitlab-ce.repo

Set enabled=1 to enabled=0 in [gitlab_gitlab-ce]

 

VMware Workstation failed to recover error: (VMX) exception 0xc0000006 (disk error while paging) has

I am getting the following error when running vmware workstation.

Warning: the system was unable to load a page of memory; this can be caused
by network problems or a failing hard disk drive.
VMware Player unrecoverable error: (vcpu-0)
Exception 0xc0000006 (disk error while paging) has occurred.
A log file is available in “C:/My Virtual Machines/Windows 2000
Professional/vmware.log”. A core file is available in “C:/Documents and
Settings/Administrator/Application Data/VMware/vmware-vmx-1464.dmp”. Please
request support and include the contents of the log file and core file.
To collect files to submit to VMware support, run cscript vm-support.vbs.
We will respond on the basis of your support entitlement.

When my vmware stops, it uses a pause to suspend the system, which is similar to hibernating a windows system, so that all the current operations can be saved, and when it starts up again, it can go directly into operation, but today the startup error.
Then I went online and found that renaming or simply deleting the vmss file in the directory of the installed virtual machine system and reopening the virtual system would do the trick.

Raise in Oracle_APPLICATION_Error Usage

Probably not many people know what the purpose of RAISE_APPLICATION_ERROR is, although you have guessed literally what this function is for. Normally, we output the exception information through DBMS_output_line for the exception handling used to test, but in the actual application, we need to return the exception information to the calling client.
actually RAISE_APPLICATION_ERROR is the declaration that the application-specific errors are conveyed from the server side to the client application (SQLPLUS on another machine or other front-end development language)
RAISE_APPLICATION_ERROR:
PROCEDURE RAISE_APPLICATION_ERROR( error_number_in IN NUMBER, error_msg_in IN VARCHAR2);
inside the error code and content, are custom. Custom, of course, is not the system has named the existence of the error category, is a custom transaction error type, only called this function. Error_number_in allows tolerance between -20,000 and -20999 so that it does not conflict with any ORACLE error code. The length of error_MSG_in cannot exceed 2k, otherwise intercept 2k. For example,
prevents users under 18 years of age from adding to the database table temp_age.

-- building a watch
create table temp_age(
age_id number(5),
age number(3)
);

-- Build Trigger
create or replace trigger t_temp_age_check
before insert on temp_age
  for each row
    begin
      if :new.age < 18
        then
          raise_application_error(-20001,'age must at least 18 years old');
        end if;
    end;

 

-- client program
declare
  no_baby_allowed exception;
  pragma exception_init(no_baby_allowed,-20001);
  begin
    insert into temp_age(age_id,age) values(1,20);
    insert into temp_age(age_id,age) values(2,17);
    insert into temp_age(age_id,age) values(3,18);
    exception
      when no_baby_allowed
        then
          dbms_output.put_line(sqlerrm);
  end;

Client program execution output results:

Ora-20001: age must at least 18 years old
ora-06512: error during ‘lcam_develop.t_temp_age_check’, line 4
ora-04088: trigger ‘lcam_develop.t_temp_age_check’ execution

How to Uncompress 7z files on Ubuntu, Debian, Fedora

Question: How do I uncompress a *.7z file ( 7zip file ) in UNIX/Linux ?Can you explain with a simple example?
Answer: Use 7za command to unzip a 7z file ( 7zip file ) on Unix platform as shown below.

Verify whether you have 7za command on your system.

# whereis 7za
7za: /usr/bin/7za /usr/share/man/man1/7za.1.gz

If you don’t have 7za command, install p7zip package as shown below.
Install p7zip to unzip *.7z files on Fedora

# yum install p7zip

Install p7zip to unzip *.7z files on Debian and Ubuntu

$ sudo apt-get install p7zip

Uncompressing a *.7z 7zip files in Linux using 7za

$ 7za e myfiles.7z 

7-Zip (A) 9.04 beta  Copyright (c) 1999-2009 Igor Pavlov  2009-05-30
p7zip Version 9.04 (locale=C,Utf16=off,HugeFiles=on,1 CPU)

Processing archive: ../../myfiles.7z

Extracting  myfiles/test1
Extracting  myfiles/test2
Extracting  myfiles/test
Extracting  myfiles

Everything is Ok

Folders: 1
Files: 3
Size:       7880
Compressed: 404

7za – command namee – specifies the 7z to be extractedmyfiles.7z – is the file that is to be extracted
Creating a 7zip compression file in Linux

$ 7za a myfiles.7z myfiles/

7-Zip (A) 9.04 beta  Copyright (c) 1999-2009 Igor Pavlov  2009-05-30
p7zip Version 9.04 (locale=C,Utf16=off,HugeFiles=on,1 CPU)
Scanning

Creating archive myfiles.7z

Compressing  myfiles/test1
Compressing  myfiles/test2      

Everything is Ok

Files and sub directories of myfiles/ will be added to the myfiles.7z.
a – add to archivefile.7z – archive file to which these files and dir from dir1 will be added to.

Using $this when not in object context in (How to Fix)

Error message: The $this reference has no context
Reason: In PHP5, $this cannot be used in static methods of static declarations; you need to use self to refer to methods or variables in the current class.Example code is as follows:

<?php
namespace syhl\admin\page\record;  // namespace

require_once  dirname(__FILE__).'/../../../../common/smarty_loader.php';  

class record {
  
    
     public static function exec($smarty) {    
        
        $ttr=self::getres();
        $smarty->assign("arr",$ttr);      
        $smarty->display ( 'rec_mgr.html' );
    }
   function getres(){
      $arr = array (  
       "1" => 'test',  
       '2' => 'me',  
       array (  
        "3" => "beij",  
        "4" => "zz"  
       ),  
       array (  
        "5",  
        "6" => "ewrwer",  
        "7" => "ssss"  
       )  
      );  
      return $arr;
    }
}
record::exec($smarty);

?>

 

$this(getRes () method in the sample code) is not allowed in the referenced method.

How to parse JSON string in.Net [error reading job object from jsonreader. Current jsonreader item is not an obj]

Edit time: 2017-05-10. Add a method to transform list
First, I know a way to parse JSON string before, I find it a little troublesome. I got another one from somewhere else

string json = vlt.getlist();

JObject jo = JObject.Parse(json);

var data = jo.getValue("data").ToObject<T>();

T is the corresponding entity class, and can be used directly in the member variable data.member
2. Json transformation of the List is to put it into redIS cache, and then take it out for transformation
Don’t talk nonsense, code on:

            var t = new List<PcWareListByCourseId>();
            var m1 = new PcWareListByCourseId
            {
                videoId = 12,
                IsAuditions = false,
                percent = 23,
                practiceId = 43,
                statuss = 2,
                TotalTime = "12.2",
                wareId = 22,
                wareName = "courseware"
            };
            var m2 = new PcWareListByCourseId
            {
                videoId = 12,
                IsAuditions = false,
                percent = 23,
                practiceId = 43,
                statuss = 2,
                TotalTime = "12.2",
                wareId = 22,
                wareName = "courseware"
            };
            t.Add(m1);
            t.Add(m2);
            RedisInfoHelper.SetRedis("test",t);

            var get = RedisInfoHelper.GetRedisValue("test");

            var jo = JArray.Parse(get);
            var jj = jo.ToObject<List<PcWareListByCourseId>>();

Entity code:

    public class PcWareListByCourseId
    {
        public int wareId { set; get; }
        public string wareName { set; get; }
        public bool IsAuditions { set; get; }
        public int videoId { set; get; }
        public int percent { set; get; }
        public int practiceId { set; get; }
        public int statuss { set; get; }
        public string TotalTime { set; get; }//11'22"
    }



Successful to the last step, successful transformation.
This time I’m using the JArray method class.

[Maven] Fatal error compiling: invalid target release: 1.7 -> [Help 1]

Fatal error compiling: invalid target release: 1.7 -> [Help 1]

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.2:compile (default-compile) on project bugkillers-core: Fatal error compiling: invalid target release: 1.7 -> [Help 1]
[ERROR]

How to Fix
1. mvn -v displays the following results.

Apache Maven 3.2.5 (12a6b3acb947671f09b81f49094c53f426d8cea1; 2014-12-15T01:29:23+08:00)
Maven home: /usr/share/java/apache-maven-3.2.5
Java version: 1.6.0_65, vendor: Apple Inc.
Java home: /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
Default locale: en_US, platform encoding: MacRoman
OS name: "mac os x", version: "10.9.2", arch: "x86_64", family: "mac"

2. Pom Settings are as follows:

 <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>${project.build.sourceEncoding}</encoding>
                    </configuration>
                </plugin>

3. But the java-version result is as follows:

java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)

 

4. 1.7 is not used for compilation, and Maven’s Java Home is set to 1.7 (multiple versions of the JDK are set locally)
Modify maven’s configuration. Java_home points to 1.7,/etc/mavenrc, and ~/.mavenRC. Two files do not exist by default, you need to create, you can choose one
For example: vi ~/.mavenrc
Writing:

JAVA_HOME=`/usr/libexec/java_home -v 1.7`

 

5. Then mVN-V, the results are as follows:

Apache Maven 3.2.5 (12a6b3acb947671f09b81f49094c53f426d8cea1; 2014-12-15T01:29:23+08:00)
Maven home: /usr/share/java/apache-maven-3.2.5
Java version: 1.7.0_79, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.7.0_79.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.9.2", arch: "x86_64", family: "mac"

Done