Large data volume processing in java, using ibatis to insert 5 million pieces of data, low efficiency, how to solve it
Built a banking system to read text data and insert it into the database. The amount of data is too large. Now we use spring to manage transactions uniformly and use ibatis batch processing to insert data. It takes 36 seconds for 10W items, 6 minutes for 100W items, and half an hour for 500W items. How can I speed up the speed? I have considered using multi-threading, but in fact the program does not consume much time when reading and writing files, and I read text line by line. If I use RandomAccessFile, will the positioning be inaccurate? What should we do if multi-threading is only used to handle insertion work? Because the data is read and written into batch statements at the same time, it is not easy to process. There is another question, that is, using transactions, these 5 million pieces of data should be written to the cache of the database first. Will the cache of the database not overflow? The following is my code, I hope someone can give me some guidance. I don’t have much work experience. If there is anything wrong with the code, please point it out. Thank you. FileInputStream fis;…
theimportjava.util.*cannotberesolve, how to solve it
I encountered this problem because after reinstalling the system, the original JDK6 was replaced by JDK7, and an error message appeared when importing jsp files in the old project in Eclipse. Find the solution on the following page and post it: http://www.myexception.cn/eclipse/17226.html Display the import Java.util cannot be resolved, how to solve it? When I was using eclipse, I seemed to have accidentally changed the installation location (workspace). Now all packages show that they cannot be imported: the import java cannot be resolved. How to solve this problem? ——Solution——————–Solution:Right-click the project—– –buildpath——–The bottom configura. . . Select librariesFind the JRE (at this time you will find that there is a! or red X in front of the jre)Select removeReselect a JRE for the projectSelect the project, project —-cleanOK, all packages have been found——Solution——————– Install the one upstairs and configure the JAR in the project.Because you have changed the working environment, and the JAR packages in the project are all from beforeYou now configure the Java environment in the project to your current one. That’s it.
GC seems to make java server application unresponsive problem, how to solve it
GC seems to make Java server applications unresponsive, how to solve it System.gc() “calls” the garbage collector to collect garbage. This is not very rigorous, but in fact it is just a “notification” “That’s all. Whether to recycle or not is determined by the garbage collector’s algorithm. You can develop a garbage collector that does nothing, or a garbage collector that waits until the memory is occupied to exceed a certain proportion before recycling. The finalize() method is a method that will be called when a class object is destroyed. When the garbage collector finds that the class object will no longer be used, it will reclaim the memory, that is, destroy the object, and finalize() is called. System.gc() of your program is the last sentence. Obviously, the Book object created in the previous sentence will not be used later, so the garbage collection algorithm provided by JDK will call the destruction method of the object to recycle it. . The java process on the server is still there, but it is not executed. What’s going on? 1. Obviously there is no log. Any program must have corresponding log records. In this way, any problems that arise can be traced…
Reprint: High concurrency in Java, how to solve it, what method to solve it
Original text: https://www.cnblogs.com/lr393993507/p/5909804.html For the website we develop, if the website has a very large number of visits, then we need to consider the relevant Concurrent access problem. Concurrency problems are a headache for most programmers. But then again, since we can’t escape it, let’s face it calmly~ Today let’s study the common problems together Concurrency and synchronization. In order to better understand concurrency and synchronization, we need to first understand two important concepts: Synchronization and asynchronous 1. Synchronization and The difference and connection between asynchronous The so-called synchronization can be understood as waiting for the system to return a value or message after executing a function or method. At this time, the program is blocked and can only receive Execute other commands only after receiving the value or message returned by . Asynchronous, after executing the function or method, you do not have to wait for the return value or message in a blocking manner. You only need to delegate an asynchronous process to the system, then when the system receives the return value or When sending a message, the system will automatically trigger the delegated asynchronous process to complete a complete process. Synchronization can be regarded as a…
Java always reports this error when sending emails, how to solve it?
javax.mail.AuthenticationFailedException: 530 Error: A secure connection is required(such as ssl) 1234567891011121314151617181920212223242526272829303132333435363738394041424344 Properties prop = new Properties(); prop.setProperty(“mail.transport.protocol”, “smtp”); // Set the email sending protocol prop.setProperty(“mail.host”, “smtp.qq.com”); // Mail server address ssl.enable”, “true”); // Email ssl authentication prop.setProperty(“mail.smtp.auth”, “true”); // Email service authentication //prop.setProperty(“mail.smtp.localhost”, “127.0.0.1”); Session session = Session.getDefaultInstance (prop); // Sender’s email address String from = “xxxx@qq.com”; try{ Field …
Webpack package reports javaScriptheapoutofmemory, how to solve it?
12345 After upgrading nodejs from 5.1.1 to 6.10.2, perform packaging of the production environment (`set NODE_ENV=production && webpack –config webpack.production.config.js `), the console reports an error: “CALL_AND_RETYR_LAST Allocation failed -Javascript heap out of memoty”.  (This is a picture, why can’t it be uploaded?) My nodejs version is 6.10.2, and npm was originally 3.10. X, in the background, I saw someone on stackoverflow saying that updating npm to the latest version can solve this problem. npm was finally updated to 4.5.0. Whether it is Baidu or stackoverflow, I have looked for solutions (I found webpack.cmd, in the command line “node “%~dp0\node_modules\webpack\bin\ webpack.js” %* “add “-max_old_space_size = 2048” parameter) and tried it, but it didn’t work. How to fix it?
Why can’t I connect to the mysql database_java can’t connect to the database, how to solve it!
juzhengw I just did this last year，I will post my link code for you try { Class.forName(“com.microsoft.sqlserver.jdbc.SQLServerDriver”); //Load the sqlserver JDBC driver //Class .forName(“org.gjt.mm.mysql.Driver”); System.out.println(“Success loading sqlserver Driver!”); catch (Exception e) { System.out.print(“Error loading sqlserver Driver!”) “); e.printStackTrace(); } try { Connection connect = DriverManager.getConnection( “jdbc:sqlserver://localhost:1433;DataBasename=java”,”sa”,”***** **”); //Don’t worry about the address ，The user name is sa //The connection URL is jdbc:sqlserver//server address/database name ， The next two parameters are the login username and password System. out.println(“Success connect sqlserver server!”); Statement stmt = connect.createStatement(); ResultSet rs = stmt.executeQuery(“select * from Users”); //user is for you Name: If you are sure that your jadc package and link code are completely correct, I guess you may have the database not set to use password login (the table is not in the database for password login). There is no specific code and it is hard to say，Thrown What’s wrong?，I only used this two or two years ago，I’m quite familiar with it，If you still can’t solve it, you can send me a private message；Xiaobai mutual encouragement
When php connects to Oracle, it prompts CalltoundefinedfunctionOra_Logon(), how to solve it?
PHP connects to Oracle and prompts Call to undefined function Ora_Logon()A short piece of code written according to the information <? if ($cOnn=Ora_Logon( “hr@ TNSNAME “, “hr “)) { echo “SUCCESS ! Connected to database\n “; } else { echo “Failed 
Could not connect to database\n “;} Ora_Logoff($conn); phpinfo(); ?> Tip Ora_Logon function is defined , why? I have removed the semicolon of extension=php_oci8.dll in php.ini and imported php_oci8.dll into windows/system32. />——Solution——————–It’s not like you You can install the Oracle extension… And ora_logon belongs to CXIII. Oracle function (obsolete) You have to use CVII. Oracle function http://cn.php.net/manual/zh/ref.oci8.php ——Solution——————–Did you config your php with Oracle while installing it? Please check below ./configure –prefix=/appbin/php –with-apxs2=/appbin/apache/bin/apxs –with- oci8=$ORACLE_HOME $ORACLE_HOME is path which your Oracle clinet/server located, then use oci_connect() or use oci_newconnect(), Please check php doc for detail
What are the popular methods of encrypting URL parameters? PHP, how to solve it
What are the popular methods of encrypting URL parameters? PHPPHP code ——Solution—————— —The simplest and useless base64… Otherwise, write an encryption function and a decryption function yourself. . ——Solution——————–http ://hi.baidu.com/fufay/blog/item/8aee3ed1ab58b3d2572c84fa.html ——Solution——————–Encryption Or encoding? If it is encryption, you can use des/des3 http://hi.baidu.com/lael80/blog/item/58244460067226df8db10d94.html
PHP timer, how to solve it
php time timerPlease help me, experts, how to set up a time timer in php, that is to say, execute the program every once in a while? ——Solution——————–It doesn’t seem to be available in PHP.It should be in JS, or it can be implemented under linux/unix! ——Solution——————–Use sleep() to set the interval, and then run the program through the command line. ——Solution——————–Most The simple way is to determine the time in the code and run it if it arrives. If it is a static page, you can use Javascript src=’xxx.php’ to start it. The premise is that there are visitors. Without visitors, it cannot run. ——Solution——————–Write Just create a scheduled task, it can be done on win linux, and then you can set it at any time you want. ——Solution——————–1 .You can use for and then add a sleep2. Or make a scheduled task in win ——Solution——————–First Understand the principles of the web before posting. ——Solution——————–Well , use the sleep function. ~~~~~~~~ ——Solution——————–No What a realistic problem, I have encountered such a problem before. Or do it with ajax, or system scheduled tasks. Sleep will cause PHP to always have a process, which makes you feel uncomfortable. ——Solution——————–cronjob cronjob cronjob…
