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  Format JSON data on Ubuntu

JSON now becomes a very popular data format because of its simplicity and light-weight. Nowadays many RESTful APIs will offer a choice of exchanging JSON data between the server and client. Sometimes the data may not be formatted and it cannot be easily read by human beings. It's frequently desired that the unformatted JSON data should be formatted before read. Today we will show a few ways to format JSON data on Ubuntu. Assume we have a json file test.json with below content. { "title": "Test"...

   RUBY,PYTHON,NODEJS,JSON,JQ,PERL,LINUX,UBUNTU,YAJL     2016-08-17 11:05:09

  Access control in Java -- doPrivileged

Previously we have introduced how Java performs permission check to protect resource access. What if sometimes we need to give some class the temporary access to some resource which it initially doesn't have? AccessController provides six doPrivileged methods to fulfill this requirement. These six methods have below signatures : static T doPrivileged(PrivilegedAction action)static T doPrivileged(PrivilegedAction action, AccessControlContext context)static T doPrivileged(PrivilegedExceptionA...

   JAVA,SECURITY,DOPRIVILEGED     2016-03-08 05:46:42

  Different ways to print "Hello world" in Java

This post is not about best practice to print "Hello world" in Java, it is about exploring different capabilities offered by Java. Also there are articles about printing "Hello world" in different programming languages, but this post is not about that. Standard literal The most commonly used way is to use System.out to print"Hello world". System.out.println("Hello world"); Enumeration An enumeration can define a set of values belonging to one category. For example, an enumeration for all months ...

   JAVA,FEATURE     2016-05-21 21:49:48

  Gemini Example with Go

To connect and use Gemini with Go, Google's LLM, one can use their official Go SDK for doing this. In this post, we will just show a simple chat example to demonstrate how to make it work with Go. The example is just to ask the model to translate some English to Chinese and get its output. The code actually looks like: var client *genai.Client // geminiOnce.Do(func() { client, err = genai.NewClient(ctx, option.WithAPIKey(string(apiKey))) if err != nil { log.Fatal(err) } model := client.Genera...

   EXAMPLE,GO,TRANSLATION,GOLANG,GEMINI     2024-12-14 19:37:23

  How to be jQuery-free?

jQuery is now the most famous JavaScript library. There are around 57.3% websites in the world using jQuery, i.e, 6 out of 10 websites are using jQuery. If we only consider those websites which use libraries, then the percentage is even higher which is 91.7%. Although jQuery is very popular, its size is still a headache to many websites maintainers. The uncompressed jQuery 2.0 has a size of 235KB, the size is 81KB after optimization.The jQuery 1.8.3 which supports IE 6/7/8 has a uncompressed si...

   jQuery,JavaScript,ECMAScript,CSS3     2013-05-13 11:53:20

  What does super.clone() do?

Object class has a protected clone() method declared to make it possible for all classes make a clone of itself when needed. The clone() is often used when a new instance of the class is needed while at the same time to maintain the same state as the original object. Any class which wants to have clone enabled has to implement the marker interface Cloneable. If a class which implements Cloneable doesn't override the Object.clone() method, the Object.clone() method will be called to just make a b...

   Cloneable,super.clone(),clone,Java     2015-01-07 05:25:52

  Java Concurrency Basics: CountDownLatch and CyclicBarrier

CountDownLatch CountDownLatch can be used in synchronizing behavior among threads, it makes one or more threads wait for some actions in other threads to be completed. It has a property count which defines how many countDown() need to be called before other threads which called await() to be waked up.  When a thread calls CountDownLatch.await(), the thread will be blocked until the value of count becomes 0. The initial value of count can be specified when creating the CountDownLatch instanc...

   JAVA,JAVA CONCURRENCY,COUNTDOWNLATCH,CYCLICBARRIER     2018-03-25 07:02:40

  Server monitoring shell scripts

There are many open source server monitoring software such as cacti and nagios. Besides these, can we write our own shell scripts to monitor them? The shell scripts written by ourselves can fulfill our special requirements better and have a more detailed coverage. Below are some commonly used shell scripts used by Evangelist, an Oracle DBA. 1. Check network gateway traffic #!/bin/bash #network #Mike.Xu while : ; do time='date +%m"-"%d" "%k":"%M' day='date +%m"-"%d' rx_before='...

   Server monitor,CPU,memory,shell     2013-08-30 21:56:14

  Guide on recovering data in MySQL

In our daily work, there might be mistakes made which got some data or even databases deleted in MySQL. If this happens on production, it would be a nightmare. In case this happens, normally DBA would jump in to save the world. And they would try to recover the data from the backup if there is any. But if there is no backup, then the show stops. Hence database backup is necessary on production environments to avoid such awkward situation. Also normally in MySQL, binlog should be enabled as well ...

   MYSQL,DATABASE,BACKUP,BINLOG,EXAMPLE     2020-08-26 07:50:30

  Using MemoryMappedBuffer to handle large file in Java

When handling large files, it will largely affect the process speed while using traditional FileInputStream, FileOutputStream or RandomAccessFile since they trigger lots of read and write operations. In Java NIO, a new way of handling large file is introduced which is to use MmeoryMappedBuffer to create memory mapped file. Memory-mapped I/O uses the filesystem to establish a virtual memory mapping from user space directly to the applicable filesystem pages. With a memory-mapped file, you can pre...

   JAVA,IO,NIO     2015-11-13 01:58:08

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