How to use curl in java

java-curl

In this tutorial, we’re going to look at how to use the curl tool inside a Java program.

Curl is a networking tool used to transfer data between a server and the curl client using protocols like HTTP, FTP, TELNET, and SCP.

2. Basic Use of Curl

We can execute curl commands from Java by using the ProcessBuilder — a helper class for building instances of the Process class.

Let’s see an example of sending commands directly to the operating system:

String command = "curl -X GET https://postman-echo.com/get?foo1=bar1&foo2=bar2"; ProcessBuilder processBuilder = new ProcessBuilder(command.split(" "));

First, we create the command variable before passing it to the ProcessBuilder constructor.

It’s worth noting here that if the curl executable isn’t on our system path, we’ll have to provide its full path in our command string.

We can then set the working directory for the ProcessBuilder and start the process:

processBuilder.directory(new File("/home/")); Process process = processBuilder.start();

From here on, we can get the InputStream by accessing it from the Process instance:

InputStream inputStream = process.getInputStream();

When the processing is complete, we can get the exit code with:

int exitCode = process.exitValue();

If we need to run additional commands, we can reuse the ProcessBuilder instance by passing new commands and arguments in a String array:

processBuilder.command( new String[]);

Finally, to terminate each Process instance, we should use:

3. A Simple Alternative to the ProcessBuilder

As an alternative to using the ProcessBuilder class, we can use Runtime.getRuntime() to get an instance of the Process class.

Let’s see another sample curl command – this time using a POST request:

curl -X POST https://postman-echo.com/post --data foo1=bar1&foo2=bar2

Now, let’s execute the command by using the Runtime.getRuntime() method:

String command = "curl -X POST https://postman-echo.com/post --data foo1=bar1&foo2=bar2"; Process process = Runtime.getRuntime().exec(command);

Firstly, we create an instance of the Process class again, but this time using Runtime.getRuntime(). We can get an InputStream as in our previous example by calling the getInputStream() method:

When the instance is no longer needed, we should release system resources by calling the destroy() method.

4. Conclusion

In this article, we have shown two ways of using curl in Java.

This and more code examples are available over on GitHub.

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Using Curl in Java

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The Jet Profiler was built for MySQL only, so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.

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To avoid overspending on your Kubernetes cluster, definitely have a look at the free K8s cost monitoring tool from the automation platform CAST AI. You can view your costs in real time, allocate them, calculate burn rates for projects, spot anomalies or spikes, and get insightful reports you can share with your team.

Connect your cluster and start monitoring your K8s costs right away:

We’re looking for a new Java technical editor to help review new articles for the site.

1. Overview

In this tutorial, we’re going to look at how to use the curl tool inside a Java program.

Curl is a networking tool used to transfer data between a server and the curl client using protocols like HTTP, FTP, TELNET, and SCP.

2. Basic Use of Curl

We can execute curl commands from Java by using the ProcessBuilder — a helper class for building instances of the Process class.

Let’s see an example of sending commands directly to the operating system:

String command = "curl -X GET https://postman-echo.com/get?foo1=bar1&foo2=bar2"; ProcessBuilder processBuilder = new ProcessBuilder(command.split(" ")); 

First, we create the command variable before passing it to the ProcessBuilder constructor.

It’s worth noting here that if the curl executable isn’t on our system path, we’ll have to provide its full path in our command string.

We can then set the working directory for the ProcessBuilder and start the process:

processBuilder.directory(new File("/home/")); Process process = processBuilder.start(); 

From here on, we can get the InputStream by accessing it from the Process instance:

InputStream inputStream = process.getInputStream(); 

When the processing is complete, we can get the exit code with:

int exitCode = process.exitValue(); 

If we need to run additional commands, we can reuse the ProcessBuilder instance by passing new commands and arguments in a String array:

processBuilder.command( new String[]); 

Finally, to terminate each Process instance, we should use:

3. A Simple Alternative to the ProcessBuilder

As an alternative to using the ProcessBuilder class, we can use Runtime.getRuntime() to get an instance of the Process class.

Let’s see another sample curl command – this time using a POST request:

curl -X POST https://postman-echo.com/post --data foo1=bar1&foo2=bar2

Now, let’s execute the command by using the Runtime.getRuntime() method:

String command = "curl -X POST https://postman-echo.com/post --data foo1=bar1&foo2=bar2"; Process process = Runtime.getRuntime().exec(command); 

Firstly, we create an instance of the Process class again, but this time using Runtime.getRuntime(). We can get an InputStream as in our previous example by calling the getInputStream() method:

When the instance is no longer needed, we should release system resources by calling the destroy() method.

4. Conclusion

In this article, we have shown two ways of using curl in Java.

This and more code examples are available over on GitHub.

Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.

The Jet Profiler was built for MySQL only, so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.

Critically, it has very minimal impact on your server’s performance, with most of the profiling work done separately — so it needs no server changes, agents or separate services.

Basically, you install the desktop application, connect to your MySQL server, hit the record button, and you’ll have results within minutes:

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Использование Curl в Java

В этом уроке мы рассмотрим, как использовать инструмент curl внутри программы Java.

Curl — это сетевой инструмент, используемый для передачи данных между сервером и клиентом curl с использованием таких протоколов, как HTTP, FTP, TELNET и SCP.

2. Основное использование Curl​

Мы можем выполнять команды curl из Java, используя ProcessBuilder — вспомогательный класс для создания экземпляров класса Process .

Давайте посмотрим на пример отправки команд непосредственно в операционную систему:

 String command =   "curl -X GET https://postman-echo.com/get?foo1=bar1&foo2=bar2";   ProcessBuilder processBuilder = new ProcessBuilder(command.split(" ")); 

Во-первых, мы создаем командную переменную перед передачей ее конструктору ProcessBuilder .

Здесь стоит отметить, что если исполняемый файл curl не находится на нашем системном пути, нам придется указать его полный путь в нашей командной строке.

Затем мы можем установить рабочий каталог для ProcessBuilder и запустить процесс:

 processBuilder.directory(new File("/home/"));   Process process = processBuilder.start(); 

С этого момента мы можем получить InputStream , обратившись к нему из экземпляра Process :

 InputStream inputStream = process.getInputStream(); 

Когда обработка завершена, мы можем получить код выхода с помощью:

 int exitCode = process.exitValue(); 

Если нам нужно запустить дополнительные команды, мы можем повторно использовать экземпляр ProcessBuilder , передав новые команды и аргументы в массиве строк :

 processBuilder.command(   new String[]"curl", "-X", "GET", "https://postman-echo.com?foo=bar">); 

Наконец, чтобы завершить каждый экземпляр Process , мы должны использовать:

3. Простая альтернатива ProcessBuilder ​

В качестве альтернативы использованию класса ProcessBuilder мы можем использовать Runtime.getRuntime() для получения экземпляра класса Process .

Давайте посмотрим еще один пример команды curl — на этот раз с использованием POST — запроса:

 curl -X POST https://postman-echo.com/post --data foo1=bar1&foo2=bar2 

Теперь давайте выполним команду с помощью метода Runtime.getRuntime() :

 String command = "curl -X POST https://postman-echo.com/post --data foo1=bar1&foo2=bar2";   Process process = Runtime.getRuntime().exec(command); 

Во-первых, мы снова создаем экземпляр класса Process , но на этот раз с помощью Runtime.getRuntime() . Мы можем получить InputStream , как и в предыдущем примере, вызвав метод getInputStream() :

Когда экземпляр больше не нужен, мы должны освободить системные ресурсы, вызвав метод destroy() .

4. Вывод​

В этой статье мы показали два способа использования curl в Java.

Этот и другие примеры кода доступны на GitHub.

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