The first step to downloading a file is to create an HTTP client object that would issue the request to the server. For this, we will be using the CloseableHttpClient class. The code snippet that creates a new HTTP client is as follows:. We then need to create an HttpGet or HttpPost object to send the request to the server.
The request is created by the following line of code:. The execute request function is applied to the client object and returns with a response from the server. Once the request is sent to the server we need a response object to receive the data sent from the server. To catch the response from the server we use the HttpResponse class object. The data sent by the server in the form of a message is obtained through the getEntity function.
You can also obtain the response code sent by the server through the response object and use it to your specific need. The data to be downloaded is encapsulated within the entity object and can be extracted using the getContent function. The getContent function returns an InputStream object that can be further used with a BufferedInputStreamReader to enhance performance. Now all you need to do is read from the stream byte by byte and write the contents into a file using the FileOutputStream class.
The last thing required to be done is closing all the open resources in order to ensure that the system resources are not overutilized and that there are no memory leaks. So there you have it - these are the simplest ways to download a file using the basic Java code and other third party libraries.
Now that we are done with the basics, you can be as creative as you want and utilize the knowledge to suit your needs. So see you next time with a new set of concepts to help you become a better coder. To be able to do this, you need to install the JDK. Depending on your processor, the downloaded file has one of the following names, where version is the update number:. From either the Downloads window of the browser, or from the file browser, double click the file.
A Finder window appears containing an icon of an open box and the name of the. A window appears that says, 'Java 8 Update 40 is trying to install a new helper tool. Type your password to allow this. Oracle has partnered with companies that offer various products. The installer may present you with the option to install these programs when you install Java. Specify if you want these programs installed and then click Next. An Installation Progress window is displayed.
Once the software is installed, a confirmation window appears and then an applet is launched to verify the version of Java installed. If you have not yet installed Apple's Java OS X update, then you are still using a version of Apple Java 6 that includes the plug-in and the Java Preferences app.
Only one JRE can be installed. The JRE version used by the system can be determined in one of two ways:. From System Preferences click the Java icon from the Other category. This launches the Java Control Panel. The flexibility of the Java Platform enables users to develop secure, innovative products while achieving enhanced cost savings and accelerated time to market. Oracle Java SE Embedded provides a development platform for embedded devices that offers industry-leading reliability, performance, throughput, security and cross-platform support.
To get started, download an eJDK bundle suitable for your target platform and follow instructions to create a JRE that suits your application's needs. Both the bit PPC platforms ev2 and e that were previously available, are no longer offered. Copy the appropriate Java install file to your computer. Administrator privileges.
Depending on your processor, the downloaded file has one of the following names: jdk-8u version -macosx-amd Download the file. Before the file can be downloaded, you must accept the license agreement.
0コメント