First of all, thanks for the great essence articles on many editions, so that I can learn a lot of information as a rookie and complete this program
The following is a brief introduction to how HttpURLConnection accesses the server from the App
1. If you are establishing a server , the IP address used below only needs to change the location where the files are stored later. If it is not a local server, you can directly change it to the physical IP address of the server.
2. The HttpURLConnection object needs to be executed in a thread . The following program code can be directly copied to your Class and used. In the new Thread subroutine, the thread has been used, and there is no need to write another program to process it.
3. At the end of the thread, you must remember .start(); so as not to debug for a long time and have not found the problem, it turns out that you forgot to start, which is stupid
private void getJSON()
{
new Thread(new Runnable() {
@Override
public void run() {
//default IP address
String host = "http://10.0.2.2/SelectData.php";
//Create HttpURLConnection object
HttpURLConnection conn = null;
try
{
//Check if the thread is normal
if(Thread.interrupted()) throw new InterruptedException();
//set the link
URL url = new URL(host);
// open the link
conn = (HttpURLConnection) url.openConnection();
//Set the read link time, here is set to 10 seconds
conn.setReadTimeout(10000);
//Set the online link time, here is set to 15 seconds
conn.setConnectTimeout(15000);
//Use GET method to get data
conn.setRequestMethod("GET");
//URL connections can be used for input and/or output. Set the DoInput flag to true if you intend to use the URL connection for input; if you do not intend to use it, set it to false. The default value is true.
conn.setDoInput(true);
//connect to the server
conn.connect();
//Check if the thread is normal
if(Thread.interrupted()) throw new InterruptedException();
// load data with buffer
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
// read JSON line by line
String jsonString = reader.readLine();
// print JSON information
Log.d("jsonStr",jsonString);
//close the object
reader.close();
}
catch (Exception e)
{
// there is an error, throw an exception
e.printStackTrace ();
}
finally
{
//If the connection is successful, finally close the connection
if(conn != null) conn.disconnect();
}
}
//finally start the thread
}).start();
}