Could someone explain what this piece of codes means

Question

The code section is below there are few things I don't get about this code:
1:What does all that stuff that the string data equals means
// Construct data
        String data = URLEncoder.encode("key1", "UTF-8") + "=" + URLEncoder.encode("value1", "UTF-8");
        data += "&" + URLEncoder.encode("key2", "UTF-8") + "=" + URLEncoder.encode("value2", "UTF-8");2: The second thing is that I'm wondering what is the URL definining part mean, more specifically what's the 80 for and why is there that cgi line.
URL url = new URL("http://hostname:80/cgi");This is the full code that I'm getting the questions from
    try {
        // Construct data
        String data = URLEncoder.encode("key1", "UTF-8") + "=" + URLEncoder.encode("value1", "UTF-8");
        data += "&" + URLEncoder.encode("key2", "UTF-8") + "=" + URLEncoder.encode("value2", "UTF-8");
        // Send data
        URL url = new URL("http://hostname:80/cgi");
        URLConnection conn = url.openConnection();
        conn.setDoOutput(true);
        OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
        wr.write(data);
        wr.flush();
        // Get the response
        BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        while ((line = rd.readLine()) != null) {
            // Process line...
        wr.close();
        rd.close();
    } catch (Exception e) {
    }

Answer 1

The code section is below there are few things I
don't get about this code:
1:What does all that stuff that the string data
equals means
// Construct data
String data = URLEncoder.encode("key1",
"UTF-8") + "=" + URLEncoder.encode("value1",
"UTF-8");
data += "&" + URLEncoder.encode("key2",
"UTF-8") + "=" + URLEncoder.encode("value2",
"UTF-8");
Looks like data is a query string for an HTTP GET request. It has two key/value pairs encoded as UTF-8.
: The second thing is that I'm wondering what is the
URL definining part mean, more specifically what's
the 80 for and why is there that cgi line.
URL url = new
URL("http://hostname:80/cgi");
The code is making the HTTP GET request to a server named hostname via port 80 to a CGI script that will consume the request and send a response back.
This is the full code that I'm getting the questions
from
    try {
// Construct data
String data = URLEncoder.encode("key1", "UTF-8") +
"=" + URLEncoder.encode("value1", "UTF-8");
data += "&" + URLEncoder.encode("key2",
"UTF-8") + "=" + URLEncoder.encode("value2",
"UTF-8");
// Send data
URL url = new URL("http://hostname:80/cgi");
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter wr = new
OutputStreamWriter(conn.getOutputStream());
wr.write(data);
wr.flush();
// Get the response
BufferedReader rd = new BufferedReader(new
InputStreamReader(conn.getInputStream()));
String line;
while ((line = rd.readLine()) != null) {
// Process line...
wr.close();
rd.close();
} catch (Exception e) {
Very bad code. An empty catch block? Terrible.
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