Normal download and URLConnection 6 (64), urlconnection64

Normal download and URLConnection 6 (64), urlconnection64

Normal download

When the service uses breakpoint download, the response information is 206.

UrlConnection-HttpurlConnection. -Obtain the urlconnection instance through URL.

Normal download example

Package cn. demo; import java. io. fileOutputStream; import java. io. inputStream; import java. io. outputStream; import java. math. bigDecimal; import java.net. httpURLConnection; import java.net. URL; public class CommonDown {public static void main (String [] args) throws Exception {String path = "http: // localhost: 6666/day22_cos/up/video. avi "; URL url = new URL (path); HttpURLConnection con = (HttpURLConnection) u Rl. openConnection (); con. setRequestMethod ("GET"); con. setDoInput (true); con. connect (); int code = con. getResponseCode (); System. err. println (code); if (code = 200) {// obtain the file size long size = con. getContentLength (); System. err. println ("total size:" + size); // declare the downloaded byte long sum = 0; BigDecimal bd = new BigDecimal (0D); double already = 0D; inputStream in = con. getInputStream (); byte [] B = new byte [1024]; int len = -1; OutputStream out = new FileOutputStream ("d:/a/video. avi"); while (len = in. read (B ))! =-1) {out. write (B, 0, len); sum = sum + len; double percent = (double) sum)/(double) size); percent * = 100; bd = new BigDecimal (percent); bd = bd. divide (new BigDecimal (1), 0, BigDecimal. ROUND_HALF_UP); if (bd. doubleValue ()! = Already) {System. err. println (bd. intValue () + "%"); already = bd. doubleValue () ;}} out. close ();}}}

 

2. URLConnection

This class is used to simulate a browser in java code to form an http protocol to send a request (get/post) to the service ).

 

Code: package cn. hx; import java. io. IOException; import java. io. printWriter; import javax. servlet. servletException; import javax. servlet. http. httpServlet; import javax. servlet. http. httpServletRequest; import javax. servlet. http. httpServletResponse; public class OneServlet extends HttpServlet {public void doGet (HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {String name = request. getParameter ("name"); System. err. println ("this is get," + name); resp. setContentType ("text/html; charset = UTF-8"); resp. getWriter (). print ("Hello:" + name);} public void doPost (HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {request. setCharacterEncoding ("UTF-8"); String name = request. getParameter ("name"); System. err. println ("this is a post request ....... "+ name); resp. setContentType ("text/html; charset = UTF-8"); resp. getWriter (). print ("Hello:" + name );}}

 

 

 

Use urlconnection to access oneSerlvet

 

Package cn. demo; import java. io. file; import java. io. inputStream; import java. io. outputStream; import java.net. httpURLConnection; import java.net. URL; import org. junit. test; public class Demo {/*** send get request * @ throws Exception */@ Test public void testConn () throws Exception {// Step 1: declare url String urlPath = "http: // localhost: 6666/day22_cos/OneServlet? Name = Jack "; // Step 2: declare the URL object URL = new url (urlPath); // Step 3: Obtain the link HttpURLConnection con = (HttpURLConnection) URL from the url. openConnection (); // Step 4: Set the access type con. setRequestMethod ("GET"); // Step 5: send messages to the server. You can also receive information con from the server. setDoInput (true); // You can also receive information con from the server. setDoOutput (true); // you can send messages to the server. // Step 6: connect to con. connect (); // 7: Check the connection status int code = con. getResponseCode (); if (code = 200) {// 8: read data from the server InputStream in = con. getInputStream (); byte [] B = new byte [1024]; int len = 0; while (len = in. read (B ))! =-1) {String s = new String (B, 0, len, "UTF-8"); System. err. print (s) ;}// 9: disconnect con. disconnect ();}/*** send post request below */@ Test public void post () throws Exception {// Step 1: declare url String urlPath = "http: // localhost: 6666/day22_cos/OneServlet "; // Step 2: declare the URL object URL = new url (urlPath); // Step 3: obtain the link HttpURLConnection con = (HttpURLConnection) url from the url. openConnection (); // Step 4: Set the access type con. setRequestMethod ("POST "); Con. setRequestProperty ("Content-Type", "application/x-www-form-urlencoded"); // Step 5: Set to send messages to the server. You can also receive information con from the server. setDoInput (true); // you can send a message con to the server. setDoOutput (true); // You can also receive information from the server. // Step 6: send information // obtain the output stream OutputStream out = con. getOutputStream (); out. write ("name = James ". getBytes ("UTF-8"); // 7: Check the connection status int code = con. getResponseCode (); if (code = 200) {// 8: read data from the server InputStream in = con. getInputStream (); byte [] B = new byte [1024]; int len = 0; while (len = in. read (B ))! =-1) {String s = new String (B, 0, len, "UTF-8"); System. err. print (s) ;}// 9: disconnect con. disconnect ();}}