Take this example.
import java.io.InputStreamReader; import java.io.Reader; import java.net.URL; import java.net.URLConnection; public class HttpConnect { public static void main(String[] args) throws Exception { URL url = new URL("http://www.rgagnon.com/howto.html"); URLConnection con = url.openConnection(); Reader reader = new InputStreamReader(con.getInputStream()); while (true) { int ch = reader.read(); if (ch==-1) { break; } System.out.print((char)ch); } } }
The above snippet reads the HTML page and dumps it to the console.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML><HEAD> <!-- developpe par Real Gagnon, Quebec Canada --> <LINK REL="SHORTCUT ICON" HREF="http://www.maixuanviet.com/favicon.ico"> <META NAME="description" Content="Real's JAVA JAVASCRIPT WSH and PowerBuilder How-to pages with useful code snippets"> <META NAME="keywords" Content="java,javascript,wsh,vbscript,how-to,powerbuilder"> <LINK title="mystyle" href="howto.css" type="text/css" rel="stylesheet"> ...
To trace what is going on at the HTTP protocol level, we can switch the HttpURLConnection/UrlConnection in debug mode.
You must enable the java-logging mechanism by setting a special property when starting the JVM :
java.exe -Djava.util.logging.config.file=logging.properties HttpConnect
and put in logging.properties file (by default in JRE_HOME\lib) the following property
sun.net.www.protocol.http.HttpURLConnection.level = ALL
Note :
If running from Eclipse, you put the -Djava.util.logging… via the Run configuration dialog -> Arguments Tab -> VM arguments textarea.
The result is :
2010-08-07 00:00:31 sun.net.www.protocol.http.HttpURLConnection writeRequests FIN: sun.net.www.MessageHeader@16caf435 pairs: {GET /howto.html HTTP/1.1: null}{User-Agent: Java/1.6.0_20}{Host: www.maixuanviet.com}{Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2}{Connection: keep-alive} 2010-08-07 00:00:31 sun.net.www.protocol.http.HttpURLConnection getInputStream FIN: sun.net.www.MessageHeader@5ac0728 pairs: {null: HTTP/1.1 200 OK}{Date: Sat, 07 Aug 2010 04:00:33 GMT}{Server: Apache}{Accept-Ranges: bytes}{Content-Length: 17912}{Keep-Alive: timeout=5, max=64}{Connection: Keep-Alive}{Content-Type: text/html} <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML><HEAD> <!-- developpe par Real Gagnon, Quebec Canada --> <LINK REL="SHORTCUT ICON" HREF="http://www.maixuanviet.com/favicon.ico"> <META NAME="description" Content="Real's JAVA JAVASCRIPT WSH and PowerBuilder How-to pages with useful code snippets"> ...
Done! Happy Coding!
Related posts:
Java Perform to a 2D FFT Inplace Given a Complex 2D Array
Java Program to Perform Right Rotation on a Binary Search Tree
Encode/Decode to/from Base64
Simultaneous Spring WebClient Calls
Hướng dẫn Java Design Pattern – Singleton
Java Program to Check Multiplicability of Two Matrices
Jackson Ignore Properties on Marshalling
Reactive WebSockets with Spring 5
Java Program to Check Whether Topological Sorting can be Performed in a Graph
Giới thiệu Java 8
Java equals() and hashCode() Contracts
Introduction to Eclipse Collections
Java Program to Create a Random Linear Extension for a DAG
Java Program to Implement the RSA Algorithm
Java Program to Implement Weight Balanced Tree
Java Program to implement Priority Queue
Using a Mutex Object in Java
Binary Numbers in Java
Spring MVC Tutorial
The Guide to RestTemplate
Java Program to Remove the Edges in a Given Cyclic Graph such that its Linear Extension can be Found
Java Program to Implement Adjacency List
Java Program to Find Nearest Neighbor for Static Data Set
Java Program to Permute All Letters of an Input String
Spring Boot - Google OAuth2 Sign-In
Spring Security with Maven
Java Program to Implement Cartesian Tree
The SpringJUnitConfig and SpringJUnitWebConfig Annotations in Spring 5
Introduction to Using FreeMarker in Spring MVC
Spring Security Login Page with React
Bootstrapping Hibernate 5 with Spring
Java Program to Implement Traveling Salesman Problem using Nearest neighbour Algorithm