1.URL:统一资源定位符，对应着互联网的某一资源地址

2.格式：

http://localhost:8080/examples/beauty.jpg?username=Tom

协议　主机名　端口号　　　资源地址　　　　参数列表

url.getProtocol( )： 获取该URL的协议名
url.getHost( )： 获取该URL的主机名
url.getPort( )： 获取该URL的端口号
url.getPath( )： 获取该URL的文件路径
url.getFile( )： 获取该URL的文件名
url.getQuery( )： 获取该URL的查询名
　　　　

public class URLTest1 {

public static void main(String[] args) {

HttpURLConnection urlConnection = null;
InputStream is = null;
FileOutputStream fos = null;
try {
URL url = new URL("http://localhost:8080/examples/beauty.jpg");

urlConnection = (HttpURLConnection) url.openConnection();

urlConnection.connect();

is = urlConnection.getInputStream();
fos = new FileOutputStream("day10\\beauty3.jpg");

byte[] buffer = new byte[1024];
int len;
while((len = is.read(buffer)) != -1){
fos.write(buffer,0,len);
}

System.out.println("下载完成");
} catch (IOException e) {
e.printStackTrace();
} finally {
//关闭资源
if(is != null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(fos != null){
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(urlConnection != null){
urlConnection.disconnect();
}
}
}

public static void main(String[] args) {

HttpURLConnection urlConnection = null;
InputStream is = null;
FileOutputStream fos = null;
try {
URL url = new URL("http://localhost:8080/examples/beauty.jpg");

urlConnection = (HttpURLConnection) url.openConnection();

urlConnection.connect();

is = urlConnection.getInputStream();
fos = new FileOutputStream("day10\\beauty3.jpg");

byte[] buffer = new byte[1024];
int len;
while((len = is.read(buffer)) != -1){
fos.write(buffer,0,len);
}

System.out.println("下载完成");
} catch (IOException e) {
e.printStackTrace();
} finally {
//关闭资源
if(is != null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(fos != null){
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(urlConnection != null){
urlConnection.disconnect();
}
}
}
}