1. 测试InetAddress的简单用法
public class InetAddressTest
{
public static void main(String[] args) throws Exception
{
InetAddress ip = InetAddress.getByName("www.crazyit.org");
//IP字符串
System.out.println(ip.getHostAddress);
InetAddress local = InetAddress.getByAddress(new byte[] (127.0.0.1));
System.out.println("本机是否可达"+local.isReachable(5000));
//全限定域名
System.out.println(local.getCanonicalHostName());
}
}
2. 使用URLDecoder 和URLEncoder
public class URLDecoderTest
{
public static void main(String[] args) throws Exception
{
String keyWord = URLDecoder.decode("%E6%9D","UTF-8");
System.out.println(keyWord);
String urlStr = URLEncoder.encode("ROR敏捷开发最佳指南","GBK");
System.out.println(urlStr);
}
}
3 使用URL 和URLConnection
URL对象提供的openStream()可以读取该URL资源的InputStream,
通过该方法可以非常方便地读取远程资源---甚至实现多线程下载
class DownThread extends Thread
{
private final int BUFF_LEN = 32;
private long start;
private long end;
private InputStream is;
private RandomAccessFile raf;
public DownThread(long start,long end,InputStream is,RandomAccessFile raf)
{
System.out.println(start+"------->"+end);
this.start = start;
this.end = end;
this.is = is;
this.raf = raf;
}
public void run()
{
try
{
is.skip(start);
raf.seek(start);
byte[] buff = new byte[BUFF_LEN];
long contentLen =end-start;
long times = contentLen/BUFF_LEN + 4;
int hasRead = 0;
for(int i=0;i<times;i++)
{
hasRead = is.read(buff);
if(hasRead < 0)
{
break;
}
raf.write(buff,0,hasRead);
}
}
catch(Exception ex)
{
ex.printStackTrace();
}
finally
{
try
{
if(is != null)
{
is.close();
}
if(raf != null)
{
raf.close();
}
}
catch(Exception ex)
{
ex.printStackTrace();
}
}
}
}
public class MutilDown
{
public static void main(String[] args)
{
final int DOWN_THREAD_NUM = 4;
final String OUT_FILE_NAME = "down.jpg";
InputStream[] isArr = new InputStream[DOWN_THREAD_NUM];
RandomAccessFile[] outArr = new RandomAccessFile[DOWN_THREAD_NUM];
try
{
URL url = new URL("http://images.china-pub.com/shupi.jpg");
isArr[0] = url.openStream();
long fileLen = getFileLength(url);
System.out.println("网络资源的大小"+fileLen);
outArr[0] = new RandomAccessFile(OUT_FILE_NAME,"rw");
for(int i=0;i<fileLen;i++)
{
outArr[0].write(0);
}
long numPerThred = fileLen/DOWN_THREAD_NUM;
long left = fileLen % DOWN_THREAD_NUM;
for(int i=0;i<DOWN_THREAD_NUM;i++)
{
if(i !=0)
{
isArr[i] = url.openStream();
outArr[i] = new RandomAccessFile(OUT_FILE_NAME,"rw");
}
if(i = DOWN_THREAD_NUM-1)
{
new DownThread(i*numPerThred,(i+1)*numPerThred+left,isArr[i],outArr[i]).start();
}
else
{
new DownThread(i*numPerThred,(i+1)*numPerThred,isArr[i],outArr[i]).start();
}
}
}
catch(Exception ex)
{
ex.printStackTrace();
}
}
public static long getFileLength(URL url) throws Exception
{
long length=0;
URLConnection con = url.openConnection();
long size = con.getContentLength();
length = size;
return length;
}
}
4 向Web站点发送GET请求、POST请求，并从Web站点取得相应的示例
public class TestGetPost
{
public static String sendGet(String url,String param)
{
String result = "";
BufferedReader in = null;
try
{
String urlName = url + "?" +param;
URL realUrl = new URL(urlName);
URLConnection conn = realUrl.openConnection();
conn.setRequestProperty("accept","*/*");
conn.setRequestProperty("connection","Keep-Alive");
conn.setRequestProperty("user-agent","Mozilla/4.0 (compatible;MSIE 6.0;Windows NT 5.1;SV1)");
conn.connect();
Map<String, List<String>> map = conn.getHeaderFields();
for(String key : map.keySet())
{
System.out.println(key+"--->"+map.get(key));
}
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while((line = in.readLine())!=null)
{
result +="\n"+line;
}
}
catch(Exception e)
{
System.out.println("发送GET请求出现异常"+e);
e.printStackTrace();
}
finally
{
try
{
if(in != null)
{
in.close();
}
}
catch(IOException ex)
{
ex.printStackTrace();
}
}
return result;
}
}
public static String sendPost(String url,String param)
{
PrintWriter out = null;
BufferedReader in= null;
String result = "";
try
{
URL realUrl = new URL(url);
URLConnection conn = realUrl.openConnection();
conn.setRequestProperty("accept","*/*");
conn.setRequestProperty("connection","Keep-Alive");
conn.setRequestProperty("user-agent","Mozilla/4.0 (compatible;MSIE 6.0;Windows NT 5.1;SV1)");
conn.setDoOutput(true);
conn.setDoInput(true);
out = new PrintWriter(conn.getOutputStream());
out.print(param);
out.flush();
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while((line = in.readLine()) != null)
{
result + ="\n"+line;
}
}
catch(Exception e)
{
System.out.println("发送POST请求出现异常"+e);
e.printStackTrace();
}
finally
{
try
{
if(out != null)
{
out.close();
}
if(in !=null)
{
in.close();
}
}
catch(IOException ex)
{
ex.printStackTrace();
}
}
return result;
}
public static void main(String args[])
{
String s =TestGetPost.sendGet("http://localhost:8888/abc/login.jsp",null);
System.out.println(s);
String s1= TestGetPost.sendPost(http://localhost:8888/abc/a.jsp,"user=李刚&pass=abc");
System.out.println(s1);
}