Rhythmk 一步一步学 JAVA (22) JAVA 网络编程
1、获取主机信息
@Testpublic void GetDomainInfo() throws UnknownHostException {
String domain = "www.baidu.com";
InetAddress netAddress = InetAddress.getByName(domain);
// 获取主机名
System.out.println(netAddress.getHostName());
// IP地址
System.out.println(netAddress.getCanonicalHostName());
InetAddress ip2domain = InetAddress.getByAddress(new byte[] {
(byte) 115, (byte) 239, (byte) 210, (byte) 26 });
System.out.println(ip2domain.getCanonicalHostName());
System.out.println(ip2domain.getHostName());
/*
* 输出: www.baidu.com 115.239.210.26 115.239.210.26 115.239.210.26
*/
}
2、URLEncode 跟 URLDecoder
// URLDecoder和URLEncoder@SuppressWarnings("deprecation")
@Test
public void URLEncode() {
String result = URLEncoder.encode("我是Rhythmk,你呢?");
System.out.println(result);
// 输出:
// %E6%88%91%E6%98%AFRhythmk%2C%E4%BD%A0%E5%91%A2%EF%BC%9F
}
@Test
public void URLDecoder() {
String result = java.net.URLDecoder
.decode("%E6%88%91%E6%98%AFRhythmk%2C%E4%BD%A0%E5%91%A2%EF%BC%9F");
System.out.println(result);
/*
* 输出: 我是Rhythmk,你呢?
*/
}
3、POST GET 请求
@Testpublic void Get() throws IOException {
URLConnection urlConnect;
URL url = new URL("http://www.baidu.com");
urlConnect = url.openConnection();
BufferedReader biStream = null;
try {
urlConnect.connect();
Map<String, List<String>> map = urlConnect.getHeaderFields();
for (String key : map.keySet()) {
List<String> listKey = map.get(key);
for (String k : listKey) {
System.out.println("*****************" + k);
}
}
biStream = new BufferedReader(new InputStreamReader(
urlConnect.getInputStream()));
String html = "";
String line = null;
while ((line = biStream.readLine()) != null) {
html += line;
}
System.out
.println("************************* HTML 内容 ***********************");
System.out.println(html);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (biStream != null) {
biStream.close();
}
}
}
@Test
public void Post() throws IOException {
BufferedReader biStream = null;
try {
URL url = new URL("http://passport.rhythmk.com/signin");
URLConnection urlConnect = url.openConnection();
// 设置通用的请求属性
urlConnect.setRequestProperty("accept", "*/*");
urlConnect.setRequestProperty("connection", "Keep-Alive");
urlConnect.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 发送POST请求必须设置如下两行 ,需要在connect 之前设定好
urlConnect.setDoOutput(true);
urlConnect.setDoInput(true);
urlConnect.connect();
// 获取URLConnection对象对应的输出流
PrintWriter out = new PrintWriter(urlConnect.getOutputStream());
// 发送请求参数
out.print("returnUrl=http%3A%2F%2Fwww.ciwong.com%2F&username=a&password=d");
// flush输出流的缓冲
out.flush();
biStream = new BufferedReader(new InputStreamReader(
urlConnect.getInputStream()));
String html = "";
String line = null;
while ((line = biStream.readLine()) != null) {
html += line;
}
System.out
.println("************************POST* HTML 内容 ***********************");
System.out.println(html);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (biStream != null) {
biStream.close();
}
}
}
注意:
如果先
urlConnect.connect();
然后如下设置
urlConnect.setDoOutput(true);
urlConnect.setDoInput(true);
导致异常:
java.lang.IllegalStateException: Already connected
at java.net.URLConnection.setDoOutput(URLConnection.java:849)
at com.rhythmk.filedemo.net_demo1.Post(net_demo1.java:126) ....
以上是 Rhythmk 一步一步学 JAVA (22) JAVA 网络编程 的全部内容, 来源链接: utcz.com/z/393195.html