本文目录一览：
- 1、如何使用HttpClient包实现JAVA发起HTTP请求
- 2、怎样用JAVA实现模拟HTTP请求，得到服务器的响应时间等参数
- 3、怎样编写http请求的java程序
- 4、怎么用java模拟http请求
如何使用HttpClient包实现JAVA发起HTTP请求
public class HttpClientUtil {
public static String doGet(String url, MapString, String param) {
// 创建Httpclient对象
CloseableHttpClient httpclient = HttpClients.createDefault();
String resultString = "";
CloseableHttpResponse response = null;
try {
// 创建uri
URIBuilder builder = new URIBuilder(url);
if (param != null) {
for (String key : param.keySet()) {
builder.addParameter(key, param.get(key));
}
}
URI uri = builder.build();
// 创建http GET请求
HttpGet httpGet = new HttpGet(uri);
// 执行请求
response = httpclient.execute(httpGet);
// 判断返回状态是否为200
if (response.getStatusLine().getStatusCode() == 200) {
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (response != null) {
response.close();
}
httpclient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
public static String doGet(String url) {
return doGet(url, null);
}
public static String doPost(String url, MapString, String param) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建参数列表
if (param != null) {
ListNameValuePair paramList = new ArrayList();
for (String key : param.keySet()) {
paramList.add(new BasicNameValuePair(key, param.get(key)));
}
// 模拟表单
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
httpPost.setEntity(entity);
}
// 执行http请求
response = httpClient.execute(httpPost);
System.out.println(response.getStatusLine());
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
System.out.println(resultString);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return resultString;
}
public static String doPost(String url) {
return doPost(url, null);
}
public static String doPostJson(String url, String json) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建请求内容
StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
httpPost.setEntity(entity);
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return resultString;
}
}
怎样用JAVA实现模拟HTTP请求，得到服务器的响应时间等参数
java.net.*;
public class HttpDemo{
public static void main(String[] args)throws Exception{
URL url = new URL('地址');
HttpURLConnection http = (HttpURLConnection)url.openConnection();
//获取网页的源码
BufferedReader br = new BufferedReader(new InputStreamReader(http.getInputStream()));
String line = "";
while((line=br.readLine())!=null){
System.out.println(line);
}
br.close();
//获取参数：
String value = getRequestProperty(String key);
}
}
怎样编写http请求的java程序
目前web上的消息通讯方式主要有以下几种。轮询，长连接，websocket轮询：隔一段时间访问服务器，服务器不管有没有新消息都立刻返回。长连接：页面向服务器发出请求，由服务器决定什么时候返回。（如果有新消息则立刻返回，没有的话就保持连接，直到有新消息才返回）websocket：类似JavaSocket，由Http请求模拟实现的socket。要实现长连接的关键就是：由服务器端决定什么时候返回数据。比如在servlet中。doGet(){Thread.sleep(30000);return}这就是一个长连接的例子，只是没有任何意义而已。你要做的就是在doGet中阻塞住，while(!hasNewMsg){sleep(500)}returnnewMsg当然你的ajax超时时间要设置长一点。如果可以的话，最好可以使用websocket。
怎么用java模拟http请求
/*
* 得到返回的内容
*/
public static String getResult(String urlStr, String content) {
URL url = null;
HttpURLConnection connection = null;
try {
url = new URL(urlStr);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setRequestMethod("POST");
connection.setUseCaches(false);
connection.connect();
DataOutputStream out = new DataOutputStream(connection.getOutputStream());
out.writeBytes(content);
out.flush();
out.close();
BufferedReader reader = new BufferedReader(new InputStreamReader(connection
.getInputStream(), "utf-8"));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
reader.close();
return buffer.toString();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
}
return null;
}
追问：
没注释吗？
追答：
/*
* 得到返回的内容
*/
public static String getResult(String urlStr, String content) {
URL url = null;
HttpURLConnection connection = null;
try {
url = new URL(urlStr);
connection = (HttpURLConnection) url.openConnection();//新建连接实例
connection.setDoOutput(true);//是否打开输出流 true|false
connection.setDoInput(true);//是否打开输入流true|false
connection.setRequestMethod("POST");//提交方法POST|GET
connection.setUseCaches(false);//是否缓存true|false
connection.connect();//打开连接端口
DataOutputStream out = new DataOutputStream(connection.getOutputStream());//打开输出流往对端服务器写数据
out.writeBytes(content);//写数据,也就是提交你的表单 name=xxxpwd=xxx
out.flush();//刷新
out.close();//关闭输出流
BufferedReader reader = new BufferedReader(new InputStreamReader(connection
.getInputStream(), "utf-8"));//往对端写完数据 对端服务器返回数据 ,以BufferedReader流来读取
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
reader.close();
return buffer.toString();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();//关闭连接
}
}
return null;
}
