使用URLConnction发送HTTP/HTTPS请求

在java原生包中提供两种方式来模拟客户端发送http/https请求，第一种是httpClient；第二种是URLConnction。今天我们使用URLConnction来实现一下。

前提

首先我们要知道发送http/https请求的前提是什么，发送http请求需要我们构造request的几个必要的参数。第一个URL，第二个http的一些属性设值，比如ContentType、Method、Connection、userAgent等等。

使用GET方式请求

public static void get()throws Exception{
URL requestURI=new URL("https://www.baidu.com");
HttpsURLConnection conn=(HttpsURLConnection)requestURI.openConnection();//如果是https的请求则是HttpsURLConnection，如果是http则是HttpURLConnection
conn.setRequestMethod("GET");//设置请求方式
conn.setDoInput(true);//打开input流
conn.setRequestProperty("Connection","keep-alive");
conn.setRequestProperty("charset", "UTF-8");
conn.setRequestProperty("Accept", "*/*");
conn.setRequestProperty("Content-Type","text/html");
conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.89 Safari/537.36");
InputStream input=null;
BufferedReader reader=null;
StringBuffer result=new StringBuffer("");

input=conn.getInputStream();
reader=new BufferedReader(new InputStreamReader(input));
String temp=null;
while((temp=reader.readLine())!=null){
result.append(temp);
}
reader.close();
input.close();
System.out.println(result);

}

使用POST方式带参数请求

public static void post() throws Exception{
URL url=new URL("http://localhost:8080/VrSite/user/checkUser");
HttpURLConnection conn=(HttpURLConnection)url.openConnection();
conn.setRequestMethod("POST");
conn.setDoInput(true);
conn.setDoOutput(true);//上传参数，需要打开output流，将参数写到流中提交
conn.setRequestProperty("Connection","keep-alive");
conn.setRequestProperty("charset", "UTF-8");
conn.setRequestProperty("Accept", "*/*");
conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.89 Safari/537.36");
StringBuffer params=new StringBuffer();
params.append("userName=user&password=123456");
byte[] bytes=params.toString().getBytes();
conn.getOutputStream().write(bytes);

InputStream input=conn.getInputStream();
BufferedReader reader=new BufferedReader(new InputStreamReader(input));
String result="";
String temp="";
while((temp=reader.readLine())!=null){
result+=temp;
}
System.out.println(result);
}