HttpURLConnection的get和post请求实例

public class DemoConnection02 {

/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
String path = "图片路径";
//1, 得到URL对象
URL url = new URL(path);

//2, 打开连接
HttpURLConnection conn = (HttpURLConnection) url.openConnection();

//3, 设置提交方式
conn.setRequestMethod("GET");

//4, 获取响应信息
if(conn.getResponseCode() == 200)
{
InputStream is = conn.getInputStream();

byte[] buffer = new byte[1024];

int len = 0;

ByteArrayOutputStream baos = new ByteArrayOutputStream();

while ((len = is.read(buffer))!=-1) {

baos.write(buffer, 0, len);
}

//截取图片名称
String fileName = path.substring(path.lastIndexOf("/")+1);

FileOutputStream fos = new FileOutputStream("d:/"+fileName);

fos.write(baos.toByteArray());

fos.close();

System.out.println("图片下载成功!!!");
}

}

public static void main(String[] args) throws Exception {

String path = "http://localhost:8080/Day_28_Servlet/LoginServlet";

//1, 得到URL对象
URL url = new URL(path);

//2, 打开连接
HttpURLConnection conn = (HttpURLConnection) url.openConnection();

//3, 设置提交类型
conn.setRequestMethod("POST");

//4, 设置允许写出数据,默认是不允许 false
conn.setDoOutput(true);
conn.setDoInput(true);//当前的连接可以从服务器读取内容, 默认是true

//5, 获取向服务器写出数据的流
OutputStream os = conn.getOutputStream();
//参数是键值队  , 不以"?"开始
os.write("useName=abc&usePwd=123".getBytes());
os.flush();

//6, 获取响应的数据
if(conn.getResponseCode()==200)
{
//得到服务器写回的响应数据
InputStream is = conn.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String str = br.readLine();

System.out.println("响应内容为:  " + str);

}
}