java，用post方法提交数据，并且从服务器返回结果。

最新推荐文章于 2021-02-16 07:37:12 发布

原创最新推荐文章于 2021-02-16 07:37:12 发布 · 2k 阅读

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本文展示了如何使用Java进行HTTP POST请求，发送数据到服务器并接收返回的结果。客户端代码示例详细说明了这一过程。

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一下是客户端的代码：

//使用post向服务器提交数据。
public class HttpUtil {

	//private static String Path = "http://172.17.32.86:8080/TestServer/servlet/testServlet";
	private static String Path = "http://192.168.3.2:8080/TestServer/servlet/testServlet";

	private static URL url;

	public HttpUtil() {

	}

	static {
		try {
			url = new URL(Path);
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static String sendPostMessage(Map<String, String> params,
			String encode) {
		StringBuffer sb = new StringBuffer();
		if (params != null && !params.isEmpty()) {
			for (Map.Entry<String, String> entry : params.entrySet()) {
				try {
					sb.append(entry.getKey())
							.append("=")
							.append(URLEncoder.encode(entry.getValue(), encode))
							.append("&");
				} catch (UnsupportedEncodingException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			sb.deleteCharAt(sb.length() - 1);// 删除最后一个&
			System.out.println(sb.toString());
			try {
				HttpURLConnection connection = (HttpURLConnection) url
						.openConnection();
				connection.setConnectTimeout(3000);
				connection.setDoInput(true);// 表示从服务器获取数据
				connection.setDoOutput(true);// 表示想服务器写入数据
				byte[] data = sb.toString().getBytes();// 字符数字变成字节数组
				// 表示设置的请求体是文本类型
				connection.setRequestProperty("Content-Type",
						"application/x-www-form-urlencoded");
				connection.setRequestProperty("Content-Length",
						String.valueOf(data.length));
				//获得输出流，向服务器输出数据
				OutputStream outputStream = connection.getOutputStream();
				outputStream.write(data);
				int code = connection.getResponseCode();
				if (code == 200) {
					System.out.println("code====="+code);
					return changeInputStream(connection.getInputStream(),
							encode);
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return "";
	}

	/**
	 * 将一个输入流转换为指定编码的字符串
	 * 
	 * @param inputStream
	 * @param encode
	 * @return
	 */
	private static String changeInputStream(InputStream inputStream,
			String encode) {
		// TODO Auto-generated method stub
		//创建一个内存字节流
		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
		byte[] data = new byte[1024];
		int len = 0;
		String result=null;
		if (inputStream != null) {
			try {
				while ((len = inputStream.read(data)) != -1) {
					outputStream.write(data, 0, len);
				}
				//将字节转换为字符串
				result = new String(outputStream.toByteArray(), encode);
				System.out.println("result=============="+result);
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		}
		return result;
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Map<String, String> params = new HashMap<String, String>();
		params.put("username", "admin");
		params.put("password", "1234");
		sendPostMessage(params, "utf-8");
	}

}

一下是服务器端的servlet，以上是客户端把数据提交给了这个servlet。

public class testServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		String usernameString = request.getParameter("username");
		String password = request.getParameter("password");
		System.out.println("=========" + password);
		if (usernameString.equals("admin") && password.equals("1234")) {
			out.print("login success");
		}
		out.close();
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);
	}

}