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java 如何请求servlet

2026-03-25 17:04:45Java

请求 Servlet 的步骤

使用 HttpURLConnection 发送 GET 请求

创建一个 URL 对象并打开连接，设置请求方法为 GET。通过 InputStream 读取响应数据。

URL url = new URL("http://example.com/YourServlet");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");

int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
    BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
    String inputLine;
    StringBuilder response = new StringBuilder();
    while ((inputLine = in.readLine()) != null) {
        response.append(inputLine);
    }
    in.close();
    System.out.println(response.toString());
}

使用 HttpURLConnection 发送 POST 请求

设置请求方法为 POST，并启用输出流。通过 OutputStream 发送请求参数。

URL url = new URL("http://example.com/YourServlet");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);

String postData = "param1=value1&param2=value2";
try (OutputStream os = connection.getOutputStream()) {
    byte[] input = postData.getBytes(StandardCharsets.UTF_8);
    os.write(input, 0, input.length);
}

int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
    BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
    String inputLine;
    StringBuilder response = new StringBuilder();
    while ((inputLine = in.readLine()) != null) {
        response.append(inputLine);
    }
    in.close();
    System.out.println(response.toString());
}

使用 Apache HttpClient 发送请求

java 如何请求servlet

添加 Maven 依赖后，使用 CloseableHttpClient 发送请求。

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>

发送 GET 请求：

CloseableHttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://example.com/YourServlet");

CloseableHttpResponse response = httpClient.execute(httpGet);
try {
    HttpEntity entity = response.getEntity();
    if (entity != null) {
        String result = EntityUtils.toString(entity);
        System.out.println(result);
    }
} finally {
    response.close();
}

发送 POST 请求：

java 如何请求servlet

CloseableHttpClient httpClient = HttpClients.createDefault();
HttpPost httpPost = new HttpPost("http://example.com/YourServlet");

List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("param1", "value1"));
params.add(new BasicNameValuePair("param2", "value2"));
httpPost.setEntity(new UrlEncodedFormEntity(params));

CloseableHttpResponse response = httpClient.execute(httpPost);
try {
    HttpEntity entity = response.getEntity();
    if (entity != null) {
        String result = EntityUtils.toString(entity);
        System.out.println(result);
    }
} finally {
    response.close();
}

使用 Servlet 处理请求

在 Servlet 中重写 doGet 或 doPost 方法处理请求。

@WebServlet("/YourServlet")
public class YourServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String param1 = request.getParameter("param1");
        response.setContentType("text/plain");
        PrintWriter out = response.getWriter();
        out.println("Received param1: " + param1);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String param1 = request.getParameter("param1");
        response.setContentType("text/plain");
        PrintWriter out = response.getWriter();
        out.println("Received param1: " + param1);
    }
}

注意事项

确保 Servlet 已正确配置并在 web.xml 中映射或使用 @WebServlet 注解。检查 URL 是否正确指向 Servlet 路径。处理异常情况，如连接超时或服务器错误。