项目搭建

pom文件引入依赖与打包配置。

<dependencies>
        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.16.2</version>
        </dependency>

    </dependencies>

    <packaging>war</packaging>
    <build>
        <finalName>hello</finalName>
    </build>

目录结构创建。

web.xml写入配置。

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app></web-app>

idea配置tomcat。

接口使用

import com.fasterxml.jackson.databind.json.JsonMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/test")
public class HelloServlet extends HttpServlet {
    long count = 0;

    @Override
    public void init() throws ServletException {
        new Thread(() -> {
            while (true) {
                count++;
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        System.out.println("username = " + username + ", password = " + password);
        resp.setContentType("text/html; charset=utf8");
        resp.setStatus(200);
        resp.setHeader("refresh", "1");
        resp.getWriter().write("success " + count);
    }

    static class Customer {
        public String username;
        public String password;
    }

    static class ResponseMessage {
        public Integer status;
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        JsonMapper jsonMapper = new JsonMapper();
        // 入参映射转换
//        Customer customer = jsonMapper.readValue(req.getInputStream(), Customer.class);
        // 读取入参报文
        StringBuilder request = new StringBuilder();
        // 读取方式一
//        String line;
//        while ((line = req.getReader().readLine()) != null) {
//            request.append(line);
//        }
        // 读取方式二
        byte[] requestBuffer = new byte[1024];
        int length;
        while ((length = req.getInputStream().read(requestBuffer, 0, requestBuffer.length)) > 0) {
            request.append(new String(requestBuffer, 0, length));
        }
        // 组织出参报文
        resp.setContentType("application/json; charset=utf8");
        resp.setStatus(200);
        ResponseMessage responseMessage = new ResponseMessage();
        responseMessage.status = 200;
        String response = jsonMapper.writeValueAsString(responseMessage);
        resp.getWriter().write(response);
        System.out.println("request: " + request + "\n" + "response: " + response);
    }
}