文章目录

正确示例

使用字符输入流的方式来读取请求参数

  • html
    	<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
<script src="https://unpkg.com/axios/dist/axios.min.js"></script>
<script>
    window.onload = function () {
        axios({
            method: "post",
            url: "http://localhost:8080/ajax-test/test",
            data: {
                people: {
                    name: '张三',
                    age: 18
                }
            }
        }).then(function (resp) {
            console.log(resp)
        })
    }
</script>
</body>

</html>
  • servlet
    @WebServlet("/test")
public class AxiosTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf8");
        System.out.println(req.getReader().readLine());
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}
  • 控制台输出
    {"people":{"name":"张三","age":18}}

错误示例

  • 如果servlet中是通过getParameter()来获取请求参数，是获取不到的

    @WebServlet("/test")
public class AxiosTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf8");
        Object people = req.getParameter("people");
        System.out.println(people);  // 输出结果是 null
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}

  • 原因：
    getParameter()获取的是请求头中的参数，而post请求的数据被封装在了请求体中
    使用axios时，会将数据变成json字符串，并通过字节流传递（服务器通过字节流接收），并且只有一行

  • 如果希望使用getParameter()来获取参数，并且请求的方式仍然是post，可以将参数放到url中
    例如：

    • axios:
       axios({
     method: "post",
     url: "http://localhost:8080/ajax-test/test?msg=hello",
     data: {
         people: {
             name: '张三',
             age: 18
         }
     }
 }).then(function (resp) {
     console.log(resp)
 })
    • servlet
      @WebServlet("/test")
public class AxiosTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf8");
        System.out.println(req.getParameter("msg"));
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}
    • 控制台输出
      hello
      在这里插入图片描述
# servlet # java # 前端
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