AJAX

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AJAX | 拦截器、文件上传和下载

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Ajax即Asynchronous Javascript And XML（异步JavaScript和XML）；Ajax技术网页应用能够快速地将增量更新呈现在用户界面上，不需要重载（刷新）整个页面，使程序能够更快地回应用户的操作

伪造AJAX

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--自动扫描指定的包，下面所有的注解交给IOC容器管理-->
    <context:component-scan base-package="com.wei.controller"/>

    <!--静态资源过滤-->
    <mvc:default-servlet-handler/>

    <!--配置annotation-driven使：处理器映射器 和 处理器适配器 自动完成实例的注入-->
    <mvc:annotation-driven/>

    <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>

</beans>

AjaxController类

package com.wei.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@RestController
public class AjaxController {

    @RequestMapping("/t1")
    public String test(){
        return "hello";
    }

    @RequestMapping("/a1")
    public void a1(String name, HttpServletResponse response) throws IOException {
        System.out.println("a1:param=>"+name);
        if ("weishuo".equals(name)){
            response.getWriter().print("True");
        }else {
            response.getWriter().print("False");
        }
    }
}

test.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>iframe测试体验页面无刷新</title>
</head>
<body>

<div>
    <p>请输入地址:</p>
    <p>
        <input type="text" id="url" value="https://www.csdn.net/">
        <input type="button" value="提交" onclick="go()">
    </p>
</div>

<div>
    <iframe id="iframe" style="width: 100%;height: 500px"></iframe>
</div>

<script>
    function go(){
        var url = document.getElementById("url").value;
        document.getElementById("iframe").src=url;
    }
</script>
</body>
</html>

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: ws199
  Date: 2022/12/15
  Time: 17:02
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>

    <script src="${pageContext.request.contextPath}/statics/js/jquery-3.6.2.js"></script>

    <script>
        function a() {
            $.post({
                url: "${pageContext.request.contextPath}/a1",
                data: {"name": $("#username").val()},
                success: function (data,status) {
                    console.log("data=" + data);
                    console.log("status=" + status);
                }
            })
        }
    </script>
</head>
<body>

<%--失去焦点的时候，发起一个请求到后台--%>
用户名：<input type="text" id="username" οnblur="a()">

</body>
</html>

启动tomcat测试！打开浏览器的控制台，当我们鼠标离开输入框的时候，可以看到发出了一个ajax的请求

AJAX异步加载数据

user类

package com.wei.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private String name;
    private int age;
    private String sex;
}

AjaxController类

@RequestMapping("/a2")
public List<User> a2(){
    List<User> userList = new ArrayList<>();
    //添加数据
    userList.add(new User("wei_shuo",18,"男"));
    userList.add(new User("wei",17,"女"));
    userList.add(new User("shuo",8,"男"));
    return userList;
}

前端jsp页面

<%--
  Created by IntelliJ IDEA.
  User: ws199
  Date: 2022/12/17
  Time: 15:28
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script src="${pageContext.request.contextPath}/statics/js/jquery-3.6.2.js"></script>
    <script>
        $(function () {
            $("#btn").click(function () {
                $.post("${pageContext.request.contextPath}/a2", function (data) {
                    console.log(data)
                    var html = "";

                    for (let i = 0; i < data.length; i++) {
                        html += "<tr>" +
                            "<td>" + data[i].name + "</td>" +
                            "<td>" + data[i].age + "</td>" +
                            "<td>" + data[i].sex + "</td>" +
                            "</tr>"
                    }
                    $("#content").html(html);
                })
            })
        });
    </script>
</head>
<body>

<input type="button" value="加载数据" id="btn">

<table>
    <tr>
        <td>姓名</td>
        <td>年龄</td>
        <td>性别</td>
    </tr>
    <tbody id="content">
    <%--数据：后台--%>

    </tbody>
</table>
</body>
</html>

AJAX验证用户名

AjaxController类

@RequestMapping("/a3")
public String a3(String name, String pwd) {
    String msg = "";
    if (name != null) {
        if ("Admin".equals(name)) {
            msg = "OK";
        } else {
            msg = "用户名输入错误";
        }
    }

    if (pwd != null) {
        if ("123456".equals(pwd)) {
            msg = "OK";
        } else {
            msg = "密码输入错误";
        }
    }
    return msg;
}

<%--
  Created by IntelliJ IDEA.
  User: ws199
  Date: 2022/12/20
  Time: 9:01
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script src="${pageContext.request.contextPath}/statics/js/jquery-3.6.2.js"></script>
</head>
<body>

<p>
    用户名：<input type="text" id="name" οnblur="a1()">
    <span id="userInfo"></span>
</p>
<p>
    密码：<input type="text" id="pwd" οnblur="a2()">
    <span id="pwdInfo"></span>
</p>

<script>
    function a1() {
        $.post({
            url: "${pageContext.request.contextPath}/a3",
            data: {"name": $("#name").val()},
            success: function (data) {
                if (data.toString() === 'OK') {
                    $("#userInfo").css("color", "green");
                } else {
                    $("#userInfo").css("color", "red");
                }
                $("#userInfo").html(data);
            }
        })
    }

    function a2() {
        $.post({
            url: "${pageContext.request.contextPath}/a3",
            data: {"pwd": $("#pwd").val()},
            success: function (data) {
                if (data.toString() === 'OK') {
                    $("#pwdInfo").css("color", "green");
                } else {
                    $("#pwdInfo").css("color", "red");
                }
                $("#pwdInfo").html(data);
            }
        })
    }
</script>

</body>
</html>

AjaxController类

@RequestMapping("/a4")
public String a4(String name, String pwd) {
    String msg = "";
    if (name != null && pwd != null) {
        if ("Admin".equals(name) && "123456".equals(pwd)) {
            msg = "OK";
        } else {
            msg = "用户名或者密码输入错误";
        }
    }
    return msg;
}

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script src="${pageContext.request.contextPath}/statics/js/jquery-3.6.2.js"></script>
</head>
<body>

<p>
    用户名：<input type="text" id="name" οnblur="Login()">
    <span id="UserPwdInfo"></span>
</p>
<p>
    密码：<input type="text" id="pwd" οnblur="Login()">
</p>

<script>
    function Login() {
        $.post({
            url: "${pageContext.request.contextPath}/a4",
            data: {"name": $("#name").val(),"pwd":$("#pwd").val()},
            success: function (data) {
                if (data.toString() === 'OK') {
                    $("#UserPwdInfo").css("color", "green");
                } else {
                    $("#UserPwdInfo").css("color", "red");
                }
                $("#UserPwdInfo").html(data);
            }
        })
    }
</script>

</body>
</html>

拦截器

概述

SpringMVC的处理器拦截器类似于Servlet开发中的过滤器Filter,用于对处理器进行预处理和后处理。开发者可以自己定义一些拦截器来实现特定的功能

过滤器

servlet规范中的一部分，任何java web工程都可以使用

在url-pattern中配置了/*之后，可以对所有要访问的资源进行拦截

拦截器

拦截器是SpringMVC框架自己的，只有使用了SpringMVC框架的工程才能使用

拦截器只会拦截访问的控制器方法，如果访问的是jsp/html/css/image/js是不会进行拦截的

拦截器MyInterceptor类

package com.wei.config;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyInterceptor implements HandlerInterceptor {

    //在请求处理的方法之前执行
    //  return true 执行下一个拦截器
    //  return false 不执行下一个拦截器
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("======处理前======");
        return true;
    }

    //在请求处理方法执行之后执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("======处理后======");
    }

    //dispatcherServlet处理后执行,做清理工作
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("======清理======");
    }
}

applicationContext.xml拦截器配置

<!--拦截器配置-->
<mvc:interceptors>
    <mvc:interceptor>
        <!--/** 包括路径及其子路径-->
        <mvc:mapping path="/**"/>
        <!--bean配置的就是拦截器-->
        <bean class="com.wei.config.MyInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

TestController测试

@RestController
public class TestController {
    @GetMapping("t1")
    public String test(){
        System.out.println("TestController==Test");
        return "OK";
    }

结果

======处理前======
TestController==Test
======处理后======
======清理======

登录判断验证

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>

  <h1><a href="${pageContext.request.contextPath}/user/goLogin">登录页面</a></h1>
  <h1><a href="${pageContext.request.contextPath}/user/main">首页</a></h1>

  </body>
</html>

main.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

    <h1>首页</h1>
    <span>${username}</span>
    <p>
        <a href="${pageContext.request.contextPath}/user/goOut">注销</a>
    </p>
</body>
</html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>登录页面</h1>
<form action="${pageContext.request.contextPath}/user/login" method="post">
    用户名：<input type="text" name="username"/>
    密码：<input type="text" name="password"/>
    <input type="submit" value="提交">
</form>
</body>
</html>

loginController

package com.wei.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpSession;

@Controller
@RequestMapping("user")
public class loginController {

    @RequestMapping("main")
    public String main(){
        return "main";
    }

    @RequestMapping("goLogin")
    public String login(){
        return "login";
    }

    @RequestMapping("/login")
    public String  login(HttpSession session, String username, String password, Model model){
        session.setAttribute("userLoginInfo",username);
        model.addAttribute("username",username);
        return "main";
    }

    @RequestMapping("/goOut")
    public String  goOut(HttpSession session){

        //销毁session数据
        //session.invalidate();
        //移除session数据
        session.removeAttribute("userLoginInfo");

        return "main";
    }
}

拦截器LoginInterceptor.java

package com.wei.config;

import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession();
        //判断什么情况，放行

        //登录页面，放行
        if (request.getRequestURI().contains("goLogin")){
            return true;
        }

        //第一次登录，没有session，放行
        if (request.getRequestURI().contains("login")){
            return true;
        }

        if (session.getAttribute("userLoginInfo")!=null){
            return true;
        }
        //判断什么情况，拦截
        request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,response);
        return false;
    }
}

拦截器配置applicationContext.xml

<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/user/**"/>
        <bean class="com.wei.config.LoginInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

文件上传和下载

文件上传

pom.xml导入包

    <dependencies>
        <!--文件上传-->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.3</version>
        </dependency>
        <!--servlet-api导入高版本的-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
        </dependency>
    </dependencies>

applicationContext.xml

<!--文件上传配置-->
<bean id="multipartResolver"  class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- 请求的编码格式，必须和jSP的pageEncoding属性一致，以便正确读取表单的内容，默认为ISO-8859-1 -->
    <property name="defaultEncoding" value="utf-8"/>
    <!-- 上传文件大小上限，单位为字节（10485760=10M） -->
    <property name="maxUploadSize" value="10485760"/>
    <property name="maxInMemorySize" value="40960"/>
</bean>

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
    <input type="file" name="file"/>
    <input type="submit" value="upload">
</form>
</body>
</html>

FileController.java

package com.wei.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.commons.CommonsMultipartFile;

import javax.servlet.http.HttpServletRequest;
import java.io.*;

@RestController
public class FileController {

    //@RequestParam("file") 将name=file控件得到的文件封装成CommonsMultipartFile 对象
    //批量上传CommonsMultipartFile则为数组即可
    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file , HttpServletRequest request) throws IOException {

        //获取文件名 : file.getOriginalFilename();
        String uploadFileName = file.getOriginalFilename();

        //如果文件名为空，直接回到首页！
        if ("".equals(uploadFileName)){
            return "redirect:/index.jsp";
        }
        System.out.println("上传文件名 : "+uploadFileName);

        //上传路径保存设置
        String path = request.getServletContext().getRealPath("/upload");
        //如果路径不存在，创建一个
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        System.out.println("上传文件保存地址："+realPath);

        InputStream is = file.getInputStream(); //文件输入流
        OutputStream os = new FileOutputStream(new File(realPath,uploadFileName)); //文件输出流

        //读取写出
        int len=0;
        byte[] buffer = new byte[1024];
        while ((len=is.read(buffer))!=-1){
            os.write(buffer,0,len);
            os.flush();
        }
        os.close();
        is.close();
        return "redirect:/index.jsp";
    }

    /*
     * 采用file.Transto 来保存上传的文件
     */
    @RequestMapping("/upload2")
    public String  fileUpload2(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {

        //上传路径保存设置
        String path = request.getServletContext().getRealPath("/upload");
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        //上传文件地址
        System.out.println("上传文件保存地址："+realPath);
        
        //通过CommonsMultipartFile的方法直接写文件（注意这个时候）
        file.transferTo(new File(realPath +"/"+ file.getOriginalFilename()));

        return "redirect:/index.jsp";
    }
}

文件下载

FileController.java

@RequestMapping(value="/download")
public String downloads(HttpServletResponse response ,HttpServletRequest request) throws Exception{
   //要下载的图片地址
   String  path = request.getServletContext().getRealPath("/upload");
   String  fileName = "基础语法.jpg";

   //1、设置response 响应头
   response.reset(); //设置页面不缓存,清空buffer
   response.setCharacterEncoding("UTF-8"); //字符编码
   response.setContentType("multipart/form-data"); //二进制传输数据
   //设置响应头
   response.setHeader("Content-Disposition",
           "attachment;fileName="+URLEncoder.encode(fileName, "UTF-8"));

   File file = new File(path,fileName);
   //2、 读取文件--输入流
   InputStream input=new FileInputStream(file);
   //3、 写出文件--输出流
   OutputStream out = response.getOutputStream();

   byte[] buff =new byte[1024];
   int index=0;
   //4、执行 写出操作
   while((index= input.read(buff))!= -1){
       out.write(buff, 0, index);
       out.flush();
  }
   out.close();
   input.close();
   return null;
}