JSP 实战学习笔记-05-jsp 远程调用实现

╰半橙微兮° 2022-12-02 12:19 162阅读 0赞

# 说明 #

写代码时，前后端分离。

前端代码各种原因，导致不太好直接部署。

所以想着能不能自己简单模拟一下前端，然后实现文件上传操作，验证后端代码。

于是本地就验证了一下。

# 服务器 #

## 8080-模拟后端 ##

springboot 启动在 8080 端口。

提供后端解析服务。

### 后端代码 ###

package com.github.houbb.jsp.learn.hello.controller;
    
    import org.apache.commons.fileupload.FileItem;
    import org.apache.commons.fileupload.FileItemFactory;
    import org.apache.commons.fileupload.disk.DiskFileItemFactory;
    import org.apache.commons.fileupload.servlet.ServletFileUpload;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PostMapping;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.File;
    import java.util.List;
    
    /** * @author binbin.hou * @since 1.0.0 */
    @Controller
    public class ApacheController { 
    
        /** * 实现文件上传 * * @param request 请求 * @param response 响应 * @return 页面 */
        @PostMapping(value = "/apache/upload")
        public String upload(HttpServletRequest request,
                             HttpServletResponse response) throws Exception { 
            // 上传文件夹
            String uploadDir = request.getServletContext().getRealPath("/WEB-INF/upload/");
            File tempDir = new File(uploadDir);
    
            // file less than 10kb will be store in memory, otherwise in file system.
            final int threshold = 10240;
            final int maxRequestSize = 1024 * 1024 * 4;	// 4MB
    
            if(ServletFileUpload.isMultipartContent(request)) { 
                // Create a factory for disk-based file items.
                FileItemFactory factory = new DiskFileItemFactory(threshold, tempDir);
                // Create a new file upload handler
                ServletFileUpload upload = new ServletFileUpload(factory);
                // Set overall request size constraint.
                upload.setSizeMax(maxRequestSize);
    
                List<FileItem> items = upload.parseRequest(request);
    
                for(FileItem item : items) { 
                    // 普通的表单字段
                    if(item.isFormField()) { 
                        String name = item.getFieldName();
                        String value = item.getString();
                        System.out.println(name + ": " + value);
                    } else { 
                        // 真实的文件
                        //file upload
                        String fieldName = item.getFieldName();
                        String fileName = item.getName();
                        File uploadedFile = new File(uploadDir + File.separator + fieldName + "_" + fileName);
                        item.write(uploadedFile);
                    }
                }
            }  else { 
                // 文件解析失败
            }
            return "apache";
    
        }
    
    }

## 8081-模拟前端 ##

同样是 springboot 项目，主要模拟前端服务，启动在 8081 端口。

### 前端代码 ###

<!DOCTYPE html>
    <%@page contentType="text/html; charset=UTF-8" language="java"%>
    <html lang="zh">
    <head>
        <title>JSP 实现文件上传和下载</title>
    </head>
    <body>
    <form method="POST" enctype="multipart/form-data" action="http://localhost:8080/apache/upload">
        File to upload:
        <input type="file" name="file"><br/>
        Notes about the file:
        <input type="text" name="note"><br/>
        <br/>
        <input type="submit" value="Press"> to upload the file!
    </form>
    </body>
    </html>

此处的 `action=http://localhost:8080/apache/upload` 指向的是服务A。

经过测试，是可以直接上传成功的。

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