1、开发SpringBoot应用：图片上传功能

1.1 添加maven依赖：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.3.RELEASE</version>
    <relativePath/>
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <!-- servlet 依赖. -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
    </dependency>

    <!-- tomcat 的支持. -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.tomcat.embed</groupId>
        <artifactId>tomcat-embed-jasper</artifactId>
        <scope>provided</scope>
    </dependency>

</dependencies>

1.2 配置文件

由于涉及上传页面，需要使用JSP，新增配置文件application.properties, 内容如下：

server.port=8080
 
# 页面默认前缀目录
spring.mvc.view.prefix=/WEB-INF/jsp/
# 响应页面默认后缀
spring.mvc.view.suffix=.jsp
 
# 上传文件的最大值
spring.servlet.multipart.max-file-size=1000MB
spring.servlet.multipart.max-request-size=1000MB

注意：

springboot 默认 multipart.max-file-size大小是1M，max-request-size默认大小是10M，现在手机的像素都比较高，拍的照片都比较大，默认的基本不够，可根据个人情况适当调整。

1.3 编写上传页面

在webapp文件夹（如果没有，在main文件夹下创建）下新增文件夹：WEB-INF/jsp/，在jsp文件夹下新增index.jsp, 内容如下：

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
    <title>图片上传</title>
</head>
<body>
<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file" accept=".png,.jpg" multiple/>
    <button type="submit">点我上传</button>
</form>
</body>
</html>

1.4 编写首页及上传图片接口

首页：IndexController:

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
 
@Controller
public class IndexController {
 
    @GetMapping("index")
    public String index() {
        return "index";
    }
}

上传接口：

import org.springframework.util.FileCopyUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
 
import java.io.File;
import java.io.IOException;
 
@RestController
public class FileUploadController {
 
    @RequestMapping(value = "upload", method = RequestMethod.POST)
    public String fileUplaod(@RequestParam(value = "file") MultipartFile[] files) throws IOException {
        for (int i = 0; i < files.length; i++) {
            MultipartFile file = files[i];
            byte[] bytes = file.getBytes();
            String pathName = "D:\\pictures\\" + file.getOriginalFilename();
            File destFile = new File(pathName);
            FileCopyUtils.copy(bytes, destFile);
        }
        return "success";
    }
}

1.5 编写启动类：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
@SpringBootApplication
public class PicUploadApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(PicUploadApplication.class, args);
    }
}