Spring Boot入门——文件上传与下载

https://www.cnblogs.com/studyDetail/p/7003253.html

1、在pom.xml文件中添加依赖

<groupId>com.wyl</groupId>
<artifactId>SpringBootFile</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>SpringBootFile</name>
<url>http://maven.apache.org</url>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.7</java.version>
</properties>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.3.RELEASE</version>
</parent>

<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>

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


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


<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
<scope>true</scope>
</dependency>

</dependencies>
</project>

2、application.properties文件中取消模板文件缓存

spring.thymeleaf.cache=false

3、编写模板文件

file.html

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"
xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
<head>
<meta charset="UTF-8" />
<title>Insert title here</title>
</head>
<body>
<h1 th:inlines="text">文件上传</h1>
<form action="fileUpload" method="post" enctype="multipart/form-data">
<p>选择文件: <input type="file" name="fileName"/></p>
<p><input type="submit" value="提交"/></p>
</form>
</body>
</html>

multifile.html
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"
xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
<head>
<meta charset="UTF-8" />
<title>Insert title here</title>
</head>
<body>
<h1 th:inlines="text">文件上传</h1>
<form action="multifileUpload" method="post" enctype="multipart/form-data" >
<p>选择文件1: <input type="file" name="fileName"/></p>
<p>选择文件2: <input type="file" name="fileName"/></p>
<p>选择文件3: <input type="file" name="fileName"/></p>
<p><input type="submit" value="提交"/></p>
</form>
</body>
</html>

4、编写Controller

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;

@Controller
public class FileUploadController {

/*
* 获取file.html页面
*/
@RequestMapping("file")
public String file(){
return "/file";
}

/**
* 实现文件上传
* */
@RequestMapping("fileUpload")
@ResponseBody
public String fileUpload(@RequestParam("fileName") MultipartFile file){
if(file.isEmpty()){
return "false";
}
String fileName = file.getOriginalFilename();
int size = (int) file.getSize();
System.out.println(fileName + "-->" + size);

String path = "F:/test" ;
File dest = new File(path + "/" + fileName);
if(!dest.getParentFile().exists()){ //判断文件父目录是否存在
dest.getParentFile().mkdir();
}
try {
file.transferTo(dest); //保存文件
return "true";
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return "false";
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return "false";
}
}

　　/*
* 获取multifile.html页面
*/
@RequestMapping("multifile")
public String multifile(){
return "/multifile";
}

/**
* 实现多文件上传
* */
@RequestMapping(value="multifileUpload",method=RequestMethod.POST)

　　/**public @ResponseBody String multifileUpload(@RequestParam("fileName")List<MultipartFile> files) */
public @ResponseBody String multifileUpload(HttpServletRequest request){

List<MultipartFile> files = ((MultipartHttpServletRequest)request).getFiles("fileName");

if(files.isEmpty()){
return "false";
}

String path = "F:/test" ;

for(MultipartFile file:files){
String fileName = file.getOriginalFilename();
int size = (int) file.getSize();
System.out.println(fileName + "-->" + size);

if(file.isEmpty()){
return "false";
}else{
File dest = new File(path + "/" + fileName);
if(!dest.getParentFile().exists()){ //判断文件父目录是否存在
dest.getParentFile().mkdir();
}
try {
file.transferTo(dest);
}catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
return "false";
}
}
}
return "true";
}
}

5、测试

6、多文件上传中遇到的问题

org.apache.tomcat.util.http.fileupload.FileUploadBase$FileSizeLimitExceededException: The field fileName exceeds its maximum permitted size of 1048576 bytes.

Spring Boot默认文件上传大小为2M，多文档上传中总是出现文件大小超出限度

解决方法：

a、在application.properties文件中设置文件大小

# Single file max size  
multipart.maxFileSize=50Mb
# All files max size  
multipart.maxRequestSize=50Mb

　　但是，事实证明此种方法不能够解决以上问题

b、在启动类App.class文件中配置Bean来设置文件大小

import javax.servlet.MultipartConfigElement;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.MultipartConfigFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * Hello world!
 *
 */
@SpringBootApplication
@Configuration
public class App 
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
        SpringApplication.run(App.class, args);
    }
    
    /**  
     * 文件上传配置  
     * @return  
     */  
    @Bean  
    public MultipartConfigElement multipartConfigElement() {  
        MultipartConfigFactory factory = new MultipartConfigFactory();  
        //单个文件最大  
        factory.setMaxFileSize("10240KB"); //KB,MB  
        /// 设置总上传数据总大小  
        factory.setMaxRequestSize("102400KB");  
        return factory.createMultipartConfig();  
    }

7、文件下载

@RequestMapping("download")
    public String downLoad(HttpServletResponse response){
        String filename="2.jpg";
        String filePath = "F:/test" ;
        File file = new File(filePath + "/" + filename);
        if(file.exists()){ //判断文件父目录是否存在
            response.setContentType("application/force-download");
            response.setHeader("Content-Disposition", "attachment;fileName=" + filename);
            
            byte[] buffer = new byte[1024];
            FileInputStream fis = null; //文件输入流
            BufferedInputStream bis = null;
            
            OutputStream os = null; //输出流
            try {
                os = response.getOutputStream();
                fis = new FileInputStream(file); 
                bis = new BufferedInputStream(fis);
                int i = bis.read(buffer);
                while(i != -1){
                    os.write(buffer);
                    i = bis.read(buffer);
                }
                
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.out.println("----------file download" + filename);
            try {
                bis.close();
                fis.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return null;
    }