我正在学习 spring boot，我在一个名为 DocumentWeb 的项目上，它是一个简单的 Web 项目，带有控制器、jsp 模式和扩展 JpaRepository 的文档存储库（接口）
该项目应该允许用户上传图片并下载任何已上传的图片并将其作为 blob 保存到数据库中。但不能在浏览器上运行。 每当我注释掉控制器中文档存储库的实现时，它运行良好。但代码中没有错误。请帮助🙏🙏🙏
这是我的代码：
//Controller
package com.javaMadeEasy.document.controllers;
import com.javaMadeEasy.document.entities.Document;
import com.javaMadeEasy.document.repository.DocumentRepository;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
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.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;
import java.io.IOException;
import java.util.List;
@Controller
public class DocumentController {
@Autowired
DocumentRepository repository;
@RequestMapping("/displayUpload")
public String displayUpload(ModelMap modelMap){
extracted(modelMap);
return "DocumentUpload";
}
@RequestMapping(value="/upload", method = RequestMethod.POST)
public String uploadDocument(@RequestParam("document") MultipartFile multipartFile, @RequestParam("id") Long id, ModelMap modelMap){
// multipartFile.getName();
Document document = new Document();
document.setId(id);
document.setName(multipartFile.getOriginalFilename());
try {
document.setData(multipartFile.getBytes());
} catch (IOException e) {
throw new RuntimeException(e);
}
repository.save(document);
extracted(modelMap);
return "DocumentUpload";
}
@RequestMapping("/download")
public StreamingResponseBody download(@RequestParam("id") long id, HttpServletResponse response){
Document document =repository.getOne(id);
byte[] data = document.getData();
response.setHeader("Content-Disposition","attachment;filename=download.jpeg");
return outputStream -> {
outputStream.write(data);
};
}
private void extracted(ModelMap modelMap) {
List<Document> documents = repository.findAll();
System.out.println(documents.size());
modelMap.addAttribute("documents",documents);
}
}
//Model
package com.javaMadeEasy.document.entities;
import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.Lob;
@Entity
public class Document {
@Id
private Long id;
private String name;
@Lob
private byte[] data;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public byte[] getData() {
return data;
}
public void setData(byte[] data) {
this.data = data;
}
}
//Repository
package com.javaMadeEasy.document.repository;
import com.javaMadeEasy.document.entities.Document;
import org.springframework.data.jpa.repository.JpaRepository;
public interface DocumentRepository extends JpaRepository<Document,Long> {
}
//application.properties
spring.datasource.url=jdbc:mysql://localhost:3306/projectdb
spring.datasource.username=devuser
spring.datasource.password=Mamzy123
spring.jpa.show-sql=true
spring.mvc.view.prefix=/WEB-INF/jsps/
spring.mvc.view.suffix=.jsp
server.servlet.context-path=/documentWeb
logging.level.sql=debug
logging.level.web=debug
#logging.level.root=debug
//DocumentUpload.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@page isELIgnored="false" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Document Upload</title>
</head>
<h3>Upload A Photo</h3>
<body>
<form action="upload" method="post" enctype="multipart/form-data">
<pre>
Id:<input type="text" name="id"/>
Document:<input type="file" name="id"/>
<input type="submit" value="Upload"/>
<input type="reset" value="refresh"/>
</pre>
</form>
<table>
<tr>
<th>id</th>
<th>name</th>
<th>link</th>
</tr>
<c:forEach items="${documents}" var="document">
<tr>
<td>${document.id}</td>
<td>${document.name}</td>
<td><a href="download?id=${document.id}">download</a></td>
</tr>
</c:forEach>
</table>
</body>
</html>
//pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>3.0.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.javaMadeEasy.document</groupId>
<artifactId>documentWeb</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>documentWeb</name>
<description>Vendor Module</description>
<properties>
<java.version>19</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>6.0.4</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
在 Repository java 接口中使用 @Repository 注释。
并检查服务器日志。日志可能会提供有关错误的更多详细信息，例如导致问题的特定代码行。