Java中实现文件上传

目录

1、文件上传本地

1.1 原理

1.2 如何使用文件上传

1.2.1 引入文件上传的依赖

 1.2.2 配置文件上传拦截器

 1.2.3 完成文件上传的代码

2、文件上传oss服务器 

2.1 为什么需要上传到oss服务器

2.2 如何使用oss 

2.2.1 开启oss服务

 2.2.2 在Java中引入依赖

2.2.3 查看自己ID和密钥

2.2.4 代码

3、案例

3.1 引入相关依赖 

3.2  创建实体类

3.3 创建controller层

3.3.1 创建StudentController

3.3.2 创建UploadController

3.4 创建dao层

3.4.1 BaseDao

3.4.2 StudentDao

3.5 配置SpringMvc配置文件

3.6 编写upload.jsp文件

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1、文件上传本地

1.1 原理

1.2 如何使用文件上传

1.2.1 引入文件上传的依赖

 <dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.2.10.RELEASE</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.24</version></dependency><!--servlet依赖--><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version></dependency><!--jackson依赖:把controller层方法返回的java对象转化为json字符串--><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.13.3</version></dependency><!--文件上传依赖--><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.4</version></dependency></dependencies>

 1.2.2 配置文件上传拦截器

    <!--文件上传解析器 id:必须为multipartResolver--><bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"><!--设置文件上传的大小 单位为byte字节 1M=1024kb=1024b  10*1024*1024--><property name="maxUploadSize" value="10485760"/><!--设置编码--><property name="defaultEncoding" value="utf-8"/></bean>

 1.2.3 完成文件上传的代码

 <%--表单: 提交方式必须为post   enctype编码:multipart/form-data文件编码--%><form method="post" action="/upload" enctype="multipart/form-data"><%--input必须设置文件文件框 而且必须起名称--%>选择上传的文件:<input type="file" name="myfile"/><br><input type="submit" value="上传"/></form>

@Controller
public class UploadController {/**** @param myfile 接受你上传的文件对象信息封装到该类。该类中可以获取上传文件的信息。比如:文件名 文件大小 文件后缀等*               这个名称必须为文件上传表单的文件框的名称一致* @return*/@PostMapping("/upload")public String upload(MultipartFile myfile, HttpServletRequest request) throws IOException {//获取tomcat上下文中的指定目录的路径String realPath = request.getSession().getServletContext().getRealPath("/upload");//根据上面的路径创建一个文件对象File file=new File(realPath);//如果没有该目录则创建if (!file.exists()) {file.mkdirs();}//把上传的文件转移到upload目录下--重名覆盖了String uuid = UUID.randomUUID().toString().replace("-", "");File target=new File(realPath+"/"+(uuid+myfile.getOriginalFilename()));myfile.transferTo(target);return "success";}
}

2、文件上传oss服务器 

2.1 为什么需要上传到oss服务器

1. 如果项目搭建了集群。那么导致文件数据无法共享。

2. 如果项目的target删除了。导致文件数据丢失。

2.2 如何使用oss 

2.2.1 开启oss服务

oss服务器网址

点击上面链接，跳转到阿里云的oss服务器页面，完成登录后，会进入oss管理控制台，如图所示

 然后点击创建Bucket，操作如下图

 2.2.2 在Java中引入依赖

<dependency><groupId>com.aliyun.oss</groupId><artifactId>aliyun-sdk-oss</artifactId><version>3.15.1</version>
</dependency>

2.2.3 查看自己ID和密钥

2.2.4 代码

@PostMapping("/upload2")public String upload2(MultipartFile myfile){// Endpoint以华东1（杭州）为例，其它Region请按实际情况填写。String endpoint = "oss-cn-beijing.aliyuncs.com";// 填写Bucket名称，例如examplebucket。String bucketName = "XXXXX";//上传到oss后的名字String objectName = UUID.randomUUID().toString().replace("-","")+myfile.getOriginalFilename();// 创建OSSClient实例。/*** String endpoint,自己的endpoint* String accessKeyId, 自己的id* String secretAccessKey自己的密钥*/String accessKeyId="XXXXXXX";String secretAccessKey="XXXXXXX";OSS ossClient = new OSSClientBuilder().build(endpoint,accessKeyId,secretAccessKey);try {InputStream inputStream = myfile.getInputStream();// 创建PutObjectRequest对象。PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, objectName, inputStream);// 创建PutObject请求。PutObjectResult result = ossClient.putObject(putObjectRequest);} catch (Exception oe) {}finally {if (ossClient != null) {ossClient.shutdown();}}return "success";}

3、案例

springmvc+jdbc+elementui+vue

添加和展示所有的功能

3.1 引入相关依赖 

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.ykq</groupId><artifactId>qy174-springmvc04</artifactId><version>1.0-SNAPSHOT</version><packaging>war</packaging><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.2.10.RELEASE</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.24</version></dependency><!--servlet依赖--><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version></dependency><!--jackson依赖:把controller层方法返回的java对象转化为json字符串--><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.13.3</version></dependency><!--文件上传依赖--><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.4</version></dependency><!--oss的依赖--><dependency><groupId>com.aliyun.oss</groupId><artifactId>aliyun-sdk-oss</artifactId><version>3.15.1</version></dependency><!--mysql的jar--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.28</version></dependency><!--druid--><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.2.8</version></dependency></dependencies>
</project>

3.2  创建实体类

@Data
public class Student implements Serializable {private Integer id;private String name;private String phone;private String email;private Integer age;private Byte gender;private Date createtime;private String head;}

3.3 创建controller层

3.3.1 创建StudentController

@Controller
@RequestMapping("/student")
public class StudentController {private StudentDao studentDao=new StudentDao();@GetMapping("/list")@ResponseBody //把java对象转化为json字符串public List<Student> list(){List<Student> list = studentDao.findAll();return list;}@PostMapping("/add")@ResponseBody //把java对象转化为json字符串public int add(@RequestBody Student student){int add = studentDao.add(student.getName(), student.getPhone(), student.getEmail(), student.getAge(), student.getGender(), student.getHead());return add;}
}

3.3.2 创建UploadController

@Controller
public class UploadController {/**** @param myfile 接受你上传的文件对象信息封装到该类。该类中可以获取上传文件的信息。比如:文件名 文件大小 文件后缀等*               这个名称必须为文件上传表单的文件框的名称一致* @return*/@PostMapping("/upload")public String upload(MultipartFile myfile, HttpServletRequest request) throws IOException {//获取tomcat上下文中的指定目录的路径String realPath = request.getSession().getServletContext().getRealPath("/upload");//根据上面的路径创建一个文件对象File file=new File(realPath);//如果没有该目录则创建if (!file.exists()) {file.mkdirs();}//把上传的文件转移到upload目录下--重名覆盖了String uuid = UUID.randomUUID().toString().replace("-", "");File target=new File(realPath+"/"+(uuid+myfile.getOriginalFilename()));myfile.transferTo(target);return "success";}@PostMapping("/upload2")@ResponseBodypublic String upload2(MultipartFile file){// Endpoint以华东1（杭州）为例，其它Region请按实际情况填写。String endpoint = "oss-cn-beijing.aliyuncs.com";// 填写Bucket名称，例如examplebucket。String bucketName = "qy174-8888";//上传到oss后的名字String objectName = UUID.randomUUID().toString().replace("-","")+file.getOriginalFilename();// 创建OSSClient实例。/*** String endpoint,自己的endpoint* String accessKeyId, 自己的id* String secretAccessKey自己的密钥* XX* XXX*/String accessKeyId="XXX";String secretAccessKey="XXX";OSS ossClient = new OSSClientBuilder().build(endpoint,accessKeyId,secretAccessKey);try {InputStream inputStream = file.getInputStream();// 创建PutObjectRequest对象。PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, objectName, inputStream);// 创建PutObject请求。PutObjectResult result = ossClient.putObject(putObjectRequest);String path="https://"+bucketName+"."+endpoint+"/"+objectName;return path;} catch (Exception oe) {}finally {if (ossClient != null) {ossClient.shutdown();}}return "失败";}
}

3.4 创建dao层

3.4.1 BaseDao

public class BaseDao {protected Connection conn;protected PreparedStatement ps;protected ResultSet rs;//数据源对象private static DataSource dataSource;//静态代码块中static {try {//创建一个属性对象Properties properties = new Properties();//加载属性文件InputStream inputStream = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");properties.load(inputStream);//获取连接池对象dataSource = DruidDataSourceFactory.createDataSource(properties);} catch (Exception e) {e.printStackTrace();}}//获取连接对象public void getConn() throws Exception{conn = dataSource.getConnection();}//关闭资源public void closeAll(){if(rs!=null){try {rs.close();} catch (SQLException throwables) {throwables.printStackTrace();}}if(ps!=null){try {ps.close();} catch (SQLException throwables) {throwables.printStackTrace();}}if(conn!=null){try {conn.close();} catch (SQLException throwables) {throwables.printStackTrace();}}}//通用的增删改方法public int edit(String sql,Object...params){try {getConn();ps=conn.prepareStatement(sql);//为占位符赋值for(int i=0;i<params.length;i++){ps.setObject(i+1,params[i]);}int row = ps.executeUpdate();return row;} catch (Exception e) {e.printStackTrace();} finally {closeAll();}return 0;}}
/**1. 四个属性: connection preparedStatement ResultSet  DataSource2. 静态代码块:[获取连接池]3. 获取连接对象的方法4. 关闭资源方法5. 通用的增删改方法*/

3.4.2 StudentDao

public class StudentDao extends BaseDao {//求总条数 select count(*) from t_studentpublic int getCount(){try {getConn();String sql="select count(*) as c from t_student";ps=conn.prepareStatement(sql);rs=ps.executeQuery();while (rs.next()){int c = rs.getInt("c");return c;}} catch (Exception e) {e.printStackTrace();} finally {closeAll();}return 0;}//查询所有学员信息--单元测试public List<Student> findAll(){List<Student> list=new ArrayList<Student>();try {getConn();String sql="select * from t_student";ps=conn.prepareStatement(sql);rs=ps.executeQuery();while (rs.next()){Student s=new Student();s.setId(rs.getInt("id"));s.setPhone(rs.getString("phone"));s.setEmail(rs.getString("email"));s.setAge(rs.getInt("age"));s.setName(rs.getString("name"));s.setCreatetime(rs.getDate("createtime"));s.setGender(rs.getByte("gender"));s.setHead(rs.getString("head"));list.add(s);}} catch (Exception e) {e.printStackTrace();} finally {closeAll();}return list;}//根据id查询学员信息public Student findById(String id){Student s=null;try {getConn();String sql="select * from t_student where id=?";ps=conn.prepareStatement(sql);ps.setObject(1,id);rs=ps.executeQuery();while (rs.next()){s=new Student();s.setId(rs.getInt("id"));s.setPhone(rs.getString("phone"));s.setEmail(rs.getString("email"));s.setAge(rs.getInt("age"));s.setName(rs.getString("name"));s.setCreatetime(rs.getDate("createtime"));s.setGender(rs.getByte("gender"));s.setHead(rs.getString("head"));}} catch (Exception e) {e.printStackTrace();} finally {closeAll();}return s;}//添加方法public int add(String name,String phone,String email,int age,int gender,String head){String sql="insert into t_student(id,name,phone,email,age,createtime,gender,head) values(null,?,?,?,?,now(),?,?)";return edit(sql,name,phone,email,age,gender,head);}//修改public int update(String id,String name,String phone,String email,int age,int gender){String sql="update t_student set name=?,phone=?,email=?,age=?,gender=?,createtime=now() where id=?";return edit(sql,name,phone,email,age,gender,id);}//删除方法public int delete(String id){String sql="delete from t_student where id=?";return edit(sql,id);}

3.5 配置SpringMvc配置文件

<?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"><!--com.ykq 扫描该包以及该包下的子包--><context:component-scan base-package="com.Hs"/><!--开启注解驱动 不要导错mvc 默认使用的不是注解模式--><mvc:annotation-driven/><!--放行静态资源--><mvc:default-servlet-handler/><!--视图解析--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"><property name="prefix" value="/views/"/><property name="suffix" value=".jsp"/></bean><!--文件上传解析器 id:必须为multipartResolver--><bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"><!--设置文件上传的大小 单位为byte字节 1M=1024kb=1024b  10*1024*1024--><property name="maxUploadSize" value="10485760"/><!--设置编码--><property name="defaultEncoding" value="utf-8"/></bean></beans>

3.6 编写upload.jsp文件

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><%--表单: 提交方式必须为post   enctype编码:multipart/form-data文件编码--%><form method="post" action="/upload2" enctype="multipart/form-data"><%--input必须设置文件文件框 而且必须起名称--%>选择上传的文件:<input type="file" name="myfile"/><br><input type="submit" value="上传"/></form>
</body>
</html>