从springBoot框架服务器上下载文件自定义一个启动器

在springboot框架中下载服务器存储的图片：

1）springboot默认访问放行的目录只有static，在static目录下存放图片资源

2）编译后的static目录中有一个1.png

2.5)编写控制器：

@Controller
//@RequestMapping("/upload")
public class UploadController {@RequestMapping("/download")public void download( String imgName,HttpServletRequest request,HttpServletResponse response) throws IOException {response.setContentType("image/png"); // 根据实际文件类型设置response.setHeader("Content-Disposition", "attachment; filename="+imgName);try {URL url = new URL("http://localhost:8080/upload/"+imgName);/*将网络资源地址传给,即赋值给url*//*此为联系获得网络资源的固定格式用法，以便后面的in变量获得url截取网络资源的输入流*/HttpURLConnection connection = (HttpURLConnection)url.openConnection();connection.setRequestMethod("GET");DataInputStream in = new DataInputStream(connection.getInputStream());/*此处也可用BufferedInputStream与BufferedOutputStream*/DataOutputStream out = new DataOutputStream(response.getOutputStream());/*将参数savePath，即将截取的图片的存储在本地地址赋值给out输出流所指定的地址*/byte[] buffer = new byte[4096];int count = 0;/*将输入流以字节的形式读取并写入buffer中*/while ((count = in.read(buffer)) > 0) {out.write(buffer, 0, count);}out.close();/*后面三行为关闭输入输出流以及网络资源的固定格式*/in.close();connection.disconnect();} catch (Exception e) {
//            System.out.println(e + fileUrl + savePath);
//            return null;System.out.println("上传异常"+e.getMessage());System.out.println(e);}}}

3）访问控制器

自定义一个启动器：

1）创建一个Maven项目，在pom.xml文件中：

一:所有启动器配置类的创建使用spring-boot-autoconfigure实现

二:spring-boot-configuration-processor找到boot的配置文件实现映射.
<parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.4.11</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-autoconfigure</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></dependency></dependencies>

2)Maven目录结构:

DiyProperties用来映射配置文件

DiyBean用来装配diyProperties对象

DiyConfigration是一个配置类容器,存放bean对象.

DiyProperties:

package com.xja.start;import org.springframework.boot.context.properties.ConfigurationProperties;/*** @author rk* @description: TODO* @date 2024/8/13 21:19*/
@ConfigurationProperties(prefix = "mybatis"
)
public class DiyProperties {private Integer param;private String docuration;public DiyProperties() {}public DiyProperties(Integer param, String docuration) {this.param = param;this.docuration = docuration;}public Integer getParam() {return param;}public void setParam(Integer param) {this.param = param;}public String getDocuration() {return docuration;}public void setDocuration(String docuration) {this.docuration = docuration;}
}

DiyBean:

package com.xja.bean;import com.xja.start.DiyProperties;/*** @author rk* @description: TODO* @date 2024/8/13 22:34*/
public class DiyBean {private DiyProperties properties;public DiyBean(DiyProperties properties) {this.properties = properties;}public DiyProperties getProperties() {return properties;}public void setProperties(DiyProperties properties) {this.properties = properties;}
}

DiyConfigration:

package com.xja.config;import com.xja.bean.DiyBean;
import com.xja.start.DiyProperties;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;/*** @author rk* @description: TODO* @date 2024/8/13 22:29*/
@Configuration
@EnableConfigurationProperties({DiyProperties.class})
public class DiyConfigration {
//    @Autowired
//    private DiyBean diyBean;@Beanpublic DiyBean properties(DiyProperties diyProperties){return new DiyBean(diyProperties);}}

spring.factories:

本Maven项目的配置文件,这个文件给springboot框架看的,boot框架会根据该配置文件实现对配置类的装配.
org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.xja.config.DiyConfigration