标签：java 桥接模式实际 supremind new import com public

图片缩略图功能

需要对图片生产缩略图，压缩并保存到不同的介质中。输入端可能是本地图片，也可能是网络图片。保存的位置可能是本地，也有可能是第三方的minio、阿里云oss、七牛云oss。并且这些途径可能随时扩展。为了设计的灵活性，这里就要把输入可输出抽象出来，应用层通过抽象层结偶。这样的抽象和实现分离，实现层可以自由扩展，而应用层依赖于抽象层相对稳定。

整体结构是这样的

代码结构是这样的

整体实现是这样的

ThumbLoad 图片的输入信息⬇︎⬇︎⬇︎

点击查看代码

package com.supremind.modules.news.service.impl.thumb;

import com.supremind.modules.news.entity.ImageActionVo;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;

import javax.validation.constraints.NotBlank;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * 图片载入
 * 1)图片载入过程不涉及到异常处理，异常自行处理，一切结果以isSuccess为准，具体消息去message
 */
@Slf4j
public abstract class ThumbLoad {
    @Setter
    @Getter
    protected ThumbSave thumbSave;

    public ThumbLoad(ThumbSave thumbSave) {
        this.thumbSave = thumbSave;
    }

    @Getter
    @Setter
    /*load载入结果,默认为false,免去每次异常都赋值.只有操作成功后进行赋值true*/
    protected Boolean isSuccess=false;

    @Getter
    @Setter
    /*错误消息提醒*/
    protected String message =null;

    public abstract ImageActionVo thumb(String filePath);

    /**
     * 验证网络资源是否可以访问
     * @param url 网络资源地址
     * @param checkIsImage 是否强制检测为image类型的资源
     * @return
     */
    protected Boolean checkUrlIsAccess(@NotBlank String url, Boolean checkIsImage){
        log.debug("checkUrlIsAccess start ...");
        log.debug("url:{}",url);
        URL netUrl = null;
        HttpURLConnection httpURLConnection =null;
        Boolean result = true;
        try {
            netUrl = new URL(url);
            httpURLConnection = (HttpURLConnection)netUrl.openConnection();
            httpURLConnection.setConnectTimeout(2000);
            if (httpURLConnection.getResponseCode()==200) {
                String contentType = httpURLConnection.getContentType();
                if (checkIsImage){
                    if (!contentType.split("/")[0].equals("image")) {
                        result = false;
                    }
                }

            }else{
                result = false;
            }
        }catch (Exception e){
            log.error("e :{}", e);
            result = false;
        }finally {
            if (httpURLConnection != null) {
                httpURLConnection.disconnect();
            }
        }
        log.debug("checkUrlIsAccess end.");
        return result;
    }

}

ThumbSave 图片的输入信息⬇︎⬇︎⬇︎

点击查看代码

package com.supremind.modules.news.service.impl.thumb;

import com.supremind.config.FileServerConfig;
import lombok.AllArgsConstructor;
import lombok.Data;
import org.springframework.beans.factory.annotation.Autowired;

import java.io.InputStream;

/**
 * 文件保存
 * 1)文件保存到fileServer ,thumburi是fileserver返回的可以直接访问的地址
 * 2)文件保存本地，thumburi表示本地文件的完整路径
 * 注：
 * 1.文件保存类型取决与具体实现，但结构保持一致。最外层控制逻辑，是isSuccess.
 * 2.为了实现最大程度的复用，这里选择使用inputStream 进行对接saveImage.
 * 3.在扩展save策略时，注意异常处理，结果都从ImageSaveResult体现说明
 */
public abstract class ThumbSave {

    @Autowired
    protected FileServerConfig fileServerConfig;

    protected String bucketName = "thumb_images"; //file server buckete
    protected String saveUri; //处理后的文件保存路
    protected Integer width; //图片压缩宽度
    protected Integer height; //图片压缩高度

    public ThumbSave(String saveUri, Integer width, Integer height) {
        this.saveUri = saveUri;
        this.width = width;
        this.height = height;
    }

    abstract ImageSaveResult save(InputStream imageInputStream);

    @Data
    @AllArgsConstructor
    class ImageSaveResult {
        private Boolean isSuccess = false; //操作是否成功
        private String thumbUri; //缩略图文件地址
        private String msg; //消息
    }


}

下面是具体实现
LocalThumbSave 本地保存⬇︎⬇︎⬇︎

点击查看代码

package com.supremind.modules.news.service.impl.thumb;

import lombok.extern.slf4j.Slf4j;
import net.coobird.thumbnailator.Thumbnails;

import java.io.IOException;
import java.io.InputStream;

/**
 * 本地保存文件
 */
@Slf4j
public class LocalThumbSave extends ThumbSave {
    public LocalThumbSave(String saveUri, Integer width, Integer height) {
        super(saveUri, width, height);
    }

    public ImageSaveResult save(InputStream imageInputStream) {
        try {
            Thumbnails.of(imageInputStream).size(width,height).toFile(saveUri);
            return new ImageSaveResult(true,saveUri,null);
        } catch (IOException e) {
            log.error("Thumbnails toFiles error:{}",e);
            return new ImageSaveResult(false, null, e.getMessage());
        }
    }
}

FileServerThumbSave file server保存文件（这里的fileserver又做了一层抽象，可以接入不同的第三方）⬇︎⬇︎⬇︎

点击查看代码

package com.supremind.modules.news.service.impl.thumb;

import com.supremind.common.SpringContextUtil;
import com.supremind.common.utils.R;
import com.supremind.modules.news.feign.FileFeignClient;
import com.supremind.modules.news.service.impl.G;
import lombok.Cleanup;
import lombok.extern.slf4j.Slf4j;
import net.coobird.thumbnailator.Thumbnails;
import org.springframework.http.MediaType;
import org.springframework.mock.web.MockMultipartFile;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * file server保存文件
 */
@Slf4j
public class FileServerThumbSave extends ThumbSave {
    public FileServerThumbSave(String saveUri, Integer width, Integer height) {
        super(saveUri, width, height);
    }

    public ImageSaveResult save(final InputStream imageInputStream) {
        log.debug("FileServerSaveImage start ......");
        try {
            @Cleanup ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            Thumbnails.of(imageInputStream).size(width,height).toOutputStream(outputStream);
            @Cleanup ByteArrayInputStream swapStream = new ByteArrayInputStream(outputStream.toByteArray());
            FileFeignClient fileFeignClient = SpringContextUtil.getBean(FileFeignClient.class);
            MockMultipartFile mockMultipartFile = new MockMultipartFile("file.jpg","file.jpg", MediaType.IMAGE_JPEG_VALUE,swapStream);
            R image = fileFeignClient.upload(bucketName, mockMultipartFile);
            log.debug("image :{}", image);
            if (G.isSuccess(image)) {
                return new ImageSaveResult(true, image.get("data").toString(), null);
            }else{
                return new ImageSaveResult(false, null, G.getMsg(image));
            }
        } catch (IOException e) {
            log.error("FileServerSaveImage IOException :{}",e);
            return new ImageSaveResult(false, null, e.getMessage());
        }finally {
            log.debug("FileServerSaveImage end");
        }
    }
}

UriThumbLoad 读取本地资源文件⬇︎⬇︎⬇︎

点击查看代码

package com.supremind.modules.news.service.impl.thumb;

import com.supremind.modules.news.entity.ImageActionVo;
import com.supremind.modules.news.enums.ErrorMsgEnum;
import lombok.Cleanup;
import lombok.extern.slf4j.Slf4j;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

/**
 * 本地文件载入
 */
@Slf4j
public class UriThumbLoad extends ThumbLoad {
    public UriThumbLoad(ThumbSave thumbSave) {
        super(thumbSave);
    }

    public ImageActionVo thumb(String filePath) {
        //文件检查
        File file = new File(filePath);
        if (!file.exists()) {
            return new ImageActionVo(filePath,false,null, ErrorMsgEnum.FILE_NOT_FIND.getValue());
        }

        try {
            @Cleanup InputStream inputStream = new FileInputStream(file);
            ThumbSave.ImageSaveResult save = thumbSave.save(inputStream);
            return new ImageActionVo(filePath, save.getIsSuccess(), save.getThumbUri(), save.getMsg());
        } catch (Exception e) {
            log.error("FileNotFoundException :{}",e);
            return new ImageActionVo(filePath,false,null,e.getMessage());
        }

    }

}

UrlThumbLoad 读取网络资源文件⬇︎⬇︎⬇︎

点击查看代码

package com.supremind.modules.news.service.impl.thumb;

import com.supremind.modules.news.entity.ImageActionVo;
import com.supremind.modules.news.enums.ErrorMsgEnum;
import lombok.Cleanup;
import lombok.extern.slf4j.Slf4j;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * 网络图片载入
 */
@Slf4j
public class UrlThumbLoad extends ThumbLoad {
    public UrlThumbLoad(ThumbSave thumbSave) {
        super(thumbSave);
    }

    public ImageActionVo thumb(String filePath) {
        HttpURLConnection urlConnection;
        if (!checkUrlIsAccess(filePath,true)) {
            return new ImageActionVo(filePath, false, null, ErrorMsgEnum.FILE_NOT_ACCESS.getValue());
        }
        try {
            URL url = new URL(filePath);
            urlConnection = (HttpURLConnection)url.openConnection();
            urlConnection.setConnectTimeout(5000);
            @Cleanup InputStream inputStream = urlConnection.getInputStream();
            ThumbSave.ImageSaveResult save = thumbSave.save(inputStream);
            return new ImageActionVo(filePath, save.getIsSuccess(), save.getThumbUri(),save.getMsg());
        } catch (Exception e) {
            log.error("FileNotFoundException :{}",e);
            return new ImageActionVo(filePath,false,null,e.getMessage());
        }
    }

}

文件压缩也是同样的实现

标签：java,桥接,模式,实际,supremind,new,import,com,public
From： https://www.cnblogs.com/euler-blog/p/18611246

实际项目中不一样的《桥接模式》

图片缩略图功能

整体结构是这样的

代码结构是这样的

整体实现是这样的

文件压缩也是同样的实现

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