上传图片保存原始图，并且生成缩率图

古城微笑少年丶 2022-02-05 10:13 162阅读 0赞

使用：awt生成缩率图

代码如下：

package cn.j0.app.shuoba.service;
    
        import cn.j0.app.shuoba.entity.UserNote;
        import cn.j0.app.shuoba.mapper.UserNoteMapper;
        import cn.j0.app.shuoba.util.FileUtil;
        import org.apache.ibatis.annotations.Param;
        import org.springframework.beans.factory.annotation.Autowired;
        import org.springframework.beans.factory.annotation.Value;
        import org.springframework.stereotype.Service;
        import org.springframework.web.multipart.MultipartFile;
    
        import javax.imageio.ImageIO;
        import java.awt.image.BufferedImage;
        import java.io.File;
        import java.io.FileOutputStream;
        import java.io.IOException;
        import java.io.OutputStream;
        import java.util.Date;
        import java.util.HashMap;
        import java.util.List;
        import java.util.Map;
    
        /**
         * FileName: ActivityService
         * Author:   xuan zongjun
         * Date:     2019/5/5 11:22
         * Description: 用户笔记业务层
         */
    
        @Service
        public class UserNoteService {
            //缩率图的宽和高
            public static final int WIDTH = 100;
            public static final int HEIGHT = 100;
    
            @Autowired
            private UserNoteMapper userNoteMapper;
    
            @Value("${domain.upload}")
            private String showImgPath;
    
            /**
             * 添加
             *
             * @param file   图片
             * @param userId 用户ID
             * @param appId  产品ID
             * @return
             */
            public Object add(MultipartFile file, String userId, String appId) {
                Map<String, Object> resultMap = new HashMap<>();
                try {
                    UserNote userNote = new UserNote();
                    userNote.setUserId( userId );
                    userNote.setAppId( appId );
                    userNote.setCreateTime( new Date() );
                    //大图地址
                    String imageType = file.getContentType().substring( file.getContentType().indexOf( "/" ) + 1 );
                    String noteImgUrl = FileUtil.saveFileAndFilePath( file, "noteImg" );
                    String saveImg = noteImgUrl.substring( noteImgUrl.indexOf( "noteImg" ) - 1 );
                    userNote.setNoteImgUrl(saveImg);
                    //小图地址
                    File imgFile = new File( noteImgUrl );
                    String noteImgUrlSmall = createThumbnail( imgFile, noteImgUrl, imageType );
                    String saveImgSmall = noteImgUrlSmall.substring( noteImgUrlSmall.indexOf( "noteImg" ) - 1 );
                    userNote.setNoteImgUrlSmall( saveImgSmall );
                    userNoteMapper.add( userNote );
    
                    resultMap.put( "code", 1 );
                    resultMap.put( "message", "保存成功" );
                } catch (Exception ex) {
                    resultMap.put( "code", -1 );
                    resultMap.put( "message", "保存失败" );
                }
    
                return resultMap;
            }
    
            /**
             * //生成缩率图
             * @param file          缩率图文件
             * @param noteImgUrl   文件的地址
             * @param imageType     文件的类型
             * @return
             */
            private String createThumbnail(File file, String noteImgUrl, String imageType) {
                OutputStream oStream = null;
                String noteImgUrlSmall = "";
                try {
                    //缩略图的的文件名
                    String ext = noteImgUrl.substring( noteImgUrl.lastIndexOf( "." ) );
                    String uploadFileName = noteImgUrl.substring( 0, noteImgUrl.lastIndexOf( "." ) );
                    noteImgUrlSmall = uploadFileName + "_small" + ext;
                    oStream = new FileOutputStream( noteImgUrlSmall );
    
                    BufferedImage image = ImageIO.read( file );
                    int width = image.getWidth( null ); //获取原图宽度
                    int height = image.getHeight( null );//获取原图高度
                    int wrate = width / WIDTH;    //宽度缩略图
                    int hrate = height / HEIGHT;//高度缩略图
                    int rate = 0;
                    if (wrate > hrate) {//宽度缩略图比例大于高度缩略图，使用宽度缩略图
                        rate = wrate;
                    } else {
                        rate = hrate;
                    }
                    //计算缩略图最终的宽度和高度
                    int newWidth = width / rate;
                    int newHeight = height / rate;
    
                    BufferedImage bufferedImage = new BufferedImage( newWidth, newHeight, BufferedImage.TYPE_INT_RGB );
                    //图片缩略图实现
                    bufferedImage.getGraphics().drawImage( image.getScaledInstance( newWidth, newHeight, image.SCALE_SMOOTH ), 0, 0, null );
                    //*image/jpeg
                    ImageIO.write( bufferedImage, imageType, oStream );
    
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    try {
                        oStream.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                return noteImgUrlSmall;
            }
    }