前后端分离实现上传图片的功能

前后端分离实现上传图片的功能

思路

1. 前端上传图片和分类名称，保存图片文件，将数据追加到formData传给后端，回调清空。
2. 后端对图片和分类名分开进行处理。分类名进行普通的增加。图片需要借助工具类转化成统一格式，再构造出“id+.jpg”的格式上传到文件夹中。

前端

    <div class="panel panel-warning addDiv">
        <div class="panel-heading">新增分类</div>
        <div class="panel-body">
            <table class="addTable">
                <tr>
                    <td>分类名称</td>
                    <td><input  @keyup.enter="add" v-model.trim="bean.name" type="text" class="form-control"></td>
                </tr>
                <tr>
                    <td>分类图片</td>
                    <td>
                        <input id="categoryPic" accept="image/*" type="file" name="image" @change="getFile($event)" />
                    </td>
                </tr>
                <tr class="submitTR">
                    <td colspan="2" align="center">
                        <a href="#nowhere"  @click="add" class="btn btn-success">提交</a>
                    </td>
                </tr>
            </table>
        </div>
    </div>

bean 用来存放分类信息，file 用来表示上传的文件。

            bean: { id: 0, name: ''},
            file: null

---

                getFile: function (event) {
                    this.file = event.target.files[0];
                },

                add: function () {
                    if(!checkEmpty(this.bean.name, "分类名称"))
                        return;
                    if(!checkEmpty(this.file, "分类图片"))
                        return;
                    var url = this.uri;
                    //axios.js 上传文件要用 formData 这种方式
                    var formData = new FormData();
                    formData.append("image", this.file);
                    formData.append("name", this.bean.name);
                    axios.post(url,formData).then(function(response){
                        vue.list(0);
                        vue.bean = { id: 0, name: '', hp: '0'};
                        $("#categoryPic").val('');
                        vue.file = null;
                    });
                },

后端

controller

    @PostMapping("/categories")
    public Object add(Category bean, MultipartFile image, HttpServletRequest request) throws Exception {
        categoryService.add(bean);
        saveOrUpdateImageFile(bean, image, request);
        return bean;
    }
    public void saveOrUpdateImageFile(Category bean, MultipartFile image, HttpServletRequest request)
            throws IOException {
        File imageFolder= new File(request.getServletContext().getRealPath("img/category"));
        File file = new File(imageFolder,bean.getId()+".jpg");
        if(!file.getParentFile().exists())
            file.getParentFile().mkdirs();
        image.transferTo(file);
        BufferedImage img = ImageUtil.change2jpg(file);
        ImageIO.write(img, "jpg", file);
    }

service

    public void add(Category bean) {
        categoryDAO.save(bean);
    }

工具类

• change2jpg 确保图片文件的二进制格式是jpg
• resizeImage用于改变图片大小

public class ImageUtil {
  
    public static BufferedImage change2jpg(File f) {
        try {
            Image i = Toolkit.getDefaultToolkit().createImage(f.getAbsolutePath());
            PixelGrabber pg = new PixelGrabber(i, 0, 0, -1, -1, true);
            pg.grabPixels();
            int width = pg.getWidth(), height = pg.getHeight();
            final int[] RGB_MASKS = { 0xFF0000, 0xFF00, 0xFF };
            final ColorModel RGB_OPAQUE = new DirectColorModel(32, RGB_MASKS[0], RGB_MASKS[1], RGB_MASKS[2]);
            DataBuffer buffer = new DataBufferInt((int[]) pg.getPixels(), pg.getWidth() * pg.getHeight());
            WritableRaster raster = Raster.createPackedRaster(buffer, width, height, width, RGB_MASKS, null);
            BufferedImage img = new BufferedImage(RGB_OPAQUE, raster, false, null);
            return img;
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
    }
  
    public static void resizeImage(File srcFile, int width,int height, File destFile) {
        try {
            if(!destFile.getParentFile().exists())
                destFile.getParentFile().mkdirs();
            Image i = ImageIO.read(srcFile);
            i = resizeImage(i, width, height);
            ImageIO.write((RenderedImage) i, "jpg", destFile);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
      
    public static Image resizeImage(Image srcImage, int width, int height) {
        try {
  
            BufferedImage buffImg = null;
            buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            buffImg.getGraphics().drawImage(srcImage.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);
  
            return buffImg;
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
  
}