String AND Image Conversion

本文介绍如何使用Java实现图片文件与Base64编码之间的相互转换,包括从前端接收上传的图片文件并保存为Base64编码字符串,以及如何将Base64字符串还原为图片文件。

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    /*<form action="<%=basePath%>/file/test1" method="post" enctype="multipart/form-data">
        <input type="file" name="multipartFile" value="fileValues">
        <input type="submit" value="提交" style="height: 35px; ">
     </form>*/


    //  上下文是要对应的。。名字一定要一样name.multipartFile= MultipartFile.multipartFile
    @RequestMapping("/test1")
    public void runwer(MultipartFile multipartFile) throws Exception {
        byte[] data = multipartFile.getBytes();
        BASE64Encoder encoder = new BASE64Encoder();
        String encode = encoder.encode(data);//返回Base64编码过的字节数组字符串
        PrintWriter writer = new PrintWriter("D://qqqqqqqqqqqqqqq//test//abc.txt", "UTF-8");
        writer.println(encode);
        writer.close();
        System.out.println("+++++++++++++++++++++");
        // base64字符串转化成图片
        boolean a = GenerateImage(encode);
        System.out.println(a);
    }




    //图片转化成base64字符串
    public static String GetImageStr() {
        //将图片文件转化为字节数组字符串,并对其进行Base64编码处理
        String imgFile = "D://qqqqqqqqqqqqqqq//test//wx_camera_1523021056870.jpg";//待处理的图片
        InputStream in = null;
        byte[] data = null;
        //读取图片字节数组
        try {
            in = new FileInputStream(imgFile);
            data = new byte[in.available()];
            in.read(data);
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        //对字节数组Base64编码
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(data);//返回Base64编码过的字节数组字符串
    }




    //base64字符串转化成图片
    public static boolean GenerateImage(String imgStr)
    {   //对字节数组字符串进行Base64解码并生成图片
        if (imgStr == null) { //图像数据为空
            return false;
        }
        BASE64Decoder decoder = new BASE64Decoder();
        try {//Base64解码
            byte[] b = decoder.decodeBuffer(imgStr);
            for(int i=0;i<b.length;++i) {
                if(b[i]<0) {//调整异常数据
                    b[i]+=256;
                }
            }
            //生成jpg图片
            String imgFilePath = "D://qqqqqqqqqqqqqqq//test//222.jpg";//新生成的图片
            OutputStream out = new FileOutputStream(imgFilePath);
            out.write(b);
            out.flush();
            out.close();
            return true;
        } catch (Exception e) {
            return false;
        }
    }
/** * \brief Converts an immutable sensor_msgs::msg::Image message to another CvImage for display purposes, * using practical conversion rules if needed. * * Data will be shared between input and output if possible. * * Recall: sensor_msgs::msg::image_encodings::isColor and isMono tell whether an image contains R,G,B,A, mono * (or any combination/subset) with 8 or 16 bit depth. * * The following rules apply: * - if the output encoding is empty, the fact that the input image is mono or multiple-channel is * preserved in the ouput image. The bit depth will be 8. it tries to convert to BGR no matter what * encoding image is passed. * - if the output encoding is not empty, it must have sensor_msgs::msg::image_encodings::isColor and * isMono return true. It must also be 8 bit in depth * - if the input encoding is an OpenCV format (e.g. 8UC1), and if we have 1,3 or 4 channels, it is * respectively converted to mono, BGR or BGRA. * - if the input encoding is 32SC1, this estimate that image as label image and will convert it as * bgr image with different colors for each label. * * \param source A shared_ptr to a sensor_msgs::msg::Image message * \param encoding Either an encoding string that returns true in sensor_msgs::msg::image_encodings::isColor * isMono or the empty string as explained above. * \param options (cv_bridge::CvtColorForDisplayOptions) Options to convert the source image with. * - do_dynamic_scaling If true, the image is dynamically scaled between its minimum and maximum value * before being converted to its final encoding. * - min_image_value Independently from do_dynamic_scaling, if min_image_value and max_image_value are * different, the image is scaled between these two values before being converted to its final encoding. * - max_image_value Maximum image value * - colormap Colormap which the source image converted with. */ CV_BRIDGE_EXPORT CvImageConstPtr cvtColorForDisplay( const CvImageConstPtr & source, const std::string & encoding = std::string(), const CvtColorForDisplayOptions options = CvtColorForDisplayOptions()); /** * \brief Get the OpenCV type enum corresponding to the encoding. * * For example, "bgr8" -> CV_8UC3, "32FC1" -> CV_32FC1, and "32FC10" -> CV_32FC10. */ CV_BRIDGE_EXPORT int getCvType(const std::string & encoding); } // namespace cv_bridge解释代码
05-28
Develop an image converter viewer application, to perform the following. The input image must be converted into (a) grayscale image, (b) negative image, (c) red image, (d) green image, (e) blue image, (f) Sepia image, (g) mirror image and (d) image with watermark with words “@UPC 2025”. Display resulting images one after another with 5-seconds of delay between each. Here is an example is provided, where the program converts an image (Test1.jpg) to grayscale (Test2.png) and negative (Test3.png) versions, then displays them one after another with a 5-second delay between each. import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JLabel; import java.awt.FlowLayout; public class ImageConverterViewer { public static void main(String args[]) throws IOException, InterruptedException { // Load the original image BufferedImage originalImg = null; File f = null; try { f = new File("C:/Images/Test1.jpg"); originalImg = ImageIO.read(f); } catch (IOException e) { System.out.println(e); return; } // Create grayscale image BufferedImage grayImg = createGrayscaleImage(originalImg); saveImage(grayImg, "C:/Images/Test2.png", "Grayscale conversion complete."); // Create negative image BufferedImage negativeImg = createNegativeImage(originalImg); saveImage(negativeImg, "C:/Images/Test3.png", "Negative conversion complete."); // Display images one after another displayImagesWithDelay(originalImg, grayImg, negativeImg); } private static BufferedImage createGrayscaleImage(BufferedImage img) { int width = img.getWidth(); int height = img.getHeight(); BufferedImage grayImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
最新发布
07-19
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