小程序动态生成二维码，生成image图片

前端：

<image src="{{img_usrl}}" style="width:100%;height:104px;" bindlongtap="saveImg"></image>

js部分：在onLoad中请求

//我的userid 值为：239a3c37-3c2e-4a9d-be74-557638b23b63
this.setData({ img_usrl: getApp().getBaseUrl() + "/icon/" + userid });

java后台：

@RequestMapping("icon/{cateogry}")
public void getQrcodeImg(@PathVariable("cateogry") String cateogry,
        HttpServletRequest request,
        HttpServletResponse response){

    try {
        //cateogry的值为前端请求的值：239a3c37-3c2e-4a9d-be74-557638b23b63
        String url = "固定写死的url路径?id参数="+cateogry;
        BufferedImage image = QRCodeUtli.getqrcode(url);
        response.setContentType("image/png");

        OutputStream stream = response.getOutputStream();
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        ImageIO.write(image, "png",     out);
        stream.write(out.toByteArray());
        stream.flush();
        stream.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

工具QRCodeUtli类：

package com.early.api.util;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
public class QRCodeUtli {

    private static final int BLACK = 0xFF000000;
    private static final int WHITE = 0xFFFFFFFF;

    public static BufferedImage getqrcode(String code) {
        int width = 400; // 图像宽度
        int height = 400; // 图像高度
        Map<EncodeHintType, Object> hints = new HashMap<EncodeHintType, Object>();
        hints.put(EncodeHintType.MARGIN, 0);//设置白边宽度，取值0~4
        hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
        try {
            BitMatrix bitMatrix = new MultiFormatWriter().encode(code,
                    BarcodeFormat.QR_CODE, width, height, hints);
            BufferedImage image = toBufferedImage(bitMatrix);
            return image;
        } catch (WriterException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
    public static BufferedImage toBufferedImage(BitMatrix matrix) {
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        for (int x = 0; x < width; x++) {
            for (int y = 0; y < height; y++) {
                image.setRGB(x, y, matrix.get(x, y) ? BLACK : WHITE);
            }
        }
        return image;
    }
}

pom文件需要引用的包：

<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>core</artifactId>
    <version>3.3.1</version>
</dependency>

<dependency>
<groupId>com.google.zxing</groupId>
<artifactId>javase</artifactId>
<version>3.3.0</version>
</dependency>