JAVA 生成二维码 代码 显示到页面

-----引入jar 包
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;




protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String param = request.getParameter("param");
int width = 300;
int height = 300;
String format = "jpg";

Map<EncodeHintType, Object> ht = new                  

HashMap<EncodeHintType,Object>();

ht.put(EncodeHintType.CHARACTER_SET, "UTF-8");


BitMatrix bitMatrix = null;
try {

bitMatrix = new MultiFormatWriter().encode(param,BarcodeFormat.QR_CODE, width, height, ht);

} catch (WriterException e) {

e.printStackTrace();
}


MatrixToImageWriter.writeToStream(bitMatrix, format,response.getOutputStream());

}