java后台生成二维码并在jsp页面显示(初学者)
java后台生成二维码并在jsp页面显示(初学者)
注意:本人用的是:
- JDK12
- eclipse
- tomcat
使用到插件和jar包
- zxing3.2.1.jar jar包百度或者私我qq:1290792596 欢迎商讨学习
- jquery-3.4.1.js 这个js哪里都有随便百度一个就行啦
注意这里JDK12方法和JDK1.8有所差距
1.== Encoder encoder = Base64.getEncoder();==
2. byte[] binary = encoder.encode(bytes);
第一种方式生成二维码并显示在前端jsp页面:
首先我们要在jsp页面显示需要建一个web项目,这里我的web项目名字为webd01.
WebCount的创建和展示:
src的结构图:
我们从前向后写先写web层:
创建one.jsp页面:这里引入easyui/jquery-3.4.1.js ,并用 οnclick="lick()"进行传值
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="easyui/jquery-3.4.1.js"></script>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<!-- 数据发送到OneSeervlet -->
<h1>二维码</h1>
<!-- 生成的二维码图片展示 标签 img -->
<img id="img1" alt="##" src="">
<input id="in1" type="text" name = "text" >
<input type="button" onclick="lick()" value="生成二维码">
</body>
<script type="text/javascript">
function lick() {
var r = $("#in1").val();
if(r != null && r !=""){
document.getElementById("img1").src="<%=request.getContextPath() %>/OneSeervlet?text="+r+"&"+Math.random();
}
}
</script>
</html>
创建完jsp配置web.xml代码如下:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>webd01</display-name>
<welcome-file-list>
<welcome-file>one.jsp</welcome-file>
</welcome-file-list>
<!-- OneServlet 的 servlet 配置 -->
<servlet>
<description></description>
<display-name>OneSeervlet</display-name>
<servlet-name>OneSeervlet</servlet-name>
<servlet-class>com.zhiyou.servlet.OneSeervlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>OneSeervlet</servlet-name>
<url-pattern>/OneSeervlet</url-pattern>
</servlet-mapping>
</web-app>
配置完web.xml,我们写src层面(这里没有用什么框架等等,全部为最基础的Java所写)
这里我们直接用右键创建servlet(右键生成的servlet, web.xml 是不用配置的系统自己生成------>我是这样创建的)
下面是servlet代码:(这里注意我们用到Code encoder = new Code(); 还没有创建所以会报错)
package com.zhiyou.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* One.jsp的 Servlet
*/
public class OneSeervlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String content = request.getParameter("text");
System.out.println(content);
request.getSession().setAttribute("e", content);
Code encoder = new Code();
// if (content != null && content !="") {}
try {
encoder.encoderQRCoder(content, response,request);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
在上面的servlet里边我们创建啦Code encoder = new Code();所以现在我们创建 Code.class
package com.zhiyou.servlet;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.util.Base64;
import java.util.Base64.Encoder;
import java.util.HashMap;
import javax.imageio.ImageIO;
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.common.BitMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
public class Code {
public void encoderQRCoder(String content, HttpServletResponse response,HttpServletRequest request) throws Exception {
// TODO Auto-generated method stub
int width = 300;
int height = 300;
String format = "png";
String attribute = (String) request.getSession().getAttribute("e");
String content1 = attribute;
//生成 二维码参数
HashMap hints = new HashMap();
//二维码内容编码格式
hints.put(EncodeHintType.CHARACTER_SET,"utf-8");
//容错率
hints.put(EncodeHintType.ERROR_CORRECTION,ErrorCorrectionLevel.M);
//生成二维码的边框线宽度
hints.put(EncodeHintType.MARGIN, 1);
try {
BitMatrix bitMatrix = new MultiFormatWriter().encode(content1, BarcodeFormat.QR_CODE, width, height,hints);
ByteArrayOutputStream out = new ByteArrayOutputStream();
BufferedImage image = toBufferedImage(bitMatrix);
//把png格式转换成IO流
ImageIO.write(image, format, response.getOutputStream());
byte[] bytes = out.toByteArray();
//将字节数组转换为二进制
Encoder encoder = Base64.getEncoder();
//没有去除两边空格.trim()
byte[] binary = encoder.encode(bytes);
} catch (WriterException e) {
e.printStackTrace();
System.out.println(e);
}
}
private static BufferedImage toBufferedImage(BitMatrix bitMatrix) {
int width = bitMatrix.getHeight();
int height = bitMatrix.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, bitMatrix.get(x, y) ? 0xFF000000 : 0xFFFFFFFF);
}
}
return image;
}
}
代码就这么多已经完啦.
感谢大家阅读我的文章 本人是个初学者有很多地方有漏洞 也希望大家不要要求太高 我来这里的初衷还是学习—>保持学习的态度. 还有祝大家学习愉快 嘿嘿