扫描微信二维码实现快速登录

一、什么是二维码
二维码又称二维条码，常见的二维码为QR Code，QR全称Quick Response，是一个近几年来移动设备上超流行的一种编码方式，它比传统的Bar Code条形码能存更多的信息，也能表示更多的数据类型。二维条码/二维码（2-dimensional bar code）是用某种特定的几何图形按一定规律在平面（二维方向上）分布的黑白相间的图形记录数据符号信息的；在代码编制上巧妙地利用构成计算机内部逻辑基础的“0”、“1”比特流的概念，使用若干个与二进制相对应的几何形体来表示文字数值信息，通过图象输入设备或光电扫描设备自动识读以实现信息自动处理：它具有条码技术的一些共性：每种码制有其特定的字符集；每个字符占有一定的宽度；具有一定的校验功能等。同时还具有对不同行的信息自动识别功能、及处理图形旋转变化点。

二、二维码生成的几种方式：

在线二维码生成方式（http://www.liantu.com/）
Java生成二维码使用google zxing 框架
前端生成二维码使用jquery-qrcode框架

三、扫描登录及跳转原理：
3.1、使用google zxing 框架生成二维码,在二维码中绑定跳转地址
3.2、使用手机扫一扫扫描二维码跳转至地址
3.3 、如何保证二维码唯一性，及超时处理之后怎么处理。
3.3.1、使用token存储至Redis保证二维码的唯一性，
3.3.2、前端使用ajax定时发送请求，检查该token是否为登陆状态

四、扫描二维码登录代码如下：

1.在pom.xml文件中导入相应的jar包：

<!-- 二维码生成jar -->
<dependency><groupId>com.google.zxing</groupId><artifactId>core</artifactId><version>3.3.0</version>
</dependency>
<!-- 集成redis -->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!-- 集成.ftl格式templates模板-->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>

2.在application.yml写入相应的配置如下：

codersWang:baseImgUrl: http://18236a01n6.51mypc.cn:51927/updateTokenState?token=
server:port: 8080
spring:http:encoding:force: truecharset: UTF-8redis:host: 127.0.0.1port: 6379#    password: 123456freemarker:allow-request-override: falsecache: falsecheck-template-location: truecharset: UTF-8content-type: text/html; charset=utf-8expose-request-attributes: falseexpose-session-attributes: falseexpose-spring-macro-helpers: falsesuffix: .ftltemplate-loader-path: classpath:/templates

3.写二维码生成的工具类：

package com.qrcode.code;import java.awt.BasicStroke;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Shape;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.OutputStream;
import java.util.Hashtable;
import java.util.Random;
import javax.imageio.ImageIO;import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.Result;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;public class QRCodeUtil {private static final String CHARSET = "utf-8";private static final String FORMAT_NAME = "JPG";// 二维码尺寸private static final int QRCODE_SIZE = 300;// LOGO宽度private static final int WIDTH = 60;// LOGO高度private static final int HEIGHT = 60;public static BufferedImage createImage(String content, String imgPath, boolean needCompress) throws Exception {Hashtable hints = new Hashtable();hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);hints.put(EncodeHintType.CHARACTER_SET, CHARSET);hints.put(EncodeHintType.MARGIN, 1);BitMatrix bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, QRCODE_SIZE, QRCODE_SIZE,hints);int width = bitMatrix.getWidth();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);}}if (imgPath == null || "".equals(imgPath)) {return image;}// 插入图片QRCodeUtil.insertImage(image, imgPath, needCompress);return image;}private static void insertImage(BufferedImage source, String imgPath, boolean needCompress) throws Exception {File file = new File(imgPath);if (!file.exists()) {System.err.println("" + imgPath + "   该文件不存在！");return;}Image src = ImageIO.read(new File(imgPath));int width = src.getWidth(null);int height = src.getHeight(null);if (needCompress) { // 压缩LOGOif (width > WIDTH) {width = WIDTH;}if (height > HEIGHT) {height = HEIGHT;}Image image = src.getScaledInstance(width, height, Image.SCALE_SMOOTH);BufferedImage tag = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);Graphics g = tag.getGraphics();g.drawImage(image, 0, 0, null); // 绘制缩小后的图g.dispose();src = image;}// 插入LOGOGraphics2D graph = source.createGraphics();int x = (QRCODE_SIZE - width) / 2;int y = (QRCODE_SIZE - height) / 2;graph.drawImage(src, x, y, width, height, null);Shape shape = new RoundRectangle2D.Float(x, y, width, width, 6, 6);graph.setStroke(new BasicStroke(3f));graph.draw(shape);graph.dispose();}public static void encode(String content, String imgPath, String destPath, boolean needCompress) throws Exception {BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress);mkdirs(destPath);// String file = new Random().nextInt(99999999)+".jpg";// ImageIO.write(image, FORMAT_NAME, new File(destPath+"/"+file));ImageIO.write(image, FORMAT_NAME, new File(destPath));}public  BufferedImage encode(String content, String imgPath, boolean needCompress) throws Exception {BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress);return image;}public static void mkdirs(String destPath) {File file = new File(destPath);// 当文件夹不存在时，mkdirs会自动创建多层目录，区别于mkdir．(mkdir如果父目录不存在则会抛出异常)if (!file.exists() && !file.isDirectory()) {file.mkdirs();}}public static void encode(String content, String imgPath, String destPath) throws Exception {QRCodeUtil.encode(content, imgPath, destPath, false);}// 被注释的方法/** public static void encode(String content, String destPath, boolean* needCompress) throws Exception { QRCodeUtil.encode(content, null, destPath,* needCompress); }*/public static void encode(String content, String destPath) throws Exception {QRCodeUtil.encode(content, null, destPath, false);}public static void encode(String content, String imgPath, OutputStream output, boolean needCompress)throws Exception {BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress);ImageIO.write(image, FORMAT_NAME, output);}public static void encode(String content, OutputStream output) throws Exception {QRCodeUtil.encode(content, null, output, false);}public static String decode(File file) throws Exception {BufferedImage image;image = ImageIO.read(file);if (image == null) {return null;}BufferedImageLuminanceSource source = new BufferedImageLuminanceSource(image);BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));Result result;Hashtable hints = new Hashtable();hints.put(DecodeHintType.CHARACTER_SET, CHARSET);result = new MultiFormatReader().decode(bitmap, hints);String resultStr = result.getText();return resultStr;}public static String decode(String path) throws Exception {return QRCodeUtil.decode(new File(path));}}

package com.qrcode.code;import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;import com.google.zxing.LuminanceSource;public class BufferedImageLuminanceSource extends LuminanceSource {private final BufferedImage image;private final int left;private final int top;public BufferedImageLuminanceSource(BufferedImage image) {this(image, 0, 0, image.getWidth(), image.getHeight());}public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width, int height) {super(width, height);int sourceWidth = image.getWidth();int sourceHeight = image.getHeight();if (left + width > sourceWidth || top + height > sourceHeight) {throw new IllegalArgumentException("Crop rectangle does not fit within image data.");}for (int y = top; y < top + height; y++) {for (int x = left; x < left + width; x++) {if ((image.getRGB(x, y) & 0xFF000000) == 0) {image.setRGB(x, y, 0xFFFFFFFF); // = white}}}this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY);this.image.getGraphics().drawImage(image, 0, 0, null);this.left = left;this.top = top;}public byte[] getRow(int y, byte[] row) {if (y < 0 || y >= getHeight()) {throw new IllegalArgumentException("Requested row is outside the image: " + y);}int width = getWidth();if (row == null || row.length < width) {row = new byte[width];}image.getRaster().getDataElements(left, top + y, width, 1, row);return row;}public byte[] getMatrix() {int width = getWidth();int height = getHeight();int area = width * height;byte[] matrix = new byte[area];image.getRaster().getDataElements(left, top, width, height, matrix);return matrix;}public boolean isCropSupported() {return true;}public LuminanceSource crop(int left, int top, int width, int height) {return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height);}public boolean isRotateSupported() {return true;}public LuminanceSource rotateCounterClockwise() {int sourceWidth = image.getWidth();int sourceHeight = image.getHeight();AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY);Graphics2D g = rotatedImage.createGraphics();g.drawImage(image, transform, null);g.dispose();int width = getWidth();return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);}}

4.Redis工具类：

package com.qrcode.token;import java.util.List;
import java.util.concurrent.TimeUnit;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;@Component
public class RedisUtil {@Autowiredprivate StringRedisTemplate stringRedisTemplate;// 如果key存在的话返回fasle 不存在的话返回truepublic Boolean setNx(String key, String value, Long timeout) {Boolean setIfAbsent = stringRedisTemplate.opsForValue().setIfAbsent(key, value);if (timeout != null) {stringRedisTemplate.expire(key, timeout, TimeUnit.SECONDS);}return setIfAbsent;}public StringRedisTemplate getStringRedisTemplate() {return stringRedisTemplate;}public void setList(String key, List<String> listToken) {stringRedisTemplate.opsForList().leftPushAll(key, listToken);}/*** 存放string类型* * @param key*            key* @param data*            数据* @param timeout*            超时间*/public void setString(String key, String data, Long timeout) {try {stringRedisTemplate.opsForValue().set(key, data);if (timeout != null) {stringRedisTemplate.expire(key, timeout, TimeUnit.SECONDS);}} catch (Exception e) {}}/*** 开启Redis 事务* * @param*/public void begin() {// 开启Redis 事务权限stringRedisTemplate.setEnableTransactionSupport(true);// 开启事务stringRedisTemplate.multi();}/*** 提交事务* * @param*/public void exec() {// 成功提交事务stringRedisTemplate.exec();}/*** 回滚Redis 事务*/public void discard() {stringRedisTemplate.discard();}/*** 存放string类型* * @param key*            key* @param data*            数据*/public void setString(String key, String data) {setString(key, data, null);}/*** 根据key查询string类型* * @param key* @return*/public String getString(String key) {String value = stringRedisTemplate.opsForValue().get(key);return value;}/*** 根据对应的key删除key* * @param key*/public Boolean delKey(String key) {return stringRedisTemplate.delete(key);}
}

package com.qrcode.token;import java.util.ArrayList;
import java.util.List;
import java.util.UUID;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;@Component
public class GenerateToken {@Autowiredprivate RedisUtil redisUtil;/*** 生成令牌** @param keyPrefix*            令牌key前缀* @param redisValue*            redis存放的值* @return 返回token*/public String createToken(String keyPrefix, String redisValue) {return createToken(keyPrefix, redisValue, null);}/*** 生成令牌** @param keyPrefix*            令牌key前缀* @param redisValue*            redis存放的值* @param time*            有效期* @return 返回token*/public String createToken(String keyPrefix, String redisValue, Long time) {if (StringUtils.isEmpty(redisValue)) {new Exception("redisValue Not nul");}String token = keyPrefix + UUID.randomUUID().toString().replace("-", "");redisUtil.setString(token, redisValue, time);return token;}public void createListToken(String keyPrefix, String redisKey, Long tokenQuantity) {List<String> listToken = getListToken(keyPrefix, tokenQuantity);redisUtil.setList(redisKey, listToken);}public List<String> getListToken(String keyPrefix, Long tokenQuantity) {List<String> listToken = new ArrayList<>();for (int i = 0; i < tokenQuantity; i++) {String token = keyPrefix + UUID.randomUUID().toString().replace("-", "");listToken.add(token);}return listToken;}public String getListKeyToken(String key) {String value = redisUtil.getStringRedisTemplate().opsForList().leftPop(key);return value;}/*** 根据token获取redis中的value值** @param token* @return*/public String getToken(String token) {if (StringUtils.isEmpty(token)) {return null;}String value = redisUtil.getString(token);return value;}/*** 移除token** @param token* @return*/public Boolean removeToken(String token) {if (StringUtils.isEmpty(token)) {return null;}return redisUtil.delKey(token);}}

5.返回前端的controller层

package com.qrcode.controller;import com.qrcode.code.QRCodeUtil;
import com.qrcode.token.RedisUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;import javax.servlet.http.HttpServletRequest;
import java.util.UUID;/*** @author EDZ* @date 2019/5/28*/
@Controller
public class LoginController {@Autowiredprivate RedisUtil redisUtil;@Value("${codersWang.baseImgUrl}")private String baseImgUr;@RequestMapping("/qc")public String index(HttpServletRequest request) throws Exception {//获取tokenString token = getToken();request.setAttribute("token", token);return "index";
}@RequestMapping("/success")public String success() {return "success";}@RequestMapping("/updateTokenState")public String updateTokenState(String token) {String redisToken = redisUtil.getString(token);if (StringUtils.isEmpty(redisToken) || redisToken.equals("1")) {return "failure";}// 将该token的状态改为1redisUtil.setString(token, "1");return "success";}@RequestMapping("/failure")public String failure() {return "failure";}//生成token，生成二维码private String getToken() throws Exception {// 1.使用UUID生成token替换掉 "-"String token = UUID.randomUUID().toString().replace("-", "");// 2. 存放在redis中 0 表示没有被扫过，1表示已经扫过redisUtil.setString(token, "0",20000L);// 3.1存放在二维码中的内容// 3.2嵌入二维码的图片路径String imgPath = "G:/aa.jpg";// 3.3生成的二维码的路径及名称String destPath = "G:/aa" + token + ".jpg";// 4.生成二维码QRCodeUtil.encode(baseImgUr + token, imgPath, destPath, true);// 5.解析二维码QRCodeUtil.decode(destPath);return token;}
}

6.访问接口生成二维码返回前端访问地址：http://localhost:8080/qc

7.扫描以上二维码会跳转登录成功页如下：

8.前端的相应页面代码如下：
index.ftl页面：

<h1>扫一下该二维码，实现扫码登陆</h1><img src="getImg?token=${token}">
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>function checkToken() {$.ajax({url: "checkToken?token=${token}",dataType: "json",type: "get",async: "false",success: function (data) {if (data == true) {window.location.href = '/success';}} ,error: function () {}});}setInterval(checkToken, 2000);//定时请求Redis中的状态是否改变</script>

success.ftl页面：