1.基本原理
(1) 服务器生成一个全局唯一的ID，利用这个ID在网页端产生一个二维码。
(2) 用户在手机端登陆后，扫描二维码，手机端提示用户是否登陆。
(3) 用户确认登陆后，手机端将用户信息和这个全局ID一起提交到服务器。
(4) 服务器将这个ID和用户的信息绑定，通知网页端，网页端轮询后收到该信息，即可登陆。
image.png
图1 微信示例
2.java的实现
2.1 实现流程
pc端：
(1) 打开二维码登陆页面网页index.html
(2) index.html调用GetQrCodeServlet
(3) GetQrCodeServlet干2件事：
a:生成随机的[uuid]，是一个唯一标识，该标识贯穿整个流程
b:生成二维码图片，二维码信息：http://xx.xx.xx.xx:8080/QrCodeLoginPro/Login.html?uuid=[uuid]。
(4) index页面展示二维码
(5) index页面调用LongConnectionCheckServlet进行长连接轮询操作，参数为uuid
(6) LongConnectionCheckServlet做以下事情：
拿到uuid后循环检查loginUserMap中uuid是否不为null
(7) 如果为null则代表没有登陆，index.html将继续进行轮询
ps: LongConnectionCheckServlet 一个长连接请求检测登录状态
loginUserMap 是一个静态的map结构的登录池，uuid为key , 登录信息为value
手机端：
1:扫描pc端的二维码
2:打开二维码中的网页 http://xx.xx.xx.xx:8380/QrCodeLoginPro/Login.html?uuid=" + [uuid]
3:登录，将uname,upwd,uuid 传递给登录程序PhoneLoginServlet
4:PhoneLoginServlet干干以下事：
a:检测登录
b:登录成功后将登录信息插入到loginUserMap中去，uuid为key
pc端：
1:继续轮询检测uuid中是否为null
2:登录后的uuid中就不为null了，此时LongConnectionCheckServlet停止循环，返回登录状态。
2.2项目结构
image.png
2.3代码解析
GetQrCodeServlet
package cn.kuwo;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.kuwo.util.TwoDimensionCode;
/**
* 生成二维码图片以及uuid
* @author zijuntang
*
*/
public class GetQrCodeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();
//生成唯一ID
int uuid = (int) (Math.random() * 100000);
//二维码内容
String content = "http://xx.xx.xx.xx:8380/QrCodeLoginPro/Login.html?uuid=" + uuid;
//生成二维码
String imgName = uuid + "_" + (int) (new Date().getTime() / 1000) + ".png";
String imgPath = "/home/web/apache/htdocs/QrCodeLogin/" + imgName;
TwoDimensionCode handler = new TwoDimensionCode();
handler.encoderQRCode(content, imgPath, "png");
//生成的图片访问地址
String qrCodeImg = "http://xx.xx.xx.xx/QrCodeLogin/" + imgName;
String jsonStr = "{\"uuid\":" + uuid + ",\"qrCodeImg\":\"" + qrCodeImg + "\"}";
out.print(jsonStr);
out.flush();
out.close();
}
}
LongConnectionCheckServlet
package cn.kuwo;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.kuwo.vo.LoginUserVo;
import cn.kuwo.vo.UserVo;
/**
* 用长连接，检查登录状态
* @author zijuntang
*
*/
public class LongConnectionCheckServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String uuid = request.getParameter("uuid");
String jsonStr = "";
System.out.println("in");
System.out.println("uuid:" + uuid);
long inTime = new Date().getTime();
Boolean bool = true;
while (bool) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
//检测登录
UserVo userVo = LoginUserVo.getLoginUserMap().get(uuid);
System.out.println("userVo:" + userVo);
if(userVo != null){
bool = false;
jsonStr = "{\"uname\":\""+userVo.getUname()+"\"}";
LoginUserVo.getLoginUserMap().remove(uuid);
}else{
if(new Date().getTime() - inTime > 5000){
bool = false;
}
}
}
System.out.println("login ok : " + jsonStr);
PrintWriter out = response.getWriter();
out.print(jsonStr);
out.flush();
out.close();
}
}
PhoneLoginServlet
package cn.kuwo;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.kuwo.vo.LoginUserVo;
import cn.kuwo.vo.UserVo;
/**
* 二维码手机端登录
* @author zijuntang
*
*/
public class PhoneLoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public PhoneLoginServlet() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String uuid = request.getParameter("uuid");
String uname = request.getParameter("uname");
String upwd = request.getParameter("upwd");
System.out.println(uuid);
System.out.println(uname);
System.out.println(upwd);
//TODO 验证登录
boolean bool = true;
if(bool){
//将登陆信息存入map
UserVo userVo = LoginUserVo.getLoginUserMap().get(uuid);
if(userVo == null){
userVo = new UserVo();
userVo.setUname(uname);
userVo.setUpwd(upwd);
LoginUserVo.getLoginUserMap().put(uuid, userVo);
}
}
PrintWriter out = response.getWriter();
out.print(bool);
out.flush();
out.close();
}
}
cn.kuwo.util包下的生成二维码的封装类
package cn.kuwo.util;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.imageio.ImageIO;
import jp.sourceforge.qrcode.QRCodeDecoder;
import jp.sourceforge.qrcode.exception.DecodingFailedException;
import com.swetake.util.Qrcode;
public class TwoDimensionCode {
/**
* 生成二维码(QRCode)图片
* @param content 存储内容
* @param imgPath 图片路径
*/
public void encoderQRCode(String content, String imgPath) {
this.encoderQRCode(content, imgPath, "png", 7);
}
/**
* 生成二维码(QRCode)图片
* @param content 存储内容
* @param output 输出流
*/
public void encoderQRCode(String content, OutputStream output) {
this.encoderQRCode(content, output, "png", 7);
}
/**
* 生成二维码(QRCode)图片
* @param content 存储内容
* @param imgPath 图片路径
* @param imgType 图片类型
*/
public void encoderQRCode(String content, String imgPath, String imgType) {
this.encoderQRCode(content, imgPath, imgType, 7);
}
/**
* 生成二维码(QRCode)图片
* @param content 存储内容
* @param output 输出流
* @param imgType 图片类型
*/
public void encoderQRCode(String content, OutputStream output, String imgType) {
this.encoderQRCode(content, output, imgType, 7);
}
/**
* 生成二维码(QRCode)图片
* @param content 存储内容
* @param imgPath 图片路径
* @param imgType 图片类型
* @param size 二维码尺寸
*/
public void encoderQRCode(String content, String imgPath, String imgType, int size) {
try {
BufferedImage bufImg = this.qRCodeCommon(content, imgType, size);
File imgFile = new File(imgPath);
if (!imgFile.exists())
{
imgFile.mkdirs();
}
// 生成二维码QRCode图片
ImageIO.write(bufImg, imgType, imgFile);
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 生成二维码(QRCode)图片
* @param content 存储内容
* @param output 输出流
* @param imgType 图片类型
* @param size 二维码尺寸
*/
public void encoderQRCode(String content, OutputStream output, String imgType, int size) {
try {
BufferedImage bufImg = this.qRCodeCommon(content, imgType, size);
// 生成二维码QRCode图片
ImageIO.write(bufImg, imgType, output);
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 生成二维码(QRCode)图片的公共方法
* @param content 存储内容
* @param imgType 图片类型
* @param size 二维码尺寸
* @return
*/
private BufferedImage qRCodeCommon(String content, String imgType, int size) {
BufferedImage bufImg = null;
try {
Qrcode qrcodeHandler = new Qrcode();
// 设置二维码排错率，可选L(7%)、M(15%)、Q(25%)、H(30%)，排错率越高可存储的信息越少，但对二维码清晰度的要求越小
qrcodeHandler.setQrcodeErrorCorrect('M');
qrcodeHandler.setQrcodeEncodeMode('B');
// 设置设置二维码尺寸，取值范围1-40，值越大尺寸越大，可存储的信息越大
qrcodeHandler.setQrcodeVersion(size);
// 获得内容的字节数组，设置编码格式
byte[] contentBytes = content.getBytes("utf-8");
// 图片尺寸
int imgSize = 67 + 12 * (size - 1);
bufImg = new BufferedImage(imgSize, imgSize, BufferedImage.TYPE_INT_RGB);
Graphics2D gs = bufImg.createGraphics();
// 设置背景颜色
gs.setBackground(Color.WHITE);
gs.clearRect(0, 0, imgSize, imgSize);
// 设定图像颜色> BLACK
gs.setColor(Color.BLACK);
// 设置偏移量，不设置可能导致解析出错
int pixoff = 2;
// 输出内容> 二维码
if (contentBytes.length > 0 && contentBytes.length < 800) {
boolean[][] codeOut = qrcodeHandler.calQrcode(contentBytes);
for (int i = 0; i < codeOut.length; i++) {
for (int j = 0; j < codeOut.length; j++) {
if (codeOut[j][i]) {
gs.fillRect(j * 3 + pixoff, i * 3 + pixoff, 3, 3);
}
}
}
} else {
throw new Exception("QRCode content bytes length = " + contentBytes.length + " not in [0, 800].");
}
gs.dispose();
bufImg.flush();
} catch (Exception e) {
e.printStackTrace();
}
return bufImg;
}
/**
* 解析二维码（QRCode）
* @param imgPath 图片路径
* @return
*/
public String decoderQRCode(String imgPath) {
// QRCode 二维码图片的文件
File imageFile = new File(imgPath);
BufferedImage bufImg = null;
String content = null;
try {
bufImg = ImageIO.read(imageFile);
QRCodeDecoder decoder = new QRCodeDecoder();
content = new String(decoder.decode(new TwoDimensionCodeImage(bufImg)), "utf-8");
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
e.printStackTrace();
} catch (DecodingFailedException dfe) {
System.out.println("Error: " + dfe.getMessage());
dfe.printStackTrace();
}
return content;
}
/**
* 解析二维码（QRCode）
* @param input 输入流
* @return
*/
public String decoderQRCode(InputStream input) {
BufferedImage bufImg = null;
String content = null;
try {
bufImg = ImageIO.read(input);
QRCodeDecoder decoder = new QRCodeDecoder();
content = new String(decoder.decode(new TwoDimensionCodeImage(bufImg)), "utf-8");
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
e.printStackTrace();
} catch (DecodingFailedException dfe) {
System.out.println("Error: " + dfe.getMessage());
dfe.printStackTrace();
}
return content;
}
public static void main(String[] args) {
String imgPath = "D:/aaa/Michael_QRCode.png";
String encoderContent = "http://xx.xx.xx.xx:8380/QrCodeLoginPro/Login.html";
TwoDimensionCode handler = new TwoDimensionCode();
handler.encoderQRCode(encoderContent, imgPath, "png");
/*
System.out.println("========encoder success");
String decoderContent = handler.decoderQRCode(imgPath);
System.out.println("解析结果如下：");
System.out.println(decoderContent);
System.out.println("========decoder success!!!");
*/
}
}
package cn.kuwo.util;
import java.awt.image.BufferedImage;
import jp.sourceforge.qrcode.data.QRCodeImage;
public class TwoDimensionCodeImage implements QRCodeImage {
BufferedImage bufImg;
public TwoDimensionCodeImage(BufferedImage bufImg) {
this.bufImg = bufImg;
}
@Override
public int getHeight() {
return bufImg.getHeight();
}
@Override
public int getPixel(int x, int y) {
return bufImg.getRGB(x, y);
}
@Override
public int getWidth() {
return bufImg.getWidth();
}
}
数据层包括用户信息及以uuid为key，用户信息为value的hashmap
package cn.kuwo.vo;
import java.util.HashMap;
public class LoginUserVo {
private static HashMap<String, UserVo> loginUserMap = new HashMap<String, UserVo>();
private static LoginUserVo loginUserVo;
public static LoginUserVo getVo(){
if(loginUserVo == null){
loginUserVo = new LoginUserVo();
}
return loginUserVo;
}
public static HashMap<String, UserVo> getLoginUserMap() {
return loginUserMap;
}
}
package cn.kuwo.vo;
public class UserVo {
private String uname;
private String upwd;
public String getUname() {
return uname;
}
public void setUname(String uname) {
this.uname = uname;
}
public String getUpwd() {
return upwd;
}
public void setUpwd(String upwd) {
this.upwd = upwd;
}
}
3 python产生二维码与解析二维码
(1)产生二维码
pip install qrcode
先安装PIL的依赖
sudo apt-get install python-dev
sudo apt-get install libjpeg8-dev zlib1g-dev libfreetype6-dev #这些软件包安装后需要建立软连接，其中 freetype2 在/usr/include
然后安装PIL
sudo pip install PIL #无法安装，则可以手动编译安装
代码
import qrcode
qr = qrcode.QRCode(
version=2,
error_correction=qrcode.constants.ERROR_CORRECT_L,
box_size=10,
border=1
)
qr.add_data("http://jb51.net/")
qr.make(fit=True)
img = qr.make_image()
img.save("./dhqme_qrcode.png")
(2)解析二维码
在系统内和python内安装zbar，需要激活配置库，同时安装qrtools
代码
from qrtools import QR
myCode = QR(filename=u"/home/psutton/Documents/Python/qrcodes/qrcode.png")
if myCode.decode():
print myCode.data
print myCode.data_type
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