一、Maven
1.Maven示意图
类似Java访问数据库
2.创建Maven案例演示
配置阿里镜像
找到setting目录
但一开始配置不存在该文件
需要去Maven主目录下的conf拿到settings拷贝到上述目录
拷贝到admin/.m2后打开该settings
在<mirrors>内输入镜像地址
<mirror>
<id>alimaven</id>
<name>aliyun maven</name>
<url>https://maven.aliyun.com/nexus/content/groups/publichttps://maven.aliyun.com/repository/publichttps://maven.aliyun.com/nexus/content/groups/public</url>
<mirrorOf>central</mirrorOf>
</mirror>
配置pom.xml文件
</dependency><!--引入servlet.jar包--><!--1.入servlet-api.jar ，为J开发servlet2. dependency 标签是表示引入-一个包3. groupId包的公司/ 组织/开发团队/个人信息javax. servlet4. artifactId :项目名javax .servlet-api5. version 版本6. scope 表示引入的包的作用范围7. provided: 表示tomcat 本身有jar包，这里你引入的jar包，在编译，测试有效但是在打包的时候不要带上这个jar包8.下载的包在你指定的目录:C:\Users\Administrator\.m2\repository9.可以去修改我们要下载包的位置->10.我们可以去指定maven仓库，即配置maven镜像C:\Users\Administratorl.m2\settings.xml--><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency>
3.实现计算器效果
创建Tomcat的时候不要使用xxx_war包而要使用explore的
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>计算器</title>
</head>
<body><form action="/yhtomcat/calServlet" method="post">num1:<input type="text" name="num1"><br/>num2:<input type="text" name="num2"><br/><input type="submit" value="submit"></form>
</body>
</html>@WebServlet(name = "CalServlet",urlPatterns = "/calServlet")
public class CalServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String strnum1 = request.getParameter("num1");String strnum2 = request.getParameter("num2");int num1 = 0;int num2 = 0;int sum = -1;try {num1 = Integer.parseInt(strnum1);num2 = Integer.parseInt(strnum2);System.out.println("res = " + num1 + num2);sum = num1 + num2;} catch (NumberFormatException e) {System.out.println("form wrong , continue");}response.setContentType("text/html;charset=utf-8");PrintWriter writer = response.getWriter();if (!(sum == -1)) {writer.print("<h1> res = " + sum + "</h1>");}else{writer.print("<h1> wrong date please try again!! </h1>");}writer.flush();writer.close();}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request,response);}
}
二、Tomcat架构分析
我们的目标:不用Tomcat,不用系统提供的Servlet,
模拟Tomcat底层实现并能调用我们自己设计的Servle,也能完成相同的功能
说明: Tomcat有三种运行模式(BIO, NIO, APR) ,因为老师核心讲解的是Tomcat如何接收客户端请求，解析请求,调用Servlet并返回结果的机制流程，采用BIO线程模型来模拟.
模拟Tomcat底层机制
一、编写自己Tomcat
1.基于socket开发服务端流程
1. ServerSocket
在服务端监听指定端口，如果浏览器/客户端连接该端口，则建立连接，返回Socket对象
2. Socket
表示服务端和客户端/浏览器间的连接,通过Socket可以得到InputStream和OutputStream流对象。
public class YhTomcatV1 {public static void main(String[] args) throws IOException {ServerSocket serverSocket = new ServerSocket(8080);System.out.println("======yhtomcat 在8080端口监听");while (!serverSocket.isClosed()){//等待连接//如果有连接来，就创建一个socket//这socket就是服务端和浏觉器端的连接/通道Socket socket = serverSocket.accept();//先接受浏览器发来的数据//字节流InputStream inputStream = socket.getInputStream();BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"utf-8"));String mes = null;System.out.println("=====接受到浏览器发送的数据======");while ((mes = bufferedReader.readLine()) != null){if(mes.length() == 0){//读到空字符串break;}System.out.println(mes);}//我们的tomcat会送-http响应方式OutputStream outputStream = socket.getOutputStream();//构建一个http响应的头//\r\n 表示回车换行//http响应体，需要前面有两个换行 \r\n\r\nString respHeader = "HTTP/1.1 200 OK\r\n" +"Content-Type: text/html;charset=utf-8\r\n\r\n";String resp = respHeader + "<h1>hi, 这是模拟Tomcat</h1>";System.out.println("========我们的tomcat 给浏览器会送的数据======");System.out.println(resp);outputStream.write(resp.getBytes());//将resp字符串以byte[] 方式返回outputStream.flush();outputStream.close();inputStream.close();socket.close();}}
}
2.使用BIO线程模型，支持多线程
BIO线程模型介绍
需求分析
浏览器请求http:/ /localhost:8080,服务端返回hi , hspedu,后台hsptomcat使用BIO线程模型,支持多线程=>对前面的开发模式进行改造
一个持有线程的对象
public class YhRequestHandler extends Thread {
/** 1. HspRequestHandler 对象是一个线程对象* 2. 处理一个http请求的*///定义Socketprivate Socket socket = null;public YhRequestHandler(Socket socket) {this.socket = socket;}@Overridepublic void run() {//这里我们可以对客户端/浏览器进行IO编程/交互try {//1.使用BIO线程模型，支持多线程InputStream inputStream = socket.getInputStream();// //把inputStream -> BufferedReader -> 方便进行按行读取BufferedReader bufferedReader =new BufferedReader(new InputStreamReader(inputStream, "utf-8"));//// //不同的线程在和浏览器和客户端交互System.out.println("当前线程= " + Thread.currentThread().getName());System.out.println("=========hsptomcatv2 接收到的数据如下=========");String mes = null;// io - 网络 - 线程 - 反射 - 注解 - OOP [都会学会，也会学好]//while ((mes = bufferedReader.readLine()) != null) {//如果长度为0 ""if (mes.length() == 0) {break; //退出}System.out.println(mes);}//构建一下http响应头//返回的http的响应体和响应头之间有两个换行 \r\n\r\nString respHeader = "HTTP/1.1 200 OK\r\n" +"Content-Type: text/html;charset=utf-8\r\n\r\n";String resp = respHeader + "<h1>hi this is ThreadServlet</h1>";System.out.println("========Yhtomcatv2返回的数据是=========");System.out.println(resp);//返回数据给我们的浏览器/客户端-> 封装成http响应OutputStream outputStream = socket.getOutputStream();//resp.getBytes() 是把字符串转成字节数组outputStream.write(resp.getBytes());outputStream.flush();outputStream.close();inputStream.close();socket.close();} catch (IOException e) {e.printStackTrace();} finally {//最后一定确保socket要关闭if (socket != null) {try {socket.close();} catch (IOException e) {e.printStackTrace();}}}}
}
Tomcat
public class YhTomcatV2 {public static void main(String[] args) throws IOException {//在8080端口监听ServerSocket serverSocket = new ServerSocket(8080);System.out.println("=======hsptomcatV2 在8080监听=======");//只要 serverSocket没有关闭，就一直等待浏览器/客户端的连接while (!serverSocket.isClosed()) {//1. 接收到浏览器的连接后，如果成功，就会得到socket//2. 这个socket 就是 服务器和 浏览器的数据通道Socket socket = serverSocket.accept();//3. 创建一个线程对象，并且把socket给该线程// 这个是java线程基础YhRequestHandler hspRequestHandler =new YhRequestHandler(socket);new Thread(hspRequestHandler).start();}}
}
问题分析: MyT omcat只是简单返回结果，没有和Servlet,web.xml关联
3.处理 Servlet
Request处理请求信息
public class YhRequest {/*** 1. YhRequest 作用是封装http请求的数据* get /hspCalServlet?num1=10&num2=30* 2. 比如 method(get) 、 uri(/hspCalServlet) 、 还有参数列表 (num1=10&num2=30)* 3. HspRequest 作用就等价原生的servlet 中的HttpServletRequest 这里考虑的是GET请求*/private String method;private String uri;//存放参数列表 参数名-参数值 => HashMapprivate HashMap<String, String> parametersMapping =new HashMap<>();private InputStream inputStream = null;//构造器=> 对http请求进行封装 => 可以将老师写的代码封装成方法//inputStream 是和 对应http请求的socket关联public YhRequest(InputStream inputStream) {this.inputStream = inputStream;//完成对http请求数据的封装..encapHttpRequest();}/*** 将http请求的相关数据，进行封装,然后提供相关的方法，进行获取*/private void encapHttpRequest() {System.out.println("yhRequest init()");try {//inputstream -> BufferedReaderBufferedReader bufferedReader =new BufferedReader(new InputStreamReader(inputStream, "utf-8"));//读取第一行/*** GET /hspCalServlet?num1=10&num2=30 HTTP/1.1* Host: localhost:8080* User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:97.0) Gecko/20100101 Fi*/String requestLine = bufferedReader.readLine();//GET - /hspCalServlet?num1=10&num2=30 - HTTP/1.1String[] requestLineArr = requestLine.split(" ");//得到methodmethod = requestLineArr[0];//解析得到 /hspCalServlet//1. 先看看uri 有没有参数列表int index = requestLineArr[1].indexOf("?");if (index == -1) { //说明没有参数列表uri = requestLineArr[1];} else {//[0,index)uri = requestLineArr[1].substring(0, index);//获取参数列表->parametersMapping//parameters => num1=10&num2=30String parameters = requestLineArr[1].substring(index + 1);//num1=10 , num2=30 .... parametersPair= ["num1=10","num2=30" ]String[] parametersPair = parameters.split("&");//防止用户提交时 /hspCalServlet?if (null != parametersPair && !"".equals(parametersPair)) {//再次分割 parameterPair = num1=10for (String parameterPair : parametersPair) {//parameterVal ["num1", "10"]String[] parameterVal = parameterPair.split("=");if (parameterVal.length == 2) {//放入到 parametersMappingparametersMapping.put(parameterVal[0], parameterVal[1]);}}}}//这里不能关闭流 inputStream 和 socket关联//inputStream.close();} catch (Exception e) {e.printStackTrace();}}//request对象有一个特别重要方法public String getParameter(String name) {if (parametersMapping.containsKey(name)) {return parametersMapping.get(name);} else {return "";}}public String getMethod() {return method;}public void setMethod(String method) {this.method = method;}public String getUri() {return uri;}public void setUri(String uri) {this.uri = uri;}@Overridepublic String toString() {return "HspRequest{" +"method='" + method + '\'' +", uri='" + uri + '\'' +", parametersMapping=" + parametersMapping +'}';}
}
注意 这里不能关闭流 inputStream 和 socket关联
Response对象处理响应 持有socket
public class YhResponse {/*** 1. HspResponse对象可以封装OutputStream(是socket关联)* 2. 即可以通过 HspResponse对象 返回Http响应给浏览器/客户端* 3. HspResponse对象 的作用等价于原生的servlet的 HttpServletResponse*/private OutputStream outputStream = null;//写一个http的响应头 => 先死后活public static final String respHeader = "HTTP/1.1 200 OK\r\n" +"Content-Type: text/html;charset=utf-8\r\n\r\n";//说明同学们如果有兴趣, 在编写更多的方法//比如 setContentType//在创建 YhResponse 对象时，传入的outputStream是和Socket关联的public YhResponse(OutputStream outputStream) {this.outputStream = outputStream;}//当我们需要给浏览器返回数据时，可以通过HspResponse 的输出流完成//public OutputStream getOutputStream() {return outputStream;}}
设计Servlet规范类以及Servlet接口
public interface YhServlet {void init() throws Exception;void service(YhRequest request, YhResponse response) throws IOException;void destroy();
}public abstract class YhHttpServlet implements YhServlet {@Overridepublic void service(YhRequest request, YhResponse response) throws IOException {//老师说明 equalsIgnoreCase 比较字符串内容是相同，不区别大小写if("GET".equalsIgnoreCase(request.getMethod())) {//这里会有动态绑定this.doGet(request,response);} else if("POST".equalsIgnoreCase(request.getMethod())) {this.doPost(request,response);}}//这里我们使用的了模板设计模式 => java 基础的 抽象类专门讲过模板设计模式//让HspHttpServlet 子类 HspCalServlet 实现public abstract void doGet(YhRequest request, YhResponse response);public abstract void doPost(YhRequest request, YhResponse response);
}YhCalServlet实现该Servlet并写自己的业务代码
public class YhCalServlet extends YhHttpServlet {@Overridepublic void doGet(YhRequest request, YhResponse response) throws IOException {doPost(request,response);}@Overridepublic void doPost(YhRequest request, YhResponse response) throws IOException {String strnum1 = request.getParameter("num1");String strnum2 = request.getParameter("num2");int num1 = 0;int num2 = 0;int sum = -1;try {num1 = Integer.parseInt(strnum1);num2 = Integer.parseInt(strnum2);System.out.println("res = " + num1 + num2);sum = num1 + num2;} catch (NumberFormatException e) {System.out.println("form wrong , continue");}// response.setContentType("text/html;charset=utf-8"); response内已经做了OutputStream outputStream = response.getOutputStream();if (!(sum == -1)) {outputStream.write((YhResponse.respHeader + "<h1> res = " + sum + "</h1>").getBytes());}else{outputStream.write((YhResponse.respHeader + "<h1> wrong date please try again!! </h1>").getBytes());}outputStream.flush();outputStream.close();}@Overridepublic void init() {}@Overridepublic void destroy() {}
}
4.使用反射去处理查找哪个calServlet
handler管理线程代码
//=====================通过反射来实现==========// 先说明一把实现思路->【停一下】 -> 如果你自己完成？10min// 1. 得到 uri => 就是 servletUrlMapping 的 url-patternYhRequest yhRequest = new YhRequest(socket.getInputStream());YhResponse yhResponse = new YhResponse(socket.getOutputStream());String uri = yhRequest.getUri();String servletName = YhTomcatV3.servletUrlMapping.get(uri);if(servletName == null){servletName = "";}//2. 通过uri->servletName->servlet的实例 , 真正的运行类型是其子类 HspCalServletYhHttpServlet yhHttpServlet =YhTomcatV3.servletMapping.get(servletName);//3. 调用service , 通过OOP的动态绑定机制，调用运行类型的 doGet/doPostif (yhHttpServlet != null) {//得到yhHttpServlet.service(yhRequest, yhResponse);} else {//没有这个servlet , 返回404的提示信息String resp = YhResponse.respHeader + "<h1>404 Not Found</h1>";OutputStream outputStream = yhResponse.getOutputStream();outputStream.write(resp.getBytes());outputStream.flush();outputStream.close();}
模拟Tomcat利用反射和dom4j处理xml文件获取Servlet
public class YhTomcatV3 {//1. 存放容器 servletMapping// -ConcurrentHashMap// -HashMap// key - value// ServletName 对应的实例public static final ConcurrentHashMap<String, YhHttpServlet>servletMapping = new ConcurrentHashMap<>();//2容器 servletUrlMapping// -ConcurrentHashMap// -HashMap// key - value// url-pattern ServletNamepublic static final ConcurrentHashMap<String, String>servletUrlMapping = new ConcurrentHashMap<>();//你可以这里理解session, tomcat还维护一个容器public static final ConcurrentHashMap<String, HttpSession>sessionMapping = new ConcurrentHashMap<>();// //你可以这里理解filter, tomcat还维护了filter的容器// public static final ConcurrentHashMap<String, String>// filterUrlMapping = new ConcurrentHashMap<>();//// public static final ConcurrentHashMap<String, Filter>// filterMapping = new ConcurrentHashMap<>();public static void main(String[] args) throws MalformedURLException, DocumentException {YhTomcatV3 yhTomcatV3 = new YhTomcatV3();yhTomcatV3.init();//启动hsptomcat容器yhTomcatV3.startTomcatV3();}//启动HspTomcatV3容器public void startTomcatV3() {try {ServerSocket serverSocket = new ServerSocket(8080);System.out.println("=====hsptomcatv3在8080监听======");while (!serverSocket.isClosed()) {Socket socket = serverSocket.accept();YhRequestHandler yhRequestHandler =new YhRequestHandler(socket);new Thread(yhRequestHandler).start();}} catch (IOException e) {e.printStackTrace();}}//直接对两个容器进行初始化@Testpublic void init() throws MalformedURLException, DocumentException {//读取web.xml => dom4j =>//得到web.xml文件的路径 => 拷贝一份.String path = YhTomcatV3.class.getResource("/").getPath();System.out.println("path= " + path);//使用dom4j技术完成读取SAXReader saxReader = new SAXReader();//困难->真的掌握try {Document document = saxReader.read(new File(path + "web.xml"));System.out.println("document= " + document);//得到根元素Element rootElement = document.getRootElement();//得到根元素下面的所有元素List<Element> elements = rootElement.elements();//遍历并过滤到 servlet servlet-mappingfor (Element element : elements) {if ("servlet".equalsIgnoreCase(element.getName())) {//这是一个servlet配置//System.out.println("发现 servlet");//使用反射将该servlet实例放入到servletMappingElement servletName = element.element("servlet-name");Element servletClass = element.element("servlet-class");servletMapping.put(servletName.getText(),(YhHttpServlet) Class.forName(servletClass.getText().trim()).newInstance());} else if ("servlet-mapping".equalsIgnoreCase(element.getName())) {//这是一个servlet-mapping//System.out.println("发现 servlet-mapping");Element servletName = element.element("servlet-name");Element urlPatter = element.element("url-pattern");servletUrlMapping.put(urlPatter.getText(), servletName.getText());}}} catch (Exception e) {e.printStackTrace();}//老韩验证，这两个容器是否初始化成功System.out.println("servletMapping= " + servletMapping);System.out.println("servletUrlMapping= " + servletUrlMapping);}
}
二、课后作业
<html lang="en">
<head><meta charset="UTF-8"><title>计算器</title>
</head>
<body><form action="/yhCalServlet" method="GET">num1:<input type="text" name="num1"><br/>num2:<input type="text" name="num2"><br/><input type="submit" value="submit"></form>
</body>
</html>在工具类内写方法判断 如果不是servlet 就判断是不是html
public static String readHtml(String filename) {String path = com.yinhai.utils.WebUtils.class.getResource("/").getPath();StringBuilder stringBuilder = new StringBuilder();try {BufferedReader bufferedReader = new BufferedReader(new FileReader(path + filename));String buf = "";while ((buf = bufferedReader.readLine()) != null) {stringBuilder.append(buf);}} catch (Exception e) {e.printStackTrace();}return stringBuilder.toString();}如果是html 就走该if体 将方法返回
// ====================新增业务逻辑===========//(1) 判断uri是什么资源 => 工具方法//(2) 如果是静态资源,就读取该资源，并返回给浏览器 content-type text/html//(3) 因为目前老师并没有起到tomcat, 不是一个标准的web项目//(4) 把读取的静态资源放到 target/classes/cal.html//过滤，拦截 , 权限等待 => Handler.... => 分发if(WebUtils.isHtml(uri)) {//就是静态页面String content = WebUtils.readHtml(uri.substring(1));content = yhResponse.respHeader + content;//得到outputstream , 返回信息(静态页面)给浏览器OutputStream outputStream = yhResponse.getOutputStream();outputStream.write(content.getBytes());outputStream.flush();outputStream.close();socket.close();return;}//===========================================
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