最近研究一方socket编程,由于想动手写关于socket方面的东西。然而我们知道通过URL去访问某网址,其实其底层用的就是socket,于是我就写了一个很简单的tomcat服务器,主要目地在于学习,在此分享给大家。同时提供下载源工程。
我写的工程用Maven管理的,但是我没有引入其它的JAR包,为此我就不列出pom.xml文件了。
在此简要地说明每个类的作用:
Server.java
该类的作用就是将服务提起来的,并且利用线程池。
package com.cloud.tomcat.server; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.net.ServerSocket; import java.net.Socket; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class Server { private static ServerSocket serverSocket; private static ExecutorService executorService; private final static int POOL_SIZE = 15; public static void main(String[] args) throws Exception { serverSocket = new ServerSocket(8080); Socket socket = null; executorService = Executors.newFixedThreadPool(POOL_SIZE); while (true) { socket = serverSocket.accept(); PrintWriter writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream(), "UTF-8")); writer.println("HTTP/1.1 200 OK"); writer.println("Content-Type: text/html;charset=UTF-8"); writer.println(); executorService.execute(new Handler(socket, writer)); } } }
Handler.java
该类的作用是根据浏览器传过来信息做出相应的处理,同时实现Runnable接口。
package com.cloud.tomcat.server; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.Socket; import com.cloud.tomcat.servlet.HttpServlet; public class Handler implements Runnable { private Socket socket; private PrintWriter writer; public Handler(Socket socket, PrintWriter writer) { this.socket = socket; this.writer = writer; } @Override public void run() { try { InputStream inputStream = socket.getInputStream(); BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream)); String path = ""; String method = ""; while (true) { String msg = reader.readLine(); if (null == msg || "".equals(msg.trim())) { break; } String[] msgs = msg.split(" "); if (3 == msgs.length && "HTTP/1.1".equalsIgnoreCase(msgs[2])) { method = msgs[0]; path = msgs[1]; break; } } if (path.endsWith("ico")) { return; } HttpServlet httpServlet = ServletContainer.getHttpServlet(path); String html = ""; if ("GET".equals(method)) { html = httpServlet.doGet(); } else if ("POST".equals(method)) { html = httpServlet.doGet(); } writer.write(html); writer.flush(); } catch (IOException e) { e.printStackTrace(); } finally { try { writer.close(); socket.close(); } catch (Exception e) { e.printStackTrace(); } } } }
ServletContainer.java
该类首先会解析web.xml文件,然后根据url的信息,拿到相应的servlet。
package com.cloud.tomcat.server; import java.util.HashMap; import java.util.Map; import com.cloud.tomcat.model.Servlet; import com.cloud.tomcat.model.ServletMapping; import com.cloud.tomcat.servlet.HttpServlet; import com.cloud.tomcat.util.XMLUtil; public class ServletContainer { private static Map<String, Object> servletMaps = new HashMap<String, Object>(); private static Map<String, Object> servletMappingMaps = new HashMap<String, Object>(); private static Map<String, HttpServlet> servletContainer = new HashMap<String, HttpServlet>(); static { try { Map<Integer, Map<String, Object>> maps = XMLUtil.parseWebXML(); if (null != maps && 2 == maps.size()) { servletMaps = maps.get(0); servletMappingMaps = maps.get(1); } } catch (Exception e) { e.printStackTrace(); } } public static HttpServlet getHttpServlet(String path) { if (null == path || "".equals(path.trim()) || "/".equals(path)) { path = "/index"; } if (servletContainer.containsKey(path)) { return servletContainer.get(path); } if (!servletMappingMaps.containsKey(path)) { return null; } ServletMapping servletMapping = (ServletMapping) servletMappingMaps.get(path); String name = servletMapping.getName(); if (!servletMaps.containsKey(name)) { return null; } Servlet servlet = (Servlet) servletMaps.get(name); String clazz = servlet.getClazz(); if (null == clazz || "".equals(clazz.trim())) { return null; } HttpServlet httpServlet = null; try { httpServlet = (HttpServlet) Class.forName(clazz).newInstance(); servletContainer.put(path, httpServlet); } catch (Exception e) { e.printStackTrace(); } return httpServlet; } }
HttpServlet.java
为了实现起来简单方便,我自己定义了一个HttpServlet。
package com.cloud.tomcat.servlet; public interface HttpServlet { public String doGet(); public String doPost(); }
CloudServlet.java
HttpServlet的具体实现类。
package com.cloud.tomcat.servlet; public class CloudServlet implements HttpServlet { @Override public String doGet() { return this.doPost(); } @Override public String doPost() { return "<h1>Chicago at Cloud!!!</h1>"; } }
下面一一列出解析web.xml用到的类,由于我没有引入第三JAR包,可能这部分有点麻烦。
Servlet.java
package com.cloud.tomcat.model; public class Servlet { private String name; private String clazz; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getClazz() { return clazz; } public void setClazz(String clazz) { this.clazz = clazz; } }
ServletMapping.java
package com.cloud.tomcat.model; public class ServletMapping { private String name; private String url; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } }
XMLUtil.java
package com.cloud.tomcat.util; import java.io.InputStream; import java.util.HashMap; import java.util.Map; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import com.cloud.tomcat.model.Servlet; import com.cloud.tomcat.model.ServletMapping; public class XMLUtil { public static Map<Integer, Map<String, Object>> parseWebXML() throws Exception { Map<Integer, Map<String, Object>> result = new HashMap<Integer, Map<String,Object>>(); DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); InputStream in = XMLUtil.class.getClassLoader().getResourceAsStream("web.xml"); Document document = db.parse(in); Element root = document.getDocumentElement(); NodeList xmlNodes = root.getChildNodes(); for (int i = 0; i < xmlNodes.getLength(); i++) { Node config = xmlNodes.item(i); if (null != config && config.getNodeType() == Node.ELEMENT_NODE) { String nodeName1 = config.getNodeName(); if ("servlet".equals(nodeName1)) { Map<String, Object> servletMaps = null; if (result.containsKey(0)) { servletMaps = result.get(0); } else { servletMaps = new HashMap<String, Object>(); } NodeList childNodes = config.getChildNodes(); Servlet servlet = new Servlet(); for (int j = 0; j < childNodes.getLength(); j++) { Node node = childNodes.item(j); if (null != node && node.getNodeType() == Node.ELEMENT_NODE) { String nodeName2 = node.getNodeName(); String textContent = node.getTextContent(); if ("servlet-name".equals(nodeName2)) { servlet.setName(textContent); } else if ("servlet-class".equals(nodeName2)) { servlet.setClazz(textContent); } } } servletMaps.put(servlet.getName(), servlet); result.put(0, servletMaps); } else if ("servlet-mapping".equals(nodeName1)) { Map<String, Object> servletMappingMaps = null; if (result.containsKey(1)) { servletMappingMaps = result.get(1); } else { servletMappingMaps = new HashMap<String, Object>(); } NodeList childNodes = config.getChildNodes(); ServletMapping servletMapping = new ServletMapping(); for (int j = 0; j < childNodes.getLength(); j++) { Node node = childNodes.item(j); if (null != node && node.getNodeType() == Node.ELEMENT_NODE) { String nodeName2 = node.getNodeName(); String textContent = node.getTextContent(); if ("servlet-name".equals(nodeName2)) { servletMapping.setName(textContent); } else if ("url-pattern".equals(nodeName2)) { servletMapping.setUrl(textContent); } } } servletMappingMaps.put(servletMapping.getUrl(), servletMapping); result.put(1, servletMappingMaps); } } } return result; } public static void main(String[] args) throws Exception { System.out.println(parseWebXML()); } }
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <servlet> <servlet-name>cloud</servlet-name> <servlet-class>com.cloud.tomcat.servlet.CloudServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>cloud</servlet-name> <url-pattern>/index</url-pattern> </servlet-mapping> </web-app>
运行结果:
将Server类运行起来,然后用浏览器输入:
http://localhost:8080/index或http://localhost:8080
得到如下结果: