學完微型服務器（Tomcat）對其工作流程的理解，自己着手寫個簡單的tomcat
2019-05-09 19:28:42
注：項目(MyEclipse)創建的時候選擇：Web Service Project
第一步 對Tomcat工作流程進行分析
第二步 對其項目進行全局的把關
首先看看Project(FirstTomcat)的目錄結構
|-FirstTomcat
|——src
| |-org.mrzhangxd.com
| |-FirstRequest.java
| |-FirstResponse.java
| |-FirstServlet.java
| |-FirstTomcat.java
| |-FirstServletMapping.java
| |_FirstServletMappingConfig.java
| |-JRE System Library[JavaSE-x.y]
| |-JAXB x.y.z Libraries
| |-JavaEE x.y Generic Library
| |-JSTL x.y.z Library
| |-JAX-RS x.y Libraries(Project Jersey x.y)
|___|_WebRoot
第三步 代碼實現
處理請求：
- 創建一個request對象並填充那些有可能被所引用的Servlet使用的信息，如參數，頭部、cookies、查詢字符串等。
- 創建一個response對象，所引用的servlet使用它來給客戶端發送響應。
- 調用servlet的service方法，並傳入request和response對象。這裏servlet會從request對象取值，給response寫值。
- 根據servlet返回的response生成相應的HTTP響應報文。
接下來一一實現
請求：FirstRequest.java
|
package org.mrzhangxd.com; import java.io.InputStream; /** * * @author mrzhangxd * */ public class FirstRequest { //請求路徑 private String url; //請求方法 private String method; public FirstRequest(InputStream inputStream)throws Exception{ String httpRequest = ""; byte[] httpRequestBytes = new byte[1024]; int length = 0; if((length = inputStream.read(httpRequestBytes))>0){ httpRequest = new String(httpRequestBytes,0,length); } //HTTP請求協議：首行的內容依次爲：請求方法、請求路徑以及請求協議及其對應的版本號 //GET /index /HTTP/1.1 String httpHead = httpRequest.split("\n")[0];//取出HTTP協議的首行 System.out.println(httpHead); method = httpHead.split("\\s")[0];//按照空格進行分割，第一個請求方法
url = httpHead.split("\\s")[1];//按照空格進行分割，第二個是路徑 System.out.println(this.toString()); }
public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public String getMethod() { return method; } public void setMethod(String method) { this.method = method; } public String toString(){ return "MyRequest[url = "+url+",method = "+method+"]";
} } |
迴應：FirstResponse.java
|
package org.mrzhangxd.com; import java.io.IOException; import java.io.OutputStream; /** * * @author mrzhangxd * */ public class FirstResponse { private OutputStream outputStream; public FirstResponse(OutputStream outputStream){ this.outputStream = outputStream; } //將文本轉換爲字節流 public void write(String content)throws IOException{ StringBuffer httpResponse = new StringBuffer(); httpResponse.append("HTTP/1.1 200 OK\n") .append("Content-Type;text/html\n") .append("\r\n") .append("<html><link rel = \"icon\"href = \"data:;base64,=\">") .append(content)//將頁面內容寫入 .append("</body></html>") .append(""); outputStream.write(httpResponse.toString().getBytes());//將文本轉換爲字節碼 outputStream.close(); } } |
Servlet請求處理基類：FirstServlet.java
|
package org.mrzhangxd.com; /** * * @author mrzhangxd * */ public abstract class FirstServlet { public void servlet(FirstRequest firstRequest,FirstResponse firstResponse){ if(firstRequest.getMethod().equalsIgnoreCase("POST")){ doPost(firstRequest,firstResponse); }else if(firstRequest.getMethod().equalsIgnoreCase("GET")){ doGet(firstRequest,firstResponse); } } private void doGet(FirstRequest firstRequest, FirstResponse firstResponse) { // TODO Auto-generated method stub } private void doPost(FirstRequest firstRequest, FirstResponse firstResponse) { // TODO Auto-generated method stub } public void service(FirstRequest firstRequest, FirstResponse firstResponse) { // TODO Auto-generated method stub } } |
下一步servlet配置：FirstServletMapping.java
|
package org.mrzhangxd.com;
/** * * @author mrzhangxd * */ public class FirstServletMapping { private String servletName; private String url; private String clazz;
public FirstServletMapping(String servletName, String url, String clazz) { super(); this.servletName = servletName; this.url = url; this.clazz = clazz; }
public String getServletName() { return servletName; }
public void setServeletName(String servletName) { this.servletName = servletName; }
public String getUrl() { return url; }
public void setUrl(String url) { this.url = url; }
public String getClazz() { return clazz; }
public void setClazz(String clazz) { this.clazz = clazz; } } |
其他配置：FirstServletMappingConfig.java
|
package org.mrzhangxd.com; import java.util.ArrayList; import java.util.List; /** * * @author mrzhangxd * */ public class FirstServletMappingConfig { public static List<FirstServletMapping> servletMappingList = new ArrayList<>(); static { servletMappingList.add(new FirstServletMapping("index", "/index", "firstTomcat.test.IndexServlet")); servletMappingList.add(new FirstServletMapping("firstblog", "/firstblog", "firstTomcat.test.MyBlog")); } } |
核心處理類：FirstTomcat.java,處理流程如下：
1) 提供Socket服務
2) 封裝請求/響應對象
3) 將不同的請求映射到具體的Servlet處理
這裏重點說的是，要利用 ServerSocket 通過服務器上的端口通信 以及 accpt方法一直等待客戶端的請求
|
package org.mrzhangxd.com; import java.io.InputStream; import java.io.OutputStream; import java.net.ServerSocket; import java.net.Socket; import java.util.HashMap; import java.util.Map; /** * * @author mrzhangxd * */ public class FirstTomcat { private Integer port = 8080; //定義8080端口 private Map<String, String> urlServletMapping = new HashMap<>(); //存儲url和對應的類 public FirstTomcat(Integer port) { super(); this.port = port; } @SuppressWarnings("resource") public void start() { initServletMapping(); try { ServerSocket serverSocket = null; //實例化一個 ServerSocket 對象，表示通過服務器上的端口通信 serverSocket = new ServerSocket(port); System.out.println("MyTomcat is starting..."); while(true) { Socket socket = serverSocket.accept(); //服務器調用 ServerSocket 類的 accept() 方法，該方法將一直等待，直到客戶端連接到服務器上給定的端口 InputStream inputStream = socket.getInputStream(); OutputStream outputStream = socket.getOutputStream(); FirstRequest myRequest = new FirstRequest(inputStream); FirstResponse myResponse = new FirstResponse (outputStream); dispatch(myRequest, myResponse); socket.close(); } }catch(Exception e) { e.printStackTrace(); } } //初始化映射 public void initServletMapping() { for(FirstServletMapping servletMapping : FirstServletMappingConfig.servletMappingList) { urlServletMapping.put(servletMapping.getUrl(), servletMapping.getClazz()); } } //分發請求 @SuppressWarnings("unchecked") public void dispatch(FirstRequest firstRequest, FirstResponse firstResponse) { String clazz = urlServletMapping.get(firstRequest.getUrl()); try { Class<FirstServlet> firstServletClass = (Class<FirstServlet>)Class.forName(clazz); FirstServlet firstservlet = firstServletClass.newInstance(); firstservlet.service(firstRequest, firstResponse); }catch(ClassNotFoundException e) { e.printStackTrace(); }catch(InstantiationException e) { e.printStackTrace(); }catch(IllegalAccessException e) { e.printStackTrace(); } } public static void main(String[] args) { FirstTomcat myTomcat = new FirstTomcat(8080); myTomcat.start(); } } |
測試類按照上面類裏的註釋自己解決，測試結果略。
注：
編碼格式、註釋都參考《代碼整潔之道》