採坑-深入剖析Tomcat一書 第二章

項目結構：

貼代碼：

Constants：

package com.diy.tomcat.chapter2.servlet;

import java.io.File;

public class Constants {
    /**
     *  WEB_ROOT是HTML和其他文件所在的目錄。對於這個包，WEB_ROOT是工作目錄下的“webroot”目錄。工作目錄是文件系統中調用java命令的位置。
     */
    public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot/production/";
}

HttpServer1：

package com.diy.tomcat.chapter2.servlet;

import com.diy.tomcat.server.Request;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class HttpServer1 {


    private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";

    private boolean shutdown = false;

    public static void main(String[] args) {
        HttpServer1 httpServer1 = new HttpServer1();
        httpServer1.await();
    }

    public void await() {
        ServerSocket serverSocket = null;
        int port = 8080;
        try {
            serverSocket = new ServerSocket(port, 1 , InetAddress.getByName("127.0.0.1"));
        }catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }

        while (!shutdown) {
            Socket socket = null;
            InputStream inputStream = null;
            OutputStream outputStream = null;
            try {
                socket = serverSocket.accept();
                inputStream = socket.getInputStream();
                outputStream = socket.getOutputStream();

                Request1 request1 = new Request1(inputStream);
                request1.parse();

                Response1 response1 = new Response1(outputStream);
                response1.setRequest(request1);

                if (request1.getUri().startsWith("/servlet")) {
                    ServletProcessor1 processor1 = new ServletProcessor1();
                    processor1.process(request1, response1);
                } else {
                    StaticResourceProcessor processor = new StaticResourceProcessor();
                    processor.process(request1, response1);
                }

                socket.close();

                shutdown = request1.getUri().equals(SHUTDOWN_COMMAND);

            } catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }

        }



    }

}

PrimitiveServlet：

package com.diy.tomcat.chapter2.servlet;

import javax.servlet.*;
import java.io.IOException;
import java.io.PrintWriter;

public class PrimitiveServlet implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("這是自己寫的PrimitiveServlet的初始化方法");
    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("這是PrimitiveServlet中可能會被調用多次的service方法。");

        PrintWriter out = servletResponse.getWriter();
        StringBuffer sb = new StringBuffer();
        //響應頭信息
        sb.append("HTTP/1.1 200 OK\n");
        sb.append("Content-Type: text/html;charset=UTF-8\n");
        sb.append("\r\n");
        sb.append("<h1>Hello. Rose are red </h1>");

        out.println(sb.toString());
        out.println("Hello. Rose are red.!!!!!!!!!!!");
        out.print("Violets are blue");
    }

    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {
        System.out.println("這是PrimitiveServlet的destroy方法。用以關閉servlet容器和釋放內存。");
    }
}

Request1

package com.diy.tomcat.chapter2.servlet;

import javax.servlet.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;

public class Request1 implements ServletRequest {

    private InputStream inputStream;
    private String uri;

    public Request1(InputStream inputStream) {
        this.inputStream = inputStream;
    }

    public String getUri() {
        return uri;
    }

    private String parseUri(String requestString) {
        int index1, index2;
        index1 = requestString.indexOf(" ");
        if (index1 != -1) {
            index2 = requestString.indexOf(" ", index1 + 1);
            if (index2 > index1) {
                return requestString.substring(index1 + 1, index2);
            }
        }
        return null;
    }


    public void parse() {
        StringBuffer stringBuffer = new StringBuffer(2048);
        int i;
        byte[] buffer = new byte[2048];
        try {
            i = inputStream.read(buffer);
        } catch (IOException e) {
            e.printStackTrace();
            i = -1;
        }
        for (int j = 0; j < i; j++) {
            stringBuffer.append((char) buffer[j]);
        }
        System.out.println(stringBuffer.toString());
        uri = parseUri(stringBuffer.toString());
    }


    @Override
    public Object getAttribute(String s) {
        return null;
    }

    @Override
    public Enumeration<String> getAttributeNames() {
        return null;
    }

    @Override
    public String getCharacterEncoding() {
        return null;
    }

    @Override
    public void setCharacterEncoding(String s) throws UnsupportedEncodingException {

    }

    @Override
    public int getContentLength() {
        return 0;
    }

    @Override
    public String getContentType() {
        return null;
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        return null;
    }

    @Override
    public String getParameter(String s) {
        return null;
    }

    @Override
    public Enumeration<String> getParameterNames() {
        return null;
    }

    @Override
    public String[] getParameterValues(String s) {
        return new String[0];
    }

    @Override
    public Map<String, String[]> getParameterMap() {
        return null;
    }

    @Override
    public String getProtocol() {
        return null;
    }

    @Override
    public String getScheme() {
        return null;
    }

    @Override
    public String getServerName() {
        return null;
    }

    @Override
    public int getServerPort() {
        return 0;
    }

    @Override
    public BufferedReader getReader() throws IOException {
        return null;
    }

    @Override
    public String getRemoteAddr() {
        return null;
    }

    @Override
    public String getRemoteHost() {
        return null;
    }

    @Override
    public void setAttribute(String s, Object o) {

    }

    @Override
    public void removeAttribute(String s) {

    }

    @Override
    public Locale getLocale() {
        return null;
    }

    @Override
    public Enumeration<Locale> getLocales() {
        return null;
    }

    @Override
    public boolean isSecure() {
        return false;
    }

    @Override
    public RequestDispatcher getRequestDispatcher(String s) {
        return null;
    }

    /**
     * @param s
     * @deprecated
     */
    @Override
    public String getRealPath(String s) {
        return null;
    }

    @Override
    public int getRemotePort() {
        return 0;
    }

    @Override
    public String getLocalName() {
        return null;
    }

    @Override
    public String getLocalAddr() {
        return null;
    }

    @Override
    public int getLocalPort() {
        return 0;
    }

    @Override
    public ServletContext getServletContext() {
        return null;
    }

    @Override
    public AsyncContext startAsync() {
        return null;
    }

    @Override
    public AsyncContext startAsync(ServletRequest servletRequest, ServletResponse servletResponse) {
        return null;
    }

    @Override
    public boolean isAsyncStarted() {
        return false;
    }

    @Override
    public boolean isAsyncSupported() {
        return false;
    }

    @Override
    public AsyncContext getAsyncContext() {
        return null;
    }

    @Override
    public DispatcherType getDispatcherType() {
        return null;
    }
}

Response1

package com.diy.tomcat.chapter2.servlet;

import com.diy.tomcat.server.HttpServer;

import javax.servlet.ServletOutputStream;
import javax.servlet.ServletResponse;
import java.io.*;
import java.util.Locale;

public class Response1 implements ServletResponse {

    private static final int BUFFER_SIZE = 1024;
    Request1 request1;
    OutputStream outputStream;
    PrintWriter writer;

    public Response1(OutputStream outputStream) {
        this.outputStream = outputStream;
    }

    public void setRequest(Request1 request1) {
        this.request1 = request1;
    }

    public void sendStaticResource() throws IOException {
        byte[] bytes = new byte[BUFFER_SIZE];
        FileInputStream fileInputStream = null;
        try {
            File file = new File(HttpServer.WEB_ROOT, request1.getUri());

            if (file.exists()) {
                fileInputStream = new FileInputStream(file);
                int ch = fileInputStream.read(bytes, 0, BUFFER_SIZE);

                StringBuffer sb = new StringBuffer();
                //響應頭信息
                sb.append("HTTP/1.1 200 OK\n");
                sb.append("Content-Type: text/html;charset=UTF-8\n");
                sb.append("\r\n");
                while (ch != -1) {
                    sb.append(new String(bytes));
                    outputStream.write(sb.toString().getBytes());
//                    outputStream.write(bytes, 0, ch);
                    ch = fileInputStream.read(bytes, 0, BUFFER_SIZE);
                }
            } else {
                String errorMessage = "HTTP/1.1 404 File Not Found\r\n"
                        + "Content-Type: text/html\r\n"
                        + "Content-Length: 23\r\n"
                        + "\r\n"
                        + "<h1> File Not Found</h1>";
                outputStream.write(errorMessage.getBytes());
            }
        } catch (Exception e) {
            e.printStackTrace();
            // 如果不能實例化文件對象，則拋出
            System.out.println(e.toString());
        } finally {
            if (fileInputStream != null) {
                fileInputStream.close();
                outputStream.flush();
                outputStream.close();
            }
        }
    }


    @Override
    public String getCharacterEncoding() {
        return null;
    }

    @Override
    public String getContentType() {
        return null;
    }

    @Override
    public ServletOutputStream getOutputStream() throws IOException {
        return null;
    }

    @Override
    public PrintWriter getWriter() throws IOException {
        writer = new PrintWriter(outputStream, true);
        return writer;
    }

    @Override
    public void setCharacterEncoding(String s) {

    }

    @Override
    public void setContentLength(int i) {

    }

    @Override
    public void setContentType(String s) {

    }

    @Override
    public void setBufferSize(int i) {

    }

    @Override
    public int getBufferSize() {
        return 0;
    }

    @Override
    public void flushBuffer() throws IOException {

    }

    @Override
    public void resetBuffer() {

    }

    @Override
    public boolean isCommitted() {
        return false;
    }

    @Override
    public void reset() {

    }

    @Override
    public void setLocale(Locale locale) {

    }

    @Override
    public Locale getLocale() {
        return null;
    }
}

ServletProcessor1

package com.diy.tomcat.chapter2.servlet;


import javax.servlet.Servlet;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;

public class ServletProcessor1 {

    public void process (Request1 request1, Response1 response1) {
        String uri = request1.getUri();
        String servletName = uri.substring(uri.lastIndexOf("/") + 1);
        System.out.println("=="+ servletName);
        URLClassLoader urlClassLoader = null;
        try {
            // 創建一個URLClassLoader
//            URL[] urls = new URL[1];
//            URLStreamHandler urlStreamHandler = null;
//            File classPath = new File(Constants.WEB_ROOT);

//            // 存儲庫的形成是從createClassLoader方法中獲得的組織 阿帕奇.卡特琳娜.startup.ClassLoader工廠
//            String repository = (new URL("file", null, classPath.getCanonicalPath() + File.separator)).toString();
//
//            System.out.println("===" + repository);
//
//            // 形成URL的代碼取自addRepository方法阿帕奇.卡特琳娜.裝載機。默認類加載器。
//            urls[0] = new URL(null, repository, urlStreamHandler);
//
//            urlClassLoader = new URLClassLoader(urls);
            File f = new File(this.getClass().getResource("/").getPath());
            String path = "file:" + f.toString();
            URL url = new URL(path);
            urlClassLoader = new URLClassLoader(new URL[]{url});

        }catch (IOException e) {
            e.printStackTrace();
            System.out.println(e.toString());
        }

        String packagePath = "com.diy.tomcat.chapter2.servlet.";

        servletName = packagePath + servletName;

        Class myClass = null;
        try {
            myClass = urlClassLoader.loadClass(servletName);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            System.out.println(e.toString());
        }

        Servlet servlet = null;

        try {
            servlet = (Servlet) myClass.newInstance();
//            servlet.init(servlet.getServletConfig());
            servlet.service((ServletRequest) request1, (ServletResponse) response1) ;
//            servlet.destroy();
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println(e.toString());
        }catch (Throwable e) {
            e.printStackTrace();
        }

    }
}

StaticResourceProcessor

package com.diy.tomcat.chapter2.servlet;

import java.io.IOException;

public class StaticResourceProcessor {

    public void process(Request1 request1, Response1 response1) {
        try {
            response1.sendStaticResource();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

其中碰到的坑有兩個，一個就是返回信息，response.getWriter(),要跟單獨使用輸出流返回一樣，需要在返回信息前自己添加返回頭，不然成功不了。另一個就是反射，要根據包名，加類名。

 File f = new File(this.getClass().getResource("/").getPath());

這個表示獲取編譯好的文件地址。