Servlet容器的一个简单实现

1. 需要安装jdk和java ee sdk中的glassfish5/glassfish/modules/javax.servlet-api.jar
2. 运行项目，SimpleContainer—>main方法
3. 浏览器输入http://localhost:8080/servlet/Test，完成

SimpleContainer.java

public class SimpleContainer {    private boolean shutdown = false;    private static Logger log = Logger.getLogger(SimpleContainer.class.getName());    public static void main(String[] args) {        File f = new File(".");        System.out.println(f.getAbsolutePath());        SimpleContainer server = new SimpleContainer();        server.start();    }    private void start() {        ServerSocket serverSocket = null;        try {            serverSocket = new ServerSocket(8080, 10,                    InetAddress.getByName("localhost"));        } catch (IOException e) {            System.out.println("Server starts failed");            e.printStackTrace();            System.exit(1);        }        log.info("Server starts successfully.");        service(serverSocket);    }    private void service(ServerSocket serverSocket) {        while (!shutdown) {            try {                processRequest(serverSocket);            } catch (Exception e) {                e.printStackTrace();            }        }    }    private void processRequest(ServerSocket serverSocket) throws IOException {        log.info("waitting for incoming request ... ");        Socket socket = serverSocket.accept();        log.info("receive a request from "                + socket.getRemoteSocketAddress().toString());        InputStream in = socket.getInputStream();        BaseRequest request = new BaseRequest(in);        log.info("Request Object ready!");        OutputStream out = socket.getOutputStream();        BaseResponse response = new BaseResponse(out);        ServletProcessor.processServletRequest(request, response);        socket.close();    }}

BaseRequest.java

public class BaseRequest implements HttpServletRequest {    private InputStream inputStream;    private String uri;    private StringBuffer requestContentBuffer = new StringBuffer(2048);    public BaseRequest(InputStream in) {        this.inputStream = in;        prepareContent();        parseAndSetUri();    }    private void prepareContent() {        byte[] buffer = new byte[2048];        int i = -1;        try {            i = inputStream.read(buffer);        } catch (IOException e) {            e.printStackTrace();        }        for (int k = 0; k < i; k++) {            requestContentBuffer.append((char) buffer[k]);        }        System.out.println(requestContentBuffer.toString());    }    private void parseAndSetUri() {        String requestString = requestContentBuffer.toString();        int index1 = requestString.indexOf(' ');        int index2 = -1;        if (index1 != -1) {            index2 = requestString.indexOf(' ', index1 + 1);        }        this.uri = (index2 > index1) ? requestString.substring(index1 + 1,                index2) : null;    }    //其他接口空实现方法，很多} 

BaseResponse.java

public class BaseResponse implements HttpServletResponse {    private OutputStream outputStream;    public BaseResponse(OutputStream out) {        this.outputStream = out;    }    @Override    public PrintWriter getWriter() throws IOException {        return new PrintWriter(this.outputStream);        //return  null;    }    //其他接口空实现方法，很多}

ServletProcessor.java

public class ServletProcessor {    private static Logger log = Logger.getLogger(ServletProcessor.class.getName());    public static void processServletRequest(BaseRequest request,                                             BaseResponse response) {        String uri = request.getUri();        String servletName = MappingHelper.resolve(uri);        log.info("Processing servlet: " + servletName);        Servlet servlet = loadServlet(servletName);        callService(servlet, request, response);    }    private static URLClassLoader createUrlClassLoader() {        URLClassLoader loader = null;        try {            URL[] urls = new URL[1];            URLStreamHandler streamHandler = null;            File classPath = new File(Constant.RESOURCE_ROOT);            // org.apache.catalina.startup.ClassLoaderFactory              String repository = (new URL("file", null,                    classPath.getCanonicalPath() + File.separator)).toString();            urls[0] = new URL(null, repository, streamHandler);            loader = new URLClassLoader(urls);        } catch (IOException e) {            e.printStackTrace();        }        return loader;    }    private static Servlet loadServlet(String servletName) {        URLClassLoader loader = createUrlClassLoader();        Servlet servlet = null;        try {            @SuppressWarnings("unchecked")            Class<Servlet> servletClass = (Class<Servlet>) loader                    .loadClass(servletName);            servlet = (Servlet) servletClass.newInstance();        } catch (Exception e){            e.printStackTrace();        }        return servlet;    }    private static void callService(Servlet servlet, ServletRequest request,                                    ServletResponse response) {        try {            servlet.service(request, response);        } catch (Exception e) {            e.printStackTrace();        }    }} 

MappingHelper.java

public class MappingHelper {    public static Properties requestMapping;    static {        requestMapping = new Properties();        try {            File f = new File(Constant.MAPPING_FILE);            System.out.println(f.getAbsolutePath());            requestMapping.load(new FileInputStream(f));        } catch (IOException e) {            e.printStackTrace();        }    }    public static String resolve(String requestPath) {        return requestMapping.getProperty(requestPath);    }}

Constant.java

public  class Constant {    static String MAPPING_FILE = "out/production/java/mapping.txt";    static String RESOURCE_ROOT = "out/production/";}

mapping.txt

/servlet/Test=TestServlet

TestServlet.java

public class TestServlet extends HttpServlet {    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        System.out.println("TestServlet doGet.........................");        System.out.println(this.getClass().getClassLoader().getParent());        try{            //BaseResponse bresp = (BaseResponse) resp;            String str = "HTTP/1.1 200 OK\n" +                    "Server: Microsoft-IIS/5.00000\n" +                    "Date: Thu, 07 Jul 2005 13:08:16 GMT\n\n" +                    "this is from TestServlet\n";            PrintWriter out = resp.getWriter();            out.write(str);            out.flush();            out.close();        }catch (Exception e){}    }}

项目完整地址:https://u695858.pipipan.com/fs/695858-231499617
密码：778887