package cn.how2j.diytomcat.classloader;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;

import cn.hutool.core.io.FileUtil;

public class WebappClassLoader extends URLClassLoader {

	public WebappClassLoader(String docBase, ClassLoader commonClassLoader) {
		super(new URL[] {}, commonClassLoader);

		try {
			File webinfFolder = new File(docBase, "WEB-INF");
			File classesFolder = new File(webinfFolder, "classes");
			File libFolder = new File(webinfFolder, "lib");
			URL url;
			url = new URL("file:" + classesFolder.getAbsolutePath() + "/");
			this.addURL(url);
			List<File> jarFiles = FileUtil.loopFiles(libFolder);
			for (File file : jarFiles) {
				url = new URL("file:" + file.getAbsolutePath());
				this.addURL(url);
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public void stop() {
		try {
			close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}

package cn.how2j.diytomcat.catalina;

import cn.how2j.diytomcat.classloader.WebappClassLoader;
import cn.how2j.diytomcat.exception.WebConfigDuplicatedException;
import cn.how2j.diytomcat.util.ContextXMLUtil;
import cn.hutool.core.date.DateUtil;
import cn.hutool.core.date.TimeInterval;
import cn.hutool.core.io.FileUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.log.LogFactory;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import java.io.File;
import java.util.*;

public class Context {
    private String path;
    private String docBase;
    private File contextWebXmlFile;

    private Map<String, String> url_servletClassName;
    private Map<String, String> url_ServletName;
    private Map<String, String> servletName_className;
    private Map<String, String> className_servletName;

    private WebappClassLoader webappClassLoader;

    public Context(String path, String docBase) {
        TimeInterval timeInterval = DateUtil.timer();
        this.path = path;
        this.docBase = docBase;
        this.contextWebXmlFile = new File(docBase, ContextXMLUtil.getWatchedResource());

        this.url_servletClassName = new HashMap<>();
        this.url_ServletName = new HashMap<>();
        this.servletName_className = new HashMap<>();
        this.className_servletName = new HashMap<>();

        ClassLoader commonClassLoader = Thread.currentThread().getContextClassLoader();
        this.webappClassLoader = new WebappClassLoader(docBase, commonClassLoader);

        LogFactory.get().info("Deploying web application directory {}", this.docBase);
        deploy();
        LogFactory.get().info("Deployment of web application directory {} has finished in {} ms", this.docBase,timeInterval.intervalMs());
    }

    private void deploy() {
        TimeInterval timeInterval = DateUtil.timer();
        init();
        LogFactory.get().info("Deployment of web application directory {} has finished in {} ms",this.getDocBase(),timeInterval.intervalMs());
    }

    private void init() {
        if (!contextWebXmlFile.exists())
            return;

        try {
            checkDuplicated();
        } catch (WebConfigDuplicatedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return;
        }

        String xml = FileUtil.readUtf8String(contextWebXmlFile);
        Document d = Jsoup.parse(xml);
        parseServletMapping(d);
        System.out.println(url_servletClassName);
    }

    private void parseServletMapping(Document d) {
        // url_ServletName
        Elements mappingurlElements = d.select("servlet-mapping url-pattern");
        for (Element mappingurlElement : mappingurlElements) {
            String urlPattern = mappingurlElement.text();
            String servletName = mappingurlElement.parent().select("servlet-name").first().text();
            url_ServletName.put(urlPattern, servletName);
        }
        // servletName_className / className_servletName
        Elements servletNameElements = d.select("servlet servlet-name");
        for (Element servletNameElement : servletNameElements) {
            String servletName = servletNameElement.text();
            String servletClass = servletNameElement.parent().select("servlet-class").first().text();
            servletName_className.put(servletName, servletClass);
            className_servletName.put(servletClass, servletName);
        }
        // url_servletClassName
        Set<String> urls = url_ServletName.keySet();
        for (String url : urls) {
            String servletName = url_ServletName.get(url);
            String servletClassName = servletName_className.get(servletName);
            url_servletClassName.put(url, servletClassName);
        }
    }

    private void checkDuplicated(Document d, String mapping, String desc) throws WebConfigDuplicatedException {
        Elements elements = d.select(mapping);
        // 判断逻辑是放入一个集合，然后把集合排序之后看两临两个元素是否相同
        List<String> contents = new ArrayList<>();
        for (Element e : elements) {
            contents.add(e.text());
        }

        Collections.sort(contents);

        for (int i = 0; i < contents.size() - 1; i++) {
            String contentPre = contents.get(i);
            String contentNext = contents.get(i + 1);
            if (contentPre.equals(contentNext)) {
                throw new WebConfigDuplicatedException(StrUtil.format(desc, contentPre));
            }
        }

    }

    private void checkDuplicated() throws WebConfigDuplicatedException {
        String xml = FileUtil.readUtf8String(contextWebXmlFile);
        Document d = Jsoup.parse(xml);

        checkDuplicated(d, "servlet-mapping url-pattern", "servlet url 重复,请保持其唯一性:{} ");
        checkDuplicated(d, "servlet servlet-name", "servlet 名称重复,请保持其唯一性:{} ");
        checkDuplicated(d, "servlet servlet-class", "servlet 类名重复,请保持其唯一性:{} ");
    }

    public String getServletClassName(String uri) {
        return url_servletClassName.get(uri);
    }

    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }

    public String getDocBase() {
        return docBase;
    }

    public void setDocBase(String docBase) {
        this.docBase = docBase;
    }

    public WebappClassLoader getWebappClassLoader() {
        return webappClassLoader;
    }
}

package cn.how2j.diytomcat.servlets;

import cn.how2j.diytomcat.catalina.Context;
import cn.how2j.diytomcat.http.Request;
import cn.how2j.diytomcat.http.Response;
import cn.how2j.diytomcat.util.Constant;
import cn.hutool.core.util.ReflectUtil;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class InvokerServlet extends HttpServlet {
	private static InvokerServlet instance = new InvokerServlet();

	public static synchronized InvokerServlet getInstance() {
		return instance;
	}

	private InvokerServlet() {

	}

	public void service(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse)
			throws IOException, ServletException {
			Request request = (Request) httpServletRequest;
			Response response = (Response) httpServletResponse;

			String uri = request.getUri();
			Context context = request.getContext();
			String servletClassName = context.getServletClassName(uri);

			try {
				Class servletClass = context.getWebappClassLoader().loadClass(servletClassName);
				System.out.println("servletClass:" + servletClass);
				System.out.println("servletClass'classLoader:" + servletClass.getClassLoader());
				Object servletObject = ReflectUtil.newInstance(servletClass);
				ReflectUtil.invoke(servletObject, "service", request, response);
				response.setStatus(Constant.CODE_200);

			} catch (ClassNotFoundException e) {
				throw new RuntimeException(e);
			}

	}

}

<?xml version="1.0" encoding="UTF-8"?>
<Server>
    <Service name="Catalina">
        <Connector port="18080"/>
        <Connector port="18081"/>
        <Connector port="18082"/>
        <Engine defaultHost="localhost">
            <Host name = "localhost">
                <Context path="/b" docBase="d:/project/diytomcat/b" />
                <Context path="/javaweb" docBase="d:/project/javaweb/web" />
            </Host>
        </Engine>
    </Service>
</Server>

package cn.how2j.diytomcat.test;

import cn.how2j.diytomcat.util.MiniBrowser;
import cn.hutool.core.date.DateUtil;
import cn.hutool.core.date.TimeInterval;
import cn.hutool.core.util.NetUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.core.util.ZipUtil;
import cn.hutool.http.HttpUtil;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;
import sun.net.www.content.text.plain;

import java.io.ByteArrayOutputStream;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class TestTomcat {
    private static int port = 18080;
    private static String ip = "127.0.0.1";
    @BeforeClass
    public static void beforeClass() {
        //所有测试开始前看diy tomcat 是否已经启动了
        if(NetUtil.isUsableLocalPort(port)) {
            System.err.println("请先启动 位于端口: " +port+ " 的diy tomcat，否则无法进行单元测试");
            System.exit(1);
        }
        else {
            System.out.println("检测到 diy tomcat已经启动，开始进行单元测试");
        }
    }

    @Test
    public void testHelloTomcat() {
        String html = getContentString("/");
        Assert.assertEquals(html,"Hello DIY Tomcat from how2j.cn");
    }

    @Test
    public void testTimeConsumeHtml() throws InterruptedException {
        ThreadPoolExecutor threadPool = new ThreadPoolExecutor(20, 20, 60, TimeUnit.SECONDS,
                new LinkedBlockingQueue<Runnable>(10));
            TimeInterval timeInterval = DateUtil.timer();

        for(int i = 0; i<3; i++){
            threadPool.execute(new Runnable(){
                public void run() {
                    getContentString("/timeConsume.html");
                }
            });
        }
        threadPool.shutdown();
        threadPool.awaitTermination(1, TimeUnit.HOURS);

        long duration = timeInterval.intervalMs();

        Assert.assertTrue(duration < 3000);
    }

    @Test
    public void testaIndex() {
        String html = getContentString("/a");
        Assert.assertEquals(html,"Hello DIY Tomcat from index.html@a");
    }

    @Test
    public void testbIndex() {
        String html = getContentString("/b/");
        Assert.assertEquals(html,"Hello DIY Tomcat from index.html@b");
    }

    @Test
    public void test404() {
        String response  = getHttpString("/not_exist.html");
        containAssert(response, "HTTP/1.1 404 Not Found");
    }
    @Test
    public void test500() {
        String response  = getHttpString("/500.html");
        containAssert(response, "HTTP/1.1 500 Internal Server Error");
    }

    @Test
    public void testaTxt() {
        String response  = getHttpString("/a.txt");
        containAssert(response, "Content-Type: text/plain");
    }

    @Test
    public void testPNG() {
        byte[] bytes = getContentBytes("/logo.png");
        int pngFileLength = 1672;
        Assert.assertEquals(pngFileLength, bytes.length);
    }
    @Test
    public void testPDF() {
        byte[] bytes = getContentBytes("/etf.pdf");
        int pngFileLength = 3590775;
        Assert.assertEquals(pngFileLength, bytes.length);
    }

    @Test
    public void testhello() {
        String html = getContentString("/j2ee/hello");
        Assert.assertEquals(html,"Hello DIY Tomcat from HelloServlet");
    }

    @Test
    public void testJavawebHello() {
        String html = getContentString("/javaweb/hello");
        Assert.assertEquals(html,"Hello DIY Tomcat from HelloServlet@javaweb");
    }

    private byte[] getContentBytes(String uri) {
        return getContentBytes(uri,false);
    }
    private byte[] getContentBytes(String uri,boolean gzip) {
        String url = StrUtil.format("http://{}:{}{}", ip,port,uri);
        return MiniBrowser.getContentBytes(url,false);
    }
    private String getContentString(String uri) {
        String url = StrUtil.format("http://{}:{}{}", ip,port,uri);
        String content = MiniBrowser.getContentString(url);
        return content;
    }
    private String getHttpString(String uri) {
        String url = StrUtil.format("http://{}:{}{}", ip,port,uri);
        String http = MiniBrowser.getHttpString(url);
        return http;
    }
    private void containAssert(String html, String string) {
        boolean match = StrUtil.containsAny(html, string);
        Assert.assertTrue(match);
    }
}