java-實現一個簡單的java Web容器

• 最新更新

技術棧

• java.net.Socket
• java.net.ServerSocket

執行流程

1. 創建一個ServerSocket對象；
2. 調用ServerSocket對象的accept方法，等待連接，連接成功會返回一個Socket對象，否則一直阻塞等待；
3. 從Socket對象中獲取InputStream和OutputStream字節流，這兩個流分別對應request請求和response響應；
4. 處理請求：讀取InputStream字節流信息，轉成字符串形式，並解析，這里的解析比較簡單，僅僅獲取uri(統一資源標識符)信息;
5. 處理響應：根據解析出來的uri信息，從WEB_ROOT目錄中尋找請求的資源資源文件, 讀取資源文件，並將其寫入到OutputStream字節流中；
6. 關閉Socket對象；
7. 轉到步驟2，繼續等待連接請求；

代碼實現

服務器

package com.kunlinr.lifealien.servlet.server;

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

public class HttpServer {
	/**WEB_ROOT是HTML和其它文件存放的目錄. 這里的WEB_ROOT為工作目錄下的WebContent目錄*/
	public static final String WEB_ROOT = System.getProperty("user.dir")+File.separator+"WebContent";
	//關閉服務命令
	public static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
	
	public static void main(String[] args) {
		HttpServer server = new HttpServer();
		server.await();
	}

	/**
	 * 等待連接請求
	 */
	private void await() {
		ServerSocket serverSocket = null;
		int port = 8080;
		try {
			//服務器套接字對象
			serverSocket = new ServerSocket(port,0,InetAddress.getByName("127.0.0.1"));
		}catch (Exception e) {
			e.printStackTrace();
			System.exit(1);
		}
		//循環等待請求
		while(true) {
			Socket socket = null;
			InputStream input = null;
			OutputStream output = null;
			try {
				socket = serverSocket.accept();
				input = socket.getInputStream();
				output = socket.getOutputStream();
				//創建Request
				Request request = new Request(input);
				//檢查是否關閉服務命令
				if(request.getUri().equals(SHUTDOWN_COMMAND)) {
					break;
				}
				//創建Response
				Response response = new Response(output);
				response.setRequest(request);
				response.sendStaticResource();
				//關閉socket
				socket.close();
			}catch(Exception e) {
				e.printStackTrace();
				continue;
			}
		}
	}
}

Request

package com.kunlinr.lifealien.servlet.server;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;

@SuppressWarnings("unused")
public class Request {
	private InputStream input;
	private String uri;
	
	public Request(InputStream input) {
		this.input = input;
		parse();
	}

	/**
	 * 從inputStream中讀取request信息，獲取uri值。
	 */
	public void parse() {
		StringBuffer request = new StringBuffer(2048);
		int i;
		byte[] buffer = new byte[2048];
		try {
			i = input.read(buffer);
		}catch (Exception e) {
			e.printStackTrace();
			i = -1;
		}
		for(int j=0;j<i;j++) {
			request.append((char)buffer[j]);
		}
		uri = parseUri(request.toString());
	}
	
	/**
	 * requestString形式如下：
     * GET /index.html HTTP/1.1
     * Host: localhost:8080
     * Connection: keep-alive
     * Cache-Control: max-age=0
     * ...
	 * 獲取/index.html字符串
	 * @param string
	 * @return
	 */
	private String parseUri(String string) {
		int index1,index2;
		index1 = string.indexOf(' ');
		if (index1 != -1) {
            index2 = string.indexOf(' ', index1 + 1);
            if (index2 > index1)
                return string.substring(index1 + 1, index2);
        }
		return "";
	}

	public String getUri() {
        return uri;
    }
}

Response

package com.kunlinr.lifealien.servlet.server;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

public class Response {
	private static final int BUFFER_SIZE = 1024;
	private Request request;
	private OutputStream output;
	
	public Response(OutputStream output) {
        this.output = output;
    }

	public void setRequest(Request request) {
		this.request = request;
	}

	/**
	 * 發送靜態資源
	 * @throws IOException
	 */
	public void sendStaticResource() throws IOException {
		byte[] bytes = new byte[BUFFER_SIZE];
        FileInputStream fis = null;
        try {
            //將web文件寫入到OutputStream字節流中
            File file = new File(HttpServer.WEB_ROOT, request.getUri());
            if (file.exists()) {
            	fis = new FileInputStream(file);
            	List<byte[]> contentbytes = new ArrayList<>();
            	int ch = fis.read(bytes, 0, BUFFER_SIZE);
            	int size = 0;
                while (ch != -1) {
                	contentbytes.add(bytes);
                    ch = fis.read(bytes, 0, BUFFER_SIZE);
                    size += BUFFER_SIZE;
                }
                String head = "HTTP/1.1 200 OK\r\n" + "Content-Type: text/html\r\n"
                        + "Content-Length: "+size+"\r\n" + "\r\n";
                byte[] headbytes = head.getBytes();
                output.write(headbytes,0,headbytes.length);
                for(byte[] contentbyte:contentbytes) {
                	output.write(contentbyte);
                }
            } else {
                // file not found
                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>";
                output.write(errorMessage.getBytes());
            }
        } catch (Exception e) {
            // thrown if cannot instantiate a File object
            System.out.println(e.toString());
        } finally {
            if (fis != null)
                fis.close();
        }
	}
}

簡單頁面

<html>
	<head>
		<title>Hello,this is your own Page!</title>
	</head>
	<body>
		Everything is Simple!
	</body>
</html>

效果

1. 啟動服務

2. 發送請求

3. 返回正文

<html>
	<head>
		<title>Hello,this is your own Page!</title>
	</head>
	<body>
		Everything is Simple!
	</body>
</html>

參考文檔

• 一個簡單的Java web服務器實現