实例-实现一个简单的java Web容器

• 最新更新

技术栈

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

执行流程

1. 创建一个ServerSocket对象；
2. 调用ServerSocket对象的accept方法，等待连接，连接成功会返回一个Socket对象，否则一直阻塞等待；
3. 从Socket对象中获取InputStream和OutputStream字节流，这两个流分别对应request请求和response响应；
4. 处理请求：读取InputStream字节流信息，转成字符串形式，并解析，这里的解析比较简单，仅仅获取uri(统一资源标识符)信息;
5. 处理响应：根据解析出来的uri信息，从WEB_ROOT目录中寻找请求的资源资源文件, 读取资源文件，并将其写入到OutputStream字节流中；
6. 关闭Socket对象；
7. 转到步骤2，继续等待连接请求；

代码实现

服务器

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;
    }

    /**
     * 发送静态资源
     * @throws IOException
     */
    public void sendStaticResource() throws IOException {
        byte[] bytes = new byte[BUFFER_SIZE];
        FileInputStream fis = null;
        try {
            //将web文件写入到OutputStream字节流中
            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();
        }
    }
}

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();
    }

    /**
     * 从inputStream中读取request信息，获取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
     * ...
     * 获取/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;
    }

    /**
     * 发送静态资源
     * @throws IOException
     */
    public void sendStaticResource() throws IOException {
        byte[] bytes = new byte[BUFFER_SIZE];
        FileInputStream fis = null;
        try {
            //将web文件写入到OutputStream字节流中
            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();
        }
    }
}

简单页面

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

效果

1. 启动服务

1. 发送请求

1. 返回正文

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

参考文档

• 一个简单的Java web服务器实现

java-实现一个简单的java Web容器

原文：https://www.cnblogs.com/kunlingou/p/11198007.html