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一个简单的 Java web 服务器实现,比较简单,基于 java.net.Socket 和 java.net.ServerSocket 实现;
程序执行步骤
- 创建一个 ServerSocket 对象;
- 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;
- 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;
- 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;
- 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;
- 关闭Socket 对象;
- 转到步骤 2,继续等待连接请求;
代码实现
服务器实现:
package ex01.pyrmont;
import java.net.Socket;
import java.net.ServerSocket;
import java.net.InetAddress;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.io.File;
public class HttpServer {/**
* WEB_ROOT 是 HTML 和其它文件存放的目录. 这里的 WEB_ROOT 为工作目录下的 webroot 目录
*/
public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot";
// 关闭服务命令
private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
public static void main(String[] args) {HttpServer server = new HttpServer();
//等待连接请求
server.await();}
public void await() {ServerSocket serverSocket = null;
int port = 8080;
try {//服务器套接字对象
serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
} catch (IOException e) {e.printStackTrace();
System.exit(1);
}
// 循环等待一个请求
while (true) {Socket socket = null;
InputStream input = null;
OutputStream output = null;
try {//等待连接,连接成功后,返回一个 Socket 对象
socket = serverSocket.accept();
input = socket.getInputStream();
output = socket.getOutputStream();
// 创建 Request 对象并解析
Request request = new Request(input);
request.parse();
// 检查是否是关闭服务命令
if (request.getUri().equals(SHUTDOWN_COMMAND)) {break;
}
// 创建 Response 对象
Response response = new Response(output);
response.setRequest(request);
response.sendStaticResource();
// 关闭 socket 对象
socket.close();} catch (Exception e) {e.printStackTrace();
continue;
}
}
}
}
Request 类:
package ex01.pyrmont;
import java.io.InputStream;
import java.io.IOException;
public class Request {private InputStream input;
private String uri;
public Request(InputStream input) {this.input = input;
}
//从 InputStream 中读取 request 信息,并从 request 中获取 uri 值
public void parse() {StringBuffer request = new StringBuffer(2048);
int i;
byte[] buffer = new byte[2048];
try {i = input.read(buffer);
} catch (IOException e) {e.printStackTrace();
i = -1;
}
for (int j = 0; j < i; j++) {request.append((char) buffer[j]);
}
System.out.print(request.toString());
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
* ...
* 该函数目的就是为了获取 /index.html 字符串
*/
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 String getUri() {return uri;
}
}
Response 类:
package ex01.pyrmont;
import java.io.OutputStream;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.File;
/*
HTTP Response = Status-Line
*((general-header | response-header | entity-header) CRLF)
CRLF
[message-body]
Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase CRLF
*/
public class Response {private static final int BUFFER_SIZE = 1024;
Request request;
OutputStream output;
public Response(OutputStream output) {this.output = output;
}
public void setRequest(Request request) {this.request = request;
}
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);
int ch = fis.read(bytes, 0, BUFFER_SIZE);
while (ch != -1) {output.write(bytes, 0, ch);
ch = fis.read(bytes, 0, BUFFER_SIZE);
}
} 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();}
}
}
结果测试
访问存在的资源文件(注意存放在工程目录的 webroot 文件夹里):
访问不存在的资源文件:
关闭服务器:
参考资料:《深入剖析 Tomcat》PDF 下载 http://www.linuxidc.com/Linux/2013-11/92595.htm
本文永久更新链接地址:http://www.linuxidc.com/Linux/2016-06/132497.htm
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