共计 3904 个字符,预计需要花费 10 分钟才能阅读完成。
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
正文完
星哥玩云-微信公众号