tomcat源码编写计划连载(2)

  上一次讲了一下server的基础实现,但是实现的只是简单的静态资源的请求,用过tomcat的童鞋肯定说要调用servlet啦，OK, 在上次的基础上我增加了一个请求servlet的功能。

servlet的生命周期不做多的介绍了,我主要实现两个方法init和 service ,结构目录如下：

服务器端：

HttpServer1 接收HTTP请求

Rquest
解析请求,给servlet使用

Response 返回信息,给Servlet使用

ServletProcesser1 处理servlet请求

ServletResourceProcessor 处理静态资源请求

客户端：

Client,java 发送http请求

ServletDemo1.java是我实现的Servlet，Servlet.java是我定义的servlet接口.进行规范

Client.java:

这段代码不发了,可以从上一章看到

HttpServer1:

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

/**
* Created by user1013 on 2016/7/1.
*/
public class HttpServer1 {
/** WEB_ROOT is the directory where our HTML and other files reside.
* For this package, WEB_ROOT is the "webroot" directory under the
* working directory.
* The working directory is the location in the file system
* from where the java command was invoked.
*/
public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webRoot" + "servletDemo"+File.separator +"src";
// shutdown command
private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
// the shutdown command received
private boolean shutdown = false;

public static void main(String[] args) {
HttpServer1 server = new HttpServer1();
server.await();
}

public void await() {
System.out.print("服务器启动。。。");
ServerSocket serverSocket = null;
int port = 8080;
try {
serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
}
catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
// Loop waiting for a request
while (!shutdown) {
Socket socket = null;
InputStream input = null;
OutputStream output = null;
try {
socket = serverSocket.accept();
input = socket.getInputStream();
output = socket.getOutputStream();
// create Request object and parse
Request request = new Request(input);
request.parse();
// create Response object
Response response = new Response(output);
response.setRequest(request);
// check if this is a request for a servlet or
// a static resource
// a request for a servlet begins with "/servlet/"
if (request.getUri().startsWith("/servlet/")) {
ServletProcesser1 processor = new ServletProcesser1();
processor.process(request, response);
}else {
StaticResourceProcessor processor = new StaticResourceProcessor();
processor.process(request, response);
}
// Close the socket
socket.close();
//check if the previous URI is a shutdown command
shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
}
catch (Exception e) {
e.printStackTrace();
System.exit(1);
}
}
}
}

Request.java

/**
* Created by user1013 on 2016/7/1.
*/
import java.io.InputStream;
import java.io.IOException;

public class Request {
private InputStream input;
private String uri;
public Request(InputStream input){
this.input = input;
}

public String getUri() {
return uri;
}
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 void parse() {
// Read a set of characters from the socket
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());
this.uri = parseUri(request.toString());
}
}

 Response.java

/**
* Created by user1013 on 2016/7/1.
*/
import java.io.OutputStream;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.File;
import java.io.PrintWriter;
import java.util.Locale;
public class Response {
private static final int BUFFER_SIZE = 1024;
Request request;
OutputStream output;
PrintWriter writer;
public Response(OutputStream output) {
this.output = output;
}
public void setRequest(Request request) {
this.request = request;
}
// 获取静态资源的方法
/* This method is used to serve static pages */
public void sendStaticResource() throws IOException {
byte[] bytes = new byte[BUFFER_SIZE];
FileInputStream fis = null;
try {
/* request.getUri has been replaced by request.getRequestURI */
File file = new File(HttpServer1.WEB_ROOT, request.getUri());
fis = new FileInputStream(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
*/
int ch = fis.read(bytes, 0, BUFFER_SIZE);
while (ch!=-1) {
output.write(bytes, 0, ch);
ch = fis.read(bytes, 0, BUFFER_SIZE);
}
}
catch (FileNotFoundException e) {
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());
}
finally {
if (fis!=null)
fis.close();
}
}

/**
* PrintWriter 类的构造方法的第二个参数是一个布尔值表明是否允许
自动刷新。传递 true 作为第二个参数将会使任何 println 方法的调用都会刷新输出(output)。
不过， print 方法不会刷新输出。
* @return
* @throws IOException
*/
public PrintWriter getWriter() throws IOException {
// autoflush is true, println() will flush,
// but print() will not.
writer = new PrintWriter(this.output, true);
return writer;
}
}

ServletProcesser1.java

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLStreamHandler;

/**
* 李文波
* Created by user1013 on 2016/7/1.
* ServletProcessor1 类用于处理 servlet 的 HTTP 请求。
*/
public class ServletProcesser1 {

public void process(Request request, Response response) {
//1. 初始化一些信息
URLClassLoader loader = null;
//1.获得请求的uri
String uri = request.getUri();
//2.获取uri中的请求的servlet参数
System.out.println(uri);
String servletName = uri.substring(uri.indexOf("/", 1) + 1);
System.out.println(servletName);
try {
URL[] urls = new URL[1];
URLStreamHandler urlStreamHandler = null;
File classPath = new File(HttpServer1.WEB_ROOT);
String repository = (new URL("file", null, classPath.getCanonicalPath()+ File.separator)).toString();
//            String repository = "E:\\test\\servletDemo\\src";
System.out.println(repository);
urls[0] = new URL(null, repository, urlStreamHandler);
loader = new URLClassLoader(urls);
} catch (IOException e) {
System.out.println(e.getMessage());
}

//2.加載servlet
Class myClass = null;
try {
myClass = loader.loadClass(servletName);
} catch (ClassNotFoundException e) {
System.out.println(e.getMessage());
}

//3.运行servlet的service方法
Servlet servlet = null;
try {
servlet = (Servlet) myClass.newInstance();
servlet.init();
servlet.service(request, response);
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

//    public static void main(String[] args) throws IOException {
//        File classPath = new File(HttpServer1.WEB_ROOT);
//        String repository = (new URL("file", null, classPath.getCanonicalPath()+ File.separator)).toString();
//        System.out.println(repository);
//    }
}

StaticResourceProcessor.java

import java.io.IOException;

/**
* Created by user1013 on 2016/7/1.
*/
public class StaticResourceProcessor {

public void process(Request request, Response response){
try {
response.sendStaticResource();
} catch (IOException e) {
e.printStackTrace();
}
}
}

ServletDemo1.java

import java.io.IOException;
import java.io.PrintWriter;

/**
* Created by user1013 on 2016/7/4.
*/
public class ServletDemo1 implements Servlet{
@Override
public void init() {
System.out.print("init method");
}

@Override
public void service(Request request, Response response) throws IOException {
PrintWriter writer = response.getWriter();
writer.println("servlet Demo1");
writer.flush();
}
}