手写一个民用Tomcat （04）

本文主要是介绍手写一个民用Tomcat （04），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

我们继续来 写 Tomcat  这次我们做优化，先看一下一个标准的http 协议

GET /servlet/com.yixin.HelloWorldServlet HTTP/1.1
Host: localhost:8080
Connection: keep-alive
sec-ch-ua: "Microsoft Edge";v="123", "Not:A-Brand";v="8", "Chromium";v="123"
sec-ch-ua-mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36 Edg/123.0.0.0
sec-ch-ua-platform: "Windows"
Accept: image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8

我们这一版就要是把所需要的数据 取出来，放到map 集合里边，先看第一个 我们能获取 请求方式GET， 请求路径 以及 请求协议 HTTP/1.1  然后 空一行， 获取到 请求头。

如果根据 这个报文结构，让各位写一个  获取协议 应该不难吧， 什么 split（），indexof， 什么subString  整吧，但是 tomcat 源码中就不会这么干了。

来 我们看下 ，

HttpRequestLine 类

public class HttpRequestLine {public static final int INITIAL_METHOD_SIZE = 8;public static final int INITIAL_URI_SIZE = 128;public static final int INITIAL_PROTOCOL_SIZE = 8;public static final int MAX_METHOD_SIZE = 32;public static final int MAX_URI_SIZE = 2048;public static final int MAX_PROTOCOL_SIZE = 32;//下面的属性对应于Http Request规范，即头行格式method uri protocol
//如：GET /hello.txt HTTP/1.1
//char[] 存储每段的字符串，对应的int值存储的是每段的结束位置public char[] method;public int methodEnd;public char[] uri;public int uriEnd;public char[] protocol;public int protocolEnd;public HttpRequestLine() {this(new char[INITIAL_METHOD_SIZE], 0, new char[INITIAL_URI_SIZE], 0,new char[INITIAL_PROTOCOL_SIZE], 0);}public HttpRequestLine(char[] method, int methodEnd,char[] uri, int uriEnd,char[] protocol, int protocolEnd) {this.method = method;this.methodEnd = methodEnd;this.uri = uri;this.uriEnd = uriEnd;this.protocol = protocol;this.protocolEnd = protocolEnd;}public void recycle() {methodEnd = 0;uriEnd = 0;protocolEnd = 0;}public int indexOf(char[] buf) {return indexOf(buf, buf.length);}//这是主要的方法/***   这个方法遵循的 从你查到的第一个字符串开始找*   举个例子 在helloworld 里边找or*   以第一个字符o在helloworld 开始遍历 找到符合的就返回一个pos位置*   然后以pos 为起点  开始循环依次对比 看是否后边的满足 如果不满足 返回 pos++*   继续开始这样找下去 一直遍历完所有helloworld*/public int indexOf(char[] buf, int end) {char firstChar = buf[0];int pos = 0; //pos是查找字符串buf在uri[]中的开始位置while (pos < uriEnd) {pos = indexOfChar(firstChar, pos); //首字符定位开始位置if (pos == -1) {return -1;}//uriEnd - pos 表示url的最后剩余是否小与查找字符串的长度//如果后边都没有了，依旧没有查到 难就查不到了。if ((uriEnd - pos) < end) {return -1;}for (int i = 0; i < end; i++) { //从开始位置起逐个字符比对if (uri[i + pos] != buf[i]) {break;}if (i == (end - 1)) { //每个字符都相等，则匹配上了，返回开始位置return pos;}}pos++;}return -1;}public int indexOf(String str) {return indexOf(str.toCharArray(), str.length());}//在uri[]中查找字符c的出现位置public int indexOfChar(char c, int start) {for (int i = start; i < uriEnd; i++) {if (uri[i] == c) {return i;}}return -1;}}

这个比较简单，就是查找字符串位置 

接下来 比较复杂了。

SocketInputStream 类

public class SocketInputStream extends InputStream {private static final byte CR = (byte) '\r';private static final byte LF = (byte) '\n';// 换行private static final byte SP = (byte) ' ';private static final byte HT = (byte) '\t';private static final byte COLON = (byte) ':';private static final int LC_OFFSET = 'A' - 'a';protected byte buf[];protected int count;protected int pos;protected InputStream is;public SocketInputStream(InputStream is, int bufferSize) {this.is = is;buf = new byte[bufferSize];}//从输入流中解析出request linepublic void readRequestLine(HttpRequestLine requestLine)throws IOException {int chr = 0;
//跳过空行do {try {chr = read();} catch (IOException e) {}} while ((chr == CR) || (chr == LF));
//第一个非空位置pos--;int maxRead = requestLine.method.length;int readStart = pos;int readCount = 0;boolean space = false;
//解析第一段method，以空格结束 解析出 GETwhile (!space) {if (pos >= count) {int val = read();if (val == -1) {throw new IOException("requestStream.readline.error");}pos = 0;readStart = 0;}if (buf[pos] == SP) {space = true;}requestLine.method[readCount] = (char) buf[pos];readCount++;pos++;}requestLine.methodEnd = readCount - 1; //method段的结束位置maxRead = requestLine.uri.length;readStart = pos;readCount = 0;space = false;boolean eol = false;
//解析第二段uri，以空格结束 解析出/servlet/com.yixin.HelloWorldServletwhile (!space) {if (pos >= count) {int val = read();if (val == -1)throw new IOException("requestStream.readline.error");pos = 0;readStart = 0;}if (buf[pos] == SP) {space = true;}requestLine.uri[readCount] = (char) buf[pos];readCount++;pos++;}requestLine.uriEnd = readCount - 1; //uri结束位置maxRead = requestLine.protocol.length;readStart = pos;readCount = 0;
//解析第三段protocol，以eol结尾 解析出 HTTP/1.1while (!eol) {if (pos >= count) {int val = read();if (val == -1)throw new IOException("requestStream.readline.error");pos = 0;readStart = 0;}if (buf[pos] == CR) {
// Skip CR.} else if (buf[pos] == LF) {eol = true;} else {requestLine.protocol[readCount] = (char) buf[pos];readCount++;}pos++;}requestLine.protocolEnd = readCount;}public void readHeader(HttpHeader header)throws IOException {int chr = read();if ((chr == CR) || (chr == LF)) { // Skipping CRif (chr == CR)read(); // Skipping LFheader.nameEnd = 0;header.valueEnd = 0;return;} else {pos--;}
// 正在读取 header nameint maxRead = header.name.length;int readStart = pos;int readCount = 0;boolean colon = false;while (!colon) {
// 我们处于内部缓冲区的末尾if (pos >= count) {int val = read();if (val == -1) {throw new IOException("requestStream.readline.error");}pos = 0;readStart = 0;}if (buf[pos] == COLON) {colon = true;}char val = (char) buf[pos];if ((val >= 'A') && (val <= 'Z')) {val = (char) (val - LC_OFFSET);}header.name[readCount] = val;readCount++;pos++;}header.nameEnd = readCount - 1;
// 读取 header 值（可以跨越多行）maxRead = header.value.length;readStart = pos;readCount = 0;int crPos = -2;boolean eol = false;boolean validLine = true;while (validLine) {boolean space = true;
// 跳过空格
// 注意：仅删除前面的空格，后面的不删。while (space) {
// 我们已经到了内部缓冲区的尽头if (pos >= count) {
// 将内部缓冲区的一部分（或全部）复制到行缓冲区int val = read();if (val == -1)throw new IOException("requestStream.readline.error");pos = 0;readStart = 0;}if ((buf[pos] == SP) || (buf[pos] == HT)) {pos++;} else {space = false;}}while (!eol) {
// 我们已经到了内部缓冲区的尽头if (pos >= count) {
// 将内部缓冲区的一部分（或全部）复制到行缓冲区int val = read();if (val == -1)throw new IOException("requestStream.readline.error");pos = 0;readStart = 0;}if (buf[pos] == CR) {} else if (buf[pos] == LF) {eol = true;} else {
// FIXME：检查二进制转换是否正常int ch = buf[pos] & 0xff;header.value[readCount] = (char) ch;readCount++;}pos++;}int nextChr = read();//Microsoft Edge 因为有的vlaue 值中有空格的情况if ((nextChr != SP) && (nextChr != HT)) {pos--;validLine = false;} else {eol = false;header.value[readCount] = ' ';readCount++;}}header.valueEnd = readCount;}@Overridepublic int read() throws IOException {if (pos >= count) {fill();if (pos >= count) {return -1;}}return buf[pos++] & 0xff;}public int available() throws IOException {return (count - pos) + is.available();}public void close() throws IOException {if (is == null) {return;}is.close();is = null;buf = null;}protected void fill() throws IOException {pos = 0;count = 0;int nRead = is.read(buf, 0, buf.length);if (nRead > 0) {count = nRead;}System.out.println(new String(buf));}
}

总归就是 获取 http协议中的数据 ，readRequestLine 这个方法， 别看复杂就是获取 第一行数据，GET 请求路径，等 

接下来就是获取 请求头数据放入到map 集合：

HttpHeader

public class HttpHeader {public static final int INITIAL_NAME_SIZE = 64;public static final int INITIAL_VALUE_SIZE = 512;public static final int MAX_NAME_SIZE = 128;public static final int MAX_VALUE_SIZE = 1024;public char[] name;public int nameEnd;public char[] value;public int valueEnd;protected int hashCode = 0;public HttpHeader() {this(new char[INITIAL_NAME_SIZE], 0, new char[INITIAL_VALUE_SIZE], 0);}public HttpHeader(char[] name, int nameEnd, char[] value, int valueEnd) {this.name = name;this.nameEnd = nameEnd;this.value = value;this.valueEnd = valueEnd;}public HttpHeader(String name, String value) {this.name = name.toLowerCase().toCharArray();this.nameEnd = name.length();this.value = value.toCharArray();this.valueEnd = value.length();}public void recycle() {nameEnd = 0;valueEnd = 0;hashCode = 0;}
}

这是一个请求头的类

JxdRequest 这个类 需要 只显示 变更的部分：

private InputStream input;
private SocketInputStream sis;
private String uri;
InetAddress address;
int port;
protected HashMap<String, String> headers = new HashMap<>();
protected Map<String, String> parameters = new ConcurrentHashMap<>();
HttpRequestLine requestLine = new HttpRequestLine();public void parse(Socket socket) {try {input = socket.getInputStream();this.sis = new SocketInputStream(this.input, 2048);parseConnection(socket);this.sis.readRequestLine(requestLine);parseHeaders();} catch (IOException e) {e.printStackTrace();} catch (ServletException e) {e.printStackTrace();}this.uri = new String(requestLine.uri, 0, requestLine.uriEnd);
}private void parseConnection(Socket socket) {address = socket.getInetAddress();port = socket.getPort();
}private void parseHeaders() throws IOException, ServletException {while (true) {HttpHeader header = new HttpHeader();sis.readHeader(header);//表示读取完毕if (header.nameEnd == 0) {if (header.valueEnd == 0) {return;} else {throw new ServletException("httpProcessor.parseHeaders.colon");}}String name = new String(header.name, 0, header.nameEnd);String value = new String(header.value, 0, header.valueEnd);// 设置相应的请求头if (name.equals(DefaultHeaders.ACCEPT_LANGUAGE_NAME)) {headers.put(name, value);} else if (name.equals(DefaultHeaders.CONTENT_LENGTH_NAME)) {headers.put(name, value);} else if (name.equals(DefaultHeaders.CONTENT_TYPE_NAME)) {headers.put(name, value);} else if (name.equals(DefaultHeaders.HOST_NAME)) {headers.put(name, value);} else if (name.equals(DefaultHeaders.CONNECTION_NAME)) {headers.put(name, value);} else if (name.equals(DefaultHeaders.TRANSFER_ENCODING_NAME)) {headers.put(name, value);} else {headers.put(name, value);}}
}

这个请求request  里边有各种方法 ，解析 i请求头，解析请求 路径 方式等，

其他的没有变化 ，然后 可以用上一节的main 方法 运行一下，结果是一样的。

这篇关于手写一个民用Tomcat （04）的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！

---