1、创建HttpRequest对象

HttpRequest对象中的属性与HTTP协议中的内容对应，用于后序servlet从request中获取请求中的参数。

参照http请求报文：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;public class HttpRequest {private String method;private String url;private String version;// 存储请求头中的KVprivate Map<String, String> headers = new HashMap<>();// url 中的参数和 body 中的参数都放到这个 parameters hash 表中.private Map<String, String> parameters = new HashMap<>();// 存储Cookieprivate Map<String, String> cookies = new HashMap<>();private String body;public static HttpRequest build(InputStream inputStream) throws IOException {HttpRequest request = new HttpRequest();BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));// 1. 处理首行 GET /url /HTTP/1.1String firstLine = bufferedReader.readLine();String[] firstLineTokens = firstLine.split(" ");request.method = firstLineTokens[0];request.url = firstLineTokens[1];request.version = firstLineTokens[2];// 2. 解析 urlint pos = request.url.indexOf("?");//2.1 如果有？号，也间接说明这是一个GET请求if (pos != -1) {// 2.1.1截取出所有参数String queryString = request.url.substring(pos + 1);// 2.2.2将参数解析为KV后存储parseKV(queryString, request.parameters);}// 3. 循环处理 header 部分String line = "";while ((line = bufferedReader.readLine()) != null && line.length() != 0) {String[] headerTokens = line.split(": ");request.headers.put(headerTokens[0], headerTokens[1]);}// 4. 解析 cookieString cookie = request.headers.get("Cookie");if (cookie != null) {// 把 cookie 进行解析parseCookie(cookie, request.cookies);}// 5. 解析 bodyif ("POST".equalsIgnoreCase(request.method)|| "PUT".equalsIgnoreCase(request.method)) {// 这两个方法需要处理 body, 其他方法暂时不考虑// 需要把 body 读取出来.// 需要先知道 body 的长度. Content-Length 就是干这个的.// 此处的长度单位是 "字节"int contentLength = Integer.parseInt(request.headers.get("Content-Length"));// 注意体会此处的含义~~// 例如 contentLength 为 100 , body 中有 100 个字节.// 下面创建的缓冲区长度是 100 个 char (相当于是 200 个字节)// 缓冲区不怕长. 就怕不够用. 这样创建的缓冲区才能保证长度管够~~char[] buffer = new char[contentLength];// 把int len = bufferedReader.read(buffer);request.body = new String(buffer, 0, len);// body 中的格式形如: username=tanglaoshi&password=123parseKV(request.body, request.parameters);}return request;}private static void parseCookie(String cookie, Map<String, String> cookies) {// 1. 按照 分号空格 拆分成多个键值对String[] kvTokens = cookie.split("; ");// 2. 按照 = 拆分每个键和值for (String kv : kvTokens) {String[] result = kv.split("=");cookies.put(result[0], result[1]);}}private static void parseKV(String queryString, Map<String, String> parameters) {// 1. 按照 & 拆分成多个键值对String[] kvTokens = queryString.split("&");// 2. 按照 = 拆分每个键和值for (String kv : kvTokens) {String[] result = kv.split("=");parameters.put(result[0], result[1]);}}public String getMethod() {return method;}public String getUrl() {return url;}public String getVersion() {return version;}public String getBody() {return body;}public String getParameter(String key) {return parameters.get(key);}public String getHeader(String key) {return headers.get(key);}public String getCookie(String key) {return cookies.get(key);}
}

2、创建HttpResponse对象

参照http请求报文：

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.util.HashMap;
import java.util.Map;public class HttpResponse {private String version = "HTTP/1.1";private int status;private String message;private Map<String, String> headers = new HashMap<>();private StringBuilder body = new StringBuilder();private OutputStream outputStream = null;public static HttpResponse build(OutputStream outputStream) {HttpResponse response = new HttpResponse();response.outputStream = outputStream;return response;}public void setVersion(String version) {this.version = version;}public void setStatus(int status) {this.status = status;}public void setMessage(String message) {this.message = message;}public void setHeader(String key, String value) {headers.put(key, value);}public void writeBody(String content) {body.append(content);}public void flush() throws IOException {BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream));bufferedWriter.write(version + " " + status + " " + message + "\n");headers.put("Content-Length", body.toString().getBytes().length + "");for (Map.Entry<String, String> entry : headers.entrySet()) {bufferedWriter.write(entry.getKey() + ": " + entry.getValue() + "\n");}bufferedWriter.write("\n");bufferedWriter.write(body.toString());bufferedWriter.flush();}
}