Sample.java
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.ReentrantLock;
public class TodoHttpServerSample {
static final int PORT = 8082;
static final String CSV_FILE = "todos.csv";
// 複数スレッドから同時に CSV を操作しないようにロックを使う
static final ReentrantLock lock = new ReentrantLock();
// CSV からTODO一覧を読み込む
static List<String[]> loadTodos() throws IOException {
List<String[]> todos = new ArrayList<>();
File file = new File(CSV_FILE);
if (!file.exists()) return todos;
try (BufferedReader reader = new BufferedReader(
new InputStreamReader(new FileInputStream(file), StandardCharsets.UTF_8))) {
String line;
while ((line = reader.readLine()) != null) {
String[] parts = line.split(",", 2);
if (parts.length == 2) {
todos.add(parts);
}
}
}
return todos;
}
// TODO を CSV に追記（Java 8: OutputStreamWriter でエンコーディングを明示）
static void addTodo(String id, String title) throws IOException {
// Java 8 では new FileWriter(file, Charset, append) が使えないため
// OutputStreamWriter + FileOutputStream を組み合わせる
try (PrintWriter writer = new PrintWriter(
new OutputStreamWriter(
new FileOutputStream(CSV_FILE, true), StandardCharsets.UTF_8))) {
writer.println(id + "," + title.replace(",", "，"));
}
}
// TODO を CSV から削除
static void deleteTodo(String id) throws IOException {
List<String[]> todos = loadTodos();
try (PrintWriter writer = new PrintWriter(
new OutputStreamWriter(
new FileOutputStream(CSV_FILE, false), StandardCharsets.UTF_8))) {
for (String[] todo : todos) {
if (!todo[0].equals(id)) {
writer.println(todo[0] + "," + todo[1]);
}
}
}
}
// HTML ページを生成
static String buildHtml(List<String[]> todos) {
StringBuilder sb = new StringBuilder();
sb.append("<!DOCTYPE html><html><head><meta charset='UTF-8'>");
sb.append("<title>TODO リスト</title></head><body>");
sb.append("<h1>TODO リスト</h1>");
sb.append("<form method='POST' action='/add'>");
sb.append("<input name='title' placeholder='新しいTODO' required>");
sb.append("<button>追加</button></form><ul>");
for (String[] todo : todos) {
sb.append("<li>").append(escapeHtml(todo[1]));
sb.append(" <form method='POST' action='/delete' style='display:inline'>");
sb.append("<input type='hidden' name='id' value='").append(todo[0]).append("'>");
sb.append("<button>削除</button></form></li>");
}
sb.append("</ul></body></html>");
return sb.toString();
}
// HTML エスケープ（XSS 対策）
static String escapeHtml(String text) {
return text.replace("&", "&").replace("<", "<").replace(">", ">");
}
static void sendResponse(OutputStream out, int status, String msg,
String type, String body) throws IOException {
byte[] bytes = body.getBytes("UTF-8");
PrintWriter w = new PrintWriter(new OutputStreamWriter(out, "UTF-8"), true);
w.print("HTTP/1.1 " + status + " " + msg + "\r\n");
w.print("Content-Type: " + type + "; charset=UTF-8\r\n");
w.print("Content-Length: " + bytes.length + "\r\n");
w.print("Connection: close\r\n\r\n");
w.flush();
out.write(bytes);
out.flush();
}
static void sendRedirect(OutputStream out) throws IOException {
PrintWriter w = new PrintWriter(new OutputStreamWriter(out, "UTF-8"), true);
w.print("HTTP/1.1 303 See Other\r\nLocation: /\r\nContent-Length: 0\r\nConnection: close\r\n\r\n");
w.flush();
}
static void handleRequest(Socket socket) throws IOException {
try (InputStream in = socket.getInputStream();
OutputStream out = socket.getOutputStream()) {
BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));
String requestLine = reader.readLine();
if (requestLine == null) return;
String[] parts = requestLine.split(" ");
String method = parts[0];
String path = parts.length > 1 ? parts[1] : "/";
// Content-Length を取得
int contentLength = 0;
String line;
while ((line = reader.readLine()) != null && !line.isEmpty()) {
if (line.toLowerCase().startsWith("content-length:")) {
contentLength = Integer.parseInt(line.split(":")[1].trim());
}
}
String body = "";
if (contentLength > 0) {
char[] buf = new char[contentLength];
reader.read(buf, 0, contentLength);
body = new String(buf);
}
lock.lock();
try {
if ("GET".equals(method) && "/".equals(path)) {
List<String[]> todos = loadTodos();
sendResponse(out, 200, "OK", "text/html", buildHtml(todos));
} else if ("POST".equals(method) && "/add".equals(path)) {
String title = "";
for (String kv : body.split("&")) {
String[] pair = kv.split("=", 2);
if ("title".equals(URLDecoder.decode(pair[0], "UTF-8"))) {
title = URLDecoder.decode(pair[1], "UTF-8");
}
}
if (!title.isEmpty()) {
addTodo(String.valueOf(System.currentTimeMillis()), title);
}
sendRedirect(out);
} else if ("POST".equals(method) && "/delete".equals(path)) {
String id = "";
for (String kv : body.split("&")) {
String[] pair = kv.split("=", 2);
if ("id".equals(URLDecoder.decode(pair[0], "UTF-8"))) {
id = URLDecoder.decode(pair[1], "UTF-8");
}
}
if (!id.isEmpty()) {
deleteTodo(id);
}
sendRedirect(out);
} else {
sendResponse(out, 404, "Not Found", "text/plain", "404 Not Found");
}
} finally {
lock.unlock();
}
}
}
public static void main(String[] args) throws IOException {
ExecutorService executor = Executors.newFixedThreadPool(10);
System.out.println("TODO HTTP サーバー起動中... http://localhost:" + PORT);
System.out.println("ブラウザで http://localhost:" + PORT + " を開いてください");
try (ServerSocket serverSocket = new ServerSocket(PORT)) {
while (true) {
Socket client = serverSocket.accept();
executor.submit(() -> {
try { handleRequest(client); }
catch (IOException e) { System.out.println("エラー: " + e.getMessage()); }
finally { try { client.close(); } catch (IOException ignored) {} }
});
}
}
}
}