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第18章

コード18-01

Main.java

import java.io.*;

public class Main {
  public static void main(String[] args) throws Exception {
    FileReader fr = new FileReader("data.txt");
    int input = fr.read();
    while (input != -1) {
      System.out.print((char)input);
      input = fr.read();
    }
    fr.close();
  }
}

コード18-02

Main.java

import java.io.*;

public class Main {
  public static void main(String[] args) throws Exception {
    FileWriter fw = new FileWriter("data.txt");
    fw.write('そ');
    fw.write('れ');
    fw.write('で');
    fw.write('は');
    fw.close();
  }
}

コード18-03

Main.java

import java.io.InputStream;
import java.net.URL;

public class Main {
  public static void main(String[] args) throws Exception {
    URL u = new URL("https://book.impress.co.jp/");
    InputStream is = u.openStream();
    int i = is.read();
    while (i != -1) {
      char c = (char)i;
      System.out.print(c);
      i = is.read();
    }
  }
}

コード18-04

Main.java

import java.sql.*;

public class Main {
  public static void main(String[] args) throws Exception {
    Class.forName("org.h2.Driver");
    String dburl = "jdbc:h2:~/test";
    String sql = "INSERT INTO EMPLOYEES(NAME) VALUES('aoki')";
    Connection conn = DriverManager.getConnection(dburl);
    conn.createStatement().executeUpdate(sql);
    conn.close();
  }
}

コード18-05

Main.java

import java.awt.FlowLayout;
import javax.swing.*;

public class Main {
  public static void main(String[] args) {
    JFrame frame = new JFrame("はじめてのGUI");
    JLabel label = new JLabel("Hello World!!");
    JButton button = new JButton("押してね");
    frame.getContentPane().setLayout(new FlowLayout());
    frame.getContentPane().add(label);
    frame.getContentPane().add(button);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300, 100);
    frame.setVisible(true);
  }
}

コード18-06

HelloServlet.java

import java.io.*;
import java.util.Date;
import javax.servlet.http.*;

@WebServlet("/HelloServlet")
public class HelloServlet extends HttpServlet {
  protected void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException {
    Date d = new Date();
    PrintWriter w = res.getWriter();
    res.setContentType("text/html");
    w.write("<html><body>");
    w.write("Today is " + d.toString());
    w.write("</body></html>");
  }
}

コード18-07

MonsterController.java

package com.example.restservice; 

import org.springframework.web.bind.annotation.*;

@RestController
public class MonsterController {
  @GetMapping("/monster")
  public Monster monster(
    @RequestParam(value = "id") String id) {
      return new Monster(id);
    }
}