JAVAの掲示板作成

JAVAで掲示板を作成しているが、ファイルに書き込めるが、nullと表示されているので、原因を教えてください。

BoardSevlet.java

import java.io.IOException;
import java.io.PrintWriter;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.util.ArrayList;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/BordServlet")
public class BordServlet extends HttpServlet {

@Override
protected void doPost( HttpServletRequest request, HttpServletResponse response ) throws ServletException, IOException {

    this.doGet( request, response );
}


@SuppressWarnings("unused")
@Override
protected void doGet( HttpServletRequest request, HttpServletResponse response ) throws ServletException, IOException {

    response.setContentType( "text/html;charset=UTF-8" );
    PrintWriter out = response.getWriter();
	



    out.println( "<html>" );
    out.println( "<head>" );
    out.println( "<title>BordServlet</title>" );
    out.println( "</head>" );
    out.println( "<body>" );
    out.println( "<h1>掲示板</h1>" );

    out.println( "<form action='/TomcatTest/BordServlet' method='get'>" );

    out.println( "<table>" );
	out.println( "<tr><th>発信者ID</th><td><input type = text name = \"id1\"></td></tr>" );
    out.println( "<tr><th>タイトル</th><td><input type = text name = \"title1\"></td></tr>" );
    out.println( "<tr><th>本文</th><td>    <          textarea name = \"body1\" rows=5></textarea></td></tr>" );
    out.println( "</table>" );
    out.println( "<br>" );
    out.println( "<input type=submit value=\"投稿\">" );
    out.println( "</form>" );


	String id1 = null;
    String title1 = null;
    String body1 = null;


    if ( request.getParameter( "id" ) == null && request.getParameter( "title" ) == null && request.getParameter( "body" ) == null ) {
    	
    	id1 = "";
        title1 = "";
        body1 = "";
    	
    } else {
    	
    	id1 = new String( request.getParameter( "id" ) );
        title1 = new String( request.getParameter( "title" ) );
        body1 = new String( request.getParameter( "body" ) );
    }
	
	FileWriter fw = new FileWriter(request.getRealPath("WEB-INF\\classes\\bbs_history.txt"));
	
	BufferedWriter bw = new BufferedWriter(fw);
	
	bw.write(request.getParameter("id1") + "\r\n");
	bw.write(request.getParameter("title1") + "\r\n");
	bw.write(request.getParameter("body1") + "\r\n");
	bw.close(); 

    ArrayList<Article> aList = new ArrayList<>();

    ServletContext sc = this.getServletContext();

    aList = (ArrayList<Article>) sc.getAttribute( "0" );

    if ( aList == null ) {
        aList = new ArrayList<>();
    }


    if ( id1.equals( "" ) && title1.equals( "" ) && body1.equals( "" ) ) {

    } else {
        for ( Article article : aList ) {
            if ( article.getSenderID().equals( "" ) && article.getTitle().equals( "" ) && article.getBody().equals( "" ) ) {
            } else {
                out.println( "<hr>" );
                out.println( "発信者ID" );
                out.println( "<p>" + article.getSenderID() + "</p>" );
            	out.println( "タイトル" );
                out.println( "<p>" + article.getTitle() + "</p>" );
                out.println( "本文" );
                out.println( "<pre>" + article.getBody() + "</pre>" );
                out.println( "<hr>" );
            }
        }

    }
    sc.setAttribute( "0", aList );
    out.println( "</body>" );
    out.println( "</html>" );

}

}

Article.java

public class Article {

private String id;

private String title;

private String body;




public Article( String id, String title, String body ) {

	setSenderID( id );
    setTitle( title );
    setBody( body );

}

public String getSenderID() {
	
	return id;
}

public String getTitle() {

    return title;
}

public String getBody() {

    return body;
}


public void setSenderID( String string ){
	
	id = string;
}

public void setTitle( String string ) {

    title = string;
}

public void setBody( String string ) {

    body = string;
}

}

m.ts10806

2017/07/26 07:34

プログラムコードは```で囲ってください。（わからなければ質問編集画面でコード部分を選択し<code>ボタンを押してください）

行動規範の内容に同意します

回答1件

自分の環境で試しましたが、正しく出力されましたよ。

nullになるのはどのタイミングでしょうか？
投稿ボタンクリック後で合ってますか？

あと、回答とは関係ないですが、基本的なことでアドバイスします。

POSTとGETの使い方についてです。

入力データを送信するときはPOST（doPost）、画面を表示するときはGET（doGet）で行うようにしてください。

formタグのmethod属性は、投稿情報の送信時に使用するので、上記の修正に合わせてください。

BoardServlet.java

java
1@WebServlet("/board")
2public class BoardServlet extends HttpServlet {
3
4    @Override
5    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
6        
7        String id = Optional.ofNullable(request.getParameter("id")).orElse("");
8        String title = Optional.ofNullable(request.getParameter("title")).orElse("");
9        String body = Optional.ofNullable(request.getParameter("body")).orElse("");
10
11        FileWriter fw = new FileWriter(request.getRealPath("/WEB-INF/classes/bbs_history.txt"),true);
12
13        try (BufferedWriter bw = new BufferedWriter(fw)) {
14            bw.write(id + "\r\n");
15            bw.write(title + "\r\n");
16            bw.write(body + "\r\n");
17        } 
18        
19        saveArticle(new Article(id,title,body));
20        
21        response.sendRedirect("board");
22    }
23
24    @SuppressWarnings("unused")
25    @Override
26    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
27
28        response.setContentType("text/html;charset=UTF-8");
29        PrintWriter out = response.getWriter();
30
31        out.println("<html>");
32        out.println("<head>");
33        out.println("<title>BordServlet</title>");
34        out.println("</head>");
35        out.println("<body>");
36        out.println("<h1>掲示板</h1>");
37
38        out.println("<form action='board' method='POST'>");
39
40        out.println("<table>");
41        out.println("<tr><th>発信者ID</th><td><input type = text name='id'></td></tr>");
42        out.println("<tr><th>タイトル</th><td><input type = text name='title'></td></tr>");
43        out.println("<tr><th>本文</th><td><textarea name='body' rows=5></textarea></td></tr>");
44        out.println("</table>");
45        out.println("<br>");
46        out.println("<input type=submit value='投稿'>");
47        out.println("</form>");
48
49        List<Article> articles = getArticleList();
50
51        articles.stream().forEach(article -> {
52            out.println("<hr>");
53            out.println("発信者ID");
54            out.println("<p>" + article.getSenderID() + "</p>");
55            out.println("タイトル");
56            out.println("<p>" + article.getTitle() + "</p>");
57            out.println("本文");
58            out.println("<pre>" + article.getBody() + "</pre>");
59            out.println("<hr>");
60        });
61        
62        out.println("</body>");
63        out.println("</html>");
64    }
65    
66    private List<Article> getArticleList(){
67        return Optional.ofNullable((List<Article>)this.getServletContext().getAttribute("articles")).orElse(new ArrayList<>());
68    }
69    
70    private void saveArticle(Article article){
71        List<Article> articles = getArticleList();
72        articles.add(article);
73        this.getServletContext().setAttribute("articles", articles);
74    }
75}