Java : ServletからServletへ値を送る方法

ServletからServletへ値を送る方法

request.setAttribute(java.lang.String name, java.lang.Object o)で値をセットし、getAttribute(java.lang.String name) で値を取り出す。

サンプル

• フォルダ構成
  • webTest
    • Hoge.java
    • Test1.java
    • Test2.java
  • webTest2
    • Moge.java
  • WebContent
    • test.jsp
• Test1.javaを実行すれば動きます

Test1.java

package webTest;


import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import webTest2.Moge;

/**
 * Servlet implementation class Test1
 */
@WebServlet("/Test1")
public class Test1 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Test1() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //response.getWriter().append("Served at: ").append(request.getContextPath());

        Moge m = new Moge(1,2);

        request.setAttribute("bean", m);

        //JSPに遷移する
        RequestDispatcher disp = request.getRequestDispatcher("/Test2");
        disp.forward(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

Test2.java

package webTest;


import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import webTest2.Moge;

/**
 * Servlet implementation class Test1
 */
@WebServlet("/Test2")
public class Test2 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Test2() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //response.getWriter().append("Served at: ").append(request.getContextPath());

        Moge m = (Moge)request.getAttribute("bean");
        Hoge h = new Hoge(3,4, m);

        request.setAttribute("bean", h);

        //JSPに遷移する
        RequestDispatcher disp = request.getRequestDispatcher("/test.jsp");
        disp.forward(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

Moge.java

package webTest2;

public class Moge {
    private int a;
    private int b;

    public Moge(){

    }

    public Moge(int a, int b){
        this.a = a;
        this.b = b;
    }

    public int getA() {
        return a;
    }

    public void setA(int a) {
        this.a = a;
    }

    public int getB() {
        return b;
    }

    public void setB(int b) {
        this.b = b;
    }

    @Override
    public String toString() {
        return "Hoge [a=" + a + ", b=" + b + "]";
    }
}

Hoge.java

package webTest;

import webTest2.Moge;

public class Hoge {
    private int a;
    private int b;
    private Moge m;

    public Moge getM() {
        return m;
    }

    public void setM(Moge m) {
        this.m = m;
    }

    public Hoge(){

    }

    public Hoge(int a, int b, Moge m) {
        super();
        this.a = a;
        this.b = b;
        this.m = m;
    }

    public int getA() {
        return a;
    }

    public void setA(int a) {
        this.a = a;
    }

    public int getB() {
        return b;
    }

    public void setB(int b) {
        this.b = b;
    }

    @Override
    public String toString() {
        return "Hoge [a=" + a + ", b=" + b + ", m=" + m + "]";
    }


}

test.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

<jsp:useBean
        id="bean"
        class="webTest.Hoge"
        scope="request" />

<%@ page import="webTest2.Moge"%>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>

    <%= bean.getM() %>
</body>
</html>