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问Tomcat/JSP/servlets web-project
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Code Review用户

提问于 2012-03-08 13:35:33

回答 1查看 1.1K关注 0票数 2

这是一种简单的数组。数组(实际上我使用了ArrayList)存储在服务器上的default_list.txt文件中，对它的所有更改都是使用servlet进行的。

Add.java:

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Add extends HttpServlet {

    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        addNumber(request);
        goToPage("/index.jsp", request, response);
    }

    private void goToPage(String address, HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher dispatcher = getServletContext()
                .getRequestDispatcher(address);
        dispatcher.forward(request, response);
    }

    public static void addNumber(HttpServletRequest request) {

        try {
            HttpSession session = request.getSession(true);
            String path = session.getServletContext().getRealPath("/")
                    + "default_list.txt";
            String path2 = session.getServletContext().getRealPath("/")
                    + "sorted_list.txt";
            int numbers = Integer.parseInt(request.getParameter("textarea1"));
            FileWriter writer = new FileWriter(path, true);
            writer.write(numbers + "\n");
            writer.flush();
            writer.close();

            List<String> buf = new ArrayList<String>();
            File sorted_list = new File(path2);
            sorted_list.delete();
            ArrayList<Integer> arr = new ArrayList<Integer>();
            FileReader filereader = new FileReader(path);
            BufferedReader br = new BufferedReader(filereader);
            String eachLine = br.readLine();
            while (eachLine != null) {
                arr.add(Integer.parseInt(eachLine));
                eachLine = br.readLine();
            }
            filereader.close();

            long timeout = System.currentTimeMillis();
            Collections.sort(arr);
            timeout = System.currentTimeMillis() - timeout;

            writer = new FileWriter(path2, true);
            for (int i = 0; i < arr.size(); ++i)
                buf.add(arr.get(i) + "\n");
            for (String record : buf) {
                writer.write(record);
            }
            if (arr.size() > 0) {
                writer.write("Sort method executed in " + timeout + " ms.\n");
            }
            writer.flush();
            writer.close();

        } catch (Exception e) {
        }
    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

}

Delete.java:

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Delete extends HttpServlet {

    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        addNumber(request);
        goToPage("/index.jsp", request, response);
    }

    private void goToPage(String address, HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher dispatcher = getServletContext()
                .getRequestDispatcher(address);
        dispatcher.forward(request, response);
    }

    public static void addNumber(HttpServletRequest request) {

        try {
            HttpSession session = request.getSession(true);
            List<String> buf = new ArrayList<String>();
            List<String> buf2 = new ArrayList<String>();
            String path = session.getServletContext().getRealPath("/")
                    + "default_list.txt";
            String path2 = session.getServletContext().getRealPath("/")
                    + "sorted_list.txt";

            ArrayList<Integer> arr = new ArrayList<Integer>();
            FileReader filereader = new FileReader(path);
            BufferedReader br = new BufferedReader(filereader);
            String eachLine = br.readLine();
            while (eachLine != null) {
                arr.add(Integer.parseInt(eachLine));
                eachLine = br.readLine();
            }
            filereader.close();

            if (arr.size() > 0) {
                arr.remove(arr.size() - 1);
                File path_buf = new File(path);
                path_buf.delete();

                FileWriter writer = new FileWriter(path, true);
                for (int i = 0; i < arr.size(); ++i)
                    buf.add(arr.get(i) + "\n");
                for (String record : buf) {
                    writer.write(record);
                }
                buf.clear();
                arr.clear();
                writer.flush();
                writer.close();
            }

            File sorted_list = new File(path2);
            sorted_list.delete();
            filereader = new FileReader(path);
            br = new BufferedReader(filereader);
            eachLine = br.readLine();
            while (eachLine != null) {
                arr.add(Integer.parseInt(eachLine));
                eachLine = br.readLine();
            }
            filereader.close();
            long timeout = System.currentTimeMillis();
            Collections.sort(arr);
            timeout = System.currentTimeMillis() - timeout;
            FileWriter writer = new FileWriter(path2, true);
            for (int i = 0; i < arr.size(); ++i)
                buf.add(arr.get(i) + "\n");
            for (String record : buf) {
                writer.write(record);
            }
            if (arr.size() > 0) {
                writer.write("Sort method executed in " + timeout + " ms.\n");
            }
            writer.flush();
            writer.close();

        }

        catch (Exception e) {
        }
    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

}

Erase.java:

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Erase extends HttpServlet {

    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        addNumber(request);
        goToPage("/index.jsp", request, response);
    }

    private void goToPage(String address, HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher dispatcher = getServletContext()
                .getRequestDispatcher(address);
        dispatcher.forward(request, response);
    }

    public static void addNumber(HttpServletRequest request) {

        try {
            HttpSession session = request.getSession(true);

            String path = session.getServletContext().getRealPath("/")
                    + "default_list.txt";
            File list = new File(path);
            list.delete();
            FileWriter writer = new FileWriter(path, true);
            writer.flush();
            writer.close();

            path = session.getServletContext().getRealPath("/")
                    + "sorted_list.txt";
            list = new File(path);
            list.delete();
            writer = new FileWriter(path, true);
            writer.flush();
            writer.close();
        } catch (Exception e) {
        }
    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

}

Generate.java:

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Generate extends HttpServlet {

    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        addNumber(request);
        goToPage("/index.jsp", request, response);
    }

    private void goToPage(String address, HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher dispatcher = getServletContext()
                .getRequestDispatcher(address);
        dispatcher.forward(request, response);
    }

    public static void addNumber(HttpServletRequest request) {

        try {
            HttpSession session = request.getSession(true);
            List<String> buf = new ArrayList<String>();
            String path = session.getServletContext().getRealPath("/")
                    + "default_list.txt";
            String path2 = session.getServletContext().getRealPath("/")
                    + "sorted_list.txt";
            try {
                short amount = Short.parseShort(request
                        .getParameter("textarea2"));
                Random randomGenerator = new Random();
                FileWriter writer = new FileWriter(path, true);
                for (int i = 0; i < amount; ++i)
                    buf.add(randomGenerator.nextInt(100) + "\n");
                for (String record : buf) {
                    writer.write(record);
                }
                writer.flush();
                writer.close();
                buf.clear();

                File sorted_list = new File(path2);
                sorted_list.delete();
                ArrayList<Integer> arr = new ArrayList<Integer>();
                FileReader filereader = new FileReader(path);
                BufferedReader br = new BufferedReader(filereader);
                String eachLine = br.readLine();
                while (eachLine != null) {
                    arr.add(Integer.parseInt(eachLine));
                    eachLine = br.readLine();
                }
                filereader.close();
                long timeout = System.currentTimeMillis();
                Collections.sort(arr);
                timeout = System.currentTimeMillis() - timeout;
                FileWriter writer2 = new FileWriter(path2, true);
                for (int i = 0; i < arr.size(); ++i)
                    buf.add(arr.get(i) + "\n");
                for (String record : buf) {
                    writer2.write(record);
                }
                if (arr.size() > 0) {
                    writer2.write("Sort method executed in " + timeout
                            + " ms.\n");
                }
                writer2.flush();
                writer2.close();

            } catch (Exception e) {
            }
            ;
        } catch (Exception e) {
        }
    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

}

index.jsp:

<%@ page import="java.util.*" %>
<%@ page import="java.io.*" %>
<HTML>
<HEAD>
<TITLE>Sample sort</TITLE>
</HEAD>
<BODY>
<H1>JSP/Servlet sorting sample.</H1>
<FORM ACTION="list.add" METHOD="POST">
  Input a number:
  <input type="text" name="textarea1">
  <INPUT TYPE="SUBMIT" VALUE="Add">
</form>
<FORM ACTION="list.gen" METHOD="POST">
  Enter amount of numbers to generate:
  <input type="text" name="textarea2">
  <input type="SUBMIT" value="Generate">
</FORM>
<table>
<tr>

<td><form action="list.del" method="POST">
  <input type="SUBMIT" value="Delete last">
</form></td>
<td><form action="list.erase" method="POST">
  <input type="SUBMIT" value="Clear">
</form></td>
  </tr>
</table>
<table width="500">
<tr>
<td width="250">
Your list:
<br>
<br>    
<%
String file = application.getRealPath("/") + "default_list.txt";
FileReader filereader = new FileReader(file);
BufferedReader br = new BufferedReader(filereader);
String eachLine = br.readLine();
while (eachLine != null) {
out.println(eachLine);
out.println("<br>");
eachLine = br.readLine();
}
filereader.close();       
%>
</td>
<td width="250">
Sorted list:
<br>
<br>
<%
String file2 = application.getRealPath("/") + "sorted_list.txt";
FileReader filereader2 = new FileReader(file2);
BufferedReader br2 = new BufferedReader(filereader2);
String eachLine2 = br2.readLine();
while (eachLine2 != null) {
out.println(eachLine2);
out.println("<br>");
eachLine2 = br2.readLine();
}
filereader2.close();       
%>
</td>
  </tr>
</table>
</BODY>
<HTML>

或者，整个项目是这里.fcjrg5nms979in9

我想要的是：

我做得好吗？可能会有一些重大的错误？
你建议我做些什么让它变得更好？(更安全、更快、更简单)

servlets

java

jsp

回答 1

Code Review用户

发布于 2012-03-08 14:16:26

快速浏览，这里有几个提示

1)关注点分离(SoC)。让您的视图(jsp)处理呈现，Controller (servlet)处理应用程序的流，并在另一组类中处理所有处理。这将是MVC的基础。下面是一个简单布局的维基百科定义。

模型--该模型是Java类的集合，这些类构成了一个软件应用程序，用于存储数据，并可选择地分离数据。可以与任何用户界面通信的单个前端类(例如:控制台、图形用户界面或web应用程序)。视图-视图由Java表示，数据被传输到HttpServletRequest或HttpSession中的页面。控制器- Controller与模型的前端通信，并在转发HttpServletRequest和使用RequestDispatcher向RequestDispatcher响应之前加载适当的数据。

2)在JSP中不要使用scriptlet。在养成使用scriptlet的习惯之前，请考虑学习jstl。为什么脚本是坏的？阅读这个详细的答案

3)所有servlet都有goToPage()、doGet()、doPost()和ProcessRequest()方法。每次创建新的servlet时，都要重写大量的内容。考虑在servlet和HttpServlet之间创建一个抽象类，它定义了这些方法。

public abstract class BaseServlet extends HttpServlet{
    //You must define this 
    protected abstract void processRequest(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException;

    protected void goToPage(String address, HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(address);
        dispatcher.forward(request, response);

    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }
}

现在，您所要做的就是扩展BaseServlet而不是HttpServlet，并且您可以使用这些方法而不需要重写。如果您以后要找到一个bug，或者现在想重写它，您只需在一个地方查看，而不是在每个servlet中更改它。

票数 2

页面原文内容由Code Review提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://codereview.stackexchange.com/questions/9865

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问Tomcat/JSP/servlets web-project
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Add.java:

Delete.java:

Erase.java:

Generate.java:

index.jsp:

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