java - 如何在servlet中使用或调用java类并将结果显示到jsp-6ren

java - 如何在servlet中使用或调用java类并将结果显示到jsp

转载作者：行者123 更新时间：2023-12-01 09:24:12

我能够将 NewFile.jsp 中的搜索词传递给 HelloWorld servlet 并在 wecome jsp 中显示结果。我在新的java类中编写了另一个程序。我不知道如何将searchterm传递给java类。从而运行程序。

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" 
    xmlns="http://java.sun.com/xml/ns/j2ee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <servlet>
    <servlet-name>Hello</servlet-name>
    <servlet-class>HelloWorld</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Hello</servlet-name>
    <url-pattern>/HelloWorld</url-pattern>
  </servlet-mapping>
</web-app>

NewFile.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"  
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
    "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
        <title> My JSP page </title>
    </head> 
    <body>      
        <form method="post" action="HelloWorld">            
             Please enter a Keyword <br>
            <input type="text" name="searchTerm"size="20px">
            <input type="submit" value="submit">                        
        </form>     
    </body> 
</html>

welcomepage.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%String X = (String)request.getAttribute("searchTerm");%>

 The search word is<%=X %>

<%-- welcom <%=request.getAttribute("searchTerm")%> --%>

</body>
</html>

servlet:HelloWorld.java

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;

public class HelloWorld extends HttpServlet { 
  protected void doGet(HttpServletRequest request, 
      HttpServletResponse response) throws ServletException, IOException 
  {
    doPost(request,response);

  }

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


    // ..........reading the user input
    String searchTerm= request.getParameter("searchTerm");  
  request.setAttribute("searchTerm",searchTerm);
  request.getRequestDispatcher("welcomepage.jsp").forward(request, response);


  }  

  }

其他 JavaScript:Myprogram.java

public class ParameterPy {

public static void main(String a[]){
try{

String searchTerm="google";

ProcessBuilder pb = new ProcessBuilder("C:/Python27/python","D://program.py",""+searchTerm);
Process p = pb.start();

BufferedReader bfr = new BufferedReader(new InputStreamReader(p.getInputStream()));

System.out.println(".........start   process.........");  
String line = "";     
while ((line = bfr.readLine()) != null){
    System.out.println("Python Output: " + line);
}
System.out.println("........end   process.......");


}catch(Exception e){System.out.println(e);}
}
}

如何将 Myprogram.java 中的变量 searchterm 与 HelloWorld.java 中的变量链接(将“google”替换为实时用户输入的搜索词)，因为 HelloWorld.java 是一个可以显示到 jsp 的 servlet。

最佳答案

使用以下代码:
ParameterPy类

import java.io.BufferedReader;
import java.io.InputStreamReader;
public class ParameterPy
{

    public static void myMethodName(String searchTerm)  
        {
            try
                {
                    ProcessBuilder pb = new ProcessBuilder("C:/Python27/python", "D://program.py", ""+ searchTerm);
                    Process p = pb.start();

                    BufferedReader bfr = new BufferedReader(new InputStreamReader(p.getInputStream()));

                    System.out.println(".........start   process.........");
                    String line = "";
                    while ((line = bfr.readLine()) != null)
                        {
                            System.out.println("Python Output: " + line);
                        }
                    System.out.println("........end   process.......");

                } catch (Exception e)
                {
                    System.out.println(e);
                }
        }
}

HelloWorld Servlet:

import java.io.IOException;

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

public class HelloWorld extends HttpServlet {
private static final long serialVersionUID = 1L;

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

      }

      protected void doPost(HttpServletRequest request, 
              HttpServletResponse response) throws ServletException, IOException 
          {
        // ..........reading the user input

      String searchTerm= request.getParameter("searchTerm");  

      ParameterPy.myMethodName(searchTerm);//Call to java class method

      request.setAttribute("searchTerm",searchTerm);
      request.getRequestDispatcher("welcomepage.jsp").forward(request, response);

      }  
}

对于注释中的查询，现在您正在 System.out 上打印 ParameterPy 的结果。为了在 jsp 网页上显示结果，您需要 JspWriter 对象，即 out。
为此，我修改了您的逻辑，如下所示，将结果返回为 String。这个String结果将显示在jsp页面上。

import java.io.BufferedReader;
import java.io.InputStreamReader;
public class ParameterPy
{
    public static String myMethodName2(String searchTerm)   
        {
            StringBuilder sb=null;
            try
                {
                    ProcessBuilder pb = new ProcessBuilder("C:/Python27/python", "D://program.py", ""+ searchTerm);
                    Process p = pb.start();

                    BufferedReader bfr = new BufferedReader(new InputStreamReader(p.getInputStream()));

                    sb=new StringBuilder();
                    sb.append(".........start   process.........");
                    String line = "";
                    while ((line = bfr.readLine()) != null)
                        {
                            sb.append("Python Output: " + line);
                        }
                    sb.append("........end   process.......");

                } catch (Exception e)
                {
                    System.out.println(e);
                }
                return sb.toString();
        }
}

JSP:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1" import="stack.filter.ParameterPy"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
    String searchTerm = request.getParameter("searchTerm");
    out.println(ParameterPy.myMethodName2(searchTerm));
%>
</body>
</html>