Question

我有一个成功的ajax，它采用了一系列网址，例如＆＃34; www.asd.com，www.efuief.com＆＃34;和POST到我的生成servlet。当我在ajax javascript文件中提醒它时，我可以看到数组字符串。我可以看到用于生成servlet的POST来自浏览器网络选项卡。

数组传递给我的生成serlvet，我想

a）查看数组的内容，但我不确定如何。我有一些system.out.printlns，但是当我运行网页并点击按钮时，他们似乎什么都不做。

b）获取数组的内容（如果它们不是字符串），然后将它们解析为java arraylist。一个网站给了我（相当longwinded）方法来做到这一点，我将数组转换为List（对象？）然后将List转换为ArrayList字符串

c）最后我想将数组提供给我的imageController，它试图遍历arraylist。但是，它给了我消息＆＃34;对象无法转换为字符串＆＃34; ，表明某些事情没有起作用？

代码很长但我认为问题领域非常明显（我评论了两个可疑区域）。如果你可以看一看会很棒。如果有的话，也许你可以告诉我如何以某种方式将这些值打印到我的屏幕上，因为我的system.out.println事情并没有被激活....

三江源

Ajax（应该正常工作......）

$(document).ready(function () {
    $('#button').click(function () {

        var array = [];

        $('#sortable2 .selectedItemImg').each(function () {

            array.push($(this).attr('src'));
        });

      alert(array);

        $.ajax({
            url: 'generate',
            type: 'POST',
            dataType: 'array',
            data: (array),

            success: function (data) {
//                alert("test44");
            }

// send url to user
// 
//
        }
        );
    });
    return false;
    }
    );

的Servlet

 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package main;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author J
 */
@WebServlet(name = "ImageGenerationServlet", urlPatterns = {"/generate"})
public class ImageGenerationServlet extends HttpServlet {



    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet ImageGenerationServlet</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet ImageGenerationServlet at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);


        // THESE PARTS DONT APPEAR TO WORK!! :)

        List imageList = Arrays.asList(request.getParameter("button"));

        System.out.println(imageList);

        ArrayList <String> imageURLs = new ArrayList(Arrays.asList(imageList));

        System.out.println(imageURLs);

        ImageController imgc = new ImageController(imageURLs);




         // 1) retrieve array of urls
         // 2) send to imagegenerationcontroller
         // 3) send to uploadcontroller
         // 4) retrieve and parse the json response to get the imgur url
         // 5) response from here to user


    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}

ImageController（用字符串做的东西，除了它似乎没有变成字符串）

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package main;

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;

/**
 *
 * @author J
 */
public class ImageController {

//int roundUp(int numToRound, int multiple) 
//{ 
// if(multiple == 0) 
// { 
//  return numToRound; 
// } 
//
// int remainder = numToRound % multiple;
// if (remainder == 0)
//  return numToRound;
// return numToRound + multiple - remainder;
//}

    int roundUp(int numToRound, int multiple) {
    return (numToRound+multiple-1) / multiple;
}

public ImageController(ArrayList imageURLs) throws IOException

  {



//      ArrayList <String> imageURLs = new ArrayList<>();

//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");

//Integer totalHeight= 300*((Math.round(imageURLs.size()/6)));

//Integer totalHeight = imageURLs.size()*300/4;


//Integer totalHeight = 300*(roundUp(imageURLs.size(), 4));

Integer totalHeight = (roundUp(imageURLs.size(),4))*200;

System.out.println(imageURLs.size());
System.out.println(totalHeight);

// height = numberofentries / 4 rounded up to the nearest multiple of 4

// height = numberofentries rounded up to the nearest 4, divided by 4, times 300px

//Double heightMath= 300*(4*(Math.ceil(Math.abs(imageURLs.size()/4.0))));

//Long heightMath= 300*(long)Math.floor(imageURLs.size() + 1d);

//Integer totalHeight = (int) (double) heightMath;

//if (totalHeight < 300){ 
//      totalHeight = 300; 
//  }

BufferedImage result = new BufferedImage(
                               736, totalHeight, //work these out
                               BufferedImage.TYPE_INT_RGB);

Graphics g = result.getGraphics();

Integer x = 0;
Integer y = 0;



//THIS SAYS "OBJECT CANNOT BE CONVERTED TO STRING!"
// IT SHOULD HAVE BEEN PARSED INTO AN ARRAYLIST<STRING> ALREADY?

for(String imageURL : imageURLs){

        BufferedImage bi = ImageIO.read(new File(imageURL));
        g.drawImage(bi, x, y, null);
        x += 184;
        if(x >= result.getWidth()){
            x = 0;
            y += bi.getHeight();
        }

          ImageIO.write(result,"png",new File("C:\\Users\\J\\Desktop\\resultimage.jpg"));
    }
}
}

编辑我的所有文件（更新版本）：

索引jsp

<%@page language ="java" contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>Anime List Creator</title>

        <script src="webresources/jquery-2.1.3.min.js"></script>
        <!--<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>-->
        <script src="webresources/basic.js"></script>
<script src="webresources/submitList.js"></script>
        <link rel="stylesheet" href="//code.jquery.com/ui/1.11.4/themes/smoothness/jquery-ui.css">
        <script src="//code.jquery.com/jquery-1.10.2.js"></script>
        <script src="//code.jquery.com/ui/1.11.4/jquery-ui.js"></script>
        <!--<link rel="stylesheet" href="/resources/demos/style.css">-->
        <style>

            body {
                background-color: #ffffff;
            }

            #sortable1 {
                /*                border: 1px solid #eee;
                                width: 142px;
                                min-height: 20px;
                                list-style-type: none;
                                margin: 0;
                                padding: 5px 0 0 0;
                                float: left;
                                margin-right: 10px;*/

                list-style-type: none; padding: 0px; width: 926px; border-style: solid; border-width: 2px; min-height: 310px; float: left; background-color: #e9e9e9; max-height: 1240px; overflow: auto;
            }

            #sortable2 {
                /*                border: 1px solid #eee;
                                width: 142px;
                                min-height: 20px;
                                list-style-type: none;
                                margin: 0;
                                padding: 5px 0 0 0;
                                float: left;
                                margin-right: 10px;*/

                list-style-type: none; padding: 0px; width: 926px; margin-left: 30px; border-style: solid; border-width: 2px; min-height: 310px; float: left; background-color: #7fc1ff;
            }


            #sortable1 li, #sortable2 li {
                /*                margin: 0 5px 5px 5px;
                                padding: 5px;
                                font-size: 1.2em;
                                width: 120px;*/

                margin: 10px 0px 45px 10px; padding: 0px; width: 216px; height: 300px; font-size: 16px; text-align: center; float: left; color: white; border-style: none; font-family: Geneva,Tahoma,Verdana,sans-serif;
            }





        </style>
        <script>
            $(function () {
                $("#sortable1, #sortable2").sortable({
                    connectWith: ".connectedSortable"
                }).disableSelection();
            });
        </script>

        <script>


//            $("#button").click(function() {
//
////            function loop() {
////            alert()
////                    $('#sortable2 .row.selected img').each(function() {
////            alert($(this).attr('src'))
////            })
//
//alert("hi");

//$(document).ready(function() {
//  $("#button").click(function () {
//    alert("Hello1");


//        $('#sortable2 .selectedItemImg').each(function() {
//$('img.selectedItemImg').each(function() {
//        alert(this.src);

//    $('.userList .selectedItemId .selectedItemImg img').each(function() {
//    $(".userList").each(function() {
//        $('.userList').find('#textid');
//        alert($('.userList id img'));
//        alert($(this).attr.div($(this).attr("id")));
//        alert($(this).attr("id"));
//        alert($(this).attr("src"));
//        alert("Hello2!");
//            });
//  });




        </script>


<!--        <script src="${page.request.contextPath}/webresources/jquery-2.1.3.min.js"></script>
        <script src="${page.request.contextPath}/webresources/basic.js"></script>-->


        <!--<link rel="stylesheet" href="webresources/css/basic.css" type="text/css" media="screen"/>-->
    </head>

    <body background-color:black;>
          <h1>Anime List Creator</h1>

        <form id="searchForm">
            <label for="searchQuery">Make a search</label>
            <input type="text" id="searchQuery" name="searchQuery"/>
            <input type="submit"/>
        </form>

        <div id="searchContainer1"></div>




        <!--<p id="displaySearchResults"><p/>-->

        <!--        <div id="searchContainer1"
                <p id="displaySearchResults1"><p/>
                <p id="displaySearchResults2"><p/>
                <p id="displaySearchResults3"><p/>
                </div>-->


        <hr/>

        <ul id="sortable1" class="connectedSortable">
            <!--            <li class="ui-state-default">Item 1</li>
                        <li class="ui-state-default">Item 2</li>
                        <li class="ui-state-default">Item 3</li>
                        <li class="ui-state-default">Item 4</li>
                        <li class="ui-state-default">Item 5</li>-->
        </ul>

        <ul id="sortable2" class="connectedSortable">
            <!--            <li class="ui-state-highlight">Item 1</li>
                        <li class="ui-state-highlight">Item 2</li>
                        <li class="ui-state-highlight">Item 3</li>
                        <li class="ui-state-highlight">Item 4</li>
                        <li class="ui-state-highlight">Item 5</li>-->
        </ul>

        <hr/>

        <button id="button" name="button">Save List</button>

    </body>
</html>

图片servlet

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package main;

import com.google.gson.Gson;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author J
 */
@WebServlet(name = "ImageGenerationServlet", urlPatterns = {"/generate"})
public class ImageGenerationServlet extends HttpServlet {



    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet ImageGenerationServlet</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet ImageGenerationServlet at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);


        // THESE PARTS DONT APPEAR TO WORK!! :)

//        List imageList = Arrays.asList(request.getParameter("button"));
//        
//        System.out.println(imageList);
//         
//        ArrayList <String> imageURLs = new ArrayList(Arrays.asList(imageList));
//        
//        System.out.println(imageURLs);

//         ArrayList <String> imageURLs = new ArrayList(request.getParameter("button"));

//        String postResponse = request.getParameter("button");

//        ArrayList<Map> imageMap = new ArrayList<Map>();

//        String[] urls1 = postResponse.split(",");


//        ImageController.controlImage(urls1);

        List<String> imageURLs = new ArrayList<String>();
try {
    BufferedReader reader = request.getReader();
    String line;
    do {
        line = reader.readLine();
        imageURLs.add(line);

    } while (line != null);
}catch(Exception e){};

//int size = imageURLs.length();

        ImageController.controlImage((ArrayList<String>) imageURLs);


         // 1) retrieve array of urls
         // 2) send to imagegenerationcontroller
         // 3) send to uploadcontroller
         // 4) retrieve and parse the json response to get the imgur url
         // 5) response from here to user


    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}

图像控制器

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package main;

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;

/**
 *
 * @author J
 */
public class ImageController {

//int roundUp(int numToRound, int multiple) 
//{ 
// if(multiple == 0) 
// { 
//  return numToRound; 
// } 
//
// int remainder = numToRound % multiple;
// if (remainder == 0)
//  return numToRound;
// return numToRound + multiple - remainder;
//}





public static void controlImage(ArrayList<String>imageURLs ) throws IOException

  {



//      ArrayList <String> imageURLs = new ArrayList<>();

//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");
//imageURLs.add("C:\\Users\\J\\Desktop\\test5.jpg");


//Integer totalHeight= 300*((Math.round(imageURLs.size()/6)));
//
//Integer totalHeight = imageURLs.size()*300/4;
//
//Integer totalHeight = 300*(roundUp(imageURLs.size(), 4));

//      int arraySize = imageURLs.length();

Integer totalHeight = (roundUp(imageURLs.size(),4))*200;


//System.out.println(imageURLs.size());
//System.out.println(totalHeight);

// height = numberofentries / 4 rounded up to the nearest multiple of 4

// height = numberofentries rounded up to the nearest 4, divided by 4, times 300px

//Double heightMath= 300*(4*(Math.ceil(Math.abs(imageURLs.size()/4.0))));

//Long heightMath= 300*(long)Math.floor(imageURLs.size() + 1d);

//Integer totalHeight = (int) (double) heightMath;

//if (totalHeight < 300){ 
//      totalHeight = 300; 
//  }

BufferedImage result = new BufferedImage(
                               736, totalHeight, //work these out
                               BufferedImage.TYPE_INT_RGB);

Graphics g = result.getGraphics();

Integer x = 0;
Integer y = 0;



//THIS SAYS "OBJECT CANNOT BE CONVERTED TO STRING!"
// IT SHOULD HAVE BEEN PARSED INTO AN ARRAYLIST<STRING> ALREADY?

for(String imageURL :  imageURLs){

        BufferedImage bi = ImageIO.read(new File(imageURL));
        g.drawImage(bi, x, y, null);
        x += 184;
        if(x >= result.getWidth()){
            x = 0;
            y += bi.getHeight();
        }

          ImageIO.write(result,"png",new File("C:\\Users\\J\\Desktop\\resultimage.jpg"));
    }
}

    private static int roundUp(int numToRound, int multiple) {
    return (numToRound+multiple-1) / multiple;
}

}

SubmitList ajax

$(document).ready(function () {
    $('#button').click(function () {

        var array1 = [];

        $('#sortable2 .selectedItemImg').each(function () {

            array1.push($(this).attr('src'));
        });

      alert(array1);

        $.ajax({
            url: 'generate',
            type: 'POST',
            dataType: 'json',
            data: (array1),

            success: function (data) {
//                alert("test44");
            }

// send url to user
// 
//
        }
        );
    });
    return false;
    }
    );

我能想到的唯一奇怪的事情就是我删除了我的WEB-INF配置文件（servlet映射的东西），因为它在我重命名文件时有奇怪的重复。我的网络应用程序停止工作了一段时间，最终我删除了整个文件夹，它又开始工作了。所以我怀疑这与任何事都有关系。

Answer 1

这里有一些问题在起作用。请注意，ArrayList实现了List，因此您几乎不需要将List转换为ArrayList。在doPost中，request.getParameter（＆＃34; button＆＃34;）将获得表单或查询参数＆＃34; button＆＃34;你没有通过你的ajax电话。要获得原始POST主体，请使用类似这样的内容

List<String> imageURLs = new ArrayList<String>();
try {
    BufferedReader reader = request.getReader();
    String line;
    do {
        line = reader.readLine();
        imageURLs.add(line);
    } while (line != null);

在ajax调用中，dataType＆＃34;数组＆＃34;无效。 dataType还指定您希望从服务器返回的内容，如果您在doPost中调用processRequest，则该内容将为html。 You can receive a JSON object that will automatically be converted to a Javascript Object, just plain text as a string, or a few others。上面的代码已经分开了POST主体的每一行，因此下面的代码只是为了简单起见而在新行上发送每个URL。如果数据变得更复杂，您可能希望在Java中查看JSON解析。

$.ajax({
    url: 'generate',
    type: 'POST',
    contentType: 'text/plain',
    dataType: 'html'
    data: array.join('\n'),
    success: function (data) {
        // data will be html as text
        // This executes only when the request returns successfully.
    }
});

您收到编译错误＆＃34;对象无法转换为字符串＆＃34;因为当没有类型参数时，像ArrayList这样的泛型类型被隐式声明为ArrayList。查找原始类型以获取更多信息。要修复编译错误，请将ImageController的构造函数更改为

public ImageController(ArrayList<String> imageURLs)

将JQuery数组放入Java ArrayList字符串然后使用它

1 个答案: