jquery - 如何使用来自 servlet 的 JSON 对象将数据数组传递到网页

Question

我正在尝试使用 JSON 对象将从数据库检索到的数据传递到网页。但我的问题是，

• 当数据库包含更多数据时，我需要传递数组中的值
• 当我传递数组中的值时。Jquery 将结果返回为undefined.

我的 Servlet 代码是：

   String message=request.getParameter("comm");
    int itemId=Integer.parseInt(request.getParameter("data-id"));
    int albumId=Integer.parseInt(request.getParameter("data-alid"));

    PrintWriter out = response.getWriter();
    response.setContentType("text/html");
    response.setHeader("Cache-control", "no-cache, no-store");
    response.setHeader("Pragma", "no-cache");
    response.setHeader("Expires", "-1");

    response.setHeader("Access-Control-Allow-Origin", "*");
    response.setHeader("Access-Control-Allow-Methods", "GET");
    response.setHeader("Access-Control-Allow-Headers", "Content-Type");
    response.setHeader("Access-Control-Max-Age", "86400");

    Gson gson = new Gson();
    JsonObject myObj = new JsonObject();

    ArrayList<Commenter> commentInfo;
    try {
        commentInfo = commenting(uname,message,itemId,albumId);
        java.lang.reflect.Type listOfTestObject = new TypeToken<ArrayList<Commenter>>(){}.getType();
        String str = gson.toJson(commentInfo, listOfTestObject); 
        JsonElement commentObj = gson.toJsonTree(str);
        boolean nonNullElemExist= true;
        for (Commenter s: commentInfo) {
            if (s == null) {
                nonNullElemExist = false;
                break;
            }
        }
    if(nonNullElemExist == false){
        myObj.addProperty("success", false);
    }
    else {
        myObj.addProperty("success", true);
    }
    myObj.add("commentInfo", commentObj);
    out.println(myObj.toString());

    out.close();
    } catch (ClassNotFoundException | SQLException e) {
        System.out.println( "Error --> " + displayErrorForWeb(e));
    }

}



private ArrayList<Commenter> commenting(String uname,String message,int itemId,int albumId) throws ClassNotFoundException, SQLException {
   ArrayList<Commenter> commentList = new ArrayList<Commenter>();
   Connection conn = null; 
   conn=prepareConnection();
   PreparedStatement stmt = null;    
   String sql = null;

    try {     
        StringBuilder sb1=new StringBuilder(1024);
        sb1.append("insert into ").append(uname.trim()).append("comments values(?,?,?)");
        String sql1=sb1.toString();
        PreparedStatement stmt1 = conn.prepareStatement(sql1);
        stmt1.setString(1,uname);
        stmt1.setString(2,message);
        stmt1.setInt(3,itemId);
        stmt1.executeUpdate();

        StringBuilder sb=new StringBuilder(1024);
        sb.append("select * from ").append(uname.trim()).append("comments");
        sql=sb.toString();
        stmt = conn.prepareStatement(sql);
       ResultSet rs = stmt.executeQuery();

        while(rs.next()){
            Commenter comment = new Commenter();
            comment.setUname(rs.getString("uname").trim());
            comment.setComment(rs.getString("comment").trim());
            commentList.add(comment);
           }                                                                        

        rs.close();                                                              
        stmt.close();                                                            
        stmt = null;                                                             


        conn.close();                                                            
        conn = null;                                                  

    }                                                              
    catch(Exception e){System.out.println( "Error --> " + displayErrorForWeb(e));}                     

    finally {                                                      

        if (stmt != null) {                                           
            try {                                                        
                stmt.close();                                               
            } catch (SQLException sqlex) {                               
                System.out.println( "Error --> " + displayErrorForWeb(sqlex));         
            }                                                            

            stmt = null;                                           
        }                                                       

        if (conn != null) {                                     
            try {                                                  
                conn.close();                                         
            } catch (SQLException sqlex) {                         
                System.out.println( "Error --> " + displayErrorForWeb(sqlex));
            }                                                      

            conn = null;                                           
        }                                                       
    }             

    return commentList;

} 

jquery是：

  $.ajax({
       type: "GET",
        url: "Comments",
        data:'comm='+encodeURIComponent(comm)+'&'+'data-id='+encodeURIComponent(dataid)+'&'+'data-alid='+encodeURIComponent(dataalid),
        dataType: "json",
        success: function( data, textStatus, jqXHR) 
        {
            if(data.success)
            {
       /*   $.each(data, function(i, item)
                     {*/

                    var newcommhtml = '<div id="c0'+thecid+'" class="cnew clearfix"> <section class="c-author">';
                    newcommhtml = newcommhtml + '<h3>Anonymous</h3>';
                    newcommhtml = newcommhtml + '<span class="pubdate">'+month+' '+day+', '+year+'</span> </section>';
                    newcommhtml = newcommhtml + '<section class="c-content">';
                    newcommhtml = newcommhtml + '<img src="images/green-avatar.png" alt="avatar" width="80" height="80" class="ava">';
                    newcommhtml = newcommhtml + '<p>'+nl2br(data.commentInfo.comment)+'   '+nl2br(data.commentInfo.itemId)+'</p> </section></div>';
                    /*newcommhtml = newcommhtml + '<p>'+nl2br(item.commentInfo.comment)+'   '+nl2br(item.commentInfo.itemId)+'</p> </section></div>';
                    });
                    */                  
                    var thelm = "#c0"+thecid;
                    commwrap.append(newcommhtml);
                    $(thelm).hide().fadeIn('slow');

                    setTimeout(function() { $(thelm).addClass('green'); }, 800);

                    $("#comm").val("");
                    thecid++;

                    if(errorspan.html() != null) {
                        errorspan.remove();
                    }
            }

          },
     error: function(jqXHR, textStatus, errorThrown)
      {
         alert("error"+errorThrown);
         console.log("Something really bad happened " + textStatus);
      },
});

如果我使用$each() success块根本不起作用。

请任何人帮助我解决这个问题....谢谢.......