无法在JSP中打印实际值“request.getparameterValues”

时间:2013-03-18 04:58:44

标签: jsp servlets

当我通过Servlet通过以下代码调度JSP页面时:

String[] UserList = ViewAllUserBasedOnRights(UserViewBy);
request.getRequestDispatcher("/test/TestGetParameterValues.jsp?UserList="+UserList+"").forward(request, response);

JSP页面显示“ [Ljava.lang.String; @ 8b3f2a ”。

在此方法中,“ViewAllUserBasedOnRights();”值将从我的数据库中收集,它将返回NULL或一组Strings

详细说明:

public static String[] ViewAllUserBasedOnRights(String UserName) throws Exception{
                String[] retVal = null;
                Connection con=null;
                try{
                con= DatabaseConnectionManager.getDatabaseConnectionManager().getConnection(DatabaseConnectionManager.EAGRO_APP_DB);
                con.setAutoCommit(false);
                Statement stmt = (Statement) con.createStatement();
                Statement stmt1 = (Statement) con.createStatement();
                String SQLStringCount = "....";
                try(ResultSet rs = stmt.executeQuery(SQLStringCount)){
                    int count = -1;
                    while(rs.next()){
                        count = Integer.parseInt(rs.getString("COUNT"));
                    }
                    if(count > 0){
                        String SQLString =".....";

                    System.out.println("SQLString: "+SQLString);
                    try(ResultSet rs1 = stmt1.executeQuery(SQLString)){
                        ArrayList<String> stringList = new ArrayList<String>(); 
                        while(rs1.next()){
                            stringList.add(rs1.getString("USER_NAME"));
                        }
                        String[] temp = new String[stringList.size()];
                        retVal = (String[]) stringList.toArray(temp);
                        con.commit();
                        rs1.close();

                    }catch(SQLException e){
                        try{
                            if(con!=null)
                                extracted(con);
                            }catch(Exception ex){}
                        }
                }
            }catch(SQLException e){
                try{
                    if(con!=null)
                        extracted(con);
                    }catch(Exception ex){}
                }

            }catch(SQLException e){
                try{
                    if(con!=null)
                        extracted(con);
                    }catch(Exception ex){}
                }
            return retVal;
        }

我的JSP页面的代码,它非常简单,我抓住了值并打印:

<%
String[] UserList;
UserList = (String[])request.getParameterValues("UserList");
for(int i = 0; i < UserList.length; i++){
%>
<tr>
<td style="border:1px solid black;" align="center"><%=i+1%>
</td>
<td style="border:1px solid black;" align="left" ><%=UserList[i]%>
</td>
</tr>
<% } %>

3 个答案:

答案 0 :(得分:1)

不推荐在jsp中使用scriptlet。您可以使用jstl标签

<c:forEach items="UserList" var="temp">
   ${temp}
</c:forEach>

并导入<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

使用之前

答案 1 :(得分:0)

从您的代码中,我看到您在迭代ArrayList时创建ResultSet,然后创建String数组以发送值。

因为,您要将请求发送到JSP,您应该将ArrayList作为请求对象发送到JSP,然后在那里进行迭代。

ArrayList方法而不是return stringList;数组返回ViewAllUserBasedOnRights(UserViewBy)String)。

转发页面时:

List<String> userList = ViewAllUserBasedOnRights(UserViewBy);
request.setAttribute("userList", userList);
request.getRequestDispatcher("/test/TestGetParameterValues.jsp").forward(request, response);

JSP:

<%
List<String> userList;
int nSize=0;
userList = (ArrayList<String>)request.getAttribute("userList");
if(userList!=null){
nSize= userList.size();
}

for(int i = 0; i < nSize; i++){
%>
<tr>
<td style="border:1px solid black;" align="center"><%=i+1%>
</td>
<td style="border:1px solid black;" align="left" ><%=userList.get(i)%>
</td>
</tr>
<% } %>

答案 2 :(得分:0)

谢谢大家,我得到了解决方案,我已经在我的Servlet和JSP页面上编辑了

在Servlet中更改:

String[] UserList = ViewAllUserBasedOnRights(UserViewBy);
request.setAttribute("userList", UserList);
request.getRequestDispatcher("/test/TestGetParameterValues.jsp").forward(request, response);

在JSP页面中更改:

<%
String[] UserList = null;
if(request.getAttribute("UserList")!= null){
UserList = new String[((String[])request.getAttribute("UserList")).length];
UserList = ((String[])request.getAttribute("UserList"));
}
for(int i = 0; i < UserList.length; i++){
%>
<tr>
    <td style="border:1px solid black;" align="center"><%=i+1%>
    </td>
    <td style="border:1px solid black;" align="left" ><%=UserList[i]%>
    </td>
</tr>
<% } %>