Question

我的JSP中有一个依赖项下拉列表。我有一个json servlet，我填充第二个下拉列表。根据第一个下拉列表的选择将确定第二个下拉列表。我在jsonServlet类中有硬编码的值，但我希望能够从我的DAO方法调用查询。我该怎么做呢？

JsonServlet：

package master.service;

import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

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

import master.dao.MasterDataDao;
import master.dto.SiteDto;

import com.google.gson.Gson;

/**
 * Servlet implementation class JsonServlet
 * @param <E>
*/
public class JsonServlet<E> extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
 * @see HttpServlet#HttpServlet()
 */
protected void doGet(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {

    MasterDataDao masterDataDao = new MasterDataDao();
    String divisionIdName = request.getParameter("divisionIdName");
        List<String> list = new ArrayList<String>();
        List<SiteDto> site = new ArrayList<SiteDto>();
        String json = null;

        if (divisionIdName.equals("33") || divisionIdName.equals("36")) {
            try {
                site.equals(masterDataDao.getAllJJSites());
                for (Iterator<SiteDto> iter = site.iterator(); iter.hasNext(); ){
                    SiteDto element = iter.next();
                    list.addAll(-1, element);
                }
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            for (Iterator<SiteDto> iter = site.iterator(); iter.hasNext(); ){
                SiteDto element = iter.next();

            }
        } else if (divisionIdName.equals("Select Division")) {
                list.add("Select Site");

        } else {
            try {
                site.equals(masterDataDao.getAllSites());
                for (Iterator<SiteDto> iter = site.iterator(); iter.hasNext(); ){
                    SiteDto element = iter.next();
                    list.addAll(-1, element);
                }
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        json = new Gson().toJson(list);
        response.setContentType("application/json");
        response.getWriter().write(json);
}

}

基于我的JsonServlet中的divisionID选择，如果divisionID是33或36，我想在我的MasterDataDao类中调用此方法：

 public List<SiteDto> getAllJJSites() throws IOException, ClassNotFoundException, SQLException {
    List<SiteDto> siteDtoList = new ArrayList<SiteDto>();
    Connection con = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    try {
        String query = "Select Distinct Name, Id  From Addtl_Type Where Addtl_Type.is_active = '1' And Data_Field_Id = 3050 Order By Name";
        con = getConnection();
        ps = con.prepareStatement(query);
        rs = ps.executeQuery();
        // System.out.println("&*******" + rs.getFetchSize());
        while (rs.next()) {
            SiteDto siteDto = new SiteDto();
            siteDto.setId(rs.getString("Id"));
            siteDto.setName(rs.getString("Name"));
            siteDtoList.add(siteDto);
        }
    } finally {

        cleanUp(con, ps, rs);
    }
    return siteDtoList;
}

否则如果它是另一个选择值（除了Select Division），我想用MasterDataDao类调用这个方法：

 public List<SiteDto> getAllSites() throws IOException, ClassNotFoundException, SQLException {
    List<SiteDto> siteDtoList = new ArrayList<SiteDto>();
    Connection con = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    try {
        String query = "Select Distinct Name, Id  From Addtl_Type Where Addtl_Type.is_active = '1' And Data_Field_Id = 105 Order By Name";
        con = getConnection();
        ps = con.prepareStatement(query);
        rs = ps.executeQuery();
        // System.out.println("&*******" + rs.getFetchSize());
        while (rs.next()) {
            SiteDto siteDto = new SiteDto();
            siteDto.setId(rs.getString("Id"));
            siteDto.setName(rs.getString("Name"));
            siteDtoList.add(siteDto);
        }
    } finally {

        cleanUp(con, ps, rs);
    }
    return siteDtoList;
}

这可以在JsonServlet中完成吗？如果是这样的话？提前致谢。如果需要更多信息，请告诉我。

此外，我已将JSP包含在此处。最初我从这里打电话给DAO。我引用了一个bean。 JSP：

<script>
$(document).ready(function() {

    $('#divisionId').change(function(event) {
        var divisionId = $("select#divisionId").val();
        $.get('JsonServlet', {
            divisionIdName : divisionId
        }, function(response) {

            var select = $('#siteId');
            select.find('option').remove();
            $.each(response, function(index, value) {
                $('<option>').val(value).text(value).appendTo(select);
            });
        });
    });
});
</script>


 </head>
 <body>

<form name="input" action="getMasterData" method="get">



    <br /> <br />
    <h1 align='center'>Master Data File</h1>
    <br /> <br />


    <table border="0" align='center'>

        <tr>
            <td>
                <h2>Division</h2>
            </td>
            <td align='left'><jsp:useBean id="masterDaoUtil"
                    class="master.dao.util.MasterDataConstants" /> 
                    <select name="divisionId" id="divisionId">
                    <option>Select Division</option>
                    <option value="33">
 <%=MasterDataConstants.DIVISION_TYPE_AUDIT_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="31">
 <%=MasterDataConstants.DIVISION_TYPE_CHANGE_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="34">
 <%=MasterDataConstants.DIVISION_TYPE_DEA_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="35">
 <%=MasterDataConstants.DIVISION_TYPE_EHS_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="23">
 <%=MasterDataConstants.DIVISION_TYPE_EVENT_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="36">
 \
 <%=MasterDataConstants.DIVISION_TYPE_QUALITY_EVENT_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="40">
 <%=MasterDataConstants.DIVISION_TYPE_NORAMCO_AUDIT_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="43">


<%=MasterDataConstants.DIVISION_TYPE_NORAMCO_CHANGE_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="41">
 <%=MasterDataConstants.DIVISION_TYPE_NORAMCO_DEA_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="42">
 <%=MasterDataConstants.DIVISION_TYPE_NORAMCO_EHS_MANAGEMENT_GLOBAL_NAME%></option>
                    <option value="44">
 <%=MasterDataConstants.DIVISION_TYPE_NORAMCO_EVENT_MANAGEMENT_GLOBAL_NAME%></option>
            </select></td>
        </tr>
        <tr>
            <td>
                <h2>Site Name</h2>
            </td>
            <td align='left'>
 <%--               <jsp:useBean id="masterDao"
                    class="master.dao.MasterDataDao" /> 
 --%>                       
                    <select name="siteId"
                id="siteId">
                    <option>Select Site</option>
 <%--                   <option value="0">ALL</option>
                    <c:forEach items="${masterDao.allSites}" var="siteDto">
                        <option value="${siteDto.id}">${siteDto.name}
 </option>
                    </c:forEach>
 --%>                           
            </select></td>
        </tr>


    </table>
    <br /> <br />
    <div style="text-align: center">
        <input type="submit" value="Submit">
    </div>

</form>
<%
    if (request.getAttribute("message") != null) {
%>
<p>
    <font size=4 color="red"> Master_Data(timestamp).xlsx and
        Consistency_Check_Data(timestamp).xlsx are located under
        d:/stage/MasterDataReports <%--Master_Data(timestamp).xlsx and Consistency_Check_Data(timestamp).xlsx are located under /jsc/ets/u02/tools7/apache-tomcat-7.0.55/webapps/MasterData/MasterDataReport--%>
    </font>
</p>
<%
    }
%>

最初在我使用JSON和AJAX之前，我将此语句用于现已注释掉的选项。

  <%--               <jsp:useBean id="masterDao"
                class="master.dao.MasterDataDao" /> 
  --%>                       
                <select name="siteId"
            id="siteId">
                <option>Select Site</option>
  <%--                   <option value="0">ALL</option>
                <c:forEach items="${masterDao.allSites}" var="siteDto">
                    <option value="${siteDto.id}">${siteDto.name}

有没有办法可以利用这个？也许我可以从我的servlet中调用JSP函数？我知道这不是好习惯，但我想不出另一种方式。我需要获取siteDto.id值以及siteDto.name值。提前致谢

Answer 1

创建一个界面和实现DAO，例如IMasterDataDAO和MasterDataDAOImpl。

如果您将来获得更多if..else条件，请使用switch..case而不是if..else。

使用DAO中的界面为servlet创建一个对象，如下所示：

IMasterDataDAO masterDAO = new MasterDataDAOImpl()

然后根据条件调用masterDAO.getAllJSites()或masterDAO.getAllSites()。

如何从Json Servlet调用DAO方法

1 个答案: