Question

enter image description here 当我尝试从HashMap检索值时，我使用getValue方法。但getValue方法在Struts2的迭代标记内，因此它甚至显示不需要的值。我怎么能避免这个？在我的JSP页面中，我正在创建表，我想在orderdate标签内的数据库中设置<th>。我的意思是HashMap我收到orderdate，结果，dataamount，计数。在<th>我希望orderdate能够坐下来<tr>我希望剩余的三个值可以去坐下。我怎么做？

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class JanuaryAction {
    private String from; // creating variables to access input values.
    private String to; // creating variables to access input values.
    Map abc1 = new HashMap(); // Getting the map objects to store tha values

    public Map getAbc1() { /* Creating the setters and getters */
        return abc1;
    }

    public void setAbc1(Map abc1) {
        this.abc1 = abc1;
    }

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }

    public String getTo() {
        return to;
    }

    public void setTo(String to) {
        this.to = to;
    }

    public Map<String, String> getAbc() {
        return abc;
    }

    public void setAbc(Map<String, String> abc) {
        this.abc = abc;
    }

    Map<String, String> abc = new HashMap<String, String>();

    Map<String, List<ReportClass>> map = new HashMap<String, List<ReportClass>>(); // Using
                                                                                    // Map
                                                                                    // interface
                                                                                    // implementing
                                                                                    // hashmap

    public Map<String, List<ReportClass>> getMap() {
        return map;
    }

    public void setMap(Map<String, List<ReportClass>> map) {
        this.map = map;
    }

    public String execute() throws Exception {

        String fromdate = getFrom();
        System.out.println(fromdate);
        String todate = getTo();
        System.out.println(todate);

        Connection con = GetCon.getCon();
        Statement statement = con.createStatement();

        ResultSet resultset = statement
                .executeQuery("SELECT MarketPlace,OrderDate, ROUND(SUM(Total),2), COUNT(*) , ROUND(ROUND(SUM(Total),2)/ COUNT(*),2) FROM vend_printed WHERE OrderDate >='"
                        + fromdate + "' AND OrderDate <='" + todate + "' GROUP BY OrderDate,MarketPlace");

        while (resultset.next()) {
            String marketplace = resultset.getString(1);// get the first column
                                                        // in marketplace
            String orderdate = resultset.getString(2);// get the second column
                                                        // in orderdate
            Double datamount = resultset.getDouble(3);// get the third column in
                                                        // datamount
            Integer count = resultset.getInt(4);// get the fourth column in
                                                // count
            Double result = resultset.getDouble(5); // get the fifth column in
                                                    // result
            ReportClass a = new ReportClass(); // create an object to access
                                                // pojo class.

            a.setMarketplace(marketplace); // setting the values in pojo class
            a.setOrderdate(orderdate);
            a.setDataamount(datamount);
            a.setCount(count);
            a.setResult(result);

            if (map.get(marketplace) != null) { // if the value in marketplace
                                                // is null then go to else
                                                // statement or go to if
                                                // statement.
                map.get(marketplace).add(a); // using the key add one complete
                                                // row values from a to
                                                // marketplace
            } else {
                List<ReportClass> optionsVO = new ArrayList<ReportClass>(); // create
                                                                            // a
                                                                            // list
                                                                            // optionsVo
                optionsVO.add(a); // store Reportclass values in List.
                map.put(marketplace, optionsVO); // storing it in map.
                /* System.out.println(map.get(marketplace).toString()); */
            }

        }
        Set s = map.entrySet(); // A map entry (key-value pair).creating Set
                                // interface.
        Iterator i = s.iterator();
        while (i.hasNext()) {

            List<ReportClass> tempList = (List<ReportClass>) ((Entry) i.next()).getValue(); // creating
                                                                                            // a
                                                                                            // temporary
                                                                                            // list

            for (ReportClass reportClassObj : tempList) {
                System.out.println(reportClassObj.getMarketplace());// display
                                                                    // values.
                System.out.println(reportClassObj.getDataamount());
                System.out.println(reportClassObj.getOrderdate());
                System.out.println(reportClassObj.getCount());
                System.out.println(reportClassObj.getResult());
            }
        }

        /* System.out.println(map.size()); */
        return "success";
    }
}

在我的jsp中我有一个代码。

<s:iterator var="studentEntry" status="stat" value="map.entrySet()">  
Key: <s:property value="%{#studentEntry.getKey()}"/> 
Value: <s:property value="%{#studentEntry.getValue()}"/><br>  

</s:iterator>

Answer 1

是否对条目进行分组，您必须先对组进行迭代，然后按组进行其他条目获取所有值或选择要迭代的组。

<s:iterator value="map">  
 <s:iterator var="studentEntry" value="value">
  ReportClass: <s:property value="%{#studentEntry.toString()}"/><br> 
 </s:iterator>
</s:iterator>

Answer 2

实际上您不需要使用entrySet只使用map变量作为value标记的<s:iterator>属性和value关键字作为第二个迭代器的值。然后，您可以在ReportClass标记中直接引用迭代器内<s:property>的属性。

<s:iterator value="map">  
  <s:iterator value="value">
    <table>        
      <tr><th colspan="3"><s:property value="orderdate"/></th></tr>
      <tr>
        <td><s:property value="dataamount"/></td>
        <td><s:property value="count"/></td>
        <td><s:property value="result"/></td>
      </tr>
    </table>
  </s:iterator>
</s:iterator>

Answer 3

尝试以下代码，它必须有效。

<s:iterator value="map"> 
<s:iterator value="key">
<s:iterator value="value">
<th><s:property value="orderdate"/></th>
<td rowspan="4"><s:property value="marketplace"/></td>
<tr> <td><s:property value="dataamount"/></td></tr>
<tr><td><s:property value="count"/></td></tr>
<tr><td><s:property value="result"/></td></tr>
</s:iterator>
</s:iterator>
</s:iterator>

有没有办法从hashmap中获取单个值。？

3 个答案: