我需要使用来自 MySQL GROUP BY a,b,c WITH ROLLUP 查询的 JSP 将几个表格显示为 HTML。我正在寻找一个好的标签库来实现这一点。我找到了DisplayTag，但它最后一次更新是在 2008 年。我更喜欢使用 MySQL 计算的小计，这对于 DisplayTag 来说似乎很棘手。
MySQL 按adding extra rows 对结果集进行小计，组字段设置为 NULL。
还有更好的选择吗？打印表格很重要，分页和排序会很好，但我可以没有它们。不得进行任何形式的编辑。
【问题讨论】：
我写了我自己的快速而肮脏的标签。请注意，它需要 MySQL 返回的汇总数据结构，尚未使用其他任何东西对其进行测试。
使用示例：
<xxx:rollupTable cssClass="data" data="${data}">
<xxx:rollupColumn title="Person" align="left" group="true" fieldName="personName" groupFieldName="personId" tooltipLink="person"/>
<xxx:rollupColumn title="City" align="left" group="true" fieldName="cityName" groupFieldName="cityId" tooltipLink="city"/>
<xxx:rollupColumn title="Price" align="right" format="#,##0.000" fieldName="price"/>
<xxx:rollupColumn title="Amount" align="right" format="#,##0" fieldName="amount"/>
</xxx:rollupTable>
column标签的作用不大，只是将column定义添加到table标签中以备后用。
package xxx.tags;
import...
public class RollupTableColumnTag extends SimpleTagSupport {
private String title;
private boolean group = false;
private boolean sum = false;
private String fieldName; // field name to output
private String groupFieldName; // field name to test for rollup level changes
private String align;
private String format;
private String tooltipLink;
private DecimalFormat formatter;
public void doTag() throws IOException, JspTagException {
RollupTableTag parent = (RollupTableTag)findAncestorWithClass(this, RollupTableTag.class);
if (parent == null) {
throw new JspTagException("Parent tag not found.");
}
parent.addColumnDefinition(this);
}
public void setFormat(String format) {
formatter = new DecimalFormat(format);
this.format = format;
}
public DecimalFormat getFormatter() {
return formatter;
}
// other getters and setters are standard, excluded
}
表格标签做实际的工作：
package xxx.tags;
import ...
public class RollupTableTag extends BodyTagSupport {
protected String cssClass;
protected List<Map> data;
protected List<RollupTableColumnTag> columns;
protected List<Integer> groups;
public void setCssClass(String cssClass) {
this.cssClass = cssClass;
}
public void setData(List data) {
this.data = (List<Map>)data;
}
public int doStartTag() throws JspException {
columns = new ArrayList<RollupTableColumnTag>();
groups = new ArrayList<Integer>();
return EVAL_BODY_BUFFERED;
}
public int doEndTag() throws JspException {
try {
JspWriter writer = pageContext.getOut();
if (data.size() == 0) {
writer.println("<P>No data.</P>");
return EVAL_PAGE;
}
int nLevels = groups.size();
int nNormalRowCount = 0;
boolean[] bStartGroup = new boolean[nLevels];
String[] sSummaryTitle = new String[nLevels];
for (int i=0;i<nLevels;i++) {
bStartGroup[i] = true;
}
writer.println("<TABLE class=\"" + cssClass + "\">");
writer.println("<THEAD><TR>");
for (RollupTableColumnTag column : columns) {
writer.print("<TH");
if (column.getAlign() != null) {
writer.print(" align=\"" + column.getAlign() + "\"");
}
writer.print(">" + column.getTitle() + "</TH>");
}
writer.println("</TR></THEAD>");
writer.println("<TBODY>");
for (Map dataRow : data) {
StringBuffer out = new StringBuffer();
out.append("<TR>");
// grouping columns always come first
String cellClass = null;
for (int i=0;i<nLevels-1;i++) {
if (bStartGroup[i]) {
Object dataField = dataRow.get(columns.get(groups.get(i)).getFieldName());
sSummaryTitle[i] = dataField == null ? "" : dataField.toString();
}
}
int nLevelChanges = 0;
for (int i=0;i<nLevels;i++) {
if (dataRow.get( columns.get(groups.get(i)).getGroupFieldName() ) == null) {
if (i>0) {
bStartGroup[i-1] = true;
}
nLevelChanges++;
}
}
int nTotalLevel = nLevels - nLevelChanges;
if (nLevelChanges == nLevels) { // grand total row
cellClass = "grandtotal";
addCell(out, "Grand Total:", null, cellClass, nLevelChanges);
} else if (nLevelChanges > 0) { // other total row
boolean isOneLiner = (nNormalRowCount == 1);
nNormalRowCount = 0;
if (isOneLiner) continue; // skip one-line sums
cellClass = "total"+nTotalLevel;
for (int i=0;i<nLevels-nLevelChanges-1;i++) {
addCell(out," ",null,cellClass, 1);
}
addCell(out, sSummaryTitle[nLevels-nLevelChanges-1] + " total:", null, cellClass, nLevelChanges+1);
} else { // normal row
for (int i=0;i<nLevels;i++) {
if (bStartGroup[i]) {
RollupTableColumnTag column = columns.get(groups.get(i));
Object cellData = dataRow.get(column.getFieldName());
String displayVal = cellData != null ? cellData.toString() : "[n/a]";
if (column.getTooltipLink() != null && !column.getTooltipLink().isEmpty() && cellData != null) {
String tooltip = column.getTooltipLink();
int dataid = Integer.parseInt(dataRow.get(column.getGroupFieldName()).toString());
displayVal = "<div ajaxtooltip=\"" + tooltip + "\" ajaxtooltipid=\"" + dataid + "\">" + displayVal + "</div>";
}
addCell(out, displayVal, column.getAlign(), null, 1);
} else {
addCell(out," ", null, null, 1);
}
}
for (int i=0;i<nLevels-1;i++) {
bStartGroup[i] = false;
}
nNormalRowCount++;
}
// other columns
for (RollupTableColumnTag column : columns) {
if (!column.isGroup()) {
Object content = dataRow.get(column.getFieldName());
String displayVal = "";
if (content != null) {
if (column.getFormat() != null) {
float val = Float.parseFloat(content.toString());
displayVal = column.getFormatter().format(val);
} else {
displayVal = content.toString();
}
}
addCell(out,displayVal,column.getAlign(),cellClass,1);
}
}
out.append("</TR>");
// empty row for better readability
if (groups.size() > 2 && nLevelChanges == groups.size() - 1) {
out.append("<TR><TD colspan=\"" + columns.size() + "\"> </TD>");
}
writer.println(out);
}
writer.println("</TBODY>");
writer.println("</TABLE>");
} catch (IOException e) {
e.printStackTrace();
}
return EVAL_PAGE;
}
public void addCell(StringBuffer out, String content, String align, String cssClass, int colSpan) {
out.append("<TD");
if (align != null) {
out.append(" align=\"" + align + "\"");
}
if (cssClass != null) {
out.append(" class=\"" + cssClass + "\"");
}
if (colSpan > 1) {
out.append(" colspan=\"" + colSpan + "\"");
}
out.append(">");
out.append(content);
out.append("</TD>");
}
public void addColumnDefinition(RollupTableColumnTag cd) {
columns.add(cd);
if (cd.isGroup()) groups.add(columns.size()-1);
}
}
【讨论】：