定制自己的struts标签

我们知道，struts的标签都定义在*.tld标签库文件中。这样，我们就可以建一个tld文件，定义自己的个性化标签。以下以html标签为例，创建一个含有table标签的tld文件

1.mytag.tld:

<?xml version="1.0" encoding="UTF-8"?>
<taglib>
<tlibversion>1.0</tlibversion>
<jspversion>1.1</jspversion>
<tag>
<name>table</name>
<tagclass>org.apache.struts.taglib.html.Table</tagclass>
<attribute>
<name>id</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>row</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>col</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>tabindex</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>onclick</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>

 编写标签处理类Table.java:

package org.apache.struts.taglib.html;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.*;
import org.apache.struts.util.ResponseUtils;

// Referenced classes of package org.apache.struts.taglib.html:
//            BaseHandlerTag

public class Table extends BaseHandlerTag
...{

    protected String id;
    protected String text;
    protected String row;
    protected String col;

    public Table()
    ...{
        id = null;
        row = "1";
        col = "1";
    }

    public String getId()
    ...{
        return id;
    }

    public void setId(String id)
    ...{
        this.id = id;
    }

    public String getRow()
    ...{
        return row;
    }

    public void setRow(String r)
    ...{
        this.row = r;
    }
    
    public String getCol()
    ...{
        return col;
    }

    public void setCol(String c)
    ...{
        this.col = c;
    }    

    public int doStartTag()
        throws JspException
    ...{
        text = null;
        return 2;
    }

    public int doAfterBody()
        throws JspException
    ...{
        if(bodyContent != null)
        ...{
            String value = bodyContent.getString().trim();
            if(value.length() > 0)
                text = value;
        }
        return 0;
    }

    public int doEndTag()
        throws JspException
    ...{
        StringBuffer results = new StringBuffer();
        results.append("<table border="1"");
        if(id != null)
        ...{
            results.append(" id="");
            results.append(id);
            results.append(""");
        }
        if(accesskey != null)
        ...{
            results.append(" accesskey="");
            results.append(accesskey);
            results.append(""");
        }
        if(tabindex != null)
        ...{
            results.append(" tabindex="");
            results.append(tabindex);
            results.append(""");
        }
        results.append(prepareEventHandlers());
        results.append(prepareStyles());
        results.append(">");
        String[] rowdata = text.split("//n");
        String[] coldata = null;
        
            System.out.println(" text: "+text+" rowdata.length="+rowdata.length);        
        
        int r = new Integer(row).intValue();
        int c = new Integer(col).intValue();
        String v = "";
        
        for(int i=0;i<r;i++)
        ...{
            results.append("<tr>");
            v = "";
            if(i<rowdata.length && !rowdata[i].equals(""))v = rowdata[i];
            coldata = v.split("//t");
            for(int j=0;j<c;j++)
            ...{                
                results.append("<td>");
                v = "&nbsp;";
                if(j<coldata.length && !coldata[j].equals(""))v = coldata[j];
                results.append(v);                
                results.append("</td>");
            }
            results.append("</tr>");
        }
        results.append("</table>");
        ResponseUtils.write(pageContext, results.toString());
        return 6;
    }

    public void release()
    ...{
        super.release();
        id = null;
        text = null;
        row = null;
        col = null;
    }
}

在index.jsp页面中引用自定义的table标签：

<%...@page contentType="text/html;charset=UTF-8" language="java"%>
<%...@taglib uri="/WEB-INF/mytag.tld" prefix="myhtml"%>
<html>
<head><title>struts test</title></head>
<body>
   this is a table tag:
<myhtml:table id="hh" row="3" col="3">11/n21/t22</myhtml:table>
</body>
</html>

最后运行的效果