写了这么长时间的web应用了，对流行的web框架中的tag也算是精通了，不过唯一能让我在所有项目中都毫不犹豫的使用的也就是jstl了。
一般对于没有美工人员介入的项目，当选定web框架后，我会使用此web框架的html标签库，但是一旦有美工人员参与，我一般都放弃使用这些框架中的html标签库，就拿strurs和webwork来说吧，我宁愿把表单域写成这样：<input type="text" name="username" value="<c:out value="$" /> >，也不愿意用<html:text property="username" />或者<ww:textfield name="username" />。尽管后者看起来很清爽，但是这对于一个和美工合作的项目来说，对自己简直是一种折磨。
毕竟美工不会去学习这么多的标记，他们只知道原生的html，因此，我个人认为只要有美工参与，最好少用框架的html标签库，尽量不要过多的侵入原生的html。
记得以前写过一个基于webwork的formtag，为的就是减少对html的侵入，但是总感觉那个扩展性教差，所以一直也没在用了，现在又碰到了类似的问题，所以决定写一个FieldBindTag，但不知道这个Tag到底有没有什么价值？
以下为这个tag的代码，文章后有sample下载，希望大家能给出意见。
package net.libo.web.taglib;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Collection;
import java.util.Iterator;
import javax.servlet.
JSP.
JSPException;
import javax.servlet.
JSP.
JSPWriter;
import javax.servlet.
JSP.tagext.BodyContent;
import javax.servlet.
JSP.tagext.BodyTagSupport;
import org.apache.commons.beanutils.PropertyUtils;
import net.libo.web.util.HtmlEncoder;import net.libo.web.util.HtmlUtils;
/** * @author Boyce * */public class FieldBindTag extends BodyTagSupport
{ private Object[] beans = null;
private String beanNames = null;
/**
* Sets bean names with value of the "bean" attribute.
* * @param v bean names
*/ public void setBeans(String v) {
beanNames = v;
}
/**
* Gets bean names.
*
* @return bean names
*/
public String getBeans() {
return beanNames;
}
public int doStartTag() {
String[] b = beanNames.split(",");
ArrayList beanList = new ArrayList();
for (int i=0;i<b.length;i++) {
String name = b[i].trim();
if (name.length() > 0) {
Object bean = pageContext.findAttribute(name);
if (bean != null)beanList.add(bean);
}
}
beans = beanList.toArray();
return EVAL_BODY_AGAIN;
}
/**
* Performs smart form population.
* * @return SKIP_BODY
*/
public int doAfterBody() {
BodyContent body = getBodyContent();
try {
JSPWriter out = body.getEnclosingWriter();
String bodytext = body.getString();
bodytext = populateForm(bodytext);
out.print(bodytext);
} catch (Exception ex)
return SKIP_BODY;
}
/**
* End of tag.
*
* @return EVAL_PAGE
* @throws
JSPException
*/ public int doEndTag() throws
JSPException {
beans = null;
return EVAL_PAGE; }
// ---------------------------------------------------------------- populate
private String populateForm(String html) throws Exception {
int i = 0, s = 0;
StringBuffer result = new StringBuffer(html.length());
String currentSelectName = null;
while (true) {
// find starting tag
i = html.indexOf('<', s);
if (i == -1) {
result.append(html.substring(s));
break;
// input tag not found
}
result.append(html.substring(s, i));
// tag found, all before tag is stored
s = i;
// find closing tag
i =
html.indexOf('>', i);
if (i == -1) {
result.append(html.substring(s));
break;
// closing tag not found
}
i++;
// match tags
String tag = html.substring(s, i);
//System.out.println(tag);
String tagName = HtmlUtils.getTagName(tag);
if (tagName.equalsIgnoreCase("input") == true) {
String tagType = HtmlUtils.getAttribute(tag, "type");
if (tagType != null) {
String name = HtmlUtils.getAttribute(tag, "name");
HashMap params = new HashMap();
params.put("name", name);
Object vobj = findValue(name);
if (vobj != null) {
String value = vobj.toString();
tagType = tagType.toLowerCase();
if (tagType.equals("text")) {
tag = HtmlUtils.addAttribute(tag, "value", value);
} if (tagType.equals("hidden")) {
tag = HtmlUtils.addAttribute(tag, "value", value);
} if (tagType.equals("image")) {
tag = HtmlUtils.addAttribute(tag, "value", value);
} if (tagType.equals("password")) {
tag = HtmlUtils.addAttribute(tag, "value", value);
} if (tagType.equals("checkbox")) {
String tagValue = HtmlUtils.getAttribute(tag, "value");
if (tagValue == null) {
tagValue = "true";
}
if (tagValue.equals(value)) {
tag = HtmlUtils.addAttribute(tag, "checked");
}
} if (tagType.equals("radio")) {
String tagValue = HtmlUtils.getAttribute(tag, "value");
if (tagValue != null) {
if (tagValue.equals(value)) {
tag = HtmlUtils.addAttribute(tag, "checked");
}
}
}
} }
} else if (tagName.equalsIgnoreCase("textarea") == true) {
String name = HtmlUtils.getAttribute(tag, "name");
Object value = findValue(name);
if (value != null) {
if (value != null) {
tag += HtmlEncoder.encode(value.toString());
} }
} else if (tagName.equalsIgnoreCase("select") == true) {
currentSelectName = HtmlUtils.getAttribute(tag, "name");
} else if (tagName.equalsIgnoreCase("/select") == true) {
currentSelectName = null;
} else if (tagName.equalsIgnoreCase("option") == true) {
if (currentSelectName != null) {
String tagValue = HtmlUtils.getAttribute(tag, "value");
if (tagValue != null) {
Object vals = findValue(currentSelectName);
if (vals != null) {
if (vals.getClass().isArray()) {
Object[] arr = (Object[])vals;
if (arr.length > 0) {
String[] vs = new String[arr.length];
for (int j=0;j<arr.length;j++) {
vs[j] = arr[j].toString();
}
for (int k = 0; k < vs.length; k++) {
String vsk = vs[k];
if (vsk != null) {
if (vsk.equals(tagValue)) {
tag = HtmlUtils.addAttribute(tag, "selected");
}
}
}
}
} else if (vals instanceof Collection) {
Collection arr = (Collection)vals;
int arrsize = arr.size();
if (arrsize > 0) {
String[] vs = new String[arrsize];
int j=0;
for (Iterator it=arr.iterator();it.hasNext();) {
vs[j++] = it.next().toString();
}
for (int k = 0; k < vs.length; k++) {
String vsk = vs[k];
if (vsk != null) {
if (vsk.equals(tagValue)) {
tag = HtmlUtils.addAttribute(tag, "selected");
}
}
}
}
} else {
String value = vals.toString();
if (value.equals(tagValue)) {
tag = HtmlUtils.addAttribute(tag, "selected");
}
}
}
}
}
}
result.append(tag);
s = i;
}
return result.toString();
}
protected Object findValue(String name) {
Object value = null;
for (int i=0;i<beans.length;i++) {
if (beans[i] != null) {
try {
value = PropertyUtils.getProperty(beans[i], name);
} catch (Exception e)
if (value != null) break;
}
}
return value;
}}
