要的人比较多，废话少说，放代码：
ValidationError.java, 主要是错误信息的一个DTO
[java]
public class ValidationError {
private String name;
private String value;
public ValidationError() {
}
public ValidationError(String name, String value) {
this.name = name;
this.value = value;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
[/java]
ValidationService.java, buffalo要使用的service, 代码不复杂，没有注释，原理见前一篇文章
[java]
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import com.opensymphony.xwork.Action;
import com.opensymphony.xwork.ActionContext;
import com.opensymphony.xwork.ActionProxy;
import com.opensymphony.xwork.DefaultActionInvocation;
import com.opensymphony.xwork.DefaultActionProxy;
import com.opensymphony.xwork.ValidationAware;
import com.opensymphony.xwork.config.entities.ActionConfig;
public class ValidationService {
public List validate(String namespace, String action, Map parameters) {
List errorList = new ArrayList();
Action requestedAction = null;
HashMap ctx = new HashMap();
ctx.put(ActionContext.PARAMETERS, parameters);
ValidatorActionProxy proxy;
try {
proxy = new ValidatorActionProxy(namespace, action, ctx);
proxy.execute();
requestedAction = proxy.getAction();
} catch (Exception e) {
e.printStackTrace();
return null;
}
if (requestedAction instanceof ValidationAware) {
ValidationAware va = (ValidationAware) requestedAction;
Map fe = va.getFieldErrors();
for (Iterator iterator = fe.entrySet().iterator(); iterator
.hasNext();) {
Map.Entry entry = (Map.Entry) iterator.next();
String name = (String) entry.getKey();
List errors = (List) entry.getValue();
for (Iterator iterator1 = errors.iterator(); iterator1
.hasNext();) {
String error = (String) iterator1.next();
errorList.add(new ValidationError(name, error));
}
}
}
return errorList;
}
public static class ValidatorActionInvocation extends
DefaultActionInvocation {
protected ValidatorActionInvocation(ActionProxy proxy, Map extraContext)
throws Exception {
super(proxy, extraContext, true);
}
protected String invokeAction(Action action, ActionConfig actionConfig)
throws Exception {
return Action.NONE; // don’t actually execute the action
}
}
public static class ValidatorActionProxy extends DefaultActionProxy {
protected ValidatorActionProxy(String namespace,
String actionName,
Map extraContext) throws Exception {
super(namespace, actionName, extraContext, false);
}
protected void prepare() throws Exception {
invocation = new ValidatorActionInvocation(this, extraContext);
}
}
}
[/java]
buffalo-service.properties
[txt]
validationService=your.package.ValidationService
[/txt]
更改webwork模板中的simple/form.vm:
[html]
[/html]
最后，加入一个validate.js。用的是buffalo 1.1版本（写的时候的版本）。
[javascript]
var currentForm = null;
var getContextPath = function() {
var ctxPath = "";
$A(document.getElementsByTagName("script")).findAll( function(s) {
return (s.src && s.src.match(/buffalo\.js(\?.*)?$/))
}).each( function(s) {
var path = s.src.replace(/script\/buffalo\.js(\?.*)?$/,'');
ctxPath = path;
});
return ctxPath;
}
function validate(theForm) {
var buffaloURL = getContextPath()+"BUFFALO";
var buffalo = new Buffalo(buffaloURL);
buffalo.events["onLoading"] = function() {}
var parameters = {};
for (var i = 0; i < theForm.elements.length; i++) {
var e = theForm.elements[i];
parameters[e.name] = e.value;
}
currentForm = theForm;
var actionName = theForm.name;
if (actionName.indexOf("do") != 0) {
actionName = "do"+actionName.charAt(0).toUpperCase() + actionName.substring(1);
}
Form.disable(theForm.id);
buffalo.remoteCall("validationService.validate",
[theForm.getAttribute("namespace"), actionName, parameters], callback) ;
return false;
}
function callback(reply) {
Form.enable(currentForm.id);
var insideTable = currentForm.getElementsByTagName("TABLE")[0];
clearErrorRows(insideTable);
clearErrorLabels(currentForm);
var errors = reply.getResult();
if (errors == null) {alert(null); return; }
if (errors.length > 0) {
for (var i = 0; i < errors.length; i++) {
var error = errors[i];
var element = currentForm.elements[error.name];
addError(element, error.value);
}
} else {
currentForm.submit();
Form.disable(currentForm.id);
}
}
function clearErrorRows(table) {
// clear out any rows with an "errorFor" attribute
var rows = table.rows;
var rowsToDelete = new Array();
for(var i = 0; i < rows.length; i++) {
var r = rows[i];
if (r.getAttribute("errorFor")) {
rowsToDelete.push(r);
}
}
// now delete the rows
for (var i = 0; i < rowsToDelete.length; i++) {
var r = rowsToDelete[i];
table.deleteRow(r.rowIndex);
}
}
function clearErrorLabels(form) {
// set all labels back to the normal class
var elements = form.elements;
for (var i = 0; i < elements.length; i++) {
var e = elements[i];
var cells = e.parentNode.parentNode.cells;
if (cells && cells.length >= 2) {
var label = cells[0].getElementsByTagName(“label”)[0];
if (label) {
label.setAttribute(“class”, “label”);
}
}
}
}
function addError(e, errorText) {
try {
var row = e.parentNode.parentNode;
var table = row.parentNode;
var error = document.createTextNode(errorText);
var tr = document.createElement(“tr”);
var td = document.createElement(“td”);
var span = document.createElement(“span”);
td.align = “center”;
td.valign = “top”;
td.colSpan = 2;
span.className=”errorMessage”;
span.appendChild(error);
td.appendChild(span);
tr.appendChild(td);
tr.setAttribute(“errorFor”, e.id);;
table.insertBefore(tr, row);
var label = row.cells[0].getElementsByTagName(“label”)[0];
label.setAttribute(“class”, “errorLabel”);
} catch (e) {
alert(e);
}
}
[/javascript]
调用流程：实际上表单提交前buffalo将整个表单送到了后台并利用ValidationService执行了一次action，看有没有错误，如果没有错误才真正提交，否则通过js对页面进行相应的提示。
注意事项：1, 一些拦截器需要ActionContext中含有servlet等信息，由于ValidationService不带有这些信息，因此这些拦截器可能会在校验的时候报错；2, webwork的某些校验器的错误提示信息有些并不返回，因此不是所有的校验错误都能返回，但绝大多数都能满足了；3, 不要期待你写的actionError信息也能通过这种方式返回——当然你可以自己写，但在这个实现中，只能返回校验错误信息.