JSF入门实例-用户登录

package bps.com.cn.tag; import java.io.IOException; import java.util.Map; import javax.faces.component.UIInput; import javax.faces.context.FacesContext; import javax.faces.context.ResponseWriter; import javax.faces.convert.IntegerConverter; public class UISpinner extends UIInput { private static final String MORE = ".more"; private static final String LESS = ".less"; public UISpinner() { setConverter(new IntegerConverter()); setRendererType(null); } public void encodeBegin(FacesContext context) throws IOException { ResponseWriter writer = context.getResponseWriter(); String clientId = getClientId(context); encodeInputField(writer, clientId); encodeDecrementButton(writer, clientId); encodeIncrementButton(writer, clientId); } public void decode(FacesContext context) { Map requestMap = context.getExternalContext().getRequestParameterMap(); String clientId = getClientId(context); int increment; if (requestMap.containsKey(clientId + MORE)) increment = 1; else if(requestMap.containsKey(clientId + LESS)) increment = -1; else increment = 0; try { int submittedValue = Integer.parseInt((String) requestMap.get(clientId)); int newValue = getIncrementedValue(submittedValue, increment); setSubmittedValue("" + newValue); setValid(true); } catch(NumberFormatException ex) { setSubmittedValue((String) requestMap.get(clientId)); } } private void encodeInputField(ResponseWriter writer, String clientId) throws IOException { writer.startElement("input", this); writer.writeAttribute("name", clientId, "clientId"); Object v = getValue(); if (v != null) writer.writeAttribute("value", v.toString(), "value"); Integer size = (Integer)getAttributes().get("size"); if(size != null) writer.writeAttribute("size", size, "size"); writer.endElement("input"); } private void encodeDecrementButton(ResponseWriter writer, String clientId) throws IOException { writer.startElement("input", this); writer.writeAttribute("type", "submit", null); writer.writeAttribute("name", clientId + LESS, null); writer.writeAttribute("value", "<", "value"); writer.endElement("input"); } private void encodeIncrementButton(ResponseWriter writer, String clientId) throws IOException { writer.startElement("input", this); writer.writeAttribute("type", "submit", null); writer.writeAttribute("name", clientId + MORE, null); writer.writeAttribute("value", ">", "value"); writer.endElement("input"); } private int getIncrementedValue(int submittedValue, int increment){ Integer minimum = (Integer) getAttributes().get("minimum"); Integer maximum = (Integer) getAttributes().get("maximum"); int newValue = submittedValue + increment; if ((minimum == null || newValue >= minimum.intValue()) && (maximum == null || newValue <= maximum.intValue())) return newValue; else return submittedValue; } }