001/* 002 * Copyright 2002-2018 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.web.servlet.tags.form; 018 019import javax.servlet.jsp.JspException; 020 021import org.springframework.lang.Nullable; 022 023/** 024 * Abstract base class to provide common methods for 025 * implementing databinding-aware JSP tags for rendering an HTML '{@code input}' 026 * element with a '{@code type}' of '{@code checkbox}' or '{@code radio}'. 027 * 028 * @author Thomas Risberg 029 * @author Juergen Hoeller 030 * @author Rossen Stoyanchev 031 * @since 2.5 032 */ 033@SuppressWarnings("serial") 034public abstract class AbstractCheckedElementTag extends AbstractHtmlInputElementTag { 035 036 /** 037 * Render the '{@code input(checkbox)}' with the supplied value, marking the 038 * '{@code input}' element as 'checked' if the supplied value matches the 039 * bound value. 040 */ 041 protected void renderFromValue(@Nullable Object value, TagWriter tagWriter) throws JspException { 042 renderFromValue(value, value, tagWriter); 043 } 044 045 /** 046 * Render the '{@code input(checkbox)}' with the supplied value, marking the 047 * '{@code input}' element as 'checked' if the supplied value matches the 048 * bound value. 049 */ 050 protected void renderFromValue(@Nullable Object item, @Nullable Object value, TagWriter tagWriter) 051 throws JspException { 052 053 String displayValue = convertToDisplayString(value); 054 tagWriter.writeAttribute("value", processFieldValue(getName(), displayValue, getInputType())); 055 if (isOptionSelected(value) || (value != item && isOptionSelected(item))) { 056 tagWriter.writeAttribute("checked", "checked"); 057 } 058 } 059 060 /** 061 * Determines whether the supplied value matched the selected value 062 * through delegating to {@link SelectedValueComparator#isSelected}. 063 */ 064 private boolean isOptionSelected(@Nullable Object value) throws JspException { 065 return SelectedValueComparator.isSelected(getBindStatus(), value); 066 } 067 068 /** 069 * Render the '{@code input(checkbox)}' with the supplied value, marking 070 * the '{@code input}' element as 'checked' if the supplied Boolean is 071 * {@code true}. 072 */ 073 protected void renderFromBoolean(Boolean boundValue, TagWriter tagWriter) throws JspException { 074 tagWriter.writeAttribute("value", processFieldValue(getName(), "true", getInputType())); 075 if (boundValue) { 076 tagWriter.writeAttribute("checked", "checked"); 077 } 078 } 079 080 /** 081 * Return a unique ID for the bound name within the current PageContext. 082 */ 083 @Override 084 @Nullable 085 protected String autogenerateId() throws JspException { 086 String id = super.autogenerateId(); 087 return (id != null ? TagIdGenerator.nextId(id, this.pageContext) : null); 088 } 089 090 091 /** 092 * Writes the '{@code input}' element to the supplied 093 * {@link TagWriter}, 094 * marking it as 'checked' if appropriate. 095 */ 096 @Override 097 protected abstract int writeTagContent(TagWriter tagWriter) throws JspException; 098 099 /** 100 * Flags "type" as an illegal dynamic attribute. 101 */ 102 @Override 103 protected boolean isValidDynamicAttribute(String localName, Object value) { 104 return !"type".equals(localName); 105 } 106 107 /** 108 * Return the type of the HTML input element to generate: 109 * "checkbox" or "radio". 110 */ 111 protected abstract String getInputType(); 112 113}