ModelMap的作用

来源：互联网发布：python spawn 编辑：程序博客网时间：2024/06/06 10:04

最近在用ssm框架开发项目，之前都是二次开发，现在是从头开发，都有点不适应了，遇到了很多前端后台的问题。

说说ModelMap的作用

package org.springframework.ui;import java.util.Collection;import java.util.LinkedHashMap;import java.util.Map;import org.springframework.core.Conventions;import org.springframework.util.Assert;@SuppressWarnings("serial")public class ModelMap extends LinkedHashMap<String, Object> {public ModelMap() {}public ModelMap(String attributeName, Object attributeValue) {addAttribute(attributeName, attributeValue);}public ModelMap(Object attributeValue) {addAttribute(attributeValue);}public ModelMap addAttribute(String attributeName, Object attributeValue) {Assert.notNull(attributeName, "Model attribute name must not be null");put(attributeName, attributeValue);return this;}public ModelMap addAttribute(Object attributeValue) {Assert.notNull(attributeValue, "Model object must not be null");if (attributeValue instanceof Collection && ((Collection<?>) attributeValue).isEmpty()) {return this;}return addAttribute(Conventions.getVariableName(attributeValue), attributeValue);}public ModelMap addAllAttributes(Collection<?> attributeValues) {if (attributeValues != null) {for (Object attributeValue : attributeValues) {addAttribute(attributeValue);}}return this;}public ModelMap addAllAttributes(Map<String, ?> attributes) {if (attributes != null) {putAll(attributes);}return this;}public ModelMap mergeAttributes(Map<String, ?> attributes) {if (attributes != null) {for (Map.Entry<String, ?> entry : attributes.entrySet()) {String key = entry.getKey();if (!containsKey(key)) {put(key, entry.getValue());}}}return this;}public boolean containsAttribute(String attributeName) {return containsKey(attributeName);}}

代码里面有个方法：addAttribute和addAttributeAll

这个方法其实就是我们经常用的，在代码里面一般是这样体现的：

map.put("smallGoods", smallGoods);

就是把后台查询出来的集合、字符串（一般是错误信息）、对象等传到前台，当然，这个值不能是空的

前台接收参数时：两个问号是判断这个对象或者集合是否为空

<#if smallGoods??><#list smallGoods as specialControl><option id="${specialControl.goodstypeid}" name="tempgoodstypeid" value="${specialControl.goodstypeid}">${specialControl.goodsdesc}</option></#list><#else></#if>

阅读全文

1 0