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Model接口

源码

/*
 * Copyright 2002-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.ui;

import java.util.Collection;
import java.util.Map;

import org.springframework.lang.Nullable;

/**
 * Java-5-specific interface that defines a holder for model attributes.
 * Primarily designed for adding attributes to the model.
 * Allows for accessing the overall model as a {@code java.util.Map}.
 *
 * @author Juergen Hoeller
 * @since 2.5.1
 */
public interface Model {

	/**
	 * Add the supplied attribute under the supplied name.
	 * @param attributeName the name of the model attribute (never {@code null})
	 * @param attributeValue the model attribute value (can be {@code null})
	 */
	Model addAttribute(String attributeName, @Nullable Object attributeValue);

	/**
	 * Add the supplied attribute to this {@code Map} using a
	 * {@link org.springframework.core.Conventions#getVariableName generated name}.
	 * <p><i>Note: Empty {@link java.util.Collection Collections} are not added to
	 * the model when using this method because we cannot correctly determine
	 * the true convention name. View code should check for {@code null} rather
	 * than for empty collections as is already done by JSTL tags.</i>
	 * @param attributeValue the model attribute value (never {@code null})
	 */
	Model addAttribute(Object attributeValue);

	/**
	 * Copy all attributes in the supplied {@code Collection} into this
	 * {@code Map}, using attribute name generation for each element.
	 * @see #addAttribute(Object)
	 */
	Model addAllAttributes(Collection<?> attributeValues);

	/**
	 * Copy all attributes in the supplied {@code Map} into this {@code Map}.
	 * @see #addAttribute(String, Object)
	 */
	Model addAllAttributes(Map<String, ?> attributes);

	/**
	 * Copy all attributes in the supplied {@code Map} into this {@code Map},
	 * with existing objects of the same name taking precedence (i.e. not getting
	 * replaced).
	 */
	Model mergeAttributes(Map<String, ?> attributes);

	/**
	 * Does this model contain an attribute of the given name?
	 * @param attributeName the name of the model attribute (never {@code null})
	 * @return whether this model contains a corresponding attribute
	 */
	boolean containsAttribute(String attributeName);

	/**
	 * Return the attribute value for the given name, if any.
	 * @param attributeName the name of the model attribute (never {@code null})
	 * @return the corresponding attribute value, or {@code null} if none
	 * @since 5.2
	 */
	@Nullable
	Object getAttribute(String attributeName);

	/**
	 * Return the current set of model attributes as a Map.
	 */
	Map<String, Object> asMap();

}

讲解

包

package org.springframework.ui;

可以看到model接口是属于springframework.ui下的

解释

是Java-5特定接口，主要用于向模型添加属性，允许以java.util.Map访问整个模型

简而言之（用途）：

从控制层直接返回前端所需的数据

addAttribute方法

在提供的名称下添加提供的属性

Model addAttribute(String attributeName, @Nullable Object attributeValue);

参数

attributeName ：属性名（固定参数不能为空） attributeValue ：属性值 (可以为空)

使用

这个方法是很常用到的 我们可以在Controller中使用他给前端传递处理数据 案例1看最后两点实例的地方 案例2

对应

我个人觉得这个还是很明显的，首先是前端向控制层请求找到对应的属性名后再去查找对应的属性值最后返回前端向用户呈现数据（属性值）