3.SpringMVC介绍

1.采用Spring MVC的好处

Dispathcher Servlet必须做如下的事情：

1.根据URI调用相应的action

2.实例化正确的控制器类

3.根据请求参数值来构造表单bean

3.调用控制器对象的相应方法

4.转向到一个视图（JSP页面）

SpringMVC提供了Dispatcher Servlet

使用基于XML的配置文件，实例化控制器

自动绑定用户输入，正确转换数据类型

可以校验用户输入，支持国际化和本地化，

支持多种视图

2.SpringMVC的DispatcherServlet

相当于调度员Servlet

配置部署：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 
        xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern> /</url-pattern>
    </servlet-mapping>
    
</web-app>

load-on-startup 如存在，在程序启动时加载，
如不存在，在一个请求时候加载

springMVC的配置文件，可以放在WEB-INF下
也可以放在任何地方，用init-param加载该文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 
        xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/config/springmvc-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>    
    </servlet>

    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>*.action</url-pattern>
    </servlet-mapping>
</web-app>

3.Controller接口(传统风格控制器，要实现Controller接口)
2.5以前开发控制的唯一方法是org.springframework.web.servlet.mvc.Controller接口
只有一个方法handleRequest，而他的实现类只能处理一个单一动作Action
 ModelAndView handleRequest(HttpServletRequest request,HttpServletResponse response) 
而基于注解的控制器可以控制多个动作，无需实现任何接口



4.SpringMVC第一个应用
1.目录结构
spring-webmvc-x.y.z.jar包括了 DispatcherServlet

2.部署描述符文件和SpringMVC配置文件

2.1 部署文件

没有init-param，所以放在WEB-INF下

<url-pattern>/</url-pattern> 将所有的URL映射到该Servlet上

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 
        xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
</web-app>

2.2 SpringMVC的配置文件

2个控制器类

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
       
    <bean name="/product_input.action" class="app03a.controller.InputProductController"/>
    <bean name="/product_save.action" class="app03a.controller.SaveProductController"/>

</beans>

3.Controller

package app03a.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

public class InputProductController implements Controller {

    private static final Log logger = LogFactory
            .getLog(InputProductController.class);

    @Override
    public ModelAndView handleRequest(HttpServletRequest request,
            HttpServletResponse response) throws Exception {
        logger.info("InputProductController called");
        return new ModelAndView("/WEB-INF/jsp/ProductForm.jsp");
    }

}

package app03a.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import app03a.domain.Product;
import app03a.form.ProductForm;

public class SaveProductController implements Controller {

    private static final Log logger = LogFactory
            .getLog(SaveProductController.class);

    @Override
    public ModelAndView handleRequest(HttpServletRequest request,
            HttpServletResponse response) throws Exception {
        logger.info("SaveProductController called");
        ProductForm productForm = new ProductForm();
        // populate action properties
        productForm.setName(request.getParameter("name"));
        productForm.setDescription(request.getParameter("description"));
        productForm.setPrice(request.getParameter("price"));

        // create model
        Product product = new Product();
        product.setName(productForm.getName());
        product.setDescription(productForm.getDescription());
        try {
            product.setPrice(Float.parseFloat(productForm.getPrice()));
        } catch (NumberFormatException e) {
        }

        // insert code to save Product

        return new ModelAndView("/WEB-INF/jsp/ProductDetails.jsp", "product",
                product);//路径，模型名称，模型
    }

}

package app03a.form;

public class ProductForm {
    private String name;
    private String description;
    private String price;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public String getPrice() {
        return price;
    }
    public void setPrice(String price) {
        this.price = price;
    }
}

package app03a.domain;
import java.io.Serializable;

public class Product implements Serializable {
    private static final long serialVersionUID = 748392348L;
    private String name;
    private String description;
    private float price;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public float getPrice() {
        return price;
    }
    public void setPrice(float price) {
        this.price = price;
    }
}

4.View

ProductForm.jsp

<!DOCTYPE HTML>
<html>
<head>
<title>Add Product Form</title>
<style type="text/css">@import url(css/main.css);</style>
</head>
<body>

<div id="global">
<form action="product_save.action" method="post">
    <fieldset>
        <legend>Add a product</legend>
            <p>
                <label for="name">Product Name: </label>
                <input type="text" id="name" name="name" 
                    tabindex="1">
            </p>
            <p>
                <label for="description">Description: </label>
                <input type="text" id="description" 
                    name="description" tabindex="2">
            </p>
            <p>
                <label for="price">Price: </label>
                <input type="text" id="price" name="price" 
                    tabindex="3">
            </p>
            <p id="buttons">
                <input id="reset" type="reset" tabindex="4">
                <input id="submit" type="submit" tabindex="5" 
                    value="Add Product">
            </p>
    </fieldset>
</form>
</div>
</body>
</html>

ProductrDetails.jsp

<!DOCTYPE HTML>
<html>
<head>
<title>Save Product</title>
<style type="text/css">@import url(css/main.css);</style>
</head>
<body>
<div id="global">
    <h4>The product has been saved.</h4>
    <p>
        <h5>Details:</h5>
        Product Name: ${product.name}<br/>
        Description: ${product.description}<br/>
        Price: $${product.price}
    </p>
</div>
</body>
</html>

5.测试应用

 http://localhost:8080/app03a/product_input.action 

5.View Resolver

View Resolver负责配置视图解析器

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <bean name="/product_input.action" class="app03b.controller.InputProductController"/>
    <bean name="/product_save.action" class="app03b.controller.SaveProductController"/>
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

视图解析器配置了前缀和后缀两个属性：

view路径可以缩短，仅需提供myPage，无需在写/WEB-INF/jsp/myPage.jsp