Spring实战学习笔记-SpringMVC

超、凢脫俗 2022-05-26 02:47 206阅读 0赞

### 使用idea搭建spring项目 ###

#### idea创建spring项目 ####

需要idea ultimate版本，使用社区版本不支持spring开发  
![这里写图片描述][70]

#### 项目支持maven ####

![这里写图片描述][70 1]

#### pom.xml常用配置 ####

1.  spring相关

<dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>4.3.8.RELEASE</version>
    </dependency>
    
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.3.8.RELEASE</version>
    </dependency>
    
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>4.3.8.RELEASE</version>
    </dependency>
    
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>4.3.8.RELEASE</version>
    </dependency>
    
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>4.3.8.RELEASE</version>
    </dependency>
    
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>4.3.8.RELEASE</version>
    </dependency>

1.  junit测试相关包

<dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    
    
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>4.3.8.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>com.github.stefanbirkner</groupId>
        <artifactId>system-rules</artifactId>
        <version>RELEASE</version>
    </dependency>

1.  web开发tablib包

<dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

1.  其它包

<dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
    </dependency>

### 基本代码解析 ###

#### AbstractAnnotationConfigDispatcherServletInitializer ####

1.  类结构图

![这里写图片描述][70 2]

1.  初始化流程

![Image 1][]

在AbstractContextLoaderInitializer.onStartup()函数中初始化createRootApplicationContext(),  
关注的getRootConfigClasses就是这步进行注册的。  
在AbstractDispatcherServletInitializer.onStartup()函数中初始化createServletApplicationContext(),  
getServletConfigClasses在这步注册上的。

### 自定义JavaConfig ###

需要继承AbstractAnnotationConfigDispatcherServletInitializer，并实现getRootConfigClasses(),  
getServletConfigClasses()和getServletMappings()三个函数

代码如下:

package spittr.config;
    
    import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
    
    /** * Created by Administrator on 2017/5/30. */
    public class SpittrWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { 
        @Override
        protected Class<?>[] getRootConfigClasses() {
            return new Class<?>[] { RootConfig.class};
        }
    
        @Override
        protected Class<?>[] getServletConfigClasses() {
            return new Class<?>[] { WebConfig.class};
        }
    
        @Override
        protected String[] getServletMappings() {
            return new String[] {
       "/"};
        }
    }

RootConfig的实现:

package spittr.config;
    
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.FilterType;
    import org.springframework.web.servlet.config.annotation.EnableWebMvc;
    
    /** * Created by Administrator on 2017/5/30. */
    @Configuration
    @ComponentScan(basePackages={
       "spittr"},
                    excludeFilters = {
            @ComponentScan.Filter(type= FilterType.ANNOTATION, value= EnableWebMvc.class)
                    })
    public class RootConfig { 
    }

WebConfig的实现:

package spittr.config;
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.web.servlet.ViewResolver;
    import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
    import org.springframework.web.servlet.config.annotation.EnableWebMvc;
    import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
    import org.springframework.web.servlet.view.InternalResourceViewResolver;
    
    /** * Created by Administrator on 2017/5/30. */
    @Configuration
    @EnableWebMvc
    @ComponentScan("spittr.web")
    public class WebConfig extends WebMvcConfigurerAdapter { 
    
        @Bean
        public ViewResolver viewResolver() {
            InternalResourceViewResolver resolver =
                    new InternalResourceViewResolver();
            resolver.setPrefix("/WEB-INF/views/");
            resolver.setSuffix(".jsp");
            resolver.setExposeContextBeansAsAttributes(true);
            return resolver;
        }
    
        public void configureDefaultServletHandler(
                DefaultServletHandlerConfigurer configurer
        ) {
            configurer.enable();
        }
    }

### 业务逻辑实现 ###

1.  Controller的实现

package spittr.web;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import static org.springframework.web.bind.annotation.RequestMethod.GET;
    
    /** * Created by Administrator on 2017/5/30. */
    @Controller
    public class HomeController { 
        @RequestMapping(value = "/", method = GET)
        public String home() {
            System.out.println("get request!!!");
            return "home";
        }
    }

1.  view的实现  
    编辑home.jsp，并存放到WEB-INF/views/home.jsp下

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
    <%@ page session="false" %>
    
    <html>
      <head>
        <title>Spittr</title>
        <link rel="stylesheet" type="text/css" href="<c:url value='/resources/style.css' />" >
      </head>
      <body>
        <h1>Welcome to Spittr</h1>
        <a href="<c:url value='/spittles' />">Spittles</a>  |
        <a href="<c:url value='/spitter/register' />">Register</a>
      </body>
    </html>

### 跟踪Spring MVC的请求 ###

1.  请求发送到DispatcherServlet
2.  DS(DispatcherServlet)发送到处理器映射  
    根据url查找Controller
3.  DS发送到控制器  
    Controller处理业务逻辑
4.  控制器经过 模型及逻辑视图名 返回到DS  
    这一步根据Controller返回值, 包括模型和视图名
5.  DS发送到视图解析器  
    根据视图名查找到对应的jsp文件
6.  DS发送到视图

[70]: /images/20220526/e384cba991c84eaf97dce078542d7028.png
[70 1]: /images/20220526/dfdd5ae6ae694ddab4cc0c61e3bf6cf3.png
[70 2]: /images/20220526/f8a9595bb45f42dfa32e303854b59307.png
[Image 1]: