springboot学习9

springwebmvc简化之springboot ：
1.1、完全自动装配

	spirngwebmvc	springbooot
自动装配	DispatcherServlet	DispatcherServletAutoConfiguration
替换	@EnableWebMvc	WebMvcAutoConfiguration
Servlet 容器	:	ServletWebServerFactoryAutoConfiguration

1.1.2、自动配置顺序性：

绝对顺序	@AutoConfigureOrder
相对顺序	@AutoConfigureAfter

1.2、装配条件
1）Web 类型判断( ConditionalOnWebApplication )

	WebApplicationType
SERVLET 类型	WebApplicationType.SERVLET

2）API 判断( @ConditionalOnClass )

Servlet
Servlet

Spring Web MVC
DispatcherServlet
WebMvcConfigurer

如：

package org.springframework.boot.autoconfigure.web.servlet;

@ConditionalOnClass({
    
     Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
// ... 省略
public class WebMvcAutoConfiguration {
    
    
// ... 省略
}

3）Bean 判断()

当Bean不存在时	当Bean存在时
@ConditionalOnMissingBean	@ConditionalOnBean

如：
当不存在WebMvcConfigurationSupport这个Bean时，才装配WebMvcAutoConfiguration这个类。

package org.springframework.boot.autoconfigure.web.servlet;

@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
// ... 省略
public class WebMvcAutoConfiguration {
    
    
// ... 省略
}

1.3、外部化配置
1）Web MVC 配置
WebMvcProperties
2）资源配置
ResourceProperties

Spring Boot JSP 依赖：

 <!-- Provided -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-jasper</artifactId>
    <scope>provided</scope>
</dependency>

Demo：

springboot-webmvc
    ├── pom.xml
    └── src
        └── main
            ├── java
	        └── com
	        │    └── example
			│	        └── web
			│               ├── HomeController.java
			│               ├── boostrap
			│               │   └── SpringBootWebMvcBootstrap.java
			│	            └── config
			│                    └── WebMvcConfig.java
			│                
		    ├── resources
	        │   └── application.properties
		    └── webapp
		        └── WEB-INF
		            └── jsp
			              └── index.jsp

SpringBootWebMvcBootstrap：

package com.example.web.boostrap;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 *  SpringBootWebMvc 引导类
 */
@SpringBootApplication(scanBasePackages = "com.example.web")
public class SpringBootWebMvcBootstrap {
    
    

    public static void main(String[] args) {
    
    
        SpringApplication.run(SpringBootWebMvcBootstrap.class, args);
    }
}

WebMvcConfig:

package com.example.web.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

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

/**
 * Spring web mvc 配置类
 */
@Configuration
//@EnableWebMvc
public class WebMvcConfig implements WebMvcConfigurer {
    
    

//    @Bean
//    public ViewResolver viewResolver() {
    
    
//        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
//        viewResolver.setPrefix("/WEB-INF/jsp/");
//        viewResolver.setSuffix(".jsp");
//        viewResolver.setViewClass(JstlView.class);
//        return viewResolver;
//    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
    
    
         registry.addInterceptor(new HandlerInterceptor() {
    
    
             @Override
             public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
    
                 System.out.println("拦截中。。。");
                 return true;
             }
         });
    }
}

application.properties：

spring.mvc.view.prefix = /WEB-INF/jsp/
spring.mvc.view.suffix = .jsp

HomeController：

package com.example.web;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * Home {@link Controller}
 *
 */
@Controller
public class HomeController {

    @RequestMapping("")
    public String index() {
        return "index";
    }
}

pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springbootlearn</artifactId>
        <groupId>com.example</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>springboot-webmvc</artifactId>
    <packaging>war</packaging>

  	<properties>
        <java.version>1.8</java.version>
        <docker.image.prefix>springboot</docker.image.prefix>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
	<!-- 依赖-->
    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

        <!-- Provided -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

打包运行：

mvn -Dmaven.test.skip -U clean package

java -jar target/springboot-webmvc-0.0.1-SNAPSHOT.war

在浏览器输入localhost:8080即可。