参考资料

https://www.bilibili.com/video/BV1Fi4y1S7ix?p=43&vd_source=c581024b8cd9585ec6a75c56ac05571a

1. SpringMVC 简介

• SpringMVC技术与Servlet技术功能等同，均属于web层开发技术。

• SpringMVC 是一种基于Java实现MVC模型的轻量级Web框架。

• SpringMVC 是一种表现层框架技术。

• 优点：使用简单，开发便捷，灵活性强。

2. SpringMVC 入门案例

1. 导入SpringMVC依赖和Servlet依赖

<dependencies>
    
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-webmvcartifactId>
        <version>5.3.21version>
    dependency>
    
    <dependency>
        <groupId>javax.servletgroupId>
        <artifactId>javax.servlet-apiartifactId>
        <version>4.0.1version>
        <scope>providedscope>
    dependency>
    dependencies>
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2. 创建SpringMVC控制器类（相当于Servlet类）

@RestController
//@RestController = @ResponseBody + @Controller
//@Controller 将类注册到Spring容器
//@ResponseBody 将方法返回值作为响应体,不加则是跳转的页面
public class UserController {

    @RequestMapping("/save") //设置请求路径
    public String save() {
        return "save";
    }
}
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3. 创建SpringMVC的配置类，设置ComponentScan路径

@Configuration
@ComponentScan({"com.xin.web"})
public class SpringMVCConfig {
    public static void main(String[] args) {
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
    }
}
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4. 初始化Servle容器，加载SpringMVC环境配置，并设置SpringMVC处理的请求路径

public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {
	//加载Spring Web容器配置
    @Override
    protected WebApplicationContext createServletApplicationContext() {
    	//创建一个Spring Web容器
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        //加载配置
        context.register(SpringMVCConfig.class);
        return context;
    }

    @Override
    protected String[] getServletMappings() {
    	//设置交给SpringMVC处理的请求路径。"/"所有请求
        return new String[]{"/"};
    }
	
	//加载Spring容器配置。
    @Override
    protected WebApplicationContext createRootApplicationContext() {
        return null;
    }
}
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5. 部署到tomcat ，访问路径 localhost/save
   

3. 初始化Servle容器，加载SpringMVC容器配置，并设置SpringMVC处理的请求路径

方式一 继承AbstractDispatcherServletInitializer

public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {

    @Override
    protected WebApplicationContext createServletApplicationContext() {
        //创建SpringMVC容器
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        //加载配置
        context.register(SpringMVCConfig.class);
        return context;
    }

    @Override
    protected String[] getServletMappings() {
        //设置“/” 所有请求路径都交给SpringMVC控制器处理。
        return new String[]{"/"};
    }

    @Override
    protected WebApplicationContext createRootApplicationContext() {
        //创建Spring容器
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        //加载配置
        context.register(SpringConfig.class);
        return context;
    }
}
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方式二 继承AbstractAnnotationConfigDispatcherServletInitializer

public class ServletContainersInitConfig extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMVCConfig.class};
    }

    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }
}
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4. 入门案例工作流程分析

5. SpringMVC加载的Controller和Spring加载的Bean分开

@Configuration
@ComponentScan(value = {"com.xin.web"},
        excludeFilters = @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = Controller.class))
public class SpringConfig {
    public static void main(String[] args) {
        //验证下是否排除了@Controller注解下的Bean
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        UserController userController = context.getBean(UserController.class);
        System.out.println(userController);
    }
}
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6. 给Web容器添加过滤器并制定字符集

public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {
    @Override
    protected Filter[] getServletFilters() {
        //设置字符过滤,处理中文乱码
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        return new Filter[]{characterEncodingFilter};
    }
}
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7. 接收请求参数

1. 普通参数

2. POJO对象

3. 嵌套的POJO

4. 数组

5. 集合

8. 接收请求参数 JSON格式

1. 导入转json的依赖

        
        <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-databindartifactId>
            <version>2.13.3version>
        dependency>
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2. 开启注解

@ComponentScan({"com.xin.web.controller"})
@EnableWebMvc //开启json数据转换为对象
public class SpringMVCConfig {
}
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3. 形参上加@RequestBody注解，参数从请求体中获取

@RestController
@RequestMapping("/user")
public class UserController {

    @RequestMapping("/save") //设置请求路径
    public String save(@RequestBody User user) {
        System.out.println(user);
        return user.toString();
    }
}
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4. 测试
   

9. 请求参数 日期类型

10. 响应页面

@Controller
@RequestMapping("/user")
public class UserController {

    @RequestMapping("/save")
    public String save() {
        //响应到页面
        return "/index.jsp"; //页面路径
    }
}
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11. 响应数据

1. 响应字符串

@Controller
@RequestMapping("/user")
public class UserController {

    @RequestMapping("/save")
    @ResponseBody
    public String save() {
        //响应文本数据
        return "save";
    }
}
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2. 响应json数据

@Controller
@RequestMapping("/user")
public class UserController {

    @RequestMapping("/save")
    @ResponseBody
    public User save() {
        User user = new User();
        return user; //jackson帮我们将对象转为json格式的数据了。
    }
}
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12. REST 风格

13. 放行静态资源

public class SpringMVCSupport extends WebMvcConfigurationSupport {
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        //放行静态资源，不由SpringMVC控制器管理
        registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
        registry.addResourceHandler("/html/**").addResourceLocations("/html/");
        registry.addResourceHandler("/css/**").addResourceLocations("/css/");
        registry.addResourceHandler("/js/**").addResourceLocations("/js/");
        registry.addResourceHandler("/plugins/**").addResourceLocations("/plugins/");
    }
}
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@Configuration
@ComponentScan(basePackages = {"com.xin.web.controller"})
@Import(SpringMVCSupport.class) //将SpringMVCSupport对象添加到SpringMVC容器。
@EnableWebMvc //开启json数据转换为
public class SpringMVCConfig {
}
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