2021 July 20 Java后端开发

SSM-SpringMVC(五)-纯注解整合SSM

用Initializer取代web.xml

删除web.xml新建一个WebInitializer类，并实现AbstractAnnotationConfigDispatcherServletInitializer接口

 //com.zh.cfg.WebInitializer
 public class WebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
     /**
      * 父容器的配置类
      */
     @Override
     protected Class<?>[] getRootConfigClasses() {
         return new Class[]{SpringConfig.class};
     }
        
     /**
      * 子容器的配置类(SpringMVC相关的配置类)
      */
     @Override
     protected Class<?>[] getServletConfigClasses() {
         return new Class[]{SpringMVCConfig.class};
     }
        
     /**
      * 配置DispatcherServlet的url-pattern
      */
     @Override
     protected String[] getServletMappings() {
         return new String[]{"/"};
     }
        
     @Override
     public void onStartup(ServletContext servletContext) throws ServletException {
         super.onStartup(servletContext);
        
         // 添加Filter
         //post请求解决乱码问题
         FilterRegistration.Dynamic encodingFilter = servletContext.addFilter("CharacterEncodingFilter", new CharacterEncodingFilter("UTF-8"));
         encodingFilter.addMappingForUrlPatterns(null, false, "/*");
     }
 }

该类的本质是：项目部署的时候创建该对象，然后调用onStartup方法，该方法内部会自动调用getRootConfigClasses、getServletConfigClasses、getServletMappings对应的方法

Initializer的本质

AbstractAnnotationConfigDispatcherServletInitializer的本质
1. 最终是实现了WebApplicationInitializer接口
2. 项目部署到Web容器时，就会初始化实现了WebApplicationInitializer接口的实例，并调用它的onStartup方法

也可以自己定义一个类WebInitializer2，实现WebApplicationInitializer接口，然后主动调用父子容器等方法

 public class WebInitializer2 implements WebApplicationInitializer {
     @Override
     public void onStartup(ServletContext servletContext) throws ServletException {
         // 父容器配置
         AnnotationConfigWebApplicationContext springCtx = new AnnotationConfigWebApplicationContext();
         springCtx.register(SpringConfig.class);
         // 通过监听器加载配置信息
         servletContext.addListener(new ContextLoaderListener(springCtx));
    
         // 子容器配置
         AnnotationConfigWebApplicationContext mvcCtx = new AnnotationConfigWebApplicationContext();
         mvcCtx.register(SpringMVCConfig.class);
            
         //交给DispatcherServlet进行初始化子容器
         ServletRegistration.Dynamic servlet = servletContext.addServlet(
                 "DispatcherServlet",
                 new DispatcherServlet(mvcCtx));
         servlet.setLoadOnStartup(0);
         servlet.addMapping("/");
    
         // filter
         FilterRegistration.Dynamic encodingFilter = servletContext.addFilter(
                 "CharacterEncodingFilter",
                 new CharacterEncodingFilter("UTF-8"));
         encodingFilter.addMappingForUrlPatterns(null, false, "/*");
     }
 }

创建父子容器

纯注解实现Spring容器，取代applicationContext.xml

注意：SpringConfig可以不需要再写@Configuration

 //父容器存放service、dao
 //converter其他也会用到，所以放到父容器中
 @ComponentScan({"com.zh.service", "com.zh.converter"})
 @PropertySource("classpath:db.properties")
 @MapperScan("${mybatis.mapperScan}")
 @EnableTransactionManagement
 public class SpringConfig {
     @Value("${jdbc.driverClassName}")
     private String driverClassName;
     @Value("${jdbc.url}")
     private String url;
     @Value("${jdbc.username}")
     private String username;
     @Value("${jdbc.password}")
     private String password;
     @Value("${mybatis.typeAliasesPackage}")
     private String typeAliasesPackage;
     //自动注入
     @Value("${mybatis.configLocation}")
     private String configLocation;
    
     @Bean
     public DataSource dataSource() {
         DruidDataSource ds = new DruidDataSource();
         ds.setDriverClassName(driverClassName);
         ds.setUrl(url);
         ds.setUsername(username);
         ds.setPassword(password);
         return ds;
     }
    
     @Bean
     public SqlSessionFactoryBean sqlSessionFactory(DataSource dataSource) {
         SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
         bean.setDataSource(dataSource);
         bean.setTypeAliasesPackage(typeAliasesPackage);
         //单独加载mybaits核心配置文件
         bean.setConfigLocation(new ClassPathResource(configLocation));
         return bean;
     }
    
     @Bean
     public DataSourceTransactionManager txMgr(DataSource dataSource) {
         DataSourceTransactionManager mgr = new DataSourceTransactionManager();
         mgr.setDataSource(dataSource);
         return mgr;
     }
 }

纯注解实现SpringMVC容器，取代dispatcherServlet.xml

 //子容器存放controller、拦截器(仅仅用于controller层)
 @ComponentScan({"com.zh.controller", "com.zh.interceptor"})
 @EnableWebMvc
 public class SpringMVCConfig implements WebMvcConfigurer {
    
     //自动注入拦截器
     @Autowired
     private MyInterceptor myInterceptor;
     @Autowired
     private DateConverter dateConverter;
     //将拦截器对象放入容器
     @Bean
     public MyInterceptor myInterceptor() {
         return new MyInterceptor();
     }
    
     //前后缀拼接
     @Bean
     public InternalResourceViewResolver viewResolver() {
         InternalResourceViewResolver resolver = new InternalResourceViewResolver();
         resolver.setPrefix("/WEB-INF/page/");
         resolver.setSuffix(".jsp");
         return resolver;
     }
     //文件上传，相当于<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
     @Bean
     public CommonsMultipartResolver multipartResolver() {
         CommonsMultipartResolver resolver = new CommonsMultipartResolver();
         resolver.setDefaultEncoding("UTF-8");
         return resolver;
     }
    
     //设置拦截器，拦截路径，相当于 <mvc:interceptors>
     @Override
     public void addInterceptors(InterceptorRegistry registry) {
         registry.addInterceptor(myInterceptor)
                 .addPathPatterns("/**")
                 .excludePathPatterns("/asset/**");
     }
    
     //相当于<bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
     @Override
     public void addFormatters(FormatterRegistry registry) {
         registry.addConverter(dateConverter);
     }
    
     /**
      * 相当于<mvc:default-servlet-handler/>
      * 用以处理静态资源
      */
     @Override
     public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
         configurer.enable();
     }
    
     //设置返回String、json响应数据的编码 MessageConverters，相当于<mvc:message-converters>
     @Override
     public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
         // 设置返回的普通字符串的编码
         StringHttpMessageConverter stringConverter = new StringHttpMessageConverter();
         stringConverter.setDefaultCharset(StandardCharsets.UTF_8);
         converters.add(stringConverter);
    
         // 设置返回的JSON数据的编码
         MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter();
         jsonConverter.setDefaultCharset(StandardCharsets.UTF_8);
         converters.add(jsonConverter);
     }
 }

其他代码说明

service、dao、domain、controller都没有变化

新增MyInterceptor

 @Component
 public class MyInterceptor implements HandlerInterceptor {
     @Override
     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
         System.out.println("MyInterceptor - preHandle - " + request.getRequestURI());
         return true;
     }
 }

DateConverter

 @Component
 public class DateConverter implements Converter<String, Date> {
     @Override
     public Date convert(String source) {
         try {
             return new SimpleDateFormat("yyyy-MM-dd").parse(source);
         } catch (ParseException e) {
             e.printStackTrace();
             return null;
         }
     }
 }

controller添加测试

 @Controller
 public class TestControlller {
     @GetMapping("/test1")
     public String test1() {
         // /WEB-INF/page/test.jsp
         return "test";
     }
    
     @GetMapping("/test2")
     @ResponseBody
     public String test2() {
         return "测试中文数据";
     }
    
     @GetMapping("/test3")
     @ResponseBody
     public String test3(@RequestParam("birthday") Date birthday) {
         return birthday.toString();
     }
    
     @PostMapping("/test4")
     @ResponseBody
     public String test4(@RequestParam("name") String name,
                         @RequestParam("photo") MultipartFile photo) {
         return "Success - " + name + " - " + photo.toString();
     }
 }

db.properties

 jdbc.driverClassName=com.mysql.jdbc.Driver
 jdbc.url=jdbc:mysql://localhost:3306/test-mybatis
 jdbc.username=root
 jdbc.password=root
    
 mybatis.typeAliasesPackage=com.zh.domain
 mybatis.mapperScan=com.zh.dao
 mybatis.configLocation=mybatis-config.xml