使用註解方式搭建SpringMVC

時間 2019-11-17

原文原文鏈接

1.之前搭建Spring MVC 框架通常都使用配置文件的方式進行，相對比較繁瑣。spring 提供了使用註解方式搭建Spring MVC 框架的方式，方便簡潔。使用Spring IOC 做爲根容器管理service、dao、datasource，使用spring MVC 容器做爲子容器管理controller、視圖解析器java

spring 官方文檔中有相關示例web

public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

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

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class<?>[] { App1Config.class };
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/app1/*" };
    }
}

使用繼承 AbstractAnnotationConfigDispatcherServletInitializer 的方式建立啓動類，其中 getRootConfigClasses 指定父容器的配置類，至關於在web.xml 配置文件中配置監聽器加載spring的配置文件，getServletConfigClasses指定spring MVC 的配置文件，至關於在web.xml配置DispatcherServlet，getServletMappings 執行攔截路徑。spring

2.首先建立一個Maven 工程，packaging 爲war類型，並在插件中指定忽略web.xml，不然會報錯apache

<build>
      <plugins>
          <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-war-plugin</artifactId>
              <version>3.1.0</version>
              <configuration>
                  <failOnMissingWebXml>false</failOnMissingWebXml>
              </configuration>
          </plugin>
      </plugins>
  </build>

3.建立spring IOC 的配置類，管理除了Controller 之外的組件mvc

package com.spring.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.FilterType;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.stereotype.Controller;


/**
 * spring 配置文件，構建父容器，掃描service、dao 等，可是controller交給spring mvc 來管理
 * @author Administrator
 *
 */
@ComponentScan(value="com.spring",excludeFilters= {
        @Filter(type=FilterType.ANNOTATION,classes= {Controller.class})
})
public class SpringContextConfig {

}

4.建立Spring MVC 配置類，管理Controller，注意此時須要關閉compentscan 默認的掃描規則，不然會掃描到全部的組件。這樣這個容器的就造成了一種互補關係。app

@ComponentScan(value = "com.spring",includeFilters= {
        @Filter(type = FilterType.ANNOTATION,classes= {Controller.class})
},useDefaultFilters=false)
public class AppConfig extends WebMvcConfigurerAdapter{
    
}

5.建立初始化類，指定兩個容器的配置類，並指定攔截路徑框架

package com.spring;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

import com.spring.config.AppConfig;
import com.spring.config.SpringContextConfig;

public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    
    //獲取父容器的配置文件（spring IOC ，相似於spring 配置文件）
    @Override
    protected Class<?>[] getRootConfigClasses() {
        // TODO Auto-generated method stub
        return new Class<?>[] {SpringContextConfig.class};
    }
    
    //獲取父容器的配置文件（springMVC IOC ，相似於spring MVC  配置文件，獲取DispatcherServlet）
    @Override
    protected Class<?>[] getServletConfigClasses() {
        // TODO Auto-generated method stub
        return new Class<?>[] {AppConfig.class};
    }

    //獲取DispatcherServlet 的映射路徑
    @Override
    protected String[] getServletMappings() {
        // TODO Auto-generated method stub
        return new String[]{"/"};
    }

}

6.編寫測試controller ，services，啓動並測試jsp

package com.spring.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.spring.service.HelloService;

@Controller
public class HelloController {
    
    @Autowired
    HelloService helloService;
    
    
    @ResponseBody
    @RequestMapping("/hello")
    public String sayHello() {
        String sayHello = helloService.sayHello("World");
        return sayHello;
    }
    
}

7.以前採用配置文件的方式，咱們能夠須要在spring MVC 的配置文件中使用 <mvc:annotation-driven/> 去開始MVC 配置，而且配置如視圖解析器，攔截器等組件，在採用註解方式後一樣能夠完成在配置文件中完成的東西，官方文檔中給出的示例，須要咱們編寫一個配置類，而後開啓mvc註解，實現 WebMvcConfigurer 接口，這個接口定義了一系列方法對應在spring MVC 配置文件中配置組件的方法。maven

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

    // Implement configuration methods...
}

8.直接在spring MVC 容器的配置相似，實現以上功能，並配視圖解析器，靜態資源攔截，添加攔截器等。WebMvcConfigurerAdapter 這個抽象類實現了 WebMvcConfigurer ，咱們直接繼承它，從而避免去挨個實現 WebMvcConfigurer 裏面全部的方法ide

package com.spring.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import com.spring.intercepter.MyIntercepter;

/**
 * Spring mvc 配置文件，只掃描Controller
 * @author Administrator
 *
 */
@ComponentScan(value = "com.spring",includeFilters= {
        @Filter(type = FilterType.ANNOTATION,classes= {Controller.class})
},useDefaultFilters=false)
@EnableWebMvc
public class AppConfig extends WebMvcConfigurerAdapter{
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        registry.jsp("/WEB-INF/views/", ".jsp");
    }
    
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new  MyIntercepter()).addPathPatterns("/**");
    }
}

下面是自定義的攔截器

package com.spring.intercepter;

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

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class MyIntercepter implements HandlerInterceptor{

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        System.out.println("----------目標方法執行前-------------");
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("----------目標方法執行後-------------");
        
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("----------頁面響應前-------------");
        
    }

}

測試controller 以下：

package com.spring.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.spring.service.HelloService;

@Controller
public class HelloController {
    
    @Autowired
    HelloService helloService;
    
    
    @ResponseBody
    @RequestMapping("/hello")
    public String sayHello() {
        String sayHello = helloService.sayHello("World");
        return sayHello;
    }
    
    
    @RequestMapping("/helloworld")
    public String helloWorld() {
        return "hello";
    }
}