使用註解來構建簡單的spring mvc

spring mvc流程，客戶端發來的http請求經過spring的DispatcherServlet，DispatcherServlet選擇適合的Controller，通過返回視圖控制器來選擇合適的頁面

首先，先建一個WebInit類，這個類主要是加載配置類（因爲是面向註解，所以就沒有配置文件了，用配置類代替），這個類繼承自AbstractAnnotationConfigDispatcherServletInitializer

package config;

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

public class WebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer{

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return null;
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        // TODO Auto-generated method stub
        return new Class<?> [] {WebConfig.class};
    }

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

}

然後建立WebConfig類，關於配置

package 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;

@Configuration
@EnableWebMvc
@ComponentScan("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;
    }
    @Override
    public void configureDefaultServletHandling(
            DefaultServletHandlerConfigurer configurer) {
        // TODO Auto-generated method stub
        configurer.enable();
    }

}

然後寫Controller

package web;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import static org.springframework.web.bind.annotation.RequestMethod.*;

@Controller
public class HomeController {
    @RequestMapping(value="/home",method=GET)
    public String home(){
        return "home";
    }
}

最後，在WEB-INF裏創建views/home.jsp

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