SpringBoot2.0学习(二)-Servlet&J

2018-05-28 本文已影响58人 Acamy丶

本文主要介绍在SpringBoot2.0中如何使用Servlet和Jsp，如图所示，对于Servlet的创建主要使用了注解方式和API注册方式，分别讲解了Servlet, Filter和Listener的创建。对于Jsp的使用，由于SpringBoot更提倡使用模板引擎，所以对于Jsp的自动配置并不多，主要还是手动配置，本文对其步骤进行梳理。

项目结构:

Github源码地址

1. SprinbBoot中使用Servlet

1.1 注解方式

a. 首先添加组件扫描注解

@ServletComponentScan(basePackages="com.hebaohua.springbootservletjsp.anotationServlet")

b.配置Servlet

@WebServlet(
            name = "myServlet",
            urlPatterns = "/myservlet",
            initParams = @WebInitParam(name = "paramName", value = "paramValue")
)
public class MyServlet extends HttpServlet {
    String value;

    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);

        ServletContext context = getServletContext();
        context.log("init has been executed...");

        value = config.getInitParameter("paramName");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Writer writer = resp.getWriter();

        ServletContext context = getServletContext();
        context.log("doGet has been executed...");

        writer.write("<html><body>Hello, " + value + "</body></html>");
    }

    @Override
    public void destroy() {
        ServletContext context = getServletContext();
        context.log("destroy has been executed...");
    }

}

c.配置Filter

@WebFilter(urlPatterns = "/myservlet")
public class MyFilter extends OncePerRequestFilter {
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        ServletContext context = request.getServletContext();
        context.log("myservlet is filterd...");
        filterChain.doFilter(request, response);
    }
}

d. 配置Listener

@WebListener
public class MyServletRequestListener implements ServletRequestListener {

    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        HttpServletRequest request = (HttpServletRequest) sre.getServletRequest();
        ServletContext context = request.getServletContext();
        context.log("requestInitialized in Listener...");
    }

    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        HttpServletRequest request = (HttpServletRequest) sre.getServletRequest();
        ServletContext context = request.getServletContext();
        context.log("requestDestroyed in Listener...");
    }
}

1.2 API注册

a.配置Servlet

public class MyServlet2 extends HttpServlet {
    String value;

    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);

        ServletContext context = getServletContext();
        context.log("init2 has been executed...");

        value = config.getInitParameter("paramName2");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Writer writer = resp.getWriter();

        ServletContext context = getServletContext();
        context.log("doGet2 has been executed...");

        writer.write("<html><body>Hello, " + value + "</body></html>");
    }

    @Override
    public void destroy() {
        ServletContext context = getServletContext();
        context.log("destroy2 has been executed...");
    }
}

b.配置Filter

public class MyFilter2 extends OncePerRequestFilter {
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        ServletContext context = request.getServletContext();
        context.log("myservlet2 is filterd...");
        filterChain.doFilter(request, response);
    }
}

c. 配置Listener

public class MyServletRequestListener2 implements ServletRequestListener {
    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        HttpServletRequest request = (HttpServletRequest) sre.getServletRequest();
        ServletContext context = request.getServletContext();
        context.log("requestInitialized2 in Listener...");
    }

    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        HttpServletRequest request = (HttpServletRequest) sre.getServletRequest();
        ServletContext context = request.getServletContext();
        context.log("requestDestroyed2 in Listener...");
    }
}

d.注册
在主类中增加以下代码：

 @Bean
    public static ServletRegistrationBean servletRegistrationBean(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean();
        servletRegistrationBean.setServlet(new MyServlet2());
        servletRegistrationBean.addUrlMappings("/myservlet2");
        servletRegistrationBean.addInitParameter("paramName2", "myvalue2");
        return servletRegistrationBean;
    }

    @Bean
    public static FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new MyFilter2());
        filterRegistrationBean.addUrlPatterns("/myservlet2");

        return filterRegistrationBean;
    }

    @Bean
    public static ServletListenerRegistrationBean servletListenerRegistrationBean(){
        ServletListenerRegistrationBean servletListenerRegistrationBean = new ServletListenerRegistrationBean();
        servletListenerRegistrationBean.setListener(new MyServletRequestListener2());
        return  servletListenerRegistrationBean;
    }

运行日志:

上面部分为注解方式，下面为API注册方式

2. SprinbBoot中使用Jsp

2.1 添加依赖

<!-- JSP 渲染引擎 -->
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>

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

2.2 激活传统Servle部署

让主类继承SpringBootServletInitializer
public class SpringbootServletJspApplication extends SpringBootServletInitializer

2.3 组装

在主类中增加以下代码：

 protected SpringApplicationBuilder configure(SpringApplicationBuilder builder){
        builder.sources(SpringbootServletJspApplication.class);
        return builder;
    }

2.4 编写.jsp文件

创建src\main\webapp\WEB-INF\jsp文件夹并添加index.jsp文件:

<html>
<body>
Hello, ${name}
</body>
</html>

2.5 配置JSP视图

在application.properties文件中增加以下内容:

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

2.6 编写Controller

@Controller
public class JspControllerDemo {
    @GetMapping("/jsp")
    String jspTest(Model model) {
        model.addAttribute("name", "Acamy");
        return "index";
    }
}

运行测试: