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springboot原理实战(14)--springbootweb

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springboot原理实战(14)--springbootweb

原创

本文章的大纲如下:

springboot原理实战(14)--springbootweb_ide

第一部分:

一、请求method

springboot的请求注解是​​@RequestMapping(value = "/user/home",method= RequestMethod.GET)​​​ spring4.3以后可以使用: ​​@GetMapping("/user/home2")​​,​​@PostMapping("/user/create")​​等语义化表示get，post等请求方法。

springboot原理实战(14)--springbootweb_html_02

二、传递参数的3种方式

1.RequestParam

​​@RequestParam 默认必填，可以设置非必填，和默认值​​:

/**
     *  @RequestParam 注解默认是参数必须提供值
     * @param username
     * @param password
     * @return
     */
    @PostMapping("/user/create")
    @ResponseBody
    public String create(@RequestParam(value = "username",defaultValue = "admin") String username, @RequestParam(value="password",required = false) String password){
        return "user create, username=" + username + ",password="+password;
    }
2.url方式 @PathVariable
/**
     * 获取url的方式/user/1 ，/user/2
     * @param id
     * @return
     */
    @GetMapping("/user/{id}")
    @ResponseBody
    public String display(@PathVariable("id") String id){
        return "user display is=" + id;
    }
3.HttpServletRequest方式
@ResponseBody
    @GetMapping("/user/ip")
    public String edit(HttpServletRequest req){
        return "user edit " + req.getRemoteHost();
    }
三、@RestController
这个注解相当于@Controller+@RequestBody,用在视图访问层，表示当前controller的方法的返回值并可以直接用于body测试.返回json格式数据:
springboot原理实战(14)--springbootweb_spring boot_03
四、springboot的数据渲染到jsp页面
需要的步骤:
1.配置文件:
application.properties加入2个配置项，执行页面路径和后缀
spring.mvc.view.prefix=/WEB-INF/jsp/
spring.mvc.view.suffix=.jsp
2.加入 tomcat-embed-jasper的依赖
pom.xml中:
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-jasper</artifactId>
<!--  <version>9.0.27</version>-->
</dependency>
<!--servlet依赖jar-->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
</dependency>
<!--Jstl标签依赖的jar包start-->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
</dependency>
build下加入resoures
<resources>
<!--            <resource>-->
<!--                <directory>src/main/java</directory>-->
<!--                <includes>-->
<!--                    <include>**/*.xml</include>-->
<!--                </includes>-->
<!--            </resource>-->
<!--            <resource>-->
<!--                <directory>src/main/resources</directory>-->
<!--                <includes>-->
<!--                    <include>**/*.*</include>-->
<!--                </includes>-->
<!--            </resource>-->
            <resource>
                <directory>src/main/webapp</directory>
                <targetPath>META-INF/resources</targetPath>
                <includes>
                    <include>**/*.*</include>
                </includes>
            </resource>
        </resources>
    </build>
3.测试:
@Controller
public class LoginController {

@PostMapping("/login")
    public String login(@RequestParam(value = "username") String username, @RequestParam(value = "password") String password) {
        if (username.equals(password)) {
            return "ok";
        }
        return "fail";
    }

/**
     * 给jsp传参数，类似req.setAttribute
     * @param model
     * @return
     */
    @GetMapping("/login")
    public String loginIndex(Model model){
        model.addAttribute("username", "root");
        return "login";
    }
}
login.jsp页面:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
  <h1>this is login page</h1>
 <p>username is ${username}</p>
</body>
</html>
运行入口函数
@SpringBootApplication
public class Demo11Application {

public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Demo11Application.class, args);
    }

}
运行结果,显示已经数据已经渲染到jsp页面:
springboot原理实战(14)--springbootweb_html_04
五、springboot渲染数据到freemarker页面:
在springboot中使用freemarker的步骤
1. 在pom.xml里面加入依赖
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>
2.配置文件修改freemarker的位置和后缀
看配置信息可以看源码: ​​FreeMarkerProperties​​:
springboot原理实战(14)--springbootweb_spring_05
 我们在application.properties中修改配置信息:
spring.freemarker.templateLoaderPath=classpath:/ftl/
spring.freemarker.suffix=.ftl
3.测试:
@Controller
public class AccountController {

@RequestMapping("/reg")
    public String req(Model model){
        model.addAttribute("username", "root");
        return "reg";
    }
}
页面代码:
springboot原理实战(14)--springbootweb_ide_06
 运行入口函数:
@SpringBootApplication
public class Demo11Application {

public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Demo11Application.class, args);
    }

}
查看页面，显示已经渲染到HTML页面:
springboot原理实战(14)--springbootweb_spring boot_07
六、更换web容器
pringboot 容器默认使用的是tomcat作为外部容器， 可以更换为jetty。
 具体操作如下:
1.排除tomcat，加入jetty的依赖
<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
           <!--  排除tomcat-->
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jetty</artifactId>
        </dependency>
2.测试:
运行入口函数:
@SpringBootApplication
public class Demo11Application {

public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Demo11Application.class, args);
    }

}
运行结果,看打印结果，已显示为jetty:
springboot原理实战(14)--springbootweb_ide_08
源码地址:
​​ ​https://github.com/hufanglei/springboot-v-study/tree/springboot-web1​​
一、请求静态资源:
1. 放在webapp下 加resources.xml 可以访问到
做个案例，测试下：
  • 在webapp下准备一个图片和一个user.html
springboot原理实战(14)--springbootweb_html_09
pom上加入资源
<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
        <resources>
            <resource>
                <directory>src/main/webapp</directory>
                <!--注意此次必须要放在此目录下才能被访问到 -->
                <targetPath>META-INF/resources</targetPath>
                <includes>
                    <include>**/**</include>
                </includes>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
                <includes>
                    <include>**/*</include>
                </includes>
            </resource>
        </resources>

</build>
  • 入口函数启动：
@SpringBootApplication
public class Demo12Application {

public static void main(String[] args) {
        SpringApplication.run(Demo12Application.class, args);
    }

}
  • 查看效果,显示图片和页面都可以访问到：
springboot原理实战(14)--springbootweb_spring_10
2. springboot默认的静态资源的路径是:
  • “classpath:/META-INF/resources/”,
  • “classpath:/resources/”,
  • “classpath:/static/”,
  • “classpath:/public/” };
我们可以在ResourceProperties源码中找到这个原因:
springboot原理实战(14)--springbootweb_html_11
 在public下准备个文件看下能否访问到:
springboot原理实战(14)--springbootweb_ide_12
 运行入口函数：看下页面,显示已经访问到public下的html页面和css。
springboot原理实战(14)--springbootweb_spring_13
3.可以通过spring.resources.static-locations 配置项修改默认静态资源路径
 我们指定html文件下为我们的默认静态资源路径，并准备个login.html,看下能否访问：
springboot原理实战(14)--springbootweb_html_14
springboot原理实战(14)--springbootweb_spring_15
 运行,看下页面效果:
springboot原理实战(14)--springbootweb_spring_16
 结果显示已经访问到html下的页面。修改默认的静态资源路径成功。
二、sevlet，filter，listener的2种配置方式:
1.springboot如何使用servlet
有2种方式，一种是用sevlet3加入口函数注解扫码方式，一种是配置类注入servlet方式:
 现在动手试试:
① 方法一:(servlet3可以使用这种方法)
  • 1）编写servlet，然后加上响应的注解@WebServlet
  • 2）需要启用@ServletComonentScan注解
@WebServlet("/user.do")
public class BookServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

public BookServlet() {
        System.out.println("===servet BookServlet========");
    }

@Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().println("book servlet");
    }

}
@ServletComponentScan
@SpringBootApplication
public class Demo12Application {
    public static void main(String[] args) {
        SpringApplication.run(Demo12Application.class, args);
    }
}
运行入口，访问BookServlet 映射的user.do路径:
springboot原理实战(14)--springbootweb_html_17
 说明servlet已经访问成功。
② 方法2:（servlet2.5及以下版本可以使用这种方法）
  • 1） 书写servlet无需对位映射，不用加@WebServlet注解
  • 2）书写个配置类，使用@Bean注入，注入的话，需要调用ServletRegistrationBean的构造方法。
    代码如下:
    servlet:
public class BookServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

public BookServlet() {
        System.out.println("===servet BookServlet========");
    }

@Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().println("book servlet");
    }
}
@SpringBootConfiguration
public class ServletConfigration {

@Bean
    public ServletRegistrationBean createBookServlet(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new BookServlet(), "/book.do");
        return servletRegistrationBean;
    }
}
@SpringBootApplication
public class Demo12Application {

public static void main(String[] args) {
        SpringApplication.run(Demo12Application.class, args);
    }

}
启动并测试:结果显示ok:
springboot原理实战(14)--springbootweb_spring boot_18
2.springboot如何使用过滤器
使用的方式和servet差不多，一种是@WebFilter("/*")注解方式，另一种是也是通过配置类:
 不过生成filter的类是 fileter -》 FilterRegistrationBean。
方式1通过@WebFilter("/*")+入口@ServletComponentScan注解实现过滤器
@WebFilter("/*")
public class LogFilter implements  Filter {


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("==LogFilter =init===");
    }

@Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("==LogFilter =filter ==="+ request.getRemoteHost());
        chain.doFilter(request,response);
    }

@Override
    public void destroy() {
        System.out.println("=====destroy======");
    }
}
@ServletComponentScan
@SpringBootApplication
public class Demo12Application {

public static void main(String[] args) {
        SpringApplication.run(Demo12Application.class, args);
    }

}
启动入口函数，访问刚才的servlet，看下控制台打印情况:
springboot原理实战(14)--springbootweb_html_19
 显示过滤器已经被注入了。
方式2：配置类+注入bean，
public class EchoFilter implements Filter {

@Override
    public void init(FilterConfig filterConfig) throws ServletException {

}
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        System.out.println("spring boot web filter "+ req.getRequestURI());
        chain.doFilter(request,response);
    }
    @Override
    public void destroy() {

}
}
@SpringBootConfiguration
public class ServletConfigration {

@Bean
    public FilterRegistrationBean createFilterRegistrationBean(){
        FilterRegistrationBean filter = new FilterRegistrationBean();
        filter.setFilter(new EchoFilter());
        filter.setUrlPatterns(Arrays.asList("/book.do"));
        return filter;
    }
}
@SpringBootApplication
public class Demo12Application {

public static void main(String[] args) {
        SpringApplication.run(Demo12Application.class, args);
    }

}
springboot原理实战(14)--springbootweb_spring boot_20
运行结果:显示过滤器已经起作用了了。
springboot原理实战(14)--springbootweb_html_21
3.springboot如何使用监听器
1）方式1:@WebListener+@ServletComponentScan
@WebListener
public class MyListener implements ServletContextListener {

@Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("StartUpListener app startup at " + LocalDateTime.now().toString());
    }

@Override
    public void contextDestroyed(ServletContextEvent sce) {

}
}
@ServletComponentScan
@SpringBootApplication
public class Demo12Application {

public static void main(String[] args) {
        SpringApplication.run(Demo12Application.class, args);
    }

}
springboot原理实战(14)--springbootweb_html_22
2）方式2:配置类+@bean+ServletListenerRegistrationBean构造函数注入
public class StartUpListener implements ServletContextListener {

@Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("StartUpListener app startup at " + LocalDateTime.now().toString());
    }

@Override
    public void contextDestroyed(ServletContextEvent sce) {

}
}
@SpringBootConfiguration
public class ServletConfigration {

@Bean
    public ServletListenerRegistrationBean createServletListenerRegistrationBean(){
        ServletListenerRegistrationBean listener = new ServletListenerRegistrationBean(new StartUpListener());
        return listener;
    }
 }
@SpringBootApplication
public class Demo12Application {

public static void main(String[] args) {
        SpringApplication.run(Demo12Application.class, args);
    }

}
springboot原理实战(14)--springbootweb_html_23
 源码地址:
​ ​https://github.com/hufanglei/springboot-v-study/tree/demo12​​
1.拦截器：
拦截器的使用步骤
①写一个拦截器，实现HandlerInterceptor接口
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LogHandlerInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("=========preHandle===============" + handler);
        return true;
    }

@Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("=========postHandle===============" + handler);
    }

@Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("=========afterCompletion===============" + handler);
    }
}
  • preHandle： controller执行之前调用
  • postHandle： controller执行之后，且页面渲染之前调用
  • afterCompletion： 页面渲染之后调用，一般用于资源清理操作
②写一个类，实现WebMvcConfigurer接口，重写addInterceptors方法（已经过时）,并调用registry.addInterceptor把上一步的拦截器加进去
@SpringBootConfiguration
public class WebConfiguration implements WebMvcConfigurer {

//    @Override
//    public void addResourceHandlers(ResourceHandlerRegistry registry) {
//        registry.addResourceHandler("/web/**").addResourceLocations("classpath:/web/");
//    }

@Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LogHandlerInterceptor());
    }
}
写个controller
@RestController
public class UserController {

@GetMapping("/user/home")
    public String home(){
        return "user home";
    }

@GetMapping("/user/help")
    public String help()  {
        throw new IllegalArgumentException("args is empty");
    }
}
@SpringBootApplication
public class Demo13Application {
    public static void main(String[] args) {
        SpringApplication.run(Demo13Application.class, args);
    }
}
页面测试:
springboot原理实战(14)--springbootweb_ide_24
 看下控制台:
springboot原理实战(14)--springbootweb_spring boot_25
 显示已经拦截controller。
2.异常处理:
1）默认异常处理逻辑ErrorMvcAutoConfiguration
当我们访问一个不存在的url时候会出现如下页面:
springboot原理实战(14)--springbootweb_spring boot_26
 看下ErrorMvcAutoConfiguration源码:
springboot原理实战(14)--springbootweb_spring_27
springboot原理实战(14)--springbootweb_spring boot_28
排除springboot默认显示的异常页方式1：
可以看到找到就是渲染的这段代码。
 我们可以关闭这个默认异常页配置:
springboot原理实战(14)--springbootweb_ide_29
 看了源码再去修改applicaiton.properties
server.error.whitelabel.enabled=false
重新运行:
springboot原理实战(14)--springbootweb_html_30
 输入一个无效的url，就没有默认的异常处理页了。
排除springboot默认显示的异常页方式2：
也可以直接在入口函数上，用exclude去排除自动注册的这个默认异常注册类：
@SpringBootApplication(exclude = ErrorMvcAutoConfiguration.class)
public class Demo13Application {

public static void main(String[] args) {
        SpringApplication.run(Demo13Application.class, args);
    }
}
2).自处理异常
定义一个controller。手动抛出异常:
①在当前controller类使用@ExceptionHandler处理异常
@RestController
public class BookController {

//    @ExceptionHandler(value = FileNotFoundException.class)
    @ExceptionHandler(value = FileNotFoundException.class)
    public String error(Exception e){
        return "file not found exception====  " + e.getMessage();
    }

@GetMapping("/book/error1")
    public String list() throws FileNotFoundException {
        throw new FileNotFoundException("file not found");
    }

@GetMapping("/book/error2")
    public String error2() throws ClassNotFoundException {
        throw new ClassNotFoundException("file not found");
    }

@GetMapping("/user/null")
    public String empty() {
        throw new NullPointerException("args is empty");
    }
}
我们看到访问list，error2，empty的方法都会抛出异常，同时定义一个处理异常的方法error：
@ExceptionHandler(value = FileNotFoundException.class)
    public String error(Exception e){
        return "file not found exception====  " + e.getMessage();
    }
如果匹配到 @ExceptionHandler中value对应的异常，就可以在error方法中处理异常，或者跳转到错误页面。
 我们访问/user/null：
springboot原理实战(14)--springbootweb_spring boot_31
​​@GetMapping("/user/null") public String empty() { throw new NullPointerException("args is empty"); } }​​​ 对应的是空指针异常，而​​@ExceptionHandler(value = FileNotFoundException.class)​​是文件找不到的异常，所以controller没给我们处理。然后访问@GetMapping("/book/error1")
springboot原理实战(14)--springbootweb_spring boot_32
 看到已经帮我们处理了。
 如果想要@ExceptionHandler当前类全部的方法，就可以扩大异常范围,改成exception.class就可了。
@ExceptionHandler(value = Exception.class)
    public String error(Exception e){
        return " exception====  " + e.getMessage();
    }
②全局处理异常的2种方式：
  • a.方式1：使用ErrorPageRegistrar的接口
写一个类，实现ErrorPageRegistrar接口，实现registerErrorPages，在该方法里面，添加具体的错误处理逻辑
@Component
public class CommonErrorRegistry implements ErrorPageRegistrar {
    @Override
    public void registerErrorPages(ErrorPageRegistry registry) {
        ErrorPage e404 = new ErrorPage(HttpStatus.NOT_FOUND, "/404.html");
        ErrorPage e500 = new ErrorPage(INTERNAL_SERVER_ERROR, "/500.html");
        ErrorPage argsPage= new ErrorPage(IllegalArgumentException.class, "/args.html");
        registry.addErrorPages(e404, e500,argsPage);
    }
}
  • b.方式2：@ControllerAdvice
    具体做法:
-1.写一个类，需要加上@ControllerAdvice注解
 -2.写一个异常处理方法，需要加上@Exception（value=Exception.class）这个注解，在该方法上处理异常，
@ControllerAdvice
public class GloabalExceptinHandler {

@ExceptionHandler(value = Exception.class)
    @ResponseBody
    public String errorHandler(Exception e){
       return "gloabal error  " + e.getClass().getName()+ " =="+ e.getMessage();
    }

@ExceptionHandler(value = NullPointerException.class)
    @ResponseBody
    public String errorHandler2(Exception e){
        return "gloabal error2  " + e.getClass().getName()+ " =="+ e.getMessage();
    }
}
这2种方法都可以跳转到自定义的页面，或者抛出异常。
 看下这个ErrorPage类的源码:
springboot原理实战(14)--springbootweb_ide_33
 可以看到，errorpage可以通过请求响应状态码控制跳转页面，可以根据具体异常控制跳转页。
演示代码git地址:
​​ ​https://github.com/hufanglei/springboot-v-study/tree/springbootweb3​​
以上就说了springbootweb的大体内容，基础springboot2的。关于请求方法参数，数据渲染到jsp页面和freemarker页面的配置方式，替换内置tomcat的方法，请求静态页面的设置，过滤器，监听器，servlet的2种注册方式，拦截器的自定义，异常处理的类上的处理，和全局处理的2种方式。
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springboot原理实战(14)--springbootweb_spring_34

            

		
        
        
    

    

        
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