Springmvc-简单入门

1,ContextLoaderListener
应用上下文以前是
ApplicationContext app =new ClassPathXmlApplicationContext(“applicationContext.xml”);这样获取的
加载xml配置文件创建容器
每次都会加载配置创建容器我们想创建加载一次
用监听器放到ServletContext域中 ServletContextListener是监听ServletContext创建的
就可以从servletContext域中获取ApplicationContext对象了

这是自己实现监听器
在web.xml设置全局参数（设置应用上下文对象）配置监听器

    <!--全局初始化参数--><!--<context-param><param-name>contextConfigLocation</param-name><param-value>applicationContext.xml</param-value></context-param>--><!--配置监听器--><!--<listener><listener-class>com.flatly.listener.ContextLoaderListener</listener-class></listener>--><!--配置springMVC前端控制器-->

public class ContextLoaderListener implements ServletContextListener {//服务器启动public void contextInitialized(ServletContextEvent sce) {// ApplicationContext app =new ClassPathXmlApplicationContext("applicationContext.xml");//得到servletContext域ServletContext servletContext = sce.getServletContext();//读取webxml全局参数String contextConfigLocation= servletContext.getInitParameter("contextConfigLocation");ApplicationContext app =new ClassPathXmlApplicationContext(contextConfigLocation);//将Spring应用上下文对象存储到ServletContext域中servletContext.setAttribute("app",app);System.out.println("spring容器创建完毕");}public void contextDestroyed(ServletContextEvent sce) {}
}

//这是返回应用上下文对象的工具
public class WebApplicationContextUtils {//需要一个ServletContext域得到apppublic static ApplicationContext getWebApplicationContext(ServletContext servletContext){return (ApplicationContext) servletContext.getAttribute("app");}
}

@WebServlet(value = "/userServlet")
public class UserServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {ServletContext servletContext = this.getServletContext();// ApplicationContext app = (ApplicationContext) servletContext.getAttribute("app");这里我们不期望还用写app所以创建了Util直接直接给你返回应用上下文对象ApplicationContext app = WebApplicationContextUtils.getWebApplicationContext(servletContext);UserService userService = app.getBean(UserService.class);userService.save();}
}

Spring提供应用上下文的工具
1.导入坐标
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<dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>5.0.5.RELEASE</version></dependency><dependency>

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在web.xml配置sprig监听器

 <context-param><param-name>contextConfigLocation</param-name><param-value>classpath:applicationContext.xml</param-value></context-param><listener><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener>

使用

public class UserServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {ServletContext servletContext = this.getServletContext();WebApplicationContext app = WebApplicationContextUtils.getWebApplicationContext(servletContext);UserService userService = app.getBean(UserService.class);userService.save();}
}

SpringMVC快速入门

每个servlet都有共有的行为，接数据封实体，指派实体，还有特有行为
springmvc封装了前端控制器
1，导入坐标
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   <dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.0.5.RELEASE</version></dependency>

2,配置servlet配置springmvc核心控制器DispathcerServlet
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  <!--配置springMVC前端控制器--><servlet><servlet-name>DispatcherServlet</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:spring-mvc.xml</param-value></init-param><load-on-startup>1</load-on-startup><!--服务器启动时加载--></servlet><servlet-mapping><servlet-name>DispatcherServlet</servlet-name><url-pattern>/</url-pattern><!--任何servlet--></servlet-mapping>

3创建Controller类和视图页面
4使用注解配置Controller类中业务方法的映射地址

@Controller
@RequestMapping(value = "/user")
public class UserController {//请求地址http://localhost:8080/user/quick@RequestMapping("/quick")public String save(){return "/success.jsp";//加/相当于从当前应用找success.jsp}

5配置springmvc核心文件spring-mvc.xml
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 <context:component-scan base-package="com.flatly.controller"/><!--扫描包下带Controller注解的包
<context:component-scan base-package="com.flatly"><context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>
-->

@Controller用于定义Controller类实现Controller接口，实现handleRequest方法返回ModelAndView
@RequestMapping(/xxx)用于url与方法映射

@RequestMapping(
value = “/quick”,
method = RequestMethod.GET,
params = {“username”})//必须限定有请求必须要username

一些组件配置在这里

InternalResourceViewResolver->UrlBasedViewResolver
public static final String REDIRECT_URL_PREFIX = “redirect:”;
public static final String FORWARD_URL_PREFIX = “forward:”;
默认省略forword

        // return "redirect:/success.jsp";地址变

public InternalResourceViewResolver(String prefix, String suffix) {
this();
this.setPrefix(prefix);
this.setSuffix(suffix);
}可以指定跳转视图的前缀后缀
这里jsp包下有个success.jsp
//return “forword:/jsp/success.jsp”;可以写成 return “success”;//

 配置了视图资源解析器在spring-mvc.xml

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"><!--前缀后缀/jsp/xxx/.jsp--><property name="prefix" value="/jsp/"></property><property name="suffix" value=".jsp"></property></bean>

spring-mvc数据响应

1页面调转
1）直接返回字符串
2）通过ModelAndView对象返回
2会写数据
1）直接返回字符串
2）返回对象或集合（json）

通过modelAndView直接返回字符串

   /** Model模型  作用封装数据** View 视图 作用展示数据* */@RequestMapping("/quick2")public ModelAndView save2(){ModelAndView modelAndView = new ModelAndView();//设置模型数据//放到了request域中setAttibutemodelAndView.addObject("username","flatly");//设置视图modelAndView.setViewName("success");return modelAndView;}

注入参数ModelAndView 来返回参数不用自己new创建对象

  @RequestMapping("/quick3")public ModelAndView save3( ModelAndView modelAndView){modelAndView.addObject("username","flatly2");//设置视图modelAndView.setViewName("success");return modelAndView;}

视图解析器+Model模型

@RequestMapping("/quick4")public String save4(Model model){model.addAttribute("username","flatly3");return "success";}

注入原始request（不常用）

@RequestMapping("/quick5")public String save5(HttpServletRequest request){request.setAttribute("username","flatly4");return "success";}

回写数据原始注入response（不常用）

    //response.getWriter().print("aaaa")回写@RequestMapping("/quick6")public void save6(HttpServletResponse response) throws IOException {response.getWriter().print("xxx");}

直接return字符串使用@ResponseBody注解告知不要跳转页面回写

 @RequestMapping("/quick7")@ResponseBody//告诉spring不要页面调转public String save7(){return "hello flatly";}

自己拼接json返回

  @RequestMapping("/quick8")@ResponseBody//告诉spring不要页面调转public String save8(){return "{\"username\":\"zhangsan\",\"age\":18}";//{"username":"zhangsan","age":18}json字符串}

借助json工具装换
添加配置坐标jackson

<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-core</artifactId><version>2.9.0</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.9.0</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-annotations</artifactId><version>2.9.0</version></dependency>

    @RequestMapping("/quick9")@ResponseBody//告诉spring不要页面调转public String save9() throws IOException {User user = new User("lisi",18);//使用json的转换工具ObjectMapper objectMapper =new ObjectMapper();String json = objectMapper.writeValueAsString(user);return json;}

spring自己可以自动封装json格式
配置spring-mvc.xml
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   <!--配置处理器映射器-->
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"><property name="messageConverters"><list><bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/></list></property></bean>

或者直接用这个不用配处理器映射器
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 <!--mvc注解驱动需要引入mvc命名空间-->
<mvc:annotation-driven"/>

直接return对象或集合

    @RequestMapping("/quick10")@ResponseBody//告诉spring不要页面调转//期望SpringMVC自动将User转换成json字符串public User save10() throws IOException {User user = new User("lisi",18);return user;}

获得请求参数数据

获得普通类型参数
没有会报错

      //获得普通类型参数@RequestMapping("/quick11")@ResponseBody //不进行页面跳转不进行数据回写响应体为空public void save11(String username,int age) throws IOException {System.out.println(username);//http://localhost:8080/user/quick11?username=zhangsan&age=12System.out.println(age);}

根据请求自动封装实体

 //SpringMVC自动封装POJO对象@RequestMapping("/quick12")@ResponseBody //不进行页面跳转不进行数据回写响应体为空public void save12(User user) throws IOException {System.out.println(user);//User{username='zhangsan', age=12}}

获得类似爱好多个数组类型参数

   //获得数组类型参数@RequestMapping("/quick13")@ResponseBody //不进行页面跳转不进行数据回写响应体为空public void save13(String[] strs) throws IOException {System.out.println(Arrays.asList(strs));//http://localhost:8080/user/quick13?strs=aaa&strs=bbb&strs=ccc//数组会打印地址list集合重写了toString方法  [aaa, bbb, ccc]}

封装集合List list
直接封装不行得创建VO对象封装

public class VO {private List<User> userList;public VO() {}...

前端

   <form action="${pageContext.request.contextPath}/user/quick14" method="post"><%--表明第几个User对象的username--%><input type="text" name="userList[0].username"><br><input type="text" name="userList[0].age"><br><input type="text" name="userList[1].username"><br><input type="text" name="userList[1].age"><br><input type="submit"></form>

       //获得集合类型参数@RequestMapping(value = "/quick14")@ResponseBody //不进行页面跳转不进行数据回写响应体为空public void save14(VO vo) throws IOException {System.out.println(vo);//VO{userList=[User{username='zhangsan', age=12}, User{username='lisi', age=14}]}}

当前端发送的是ajax请求json格式时可以直接封装集合
这里用到jquery但是静态资源得有访问权限
在spring-mvc.xml中加入

  <!--开放资源的访问--><mvc:resources mapping="/js/**" location="/js/"/>

  var userList =new Array();userList.push({username:"zhangsan",age:18});userList.push({username:"lisi",age:18});$.ajax({type:"POST",url:"${pageContext.request.contextPath}/user/quick15",data:JSON.stringify(userList),contentType:"application/json;charset=utf-8"})

@RequestMapping(value = "/quick15")@ResponseBody //不进行页面跳转不进行数据回写响应体为空public void save15(@RequestBody List<User> userList) throws IOException {System.out.println(userList);}

如果从前端控制器中找不到则从原始的tomcat中找静态资源
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 <mvc:default-servlet-handler/>

request.setCharacterEncoding->
post请求乱码get方式tomcat8会处理
解决编码配置全局filter过滤器

在web.xml中配置
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    <filter><filter-name>CharacterEncodingFilter</filter-name><filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class><init-param><param-name>encoding</param-name><param-value>utf-8</param-value></init-param></filter><filter-mapping><filter-name>CharacterEncodingFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping>

参数绑定

  @RequestMapping("/quick16")@ResponseBody //不进行页面跳转不进行数据回写响应体为空/** value与请求参数匹配名称与形参不一样也可以* required默认true必须携带参数不然报错false可以不携带* defaultValue没有指定参数是则使用默认值* */public void save16(@RequestParam(value = "name",required = false,defaultValue = "zhangsan") String username) throws IOException {System.out.println(username);}

解析url地址一部分的参数@PathVrlable占位符

    //licalhost:8080/user/quick17/zhangsan@RequestMapping(value = "/quick17/{username}")@ResponseBody //不进行页面跳转不进行数据回写响应体为空/**restful风格* get获取，post新建put更新delete删除*  */public void save17( @PathVariable(value = "username") String username) throws IOException {System.out.println(username);}

自定义类型转换器

1，定义转换器实现Converter接口
2，在配置文件中声明转换器
3，在<annotation-driven中引用转换器

   public void save18(Date date) throws IOException {System.out.println(date);}

date=2014/12/21默认
经常用2022-12-12

//将String转换成Date
public class DateConverter implements Converter<String, Date> {@Overridepublic Date convert(String dataStr) {SimpleDateFormat format =new SimpleDateFormat("yyyy-MM-dd");Date date = null;try {date = format.parse(dataStr);} catch (ParseException e) {e.printStackTrace();}return date;}
}

在spring-mvc.xml中加入

<mvc:annotation-driven conversion-service="conversionService"/><!--声明装换器--><bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean"><property name="converters"><list><bean class="com.flatly.converter.DateConverter"></bean></list></property></bean>

springmvc获取请求数据

@RequestHeader
相当于request.getHeader(xx)

    @RequestMapping(value = "/quick19")@ResponseBody //不进行页面跳转不进行数据回写响应体为空public void save19(@RequestHeader(value = "User-Agent",required = false)String user_agent) throws IOException {System.out.println(user_agent);}

@CookieValue拿到CookieValue

  //直接拿到CookieValue@RequestMapping(value = "/quick20")@ResponseBody //不进行页面跳转不进行数据回写响应体为空public void save20(@CookieValue(value = "JSESSIONID")String jsessionId) throws IOException {System.out.println(jsessionId);}

用到的注解
@Controller
@RequestMapping
@ResponseBody
@RequestHeader
@RequestParam
@PathVariable
@CookieValue