在Web项目中,Spring提供了一个监听器ContextLoaderListener启动时加载Spring的配置文件,创建应用上下文对象ApplicationContext,在将其存储到最大的域servletContext域中,提供了一个客户端工具WebApplicationContextUtils供使用者获得应用上下文对象。
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.0.3.RELEASE</version>
</dependency>
<!--配置全局变量-->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>
<!--配置Spring监听器-->
<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener
</listener-class>
</listener>
public class UserServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp){
ServletContext servletContext = req.getServletContext();
WebApplicationContext app = WebApplicationContextUtils.getWebApplicationContext(servletContext);
UserServer userServer = app.getBean(UserServer.class);
userServer.save();
}
}
SpringMVC相关组件及执行流程:
<!--Spring坐标-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.0.3.RELEASE</version>
</dependency>
<!--SpringMVC坐标-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.0.3.RELEASE</version>
</dependency>
<!--Servlet坐标-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<!--Jsp坐标-->
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.2</version>
<scope>provided</scope>
</dependency>
<!--配置前端控制器DispatcherServlet-->
<servlet>
<servlet-name>DispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--加载配置文件-->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mvc.xml</param-value>
</init-param>
<!--服务器启动时加载Servlet-->
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>DispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
@Controller
public class UserController {
@RequestMapping("/user")
public String save(){
System.out.println("userController save running...");
return "user.jsp";
}
}
<html>
<body>
<h1>user.jsp</h1>
</body>
</html>
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!--Controller组件扫描-->
<context:component-scan base-package="cn.guixinchn">
<context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>
</beans>
http://localhost:8080/SpringMVC_01/user
SpringMVC有默认组件配置,默认组件都是DispatcherServlet.properties配置文件中,例如视图解析器:
org.springframework.web.servlet.ViewResolver=org.springframework.web.servlet.view.InternalResourceViewResolver
有默认设置:
REDIRECT_URL_PREFIX = "redirect:" --重定向前缀
FORWARD_URL_PREFIX = "forward:" --转发前缀(默认值)
prefix = ""; --视图名称前缀
suffix = ""; --视图名称后缀
<!--配置视图解析器-->
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/jsp/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
@RequestMapping(value = "/user")
public String save(){
System.out.println("userController save running...");
return "user";
}
通过ModelAndView对象返回,或者直接返回字符串并向request域存储数据
@RequestMapping(value = "/user2")
public ModelAndView save2(){
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("username","张三");
modelAndView.setViewName("user");
return modelAndView;
}
@RequestMapping(value = "/user3")
public String save3(HttpServletRequest request){
request.setAttribute("username","李四");
return "user";
}
页面跳转可以使用return"redirect:/user.jsp"重定向
注入response对象,使用response.getWriter().print(“hello world”) 回写数据
@RequestMapping(value = "/user4")
public void save4(HttpServletResponse response) throws IOException {
response.getWriter().println("Hello world");
}
直接返回字符串(需要加上@ResponseBody注解)
@RequestMapping(value = "/user5")
@ResponseBody
public String save5(){
return "Hello world";
}
返回对象或集合:
开发中往往要将复杂的java对象转换成json格式的字符串,导入jackson坐标
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.10</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.10.1</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.10</version>
</dependency>
通过jackson转换json格式字符串,回写字符串
@RequestMapping(value = "/user6")
@ResponseBody
public String save6() throws JsonProcessingException {
User user = new User();
user.setName("李四");
user.setAge(18);
ObjectMapper objectMapper = new ObjectMapper();
String s = objectMapper.writeValueAsString(user);
System.out.println(s);
return s;
}
或者使用Spring配置的方式,为处理器适配器配置消息转换参数,指定使用jackson进行对象或集合的转换
spring-mvc.xml中进行如下配置:
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
<property name="messageConverters">
<list>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"></bean>
</list>
</property>
</bean>
@RequestMapping(value = "/user7")
@ResponseBody
public User save7(){
User user = new User();
user.setName("王五");
user.setAge(20);
return user;
}
也可以使用mvc的注解驱动代替上述配置
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--SrpingMVC的注解驱动-->
<mvc:annotation-driven/>
获得基本类型参数
当使用ajax提交时@RequestBody
<script type="text/javascript" src="{pageContext.request.contextPath}/js/jquery-3.3.1.js"></script>
<script>
var userList = new Array();
userList.push({name:"张三",age:18});
userList.push({name:"lisi",age:19});.ajax({
type:"post",
url:"${pageContext.request.contextPath}/user12",
data:JSON.stringify(userList),
contentType:"application/json;charset=utf-8"
})
</script>
@RequestMapping(value = "/user12")
@ResponseBody
public void save12(@RequestBody List<User> userList){
System.out.println(userList);
}
SpringMVC的前端控制器DispatcherServlet的url-pattern配置的是/,代表对所有的资源都进行过滤操作
可以通过以下两种方式指定放行静态资源:
<!--开放资源访问,mapping是映射的路径,location是真实的地址-->
<mvc:resources mapping="/js/**" location="/js/"/>
<!--当虚拟路径缺省时,交给原始的容器处理,找静态资源-->
<mvc:default-servlet-handler/>
Restful风格的请求是使用“url+请求方式”表示一次请求目的的,HTTP 协议里面四个表示操作方式的动词如下:
自定义类型转换器的开发步骤:
定义转换器类实现Converter接口
在配置文件中声明转换器
在中引用转换器