SpringMvc


SpringMvc


初识SpringMvc

  1. 轻量级,简单易学
  2. 高效 , 基于请求响应的MVC框架
  3. 与Spring兼容性好,无缝结合
  4. 约定优于配置
  5. 功能强大:RESTful、数据验证、格式化、本地化、主题等
  6. 简洁灵活

Spring的web框架围绕DispatcherServlet设计。DispatcherServlet的作用是将请求分发到不同的处理器。从Spring 2.5开始,使用Java 5或者以上版本的用户可以采用基于注解的controller声明方式。


SpringMvc原理

执行流程:

1.设置web.xml中的DispatcherServlet:

<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

<!--  配置DispatcherServlet,这个是核心,请求分发器  -->
<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--    选择配置文件    -->
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springmvc-servlet.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

2.根据bean去找控制器,然后把路径返回:

<!--根据bean去找控制器,然后把路径返回-->
<bean id="/hello" class="com.dyd.controller.HelloController"/>

3.进入Control去处理获得的数据:

package com.dyd.controller;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.mvc.Controller;
//注意:这里我们先导入Controller接口
public class HelloController implements Controller {

    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //ModelAndView 模型和视图
        ModelAndView mv = new ModelAndView();

        //封装对象,放在ModelAndView中。Model
        mv.addObject("msg","HelloSpringMVC!");
        //封装要跳转的视图,放在ModelAndView中
        mv.setViewName("hello"); //: /WEB-INF/jsp/hello.jsp
        return mv;
    }
}

4.根据得到的数据去渲染前端:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

    <!--视图解析器:DispatcherServlet给他的ModelAndView-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--根据bean去找控制器,然后把路径返回-->
    <bean id="/hello" class="com.dyd.controller.HelloController"/>

</beans>

注解SpringMvc

spring.xml

<?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
       https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc
       https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!-- 自动扫描包,让指定包下的注解生效,由IOC容器统一管理 -->
    <context:component-scan base-package="com.dyd.controller"/>
    <!-- 让Spring MVC不处理静态资源 -->
    <mvc:default-servlet-handler />
    <!--
  支持mvc注解驱动
      在spring中一般采用@RequestMapping注解来完成映射关系
      要想使@RequestMapping注解生效
      必须向上下文中注册DefaultAnnotationHandlerMapping
      和一个AnnotationMethodHandlerAdapter实例
      这两个实例分别在类级别和方法级别处理。
      而annotation-driven配置帮助我们自动完成上述两个实例的注入。
   -->
    <mvc:annotation-driven/>

    <!-- 视图解析器 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          id="internalResourceViewResolver">
        <!-- 前缀 -->
        <property name="prefix" value="/WEB-INF/jsp/" />
        <!-- 后缀 -->
        <property name="suffix" value=".jsp" />
    </bean>
</beans>

控制器:

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class HelloController {
    //指定路径
    @RequestMapping("/hello")
    public String hello(Model model){
        //封装数据
        model.addAttribute("msg","hello,springmvcAnnotation");
        return "hello";	//WEB/INF/jsp/hello.jsp
    }
}

RestFul风格

?传参改变为路径传参,同时可以限制访问的方法,通过PathVariable来限制路径。

@Controller
public class RestFulController {
    //http://localhost:8080/add?a=1&b=1
    //RestFul:http://localhost:8080/add/a/b
    @RequestMapping(value = "/add/{a}/{b}",method = RequestMethod.GET)
    public String test1(@PathVariable int a,@PathVariable int b, Model model){
        int res=a+b;
        model.addAttribute("msg",res);
        return "test";
    }
}

请求参数及数据回显

@Controller
@RequestMapping("/user")
public class UserController {
    //http://localhost:8080/user/t1?name=xxx
    @GetMapping("/t1")
    public String test1(@RequestParam("username") String name, Model model){
        //1.接受前端参数
        System.out.println("接受前端的参数为:"+name);
        //2.将返回的结果传递给前端
        model.addAttribute("msg",name);
        //3.跳转视图
        return "test";
    }
    //接受的是一个对象:id,name,age
    /*
     1.接受的是用户传递的参数,判断参数名字,假设名字在方法上可直接使用
     2.传递的是user,匹配user如果一致则ok,否则匹配不到
    */
    @RequestMapping("/t2")
    public String test2(User user){
        System.out.println(user);
        return "test";
    }
}

乱码问题

用过滤器解决乱码,在web.xml中加入配置文件:

<!--  配置mvc乱码过滤  -->
<filter>
    <filter-name>encoding</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>encoding</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

或者用万能过滤器:

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;
 
/**
* 解决get和post请求 全部乱码的过滤器
*/
public class GenericEncodingFilter implements Filter {
 
   @Override
   public void destroy() {
  }
 
   @Override
   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
       //处理response的字符编码
       HttpServletResponse myResponse=(HttpServletResponse) response;
       myResponse.setContentType("text/html;charset=UTF-8");
 
       // 转型为与协议相关对象
       HttpServletRequest httpServletRequest = (HttpServletRequest) request;
       // 对request包装增强
       HttpServletRequest myrequest = new MyRequest(httpServletRequest);
       chain.doFilter(myrequest, response);
  }
 
   @Override
   public void init(FilterConfig filterConfig) throws ServletException {
  }
 
}
 
//自定义request对象,HttpServletRequest的包装类
class MyRequest extends HttpServletRequestWrapper {
 
   private HttpServletRequest request;
   //是否编码的标记
   private boolean hasEncode;
   //定义一个可以传入HttpServletRequest对象的构造函数,以便对其进行装饰
   public MyRequest(HttpServletRequest request) {
       super(request);// super必须写
       this.request = request;
  }
 
   // 对需要增强方法 进行覆盖
   @Override
   public Map getParameterMap() {
       // 先获得请求方式
       String method = request.getMethod();
       if (method.equalsIgnoreCase("post")) {
           // post请求
           try {
               // 处理post乱码
               request.setCharacterEncoding("utf-8");
               return request.getParameterMap();
          } catch (UnsupportedEncodingException e) {
               e.printStackTrace();
          }
      } else if (method.equalsIgnoreCase("get")) {
           // get请求
           Map<String, String[]> parameterMap = request.getParameterMap();
           if (!hasEncode) { // 确保get手动编码逻辑只运行一次
               for (String parameterName : parameterMap.keySet()) {
                   String[] values = parameterMap.get(parameterName);
                   if (values != null) {
                       for (int i = 0; i < values.length; i++) {
                           try {
                               // 处理get乱码
                               values[i] = new String(values[i]
                                      .getBytes("ISO-8859-1"), "utf-8");
                          } catch (UnsupportedEncodingException e) {
                               e.printStackTrace();
                          }
                      }
                  }
              }
               hasEncode = true;
          }
           return parameterMap;
      }
       return super.getParameterMap();
  }
 
   //取一个值
   @Override
   public String getParameter(String name) {
       Map<String, String[]> parameterMap = getParameterMap();
       String[] values = parameterMap.get(name);
       if (values == null) {
           return null;
      }
       return values[0]; // 取回参数的第一个值
  }
 
   //取所有值
   @Override
   public String[] getParameterValues(String name) {
       Map<String, String[]> parameterMap = getParameterMap();
       String[] values = parameterMap.get(name);
       return values;
  }
}

JSON

后端部署后端,提供接口;前端独立部署,负责渲染后端的数据。其中用JSON传输。

JS解析:

<script type="text/javascript">
    var user={
        name:"dyd",
        age:3,
        sex:"male"
    }
    var json = JSON.stringify(user);
    console.log(user);
    console.log(json);
    var obj = JSON.parse(json);
    console.log(obj);
</script>

导入依赖包:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.0</version>
</dependency>

json乱码问题可以在springmvc-servlet.xml中添加配置:

<!--  json乱码配置  -->
<mvc:annotation-driven>
    <mvc:message-converters register-defaults="true">
        <bean class="org.springframework.http.converter.StringHttpMessageConverter">
            <constructor-arg value="UTF-8"/>
        </bean>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                    <property name="failOnEmptyBeans" value="false"/>
                </bean>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

测试:

@ResponseBody
@RequestMapping(value = "/j2")
public String json2() throws JsonProcessingException {
    ObjectMapper mapper = new ObjectMapper();
    List<User> userList = new ArrayList<User>();
    //创建一个对象
    User user1 = new User("dyd1",3,"男");
    User user2 = new User("dyd2",3,"男");
    User user3 = new User("dyd3",3,"男");
    User user4 = new User("dyd4",3,"男");
    userList.add(user1);
    userList.add(user2);
    userList.add(user3);
    userList.add(user4);
    String str = mapper.writeValueAsString(userList);
    return str;
}

FastJson

导入fastjson的包:

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.60</version>
</dependency>

利用工具包:

public class FastJsonDemo {
   public static void main(String[] args) {
       //创建一个对象
       User user1 = new User("秦疆1号", 3, "男");
       User user2 = new User("秦疆2号", 3, "男");
       User user3 = new User("秦疆3号", 3, "男");
       User user4 = new User("秦疆4号", 3, "男");
       List<User> list = new ArrayList<User>();
       list.add(user1);
       list.add(user2);
       list.add(user3);
       list.add(user4);
 
       System.out.println("*******Java对象 转 JSON字符串*******");
       String str1 = JSON.toJSONString(list);
       System.out.println("JSON.toJSONString(list)==>"+str1);
       String str2 = JSON.toJSONString(user1);
       System.out.println("JSON.toJSONString(user1)==>"+str2);
 
       System.out.println("\n****** JSON字符串 转 Java对象*******");
       User jp_user1=JSON.parseObject(str2,User.class);
       System.out.println("JSON.parseObject(str2,User.class)==>"+jp_user1);
 
       System.out.println("\n****** Java对象 转 JSON对象 ******");
       JSONObject jsonObject1 = (JSONObject) JSON.toJSON(user2);
       System.out.println("(JSONObject) JSON.toJSON(user2)==>"+jsonObject1.getString("name"));
 
       System.out.println("\n****** JSON对象 转 Java对象 ******");
       User to_java_user = JSON.toJavaObject(jsonObject1, User.class);
       System.out.println("JSON.toJavaObject(jsonObject1, User.class)==>"+to_java_user);
  }
}

Ajax

直接用前端JS进行书写:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>iframe测试体验页面无刷新</title>

    <script>
        function go(){
            var url = document.getElementById("url").value;
            document.getElementById("iframe1").src=url;
        }
    </script>
</head>
<body>
<div>
    <p>请输入地址:</p>
    <p>
        <input type="text" id="url" value="https://www.bilibili.com/">
        <input type="button" value="提交" onclick="go()">
    </p>
</div>

<div>
    <iframe id="iframe1" style="width: 100%;height: 500px"></iframe>
</div>
</body>
</html>

拦截器

创建com.dyd.config包,构建MyInterceptor:

package com.dyd.config;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyInterceptor implements HandlerInterceptor {
    //执行下一个拦截器,放行
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("====处理前====");
        return true;
    }

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

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("====清理====");
    }
}

在application中添加配置:

<!--  拦截器配置  -->
<mvc:interceptors>
    <mvc:interceptor>
        <!--  拦截所有请求  -->
        <mvc:mapping path="/**"/>
        <bean class="com.dyd.config.MyInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

设置登录拦截

controlller:

package com.dyd.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpSession;

@Controller
@RequestMapping("/user")
public class LoginController {
    @RequestMapping("/main")
    public String main()
    {
        return "main";
    }

    @RequestMapping("/goLogin")
    public String login()
    {
        return "login";
    }

    @RequestMapping("/login")
    public String login(HttpSession session, String username, String password, Model model)
    {
        session.setAttribute("userLoginInfo",username);
        model.addAttribute("username",username);
        return "main";
    }

    @RequestMapping("/goOut")
    public String login(HttpSession session)
    {
        session.removeAttribute("userLoginInfo");
        return "login";
    }
}

设置config中的login拦截:

package com.dyd.config;

import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession();
        //登录页面也会放行
        if(request.getRequestURI().contains("goLogin"))   return true;
        //第一次登录也没有session
        if(request.getRequestURI().contains("login"))   return true;
        //判断是否设置session
        if(session.getAttribute("userLoginInfo")!=null) return true;
        request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,response);
        return false;
    }
}

利用aop进行横切:

<!--  拦截器配置  -->
<mvc:interceptors>
    <mvc:interceptor>
        <!--  拦截所有请求  -->
        <mvc:mapping path="/**"/>
        <bean class="com.dyd.config.MyInterceptor"/>
    </mvc:interceptor>
    <mvc:interceptor>
        <!--  拦截所有请求  -->
        <mvc:mapping path="/user/**"/>
        <bean class="com.dyd.config.LoginInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

文件上传

导入依赖包:

<dependencies>
    <dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.4</version>
    </dependency>
    <!--导入高版本的api-->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>4.0.1</version>
    </dependency>
</dependencies>

二进制流前端表单:

<form enctype="multipart/form-data" method="post" action="${pageContext.request.contextPath}/upFile">
  <input type="file" name="file">
  <input type="submit" value="upload">
</form>

Spring自带的文件上传,application.xml配置:

<!--4 文件上传配置-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <property name="defaultEncoding" value="utf-8"/>
    <!--最大上传大小:单位是1字节-->
    <property name="maxUploadSize" value="10485760"/>
    <property name="maxInMemorySize" value="40960"/>
</bean>

控制器:

@RestController
public class FileController {
    @RequestMapping("/upFile")
    public String upFile(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        //设置文件保存路径
        String path = request.getServletContext().getRealPath("/upload");
        System.out.println("path:" + path);
        File realPath = new File(path);
        if (!realPath.exists()) {
            realPath.mkdir();
        }
        System.out.println("上传的文件地址:" + realPath);
        //CommonsMultipartFile的方法写文件,简化
        file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));
        return "redirect:/index.jsp";
    }
}

文件下载

在文件上传的基础上,添加以下controller:

@RequestMapping(value = "/download")
public String downLoad(HttpServletResponse response, HttpServletRequest request) throws IOException {
    //手动设置,要下载的图片地址
    String path = request.getServletContext().getRealPath("/upload");
    String fileName = "1.png";
    //设置响应头
    response.reset();//设置页面不缓存,清空buffer
    response.setCharacterEncoding("UTF-8");
    response.setContentType("multipart/form-data");//二进制传输数据
    response.setHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode(fileName, "UTF-8"));
    File file = new File(path, fileName);
    //读取文件-输入流
    InputStream input = new FileInputStream(file);
    //写入文件-输出流
    OutputStream out = response.getOutputStream();
    byte[] buff = new byte[1024];
    int index = 0;
    while ((index = input.read(buff)) != -1) {
        out.write(buff,0,index);
        out.flush();
    }
    input.close();
    out.close();
    return "redirect:/index.jsp";
}


文章作者: Dydong
版权声明: 本博客所有文章除特別声明外,均采用 CC BY 4.0 许可协议。转载请注明来源 Dydong !
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