大数据正式33

大数据正式33

SpringMVC

• Servlet缺点
  1. 一个Servlet有8行配置文件
  2. 一个Servlet只能处理一个业务
  3. 一张表可能有4+n个Servlet，所以会有32+n行配置文件
  4. 获取属性只能得到字符串类型，需要自己转换类型
  5. 获取参数只能是request.getParameter()
• SpringMVC优点
  1. 不管工程中有多少servlet，只需要配置一个servlet分发器即可
  2. springmvc中使用controller替代一个controller
  3. 获取参数的类型支持自动装换，而且支持对象的自动封装
  4. SpringMvc有多种获取参数的方式

SprigMVC入门案例

• jar包
• 项目结构
• 整体流程

• 代码

  • web.xml

    
    
        
        
            springmvc
            
            org.springframework.web.servlet.DispatcherServlet
            
            
                contextConfigLocation
                classpath:/applicationContext-mvc.xml
            
        
        
            springmvc
            
            *.action
        
        
            index.jsp
        
    
    

  • applicationContext-mvc.xml

  • com.peng.controller

    • HelloController

      package com.peng.controller;
      
      import javax.servlet.http.HttpServletRequest;
      import javax.servlet.http.HttpServletResponse;
      
      import org.springframework.web.servlet.ModelAndView;
      import org.springframework.web.servlet.mvc.Controller;
      
      public class HelloController implements Controller {
      
          public ModelAndView handleRequest(HttpServletRequest request,
                  HttpServletResponse response) throws Exception {
              ModelAndView modelAndView = new ModelAndView();
              modelAndView.setViewName("index.jsp");
              modelAndView.addObject("msg", "hello");
              return modelAndView;
          }
      }
      

  • index.jsp

    <%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
    <%
        String path = request.getContextPath();
        String basePath = request.getScheme() + "://"
                + request.getServerName() + ":" + request.getServerPort()
                + path + "/";
    %>
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
        This is my JSP page.
        
    
        
    ${msg}
    
    
    

• 访问名称
  • http://localhost/SpringMVC_inroom/hello.action（注：端口为80）
• 执行结果

注解形式的SpringmMVC

package com.peng.controller;

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

@Controller
public class HelloController {
    @RequestMapping("/hello.action")
    public String helloAction(Model model) {
        model.addAttribute("msg", "hello,world!");
        return "index";
    }
}

添加前后缀的SpringMVC(applicationContext-mvc.xml)

解决乱码--过滤器(web.xml)

    
        characterFilter
        org.springframework.web.filter.CharacterEncodingFilter
        
            encoding
            utf-8
        
    
    
        characterFilter
        /*
    

数据的获取

• HttpServletRequest对象的getParameter方法

  package com.peng.controller;
  
  import javax.servlet.http.HttpServletRequest;
  
  import org.springframework.stereotype.Controller;
  import org.springframework.ui.Model;
  import org.springframework.web.bind.annotation.RequestMapping;
  
  @Controller
  public class UserController {
      @RequestMapping("/showAddUser.action")
      public String showAddUser() {
          return "addUser";
      }
  
      @RequestMapping("/addUser.action")
      public String addUser(HttpServletRequest request, Model model) {
          String username = request.getParameter("username");
          System.out.println(username);
          model.addAttribute("username", username);
          return "addUser";
      }
  }
  

• 与表单的name值一样的参数String username

  • 参数名来控制

    package com.peng.controller;
    
    import javax.servlet.http.HttpServletRequest;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    @Controller
    public class UserController {
        @RequestMapping("/showAddUser.action")
        public String showAddUser() {
            return "addUser";
        }
    
        @RequestMapping("/addUser.action")
        public String addUser(String username, Model model) {
            System.out.println(username);
            model.addAttribute("username", username);
            return "addUser";
        }
    }
    

• bean对象 User

  • 参数名来控制

    package com.peng.controller;
    
    import javax.servlet.http.HttpServletRequest;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    @Controller
    public class UserController {
        @RequestMapping("/showAddUser.action")
        public String showAddUser() {
            return "addUser";
        }
    
        @RequestMapping("/addUser.action")
        public String addUser(User user, Model model) {
            System.out.println(user.username);
            model.addAttribute("username", user.username);
            return "addUser";
        }
    }
    

• 对象中的对象

  • 参数名来控制

    • dog.name

    • gog.age

      class Dog{
          private String name;
      
          public void setName(String name){
              this.name=name;
          }
      
          public String getName(){
              return this.name;
          }
      }
      

      class User{
          private dog;
      
          public void setDog(Dog dog{
              this.dog=dog;
          }
      
          public Dog getDog(){
              return this.dog;
          }
      }
      

      package com.peng.controller;
      
      import javax.servlet.http.HttpServletRequest;
      
      import org.springframework.stereotype.Controller;
      import org.springframework.ui.Model;
      import org.springframework.web.bind.annotation.RequestMapping;
      
      @Controller
      public class UserController {
          @RequestMapping("/showAddUser.action")
          public String showAddUser() {
              return "addUser";
          }
      
          @RequestMapping("/addUser.action")
          public String addUser(String username, Model model) {
              System.out.println(user.dog.name);
              model.addAttribute("username", user.dog.name);
              return "addUser";
          }
      }
      

日期问题

• 格式问题

  2017/12/25这个错误；
  2017-12-25这个可以；
  

• 解决（Controller中）

  @InitBinder
      public void InitBinder(ServletRequestDataBinder srdb) {
          srdb.registerCustomEditor(java.util.Date.class, new CustomDateEditor(
                  new SimpleDateFormat("yyyy-MM-dd"), true));
      }   
  

参数的同名提交

• String

  a,b,c
  

• 例子

  @RequestMapping("/addUser.action")
  public String addUser(
          HttpServletRequest request,
          Model model,
          Date date,
          String like) {
      String username = request.getParameter("username");
      System.out.println(username + date.toString() + like);
      model.addAttribute("username", username);
      return "addUser";
  }
  

• String[]

  {a,b,c}数组形式
  

• 例子

  @RequestMapping("/addUser.action")
  public String addUser(
          HttpServletRequest request,
          Model model,
          Date date,
          String[] like) {
      String username = request.getParameter("username");
      System.out.println(username + date.toString() + Arrays.toString(like));
      model.addAttribute("username", username);
      return "addUser";
  }
  

参数名称不一致的问题

• 问题呈现
  • form表单提交过来的name和参数中的name值不相同时--因为要见名知义，稍微改动了参数的名称
• @RequestParam("hobby")String[] hobbies
• @RequestParam
  • value--对应form中的name值
  • defaultValue--默认的值
  • require--必须传过来时有参数
• 例子

  @RequestMapping("/addUser.action")
  public String addUser(
          HttpServletRequest request,
          Model model,
          Date date,
          @RequestParam(value = "like", defaultValue = "啥也不喜欢！") String[] likes) {
      String username = request.getParameter("username");
      System.out.println(username + date.toString() + Arrays.toString(likes));
      model.addAttribute("username", username);
      return "addUser";
  }
  

文件上传

• 注意的坑
  1. form中的参数
     1. method：post
     2. enctype：multipart/form-data
  2. file文件标签
     1. 必须有name属性
  3. 文件解析器
     1. 必须有id属性
     2. id属性的值必须是：multipartResolver

• 改三个地方

  1. jsp中

     <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
     
     
     
     
     
     
     
         
     
             
     
                 
     
                     
     用户名：
                     
     
                     
                 
                 
     
                     
     时间：
                     
     
                     
                 
                 
     
                     
     上传文件：
                     
     
                     
                 
                 
     
                     
     爱好：
                     
     篮球
                         足球 乒乓球
                 
                 
     
                     
     提交：
                     
     
                     
                 
             
         
     
     
     

  2. 解析器（必须有id和class）

  3. 后台

     package com.peng.controller;
     
     import java.io.File;
     import java.io.IOException;
     import java.text.SimpleDateFormat;
     
     import org.apache.commons.io.FileUtils;
     import org.springframework.beans.propertyeditors.CustomDateEditor;
     import org.springframework.stereotype.Controller;
     import org.springframework.web.bind.ServletRequestDataBinder;
     import org.springframework.web.bind.annotation.InitBinder;
     import org.springframework.web.bind.annotation.RequestMapping;
     import org.springframework.web.bind.annotation.RequestParam;
     import org.springframework.web.multipart.MultipartFile;
     
     @Controller
     public class UserController {
         @RequestMapping("/showAddUser.action")
         public String showAddUser() {
             return "addUser";
         }
     
         @RequestMapping("/addUser.action")
         public String addUser(@RequestParam MultipartFile file) throws IOException {
             FileUtils.writeByteArrayToFile(new File(
                     "C:\\Users\\Administrator.PC-20160710IJPJ\\Desktop\\haha.png"),
                     file.getBytes());
             System.out.println(file.toString());
             return "addUser";
         }
     
         @InitBinder
         public void InitBinder(ServletRequestDataBinder srdb) {
             srdb.registerCustomEditor(java.util.Date.class, new CustomDateEditor(
                     new SimpleDateFormat("yyyy-MM-dd"), true));
         }
     }
     

请求和重定向

• 默认是转发
• 重定向--不能直接写界面，尤其是WEB-INF下的界面

  return "redirect:请求"
  return "redirect:addUser.action"
  

补充