SpringMVC的初体验-2

原创

cerana 2022-09-30 10:17:46 博主文章分类：java ©著作权

文章标签 springmvc html spring mvc 文章分类 运维

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一. SpringMVC控制器请求应答

控制层 controller

@RequestMapping请求映射
@RequestParam请求参数
ModelAndView返回模型和视图

@Controller
@RequestMapping("/student")  //分模块
public class StudentController {

  private static List<Student> studentList=new ArrayList<Student>();
  
  static{
    studentList.add(new Student(1,"岳不群",11));
    studentList.add(new Student(2,"平一指",12));
    studentList.add(new Student(3,"张翠山",13));
  }
  
  @RequestMapping("/list")  //请求的是 /student/list.do
  public ModelAndView list(){
    ModelAndView mav=new ModelAndView();
    mav.addObject("studentList", studentList); //设定与前端view交互的参数/对象
    mav.setViewName("student/list");  //设定前端页面list.jsp
    return mav;
  }
  
  @RequestMapping("/preSave")  //请求的是 /student/preSave.do
  public ModelAndView preSave(@RequestParam(value="id",required=false) String id){
    ModelAndView mav=new ModelAndView();
    if(id!=null){
      mav.addObject("student", studentList.get(Integer.parseInt(id)-1)); //设定与前端view交互的参数/对象
      mav.setViewName("student/update"); //设定前端页面update.jsp
    }else{
      mav.setViewName("student/add"); //设定前端页面add.jsp
    }
    return mav;
  }
}

在spring-mvc.xml配置文件中对web静态资源的根目录进行了设定

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

所以视图到资源目录的对应关系如下

视图位置	资源目录
student/list	/WEB-INF/jsp/student/list
student/update	/WEB-INF/jsp/student/update
student/add	/WEB-INF/jsp/student/add

注意在客户端的浏览器中使用的URL

http://localhost:8080/SpringMVCDemo/student/list.do
http://localhost:8080/SpringMVCDemo/student/preSave.do
                                   ^
                                   |----->

视图层 view

index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<% response.sendRedirect("student/list.do"); %>

add.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>学生添加</title>
</head>
<body>
<form action="student/save.do" method="post">
<table>
    <tr>
        <th colspan="2">学生添加</th>
    </tr>
    <tr>
        <td>姓名</td>
        <td><input type="text" name="name"/></td>
    </tr>
    <tr>
        <td>年龄</td>
        <td><input type="text" name="age"/></td>
    </tr>
    <tr>
        <td colspan="2">
            <input type="submit" value="提交"/>
        </td>
    </tr>
</table>
</form>
</body>
</html>

list.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>显示学生信息</title>
</head>
<body>
<a href="${pageContext.request.contextPath}/student/preSave.do">添加学生</a>
<table>
    <tr>
        <th>编号</th>
        <th>姓名</th>
        <th>年龄</th>
        <th>操作</th>    
    </tr>
    <c:forEach var="student" items="${studentList }">
    <tr>
        <td>${student.id }</td>
        <td>${student.name }</td>
        <td>${student.age }</td>
        <td><a href="${pageContext.request.contextPath}/student/preSave.do?id=${student.id}">修改</a></td>
    </tr>
    </c:forEach>
</table>

</body>
</html>

${pageContext.request.contextPath}指的就是/WEB-INF/jsp
推荐使用上边的绝对路径形式。

update.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>更新学生信息</title>
</head>
<body>
<form action="student/save.do" method="post">
<table>
    <tr>
        <th colspan="2">学生修改</th>
    </tr>
    <tr>
        <td>姓名</td>
        <td><input type="text" name="name" value="${student.name }"/></td>
    </tr>
    <tr>
        <td>年龄</td>
        <td><input type="text" name="age" value="${student.age }"/></td>
    </tr>
    <tr>
        <td colspan="2">
            <input type="hidden" name="id" value="${student.id }"/>
            <input type="submit" value="提交"/>
        </td>
    </tr>
</table>
</form>
</body>
</html>

二. SpringMVC的控制器其他应用

SpringMVC对象属性自动封装
控制层Controller内部转发和重定向

控制层代码

@Controller
@RequestMapping("/student")
public class StudentController {
......
  
  @RequestMapping("/save")  //访问的url：/student/save.do
  // 前端表单的name属性值需要与后端实体bean中的类属性名相同，才能完成对象属性的自动封装。
  public String save(Student student){
    if(student.getId()!=0){
      Student s=studentList.get(student.getId()-1);
      s.setName(student.getName());
      s.setAge(student.getAge());
    }else{
      studentList.add(student);      
    }
    // 重定向（不能携带数据，且URL会发生改变。）
    // return "redirect:/student/list.do";
    
    // 内部转发（可以在前端页面间传递数据，且URL不会改变。）
    return "forward:/student/list.do";
  }
  
  @RequestMapping("/delete") //访问的url：/student/delete.do
  public String delete(@RequestParam("id") int id){
    studentList.remove(id-1);
    return "redirect:/student/list.do";
  }
}

POST请求乱码问题的解决
在WEB-INF/web.xml中配置一个过滤器

<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>*.do</url-pattern>
  </filter-mapping>