SpringMVC--数据绑定和表单标签的应用（附带实例）

缺乏、安全感 2021-08-13 21:35 316阅读 0赞

#### SpringMVC数据绑定和表单标签的应用 ####

**1） 创建工程并导入相关JAR包**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]

应用中需要使用 JSTL，因此不仅需要将 Spring MVC 的相关 JAR 包复制到应用的 WEN-INF/lib 目录下，还需要从 Tomcat 的 webapps\\examples\\WEB-INF\\lib 目录下将 JSTL 的相关 JAR 包复制到应用的 WEN-INF/lib 目录下。  
![format_png][]

**2）配置web.xml**

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
      <display-name>SpringMVCForm</display-name>
      
      
        <filter>
            <filter-name>encodingFilter</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>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
        </filter>
        <filter-mapping>
            <filter-name>encodingFilter</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>
        
        
        <servlet>
    	  	<servlet-name>springmvc</servlet-name>
    	  	<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    	  	
    	  	<init-param>
    	  		<param-name>contextConfigLocation</param-name>
    	  		<param-value>classpath:springmvc-servlet.xml</param-value>
    	  	</init-param>
      	</servlet>
      	<servlet-mapping>
      		<servlet-name>springmvc</servlet-name>
      		<url-pattern>*.action</url-pattern>
      	</servlet-mapping>
    </web-app>

**3）配置springmvc-servlet.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:p="http://www.springframework.org/schema/p" 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-4.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
    
            
            
            
            <context:component-scan base-package="pers.zhang"/>
            
            
            <mvc:annotation-driven/>
            
            
            <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            	<property name="prefix" value="/WEB-INF/jsp/"/>
            	<property name="suffix" value=".jsp"/>
            </bean>
    </beans>

**4）创建POJO**

package pers.zhang.pojo;
    
    public class User { 
        private String userName;
        private String[] hobby; // 兴趣爱好
        private String[] friends; // 朋友
        private String carrer;
        private String houseRegister;
        private String remark;
    	public String getUserName() { 
    		return userName;
    	}
    	public void setUserName(String userName) { 
    		this.userName = userName;
    	}
    	public String[] getHobby() { 
    		return hobby;
    	}
    	public void setHobby(String[] hobby) { 
    		this.hobby = hobby;
    	}
    	public String[] getFriends() { 
    		return friends;
    	}
    	public void setFriends(String[] friends) { 
    		this.friends = friends;
    	}
    	public String getCarrer() { 
    		return carrer;
    	}
    	public void setCarrer(String carrer) { 
    		this.carrer = carrer;
    	}
    	public String getHouseRegister() { 
    		return houseRegister;
    	}
    	public void setHouseRegister(String houseRegister) { 
    		this.houseRegister = houseRegister;
    	}
    	public String getRemark() { 
    		return remark;
    	}
    	public void setRemark(String remark) { 
    		this.remark = remark;
    	}
        
        
    }

**5）Service层**  
UserService接口：

package pers.zhang.service;
    
    import java.util.ArrayList;
    
    import pers.zhang.pojo.User;
    
    public interface UserService { 
        boolean addUser(User u);
        ArrayList<User> getUsers();
    }

UserService实现类:

package pers.zhang.service;
    
    import java.util.ArrayList;
    
    import org.springframework.stereotype.Service;
    
    import pers.zhang.pojo.User;
    
    @Service
    public class UserServiceImpl implements UserService { 
        // 使用静态集合变量users模拟数据库
        private static ArrayList<User> users = new ArrayList<User>();
    
        @Override
        public boolean addUser(User u) { 
            if (!"IT民工".equals(u.getCarrer())) {  // 不允许添加IT民工
                users.add(u);
                return true;
            }
            return false;
        }
    
        @Override
        public ArrayList<User> getUsers() { 
            return users;
        }
    }

**6）Controller 层:**  
在 Controller 类 UserController 中定义了请求处理方法，包括处理 user/input 请求的 inputUser 方法以及处理 user/save 请求的 addUser 方法，其中在 addUser 方法中用到了重定向。

在 UserController 类中，通过 @Autowired 注解在 UserController 对象中主动注入 UserService 对象，实现对 user 对象的添加和查询等操作。

通过 model 的 addAttribute 方法将 User 类对象、HashMap 类型的 hobbys 对象、String\[\] 类型的 carrers 对象以及 String\[\] 类型的 houseRegisters 对象传递给 View（userAdd.jsp）。

package pers.zhang.controller;
    
    import java.util.HashMap;
    import java.util.List;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.ModelAttribute;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import pers.zhang.pojo.User;
    import pers.zhang.service.UserService;
    
    @Controller
    @RequestMapping("/user")
    public class UserController { 
        // 得到一个用来记录日志的对象,这样在打印信息的时候能够标记打印的是哪个类的信息
        private static final Log logger = LogFactory.getLog(UserController.class);
        @Autowired
        private UserService userService;
    
        @RequestMapping(value = "/input.action")
        public String inputuser(Model model) { 
            HashMap<String, String> hobbys = new HashMap<String, String>();
            hobbys.put("篮球", "篮球");
            hobbys.put("乒乓球", "乒乓球");
            hobbys.put("电玩", "电玩");
            hobbys.put("游泳", "游泳");
            // 如果model中没有user属性，userAdd.jsp会抛出异常，因为表单标签无法找到
            // modelAttribute 属性指定的 form backing object
            model.addAttribute("user", new User());
            model.addAttribute("hobbys", hobbys);
            model.addAttribute("carrers", new String[] {  "教师", "学生", "coding 搬运工",
                    "IT民工", "其他" });
            model.addAttribute("houseRegisters", new String[] {  "北京", "上海", "广州",
                    "深圳", "其他" });
            return "userAdd";
        }
    
        @RequestMapping(value = "/save.action")
        public String addUser(@ModelAttribute User user, Model model) { 
            if (userService.addUser(user)) { 
                logger.info("成功");
                return "redirect:/user/list.action";
            } else { 
                logger.info("失败");
                HashMap<String, String> hobbys = new HashMap<String, String>();
                hobbys.put("篮球", "篮球");
                hobbys.put("乒乓球", "乒乓球");
                hobbys.put("电玩", "电玩");
                hobbys.put("游泳", "游泳");
                // 这里不需要 model.addAttribute ("user", new User ()),因为 @ModelAttribute
                // 指定 form backing object
                model.addAttribute("hobbys", hobbys);
                model.addAttribute("carrers", new String[] {  "教师", "学生",
                        " coding搬运工", "IT民工", "其他" });
                model.addAttribute("houseRegisters", new String[] {  "北京", "上海",
                        "广州", "深圳", "其他" });
                return "userAdd";
            }
        }
    
        @RequestMapping(value = "/list.action")
        public String listUsers(Model model) { 
            List<User> users = userService.getUsers();
            model.addAttribute("users", users);
            return "userList";
        }
    }

**7）View 层**  
View 层包含两个 JSP 页面，一个是信息输入页面 userAdd.jsp，一个是信息显示页面 userList.jsp。在 springMVCDemo04 应用的 WEB-INF/jsp 目录下创建这两个 JSP 页面。

在 userAdd.jsp 页面中将 Map 类型的 hobbys 绑定到 checkboxes 上，将 String\[\] 类型的 carrers 和 houseRegisters 绑定到 select 上，实现通过 option 标签对 select 添加选项，同时表单的 method 方法需指定为 post 来避免中文乱码问题。

在 userList.jsp 页面中使用 JSTL 标签遍历集合中的用户信息 。

userAdd.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <%@taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
        <form:form modelAttribute="user" method="post" action="${pageContext.request.contextPath }/user/save.action">
            <fieldset>
                <legend> 添加一个用户 </legend>
                <P>
                    <label>用户名:</label>
                    <form:input path="userName" />
                </p>
                <P>
                    <label>爱好:</label>
                    <form:checkboxes items="${hobbys}" path="hobby" />
                </p>
                <P>
                    <label>朋友:</label>
                    <form:checkbox path="friends" value="张三" /> 张三
                    <form:checkbox path="friends" value="李四" /> 李四
                    <form:checkbox path="friends" value="王五" /> 王五
                    <form:checkbox path="friends" value="赵六" /> 赵六
                </p>
                <P>
                    <label>职业:</label>
                    <form:select path="carrer">
                        <option />请选择职业
                        <form:options items="${carrers }" />
                    </form:select>
                </p>
                <P>
                    <label>户籍：</label>
                    <form:select path="houseRegister">
                        <option />请选择户籍
                        <form:options items="${houseRegisters }" />
                    </form:select>
                </p>
                <P>
                    <label>个人描述:</label>
                    <form:textarea path="remark" rows="5" />
                </p>
                <p id="buttons">
                    <input id="reset" type="reset">
                    <input id="submit" type="submit" value="添加">
                </p>
            </fieldset>
        </form:form>
    </body>
    </html>

userList.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 PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>用户列表</title>
    </head>
    <body>
        <h1>用户列表</h1>
        <a href="<c:url value="/user/input.action"/>">继续添加</a>
        <table>
            <tr>
                <th>用户名</th>
                <th>兴趣爱好</th>
                <th>朋友</th>
                <th>职业</th>
                <th>户籍</th>
                <th>个人描述</th>
            </tr>
            <c:forEach items="${users}" var="user">
                <tr>
                    <td>${user.userName }</td>
                    <td>
                        <c:forEach items="${user.hobby }" var="hobby">
                            ${hobby } 
                        </c:forEach>
                    </td>
                    <td>
                        <c:forEach items="${user.friends}" var="friend">
                            ${friend } 
                        </c:forEach>
                    </td>
                    <td>${user.carrer }</td>
                    <td>${user.houseRegister }</td>
                    <td>${user.remark }</td>
                </tr>
            </c:forEach>
        </table>
    </body>
    </html>

**8）测试：**  
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![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 2]

更换职业，添加成功  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 3]  
显示列表  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 4]

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[format_png]: /images/20210813/7afdb136b33b4119b552b3ea83d187ae.png
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