SpringMVC的异常处理和REST风格的实例应用(十三)下

2021-06-24 23:44:21

五. REST 风格的CRUD

不熟悉SpringMVC 的JSON用法的，可以参照老蝴蝶以前写的文章： SpringMVC的JSON处理及FastJSON的整合使用(七)

对 form 表单传递的 _method ，不熟悉的，可以参照老蝴蝶以前写的文章:

SpringMVC的form表单标签使用(八)

json使用的是fastjson.

五.一 User.java 实体类

public class User implements Serializable{
    private static final long serialVersionUID = 1L;
    private Integer id;
    private String name;
    private String sex;
    private Integer age;
    private String description;
    private String password;
    public User() {
        super();
    }
    public User(Integer id, String name, String password,String sex, Integer age, String description) {
        super();
        this.id = id;
        this.name = name;
        this.password=password;
        this.sex = sex;
        this.age = age;
        this.description = description;
    }
    //省略了setter和getter方法
}

五.二 Dao接口和实现类来存储数据

利用静态类进行存储数据，而不是存储在数据库里。 SpringMVC与数据库整合，老蝴蝶放在下面的文章中讲。

UserDao.java

package com.yjl.dao;

import java.util.List;

import com.yjl.pojo.User;

public interface UserDao {
    int addUser(User user);
    int deleteUserById(int id);
    int updateUser(User user);
    List<User> findAll();
    User findById(int id);
}

UserDaoImpl.java

package com.yjl.dao;

import java.util.ArrayList;
import java.util.List;

import org.springframework.stereotype.Repository;

import com.yjl.pojo.User;

@Repository
public class UserDaoImpl implements UserDao{
    private static List<User> userList=new ArrayList<User>();
    static {
    //好久没有用这些人名了，都快忘记自己的初心了。
        User user1=new User(1,"父亲","123","男",50,"爸爸");
        User user2=new User(2,"母亲","123","女",48,"妈妈");
        User user3=new User(3,"慧芳","123","女",27,"大姐");
        User user4=new User(4,"正伟","123","男",28,"大姐夫");
        User user5=new User(5,"莉莉","123","女",25,"二姐");
        User user6=new User(6,"敬龙","123","男",26,"二姐夫");
        User user7=new User(7,"两个蝴蝶飞","123","男",24,"在下");
        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        userList.add(user4);
        userList.add(user5);
        userList.add(user6);
        userList.add(user7);
    }
    @Override
    public int addUser(User user) {
        userList.add(user);
        return 1;
    }
    @Override
    public int deleteUserById(int id) {
        //如果id一样，就表示是同一个对象。
        User user=findById(id);
        if(user!=null){
            userList.remove(user);
        }
        return 1;
    }
    @Override
    public int updateUser(User user) {
        User user1=findById(user.getId());
      //应该是修改，老蝴蝶这为了方便，先删除，再添加。
        if(user1!=null){
            userList.remove(user1);
        }
        userList.add(user);
        return 1;
    }
    @Override
    public List<User> findAll() {
        return userList;
    }
    @Override
    public User findById(int id) {
        for(User user:userList){
            if(user.getId()==id){
                return user;
            }
        }
        return null;
    }
}

这里，省略service层，直接Action层调用。

五.三后端UserAction 实现

package com.yjl.action;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.yjl.dao.UserDao;
import com.yjl.pojo.User;

/**
@atuhor:yuejl
@Description: 类描述
*/
@Controller
@RequestMapping(value="/user")
public class UserAction {
    @Autowired
    private UserDao userDao;
    //转到登录的页面
    @RequestMapping(value="toLogin")
    public String toLogin(Model model){
        model.addAttribute("user",new User());
        return "user/login";
    }
    //在后端的时候， 用@PathVariable 注解进行接收REST 风格的传参。
    //一定不要忘记添加 produces 属性。  添加时，方法为POST
    @RequestMapping(value="add",method=RequestMethod.POST,produces={"application/json"})
    public @ResponseBody Map<String,Object> add(User user){
        System.out.println("user:"+user.toString());
        userDao.addUser(user);
        Map<String,Object> resultMap=new HashMap<String,Object>();
        resultMap.put("request_status",true);
        return resultMap;
    }
    //修改时，方法为PUT   
    @RequestMapping(value="edit/{id}",method=RequestMethod.PUT,produces={"application/json"})
    public @ResponseBody Map<String,Object> edit(User user){
        userDao.updateUser(user);
        Map<String,Object> resultMap=new HashMap<String,Object>();
        resultMap.put("request_status",true);
        return resultMap;
    }
    //删除时，方法用DELETE
    @RequestMapping(value="deleteById/{id}",method=RequestMethod.DELETE,produces={"application/json"})
    public @ResponseBody Map<String,Object> deleteById(@PathVariable(value="id") int id){
        userDao.deleteUserById(id);
        Map<String,Object> resultMap=new HashMap<String,Object>();
        resultMap.put("request_status",true);
        return resultMap;
    }
    //查询时，用GET
    @RequestMapping(value="findById/{id}",method=RequestMethod.GET,produces={"application/json"})
    public @ResponseBody Map<String,Object> findById(@PathVariable(value="id") int id){
        User user=userDao.findById(id);
        Map<String,Object> resultMap=new HashMap<String,Object>();
        resultMap.put("request_status",true);
        resultMap.put("user",user);
        return resultMap;
    }
    //查询时，用GET
    @RequestMapping(value="findAll",method=RequestMethod.GET,produces={"application/json"})
    public @ResponseBody Map<String,Object> findAll(){
        List<User> userList=userDao.findAll();
        Map<String,Object> resultMap=new HashMap<String,Object>();
        resultMap.put("request_status",true);
        resultMap.put("userList",userList);
        return resultMap;
    }
}

定义一个resultMap 对象，返回json数据，为true表示成功，来提示前端。前端根据request_status 来确定是否成功执行后端程序。

五.四 springmvc.xml 配置JSON

springmvc.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:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx"
    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/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd ">
    <!-- 配置的是注解的,重写视图解析器 -->
    <context:component-scan base-package="com.yjl"></context:component-scan>
    
    <!--配置静态资源 -->
    <mvc:resources location="/js/" mapping="/js/**"></mvc:resources>
    <mvc:resources location="/css/" mapping="/css/**"></mvc:resources>
    <mvc:resources location="/image/" mapping="/image/**"></mvc:resources>
    
    <!-- 设置fastjson的配置方案 -->
    <mvc:annotation-driven>
        <!-- 设置不使用默认的消息转换器 -->
        <mvc:message-converters register-defaults="false">
            <!-- 配置Spring的转换器 -->
            <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.xml.XmlAwareFormHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.BufferedImageHttpMessageConverter"/>
            <!-- 配置fastjson中实现HttpMessageConverter接口的转换器 -->
            <bean id="fastJsonHttpMessageConverter" 
                class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
                <!-- 加入支持的媒体类型：返回contentType -->
                <property name="supportedMediaTypes">
                    <list>
                        <!-- 这里顺序不能反，一定先写text/html,不然ie下会出现下载提示 -->
                       <value>text/html;charset=UTF-8</value>
                        <value>application/json;charset=UTF-8</value>
                    </list>
                </property>
                 <!-- 可添加其他的属性来扩展功能,如日期 -->
                 <property name="features">
                    <list>
                    <!-- 默认的意思就是不配置这个属性，配置了就不是默认了 -->
                       <!-- 是否输出值为null的字段 ，默认是false-->
                        <value>WriteMapNullValue</value>
                        
                        <value>WriteNullNumberAsZero</value>
                        <value>WriteNullListAsEmpty</value>
                        <value>WriteNullStringAsEmpty</value>
                        <value>WriteNullBooleanAsFalse</value>
                        <value>WriteDateUseDateFormat</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
    
    <!-- 视图解析器 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!-- 前缀 -->
        <property name="prefix" value="/WEB-INF/jsp/"></property>
        <!-- 后缀 -->
        <property name="suffix" value=".jsp"></property>
    </bean>
</beans>

五.六 web.xml 配置

配置过滤器，顺序不能弄错。

<!--配置中文乱码过滤器-->
  <filter>
    <filter-name>EncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter
    </filter-class>
    <init-param>
        <!-- 类里面有一个属性 encoding,来动态注入编码 -->
        <param-name>encoding</param-name>
        <param-value>utf-8</param-value>
    </init-param>
    <init-param>
        <!-- 是否强制使用encoding的编码方式。 默认为false -->
        <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>
  
   <!-- 配置隐藏请求方法过滤器 -->
     <filter>  
       <filter-name>hiddenHttpMethodFilter</filter-name>  
       <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>  
    </filter>  
    <filter-mapping>  
       <filter-name>hiddenHttpMethodFilter</filter-name>  
       <url-pattern>/*</url-pattern>  
    </filter-mapping>
  
  <!-- 过滤器 -->
  <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.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>

五.七前端Ajax 实现

<body>
    <h2>两个蝴蝶飞,REST使用</h2>
    <form:form commandName="user" type="post">
        <button type="button" id="add" onclick="addJson()">添加</button><br/>
        <button type="button" id="edit" onclick="editJson()">修改</button><br/>
        <button type="button" id="delete" onclick="delJson()">删除</button><br/>
        <button type="button" id="findById" onclick="findByIdJson()">查询id></button><br/>
        <button type="button" id="findAll" onclick="findAllJson()">查询全部</button><br/>
        <div id="showId"> 展示的信息</div>
    </form:form>
    
    <script>
    function addJson(){
    //添加一个id=10的数据
        jsonAjax("add","add","id=10&name=精灵妹&password=1234&sex=女&age=24&description=一个快乐的精灵&_method=POST");
    }
    function editJson(){
    //修改id=10的数据， 修改名称和描述
        jsonAjax("edit","edit/10","id=10&name=精灵妹&description=一个快乐的精灵哈哈&_method=PUT");      
        }
    function delJson(){
    //删除id=10的元素
        jsonAjax("delete","deleteById/10","_method=DELETE");
    }
    function findByIdJson(){
    //查询id=10的数据
        jsonAjax("findById","findById/10","_method=GET");
    }
    function findAllJson(){
    //查询全部
        jsonAjax("findAll","findAll","_method=GET");
    }
    function jsonAjax(sign,url,data){
        var message="";
        switch(sign){
            case "add":{
                message="添加成功";
                break;
            }
            case "edit":{
                message="修改成功";
                break;
            }
            case "delete":{
                message="删除成功";
                break;
            }
            case "findById":{
                message="查询单个成功";
                break;
            }
            case "findAll":{
                message="查询全部成功";
                break;
            }
        }
        
        $.ajax({
            type:"post", 
            url:url,  //注意请求路径
            data:data,
            success:function(resultData){
                if(resultData.request_status){
                    //清空
                    $("#showId").empty();
                    //追加
                    $("#showId").append(message+"<br/>");
                    
                    if(sign=="findById"){
                        var data=resultData.user;
                        var str="<table><tr><th>编号</th><th>姓名</th><th>描述</th></tr>";
                        str+="<tr>"; 
                        str+="<td>"+data.id+"</td>"; 
                        str+="<td>"+data.name+"</td>"; 
                        str+="<td>"+data.description+"</td>"; 
                        str+="</tr>"; 
                        str+="</table>";
                        $("#showId").append(str);
                    }
                    if(sign=="findAll"){
                        var data=resultData.userList;
                        var str="<table><tr><th>编号</th><th>姓名</th><th>描述</th></tr>";
                        $.each(data,function(idx,item){ 
                            str+="<tr>"; 
                            str+="<td>"+item.id+"</td>"; 
                            str+="<td>"+item.name+"</td>"; 
                            str+="<td>"+item.description+"</td>"; 
                            str+="</tr>"; 
                        }) 
                        str+="</table>";
                        $("#showId").append(str);
                    }
                }
            }
        })
    }
    </script>
</body>