JAVA 实现下拉列表代码案例

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jack 2024-10-30 23:52:36

文章标签 JAVA 实现下拉列表代码案例 vue.js spring boot spring User 文章分类 Java 后端开发

下拉列表

1. 第一种下拉（查询）：

1.1 创建springboot工程 (pvue0106)
1.2 导入pom依赖（要写的两个）
1.3 application.yml
1.4 cn.kgc.entity/ Dept、User
1.5 cn.kgc.mapper/UserMapper
1.6 resources/mapper/UserMapper.xml
1.7 cn.kgc.service/UserService、UserServiceImpl
1.8 cn.kgc.controller/UserController
1.9 loback.xml日志（省略）
1.10 vue 新建文件夹

2. 第二种下拉（添加）：

2.1 创建springboot工程 (pvue0106)
2.2 导入pom依赖（要写的两个）
2.3 application.yml
2.4 cn.kgc.entity/ Classes、Student
2.5 cn.kgc.mapper/ StudentMapper
2.6 resources/mapper/ StudentMapper.xml
2.7 cn.kgc.service/ StudentService、StudentServiceImpl
2.8 cn.kgc.controller/ StudentController
2.9 loback.xml日志（省略）
2.10 vue 新建文件夹

3. 第三种下拉（修改）：

3.1 测试

1. 第一种下拉（查询）：

1.1 创建springboot工程 (pvue0106)

Spring Web
MyBatis Framework
MySQL Driver

1.2 导入pom依赖（要写的两个）

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.21</version>
</dependency>
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.4.1</version>
</dependency>

1.3 application.yml

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/db_vue2_user
?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&zeroDateTimeBehavior=CONVERT_TO_NULL
    username: root
    password: zjj
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/*Mapper.xml
pagehelper:
  helper-dialect: mysql
  reasonable: true
server:
  port: 8093

1.4 cn.kgc.entity/ Dept、User

User

package cn.kgc.entity;
import java.io.Serializable;

public class User implements Serializable {
    private Integer id;
    private String name;
    private String pwd;
	private Integer deptId;
//省略getter和setter方法
}

Dept

package cn.kgc.entity;
import java.io.Serializable;

public class Dept implements Serializable {
    private Integer id;
    private String name;
//省略getter和setter方法
}

1.5 cn.kgc.mapper/UserMapper

package cn.kgc.mapper;

import cn.kgc.entity.Dept;
import cn.kgc.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

@Mapper
public interface UserMapper {
    //1.分页查询所有用户信息列表
    List<User> findAllByPage();

    //2.通过部门id查询用户信息列表
    List<User> findByDeptId(@Param("deptId") Integer deptId);

    //3.查询所有部门信息列表
    List<Dept> findAllDept();
}

1.6 resources/mapper/UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.kgc.mapper.UserMapper">
    <select id="findAllByPage" resultType="cn.kgc.entity.User">
        select * from t_user
    </select>
    <select id="findByDeptId" resultType="cn.kgc.entity.User">
        select * from t_user where 1=1
        <if test="deptId != null and deptId != -1">
            and deptId = #{deptId}
        </if>
    </select>
<!--    如果用美元符号就不用写注解了-->
    <select id="findAllDept" resultType="cn.kgc.entity.Dept">
        select * from t_dept
    </select>
</mapper>

1.7 cn.kgc.service/UserService、UserServiceImpl

UserService

package cn.kgc.service;

import cn.kgc.entity.Dept;
import cn.kgc.entity.User;
import com.github.pagehelper.PageInfo;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface UserService {
    PageInfo<User> findAllByPage(Integer pageNo);
    PageInfo<User> findByDeptId(Integer pageNo,@Param("deptId") Integer deptId);
    List<Dept> findAllDept();
}

UserServiceImpl

package cn.kgc.service;

import cn.kgc.entity.Dept;
import cn.kgc.entity.User;
import cn.kgc.mapper.UserMapper;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.List;

@Service
@Transactional
public class UserServiceImpl implements UserService {
    @Resource
    private UserMapper userMapper;
    @Override
    public PageInfo<User> findAllByPage(Integer pageNo) {
        PageHelper.startPage(pageNo,3);
        return new PageInfo<>(userMapper.findAllByPage());
    }

    @Override
    public PageInfo<User> findByDeptId(Integer pageNo,Integer deptId) {
        PageHelper.startPage(pageNo,3);
        return new PageInfo<>(userMapper.findByDeptId(deptId));
    }

    @Override
    public List<Dept> findAllDept() {
        return userMapper.findAllDept();
    }
}

1.8 cn.kgc.controller/UserController

package cn.kgc.controller;

import cn.kgc.entity.Dept;
import cn.kgc.entity.User;
import cn.kgc.service.UserService;
import com.github.pagehelper.PageInfo;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;

@RestController
@CrossOrigin
public class UserController {
    @Resource
    private UserService userService;
    @RequestMapping("/findAllByPage")
    public PageInfo<User> findAllByPage(@RequestParam(defaultValue = "1") Integer pageNo){
        return userService.findAllByPage(pageNo);
    }
//上面的是老版本，新版本用下面的。
    @RequestMapping("/findByDeptId")
    public PageInfo<User> findByDeptId(@RequestParam(defaultValue = "1") Integer pageNo,
                                       Integer deptId){
//后端有可能也需要进行处理和测试，所以可以加个来进行测试 前后端分离
        return userService.findByDeptId(pageNo, deptId);
    }
    @RequestMapping("/findAllDept")
    public List<Dept> findAllDept(){
        return userService.findAllDept();
    }
}

1.9 loback.xml日志（省略）

1.10 vue 新建文件夹

新建一个文件夹vue0106，并作一系列操作

JAVA 实现下拉列表代码案例_JAVA 实现下拉列表代码案例

src/App.vue（省略）
src/Views
list.vue
src/router/index.js(省略)
views/List.vue

<!--  -->
<template>
    <div class=''>
        部门分类：
        <select v-model="queryPage.deptId">
            <!-- Vue中使用v-model指令来实现表单元素和数据的双向绑定。监听用户的输入，然后更新数据。 -->
            <option value="-1">全部</option>
            <option v-for="dept in depts" :key="dept.id" :value="dept.id">{{dept.name}}</option>
            <!-- ： 就是动态 
            :key="dept.id" 第二种写法 这个更好-->
        </select>

        <input type="button" value="查询" @click="getPage(1)">

        <table border="1px solid">
            <tr>
                <td>编号</td>
                <td>姓名</td>
                <td>密码</td>
                <td>部门编号</td>
            </tr>
            <tr v-for="(user,index) in page.list" :key="index" style="text-align:center">
                <td>{{user.id}}</td>
                <td>{{user.name}}</td>
                <td>{{user.pwd}}</td>
                <td>{{user.deptId}}</td>
                <!-- 双向绑定 既能获取值 又能发送值  省略了各种jquery的操作-->
            </tr>
            <tr>
                <td colspan="4" style="text-align:center">
                    <a href="javascript:void(0)" @click="getPage(1)">首页</a>
                    <a href="javascript:void(0)" @click="getPage(page.prePage)">上一页</a>
                    <a href="javascript:void(0)" @click="getPage(page.nextPage)">下一页</a>
                    <a href="javascript:void(0)" @click="getPage(page.pages)">末页</a>
                </td>
            </tr>
        </table>
    </div>
</template>

<script>
import axios from "axios"
export default {  
    components: {},
    data() {
        return {
            depts:[],
            //定义数组 是个集合
            page: {},
            queryPage:{
                pageNo:1,
                deptId:-1
            }
        };
    },
    //监听属性 类似于data概念
    computed: {},
    //监控data中的数据变化
    watch: {},
    
    methods: {
        getDept(){
            axios.get("http://localhost:8092/findAllDept").then(data=>{
                this.depts = data.data;
            });
        },
        getPage(pageNo){
            this.queryPage.pageNo = pageNo;
            // 以json的格式   params:this.queryPage 传对象
            axios.get("http://localhost:8092/findByDeptId",{params:this.queryPage}).then(data=>{
                this.page = data.data;
            })
        }
    },
    //生命周期 - 挂载完成（可以访问DOM元素）
    mounted() {
        this.getDept();
        this.getPage(1);
    },
    }
</script>
<style scoped>
</style>

JAVA 实现下拉列表代码案例_User_02

6. 测试

http://localhost:8081/

JAVA 实现下拉列表代码案例_vue.js_03

JAVA 实现下拉列表代码案例_JAVA 实现下拉列表代码案例_04

JAVA 实现下拉列表代码案例_JAVA 实现下拉列表代码案例_05

2. 第二种下拉（添加）：

2.1 创建springboot工程 (pvue0106)

Spring Web
MyBatis Framework
MySQL Driver

2.2 导入pom依赖（要写的两个）

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.21</version>
</dependency>
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.4.1</version>
</dependency>

2.3 application.yml

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/db_vue3_student
?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&zeroDateTimeBehavior=CONVERT_TO_NULL
    username: root
    password: zjj
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/*Mapper.xml
pagehelper:
  helper-dialect: mysql
  reasonable: true
server:
  port: 8093

2.4 cn.kgc.entity/ Classes、Student

Classes

package cn.kgc.entity;

import java.io.Serializable;

public class Classes implements Serializable {
    private Integer id;
    private String name;
 //省略getter和setter方法
}

Student

package cn.kgc.entity;

import java.io.Serializable;

//实体类不受数据库约束，类型可以随便写
public class Student implements Serializable {
    private Integer id;
    private String name;
    private Integer age;
    private String gender;
    private String telephone;
    private String email;
    private Integer classId;
//省略getter和setter方法
}

2.5 cn.kgc.mapper/ StudentMapper

package cn.kgc.mapper;

import cn.kgc.entity.Classes;
import cn.kgc.entity.Student;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;
@Mapper
public interface StudentMapper {
    List<Student> findAllStu();
    Integer addStudent(Student student);
    List<Classes> findAllCla();

    Integer update(Student student);
    Student findById(Integer id);
}

2.6 resources/mapper/ StudentMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.kgc.mapper.StudentMapper">
    <select id="findAllStu" resultType="cn.kgc.entity.Student">
        select * from student
    </select>
    <insert id="addStudent" parameterType="cn.kgc.entity.Student">
        insert into student(`name`,age,gender,telephone,email,classId)
        values (#{name},#{age},#{gender},#{telephone},#{email},#{classId})
    </insert>
    <select id="findAllCla" resultType="cn.kgc.entity.Classes">
        select * from classes
    </select>
    <update id="update" parameterType="cn.kgc.entity.Student">
        update student set `name`=#{name},age=#{age},gender=#{gender},telephone=#{telephone},email=#{email},classId=#{classId}
        where id =#{id}
    </update>
    <select id="findById" parameterType="java.lang.Integer" resultType="cn.kgc.entity.Student">
        select * from student where id = #{id}
    </select>
</mapper>

2.7 cn.kgc.service/ StudentService、StudentServiceImpl

StudentService

package cn.kgc.service;

import cn.kgc.entity.Classes;
import cn.kgc.entity.Student;
import com.github.pagehelper.PageInfo;

import java.util.List;

public interface StudentService {
    PageInfo<Student> findAllStu(Integer pageNo);
    Integer addStudent(Student student);
    List<Classes> findAllCla();
    Integer update(Student student);
    Student findById(Integer id);
}

StudentServiceImpl

package cn.kgc.service;

import cn.kgc.entity.Classes;
import cn.kgc.entity.Student;
import cn.kgc.mapper.StudentMapper;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.List;

@Service
@Transactional
public class StudentServiceImpl implements StudentService {
    @Resource
    private StudentMapper studentMapper;
    @Override
    public PageInfo<Student> findAllStu(Integer pageNo) {
        PageHelper.startPage(pageNo,3);
        return new PageInfo<>(studentMapper.findAllStu());
    }

    @Override
    public Integer addStudent(Student student) {  return studentMapper.addStudent(student); }

    @Override
    public List<Classes> findAllCla() { return studentMapper.findAllCla(); }

    @Override
    public Integer update(Student student) {  return studentMapper.update(student);  }

    @Override
    public Student findById(Integer id) {  return studentMapper.findById(id); }
}

2.8 cn.kgc.controller/ StudentController

package cn.kgc.controller;

import cn.kgc.entity.Classes;
import cn.kgc.entity.Student;
import cn.kgc.service.StudentService;
import com.github.pagehelper.PageInfo;
import org.springframework.web.bind.annotation.*;

import javax.annotation.Resource;
import java.util.List;

@RestController
@CrossOrigin
public class StudentController {
    @Resource
    private StudentService studentService;
    @RequestMapping("/findAllStu")
    public PageInfo<Student> findAllStu(@RequestParam(defaultValue = "1") Integer pageNo){
        return studentService.findAllStu(pageNo);
    }
    @RequestMapping("/addStudent")
    private Integer addStudent(@RequestBody Student student){
        return studentService.addStudent(student);
    }
    @RequestMapping("/findAllCla")
    private List<Classes> findAllCla(){
        return studentService.findAllCla();
    }
    @RequestMapping("/update")
    private Integer update(@RequestBody Student student){
        return studentService.update(student);
    }
    @RequestMapping("/findById")
    private Student findById(Integer id){
        return studentService.findById(id);
    }
}

2.9 loback.xml日志（省略）

2.10 vue 新建文件夹

1.建工程
之前的基础上建个demo0107,然后按照步骤来（跳过）

2.views/List.vue

<!--  -->
<template>
  <div>
    <table border="1px solid">
        <tr><th colspan="8">学生查询列表</th></tr>
      <tr>
        <td>学员编号</td>
        <td>学员名称</td>
        <td>学员年龄</td>
        <td>性别</td>
        <td>电话</td>
        <td>Email</td>
        <td>班级编号</td>
        <td>操作</td>
      </tr>
      <tr v-for="stu in stus.list" :key="stu.id" :class="{on:stu.id%2==0,off:stu.id%2!=0}">
        <td>{{ stu.id }}</td>
        <td>{{ stu.name }}</td>
        <td>{{ stu.age }}</td>
        <td>{{ stu.gender }}</td>
        <td>{{ stu.telephone }}</td>
        <td>{{ stu.email }}</td>
        <td>{{ stu.classId }}</td>
         <td colspan="8">
          <a href="javascript:void(0)" @click="update(stu.id)">修改</a>
        </td>
      </tr>
      <tr>
        <td colspan="8" style="text-align:center">
          <a href="javascript:void(0)" @click="getPage(1)">首页</a> 
          <a href="javascript:void(0)" @click="getPage(stus.prePage)">上一页</a> 
          <a href="javascript:void(0)" @click="getPage(stus.nextPage)">下一页</a> 
          <a href="javascript:void(0)" @click="getPage(stus.pages)">末页</a>
        </td>
      </tr>
      <tr>
        <td colspan="8" style="text-align:center">
          <a href="javascript:void(0)" @click="add()">添加</a>
        </td>
      </tr>
    </table>
  </div>
</template>

<script>
import axios from "axios"
export default {
  components: {},
  data() {
    return {
      stus: {},
      queryPage: {
        pageNo: 1
      },
    };
  },
  //监听属性 类似于data概念
  computed: {},
  //监控data中的数据变化
  watch: {},
  methods: {
    update(id){
      this.$router.push("/update?id="+id);
    },
    add(){
      this.$router.push("/add");
    },
      getPage(pageNo){
        //   this.queryPage.pageNo=pageNo;
        //   axios.get("http://localhost:8095/findAllStu",{params:this.queryPage}).then(data=>{
        //     this.stus = data.data; })
        axios.get("http://localhost:8095/findAllStu?pageNo="+pageNo).then(data=>{
            this.stus = data.data
        })
         
      }
  },
  //生命周期 - 挂载完成（可以访问DOM元素）
  mounted() {
      this.getPage(1);
  },
};
</script>
<style scoped>
.on{
  background: white;
  border: 1px solid blue;
}
.off{
  background: yellow;
  border: 1px solid black;
}
</style>

3.views/Add.vue

<!--  -->
<template>
  <div >
    <table border="1px solid">
      <tr>
        <th colspan="2">添加学员信息</th>
      </tr>
      <tr>
        <td>学员名称</td>
        <td><input v-model="newStu.name"></td>
      </tr>
      <tr>
        <td>学员年龄</td>
        <td><input v-model="newStu.age"></td>
      </tr>
      <tr>
        <td>性别</td>
        <td><input v-model="newStu.gender"></td>
      </tr>
      <tr>
        <td>电话</td>
        <td><input v-model="newStu.telephone"></td>
      </tr>
      <tr>
        <td>Email</td>
        <td><input v-model="newStu.email"></td>
      </tr>
      <tr>
        <td>班级编号</td>
        <td>
            <select v-model="newStu.classId">
                <option value="-1">--全部--</option>
                <option v-for="class1 in classes" :key="class1.id" :value="class1.id">{{class1.name}}</option>
            </select>
        </td>
      </tr>
      <tr>
        <td colspan="2" style="text-align:center">
          <input type="button" value="新增" @click="add()" /> 
          <input type="button" value="返回" @click="retu()" />
        </td>
      </tr>
    </table>
  </div>
</template>

<script>
import axios from "axios"
export default {
  components: {},
  data() {
    return {
        classes:[],
        newStu:{
            name:'',
            age:'',
            gender:'',
            telephone:'',
            email:'',
            classId:-1
        }
    };
  },
  //监听属性 类似于data概念
  computed: {},
  //监控data中的数据变化
  watch: {},

  methods: {
      retu(){
            this.$router.push("/")
        },
      add(){
          axios.post("http://localhost:8095/addStudent",this.newStu).then(data=>{
              if(data.data ==1){
                  alert("新增成功");
                  this.$router.push("/")
              }else{
                  alert("新增失败")
              }
          })
      },
      getAllCla(){
          axios.get("http://localhost:8095/findAllCla").then(data=>{
              this.classes = data.data
          });
      }
  },
  //生命周期 - 挂载完成（可以访问DOM元素）
  mounted() {
      this.getAllCla();
  },
};
</script>
<style scoped>
</style>

3. 第三种下拉（修改）：

views/Update.vue

<!--  -->
<template>
    <div>
         <table border="1px solid">
      <tr>
        <th colspan="2">修改学员信息</th>
      </tr>
      <tr>
        <td>学员编号</td>
        <td><input v-model="newStu.id" readonly></td>
      </tr>
      <tr>
        <td>学员名称</td>
        <td><input v-model="newStu.name"></td>
      </tr>
      <tr>
        <td>学员年龄</td>
        <td><input v-model="newStu.age"></td>
      </tr>
      <tr>
        <td>性别</td>
        <td><input v-model="newStu.gender"></td>
      </tr>
      <tr>
        <td>电话</td>
        <td><input v-model="newStu.telephone"></td>
      </tr>
      <tr>
        <td>Email</td>
        <td><input v-model="newStu.email"></td>
      </tr>
      <tr>
        <td>班级编号</td>
        <td>
           <select v-model="newStu.classId">
               <option value="-1">--全部--</option>
               <option v-for="class2 in classes" :key="class2.id"  :value="class2.id">{{class2.name}}</option>
           </select>
        </td>
      </tr>
      <tr>
        <td colspan="2" style="text-align:center">
            <input type="button" value="修改" @click="update()" /> 
            <input type="button" value="返回" @click="retu()" />
        </td>
      </tr>
    </table>
    </div>
</template>

<script>
import axios from "axios"
export default {
    
    components: {},
    data() {
        
        return {
            classes:[],
            newStu:{
                id:'',
                name:'',
                age:'',
                gender:'',
                telephone:'',
                email:'',
                classId:-1
            }
        };
    },
    //监听属性 类似于data概念
    computed: {},
    //监控data中的数据变化
    watch: {},
    
    methods: {
        retu(){
            this.$router.push("/")
        },
        update(){
            axios.post("http://localhost:8095/update",this.newStu).then(data=>{
                if(data.data ==1){
                    alert("修改成功")
                    this.$router.push("/");
                }else{
                    alert("修改失败")
                }
            });
        },
        getAllCla(){
            axios.get("http://localhost:8095/findAllCla").then(data=>{
                this.classes = data.data
            })
        },
        findById(id){
            axios.get("http://localhost:8095/findById?id="+id).then(data=>{
                this.newStu = data.data
            })
        }
    },
    //生命周期 - 挂载完成（可以访问DOM元素）
    mounted() {
        this.getAllCla();
        var id = this.$route.query.id;
        this.findById(id);
    },
    }
</script>
<style scoped>
</style>

3.1 测试

JAVA 实现下拉列表代码案例_vue.js_06

JAVA 实现下拉列表代码案例_JAVA 实现下拉列表代码案例_07

JAVA 实现下拉列表代码案例_vue.js_08

题外话：

npm install 命令

如果把node_modules删掉，

输入这个命令就可以出来了。

作用： 对各种依赖的定义去安装这些依赖

----2022.01.06&07&08

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