修改admin.blade.php如下：

@extends('admin.common')
@section('content')
<button type="button" class="btn btn-primary" style="margin:10px auto;" onclick="onShowAdd()">添加</button>
      <table class="table table-hover table-bordered">
        <thead>
          <tr>
            <th scope="col">ID</th>
            <th scope="col">名称</th>
            <th scope="col">操作</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <th scope="row">1</th>
            <td>@mdo</td>
            <td>
              <button type="button" class="btn btn-outline-primary">编辑</button>
              <button type="button" class="btn btn-outline-danger">删除</button>  
            </td>
          </tr>
          <tr>
            <th scope="row">2</th>  
            <td>@fat</td>
            <td>
              <button type="button" class="btn btn-outline-primary">编辑</button>
              <button type="button" class="btn btn-outline-danger">删除</button>  
            </td>
          </tr>
        </tbody>
      </table>
      <nav aria-label="Page navigation example">
        <ul class="pagination justify-content-center">
          <li class="page-item"><a class="page-link" href="#">Previous</a></li>
          <li class="page-item"><a class="page-link" href="#">1</a></li>
          <li class="page-item"><a class="page-link" href="#">2</a></li>
          <li class="page-item"><a class="page-link" href="#">3</a></li>
          <li class="page-item"><a class="page-link" href="#">Next</a></li>
        </ul>
      </nav>

      <!-- 添加弹框 -->
      <div class="modal fade" id="addModel" tabindex="-1" aria-labelledby="exampleModalLabel" aria-hidden="true">
        <div class="modal-dialog modal-dialog-centered">
          <div class="modal-content">
            <div class="modal-header">
              <h5 class="modal-title" id="exampleModalLabel">添加人员</h5>
              <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                <span aria-hidden="true">×</span>
              </button>
            </div>
            <div class="modal-body">
            <div class="form-group">
              <label for="username_id">用户名</label>
              <input type="username" class="form-control" id="username_id" aria-describedby="emailHelp">
              <small id='username_err_id'></small>
            </div>
            <div class="form-group">
              <label for="passwd_id">密码</label>
              <input type="password" class="form-control" id="password_id">
              <small id='password_err_id'></small>
            </div>
            </div>
            <div class="modal-footer">
              <button type="button" class="btn btn-secondary" data-dismiss="modal">关闭</button>
              <button id="submit_id" type="button" class="btn btn-primary">确定</button>
            </div>
          </div>
        </div>
      </div>
      <style>
        #password_err_id,#username_err_id{
          color:red;
        }
      </style>
@endsection

@section('javascript')
    <script type="text/javascript">
      function onShowAdd(){
        $('#addModel').modal('show');
      }
      $('#submit_id').click(function(){
        var username = $('#username_id').val();
        var password = $('#password_id').val();
        console.log(username,password);
        var datas = {username,password,_token:"{{csrf_token()}}"};
        datas = JSON.stringify(datas);
        $.ajax({
          type:"post",
          url:"{{route('admin.store')}}",
          data:datas,
          dataType:"json",
          contentType:"application/json",
          success:function(data){
            $('#username_err_id').text('');
            $('#password_err_id').text('');
            if(data.code == 200)
            {
              window.location.reload();
            }else{
              if(data.code==1000)
              {
                data.msg.username && $('#username_err_id').text(data.msg.username[0]);
                data.msg.password && $('#password_err_id').text(data.msg.password[0]);
              }
            }
          },
          error:function(err){
          }
        });
      });
    </script>
    @endsection
    

点击测试，会提示没有$.ajax 这个方法，在这里我们需要在引入jquery的地方common.blade.php，更改下jquery的网址为：

<script src="https://cdn.jsdelivr.net/npm/jquery@3.2/dist/jquery.min.js"></script>

因为之前引入的是slim.min.js里是去除了某部分功能，添加完这个后就不会报错了。

创建AdminCreateRequest

现在我们需要在创建一个AdminCreateRequest表单验证来，来处理发送过来的添加数据进行验证。

php artisan make:request AdminCreateRequest

<?php

namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;
use Illuminate\Contracts\Validation\Validator;
use Illuminate\Validation\ValidationException;
use Symfony\Component\HttpFoundation\Response;

class AdminCreateRequest extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            //
            'username'=>'bail|required',
            'password'=>'bail|required|min:10|max:30'
        ];
    }
    public function messages(){
        return [
            'username.required'=>':attribute 不能为空',
            'password.required'=>':attribute 不能为空',
            'password.min'=>':attribute 最小为10位长度',
            'password.max'=>':attribute 最大为30位长度'
        ];
    }
    public function attributes(){
        return [
            'usernmae'=>'用户名',
            'password'=>'密码'
        ];
    }
    protected function failedValidation(Validator $validator)
    {
        // 此处自定义表单验证错误信息
        $data = [
            'code' => 1000,
            'msg' => $validator->errors(),
        ];
        $respone = new Response(json_encode($data));
        throw (new ValidationException($validator, $respone))
            ->errorBag($this->errorBag)
            ->redirectTo($this->getRedirectUrl());
    }
}

更改AdminController.php

<?php

namespace App\Http\Controllers\admin;

use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
use App\Http\Requests\AdminCreateRequest;
use Illuminate\Support\Facades\Hash;
use App\Models\Admin;

class AdminController extends Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        //
        return view('admin.admin');
    }

    /**
     * Show the form for creating a new resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function create()
    {
        //
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function store(AdminCreateRequest $request)
    {
        //
        $username = $request->input('username');
        $password = Hash::make($request->input('password'));
        $admin = new Admin();
        $admin->username = $username;
        $admin->password = $password;
        $state = $admin->save();
        if($state)
        {
            return response()->json(['code'=>'200','msg'=>'添加成功']);
        }else{
            return response()->json(['code'=>'1000','msg'=>'添加失败']);
        }
    }

    /**
     * Display the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function show($id)
    {
        //
    }

    /**
     * Show the form for editing the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function edit($id)
    {
        //
    }

    /**
     * Update the specified resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, $id)
    {
        //
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function destroy($id)
    {
        //
    }
}

注：执添加用户，就可以添加成功了