1.实现效果

2. 代码实现

        2.1使用elementUI文档中Tabs标签页

         2.2在components中新建两个文件  login.vue   register.vue 

                login.vue         

            回车登录（ 按钮添加native-type="submit"  登录表单添加@submit.native.prevent​​​​​​​） 

<template>
  <div class="login">
    <div class="login_form">
      <p>后台管理系统</p>
      <el-tabs v-model="activeName" @tab-click="handleClick" >
        <el-tab-pane label="登录" name="first">
          <el-form
            :model="loginForm"
            :rules="rules"
            ref="loginForm"
            @submit.native.prevent    
          >
            <el-form-item label="" prop="account" class="elItem">
              <el-input
                type="text"
                autocomplete="off"
                v-model="loginForm.account"
                prefix-icon="el-icon-user-solid"
                placeholder="请输入用户名"
              ></el-input>
            </el-form-item>
            <el-form-item label="" prop="password">
              <el-input
                type="password"
                autocomplete="off"
                v-model="loginForm.password"
                prefix-icon="el-icon-lock"
                placeholder="请输入密码"
              ></el-input>
            </el-form-item>
            <el-form-item class="btns">
              <el-button type="primary" @click="goToLogin" native-type="submit">登录</el-button>
              <el-button @click="resetLoginForm">重置</el-button>
            </el-form-item>
          </el-form>
        </el-tab-pane>
        <el-tab-pane label="注册" name="second">
            //注册组件
          <register></register>
        </el-tab-pane>
      </el-tabs>
    </div>
  </div>
</template>

<script>
//引入注册组件
import register from '@/components/register';
export default {
  data() {
    var validateAccount = (rule, value, callback) => {
      if (value === "") {
        return callback(new Error("账号不能为空"));
      } else if (value === "admin") {
        callback();
      } else {
        callback(new Error("请输入正确的用户名"));
      }
    };
    var validatePassword = (rule, value, callback) => {
      if (value === "") {
        callback(new Error("请输入密码"));
      } else if (value === "123456") {
        callback();
      } else {
        callback(new Error("请输入正确的密码"));
      }
    };
    return {
      loginForm: {
        account: "",
        password: "",
      },
      activeName:'first',//默认显示登录页面
      rules: {
        account: [
          {
            validator: validateAccount,
            trigger: "blur",
          },
        ],
        password: [
          {
            validator: validatePassword,
            trigger: "blur",
          },
        ],
      },
    };
  },
  methods: {
//固定的账户密码判断实现简单的登录跳转功能，只能测试用
    goToLogin() {
      this.$refs["loginForm"].validate((valid) => {
        if (valid) {
          if (
            this.loginForm.account != "admin" ||
            this.loginForm.password != "123456"
          ) {
            this.$message.error("账号密码不正确");
            return false;
          } else {
            this.$message({ message: "登陆成功", type: "success" });
            this.$router.push("/home");
          }
        } else {
          this.$message.error("登陆失败");
          return false;
        }
      });
    },
    resetLoginForm() {
      this.$refs["loginForm"].resetFields();
    },
    handleClick(){}
  },
  components:{
    register
  }
};
</script>

<style scoped lang='less'>
.login {
  width: 100%;
  height: 100vh;
  background-image: url("../assets/login/login.jpg");//背景图
  background-size: 100% 100%;
  background-position: center center;
  overflow: auto;
  position: relative;
  .login_form {
    width: 400px;
    height: 360px;
    position: absolute;
    left: 78%;
    top: 50%;
    margin-left: -200px;
    margin-top: -150px;
    padding: 10px;
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 0 10px #ddd;
    .btns {
      display: flex;
      justify-content: flex-end;
    }
  }
  p {
    font-size: 24px;
    text-align: center;
    font-weight: 600;
  }
}
</style>

        register.vue 

<template>
  <el-form
    :model="ruleForm"
    :rules="rules"
    ref="ruleForm"
    class="demo-ruleForm"
  >
    <el-form-item label="" prop="name"
      ><el-input
        type="text"
        autocomplete="off"
        v-model="ruleForm.name"
        prefix-icon="el-icon-user-solid"
        placeholder="请输入用户名"
      ></el-input
    ></el-form-item>
    <el-form-item label="" prop="pass"
      ><el-input
        type="password"
        autocomplete="off"
        v-model="ruleForm.pass"
        prefix-icon="el-icon-lock"
        placeholder="请输入密码"
      ></el-input
    ></el-form-item>
    <el-form-item label="" prop="checkPass"
      ><el-input
        type="password"
        autocomplete="off"
        v-model="ruleForm.checkPass"
        prefix-icon="el-icon-lock"
        placeholder="请输入密码"
      ></el-input
    ></el-form-item>
    <el-form-item class="btns">
      <el-button type="primary" @click="submitForm('ruleForm')">注册</el-button>
      <el-button @click="resetForm('ruleForm')">重置</el-button>
    </el-form-item>
  </el-form>
</template>
 
<script>
export default {
  data() {
    var validatePass = (rule, value, callback) => {
      if (value === "") {
        callback(new Error("请输入密码"));
      } else {
        if (this.ruleForm.checkPass !== "") {
          this.$refs.ruleForm.validateField("checkPass");
        }
        callback();
      }
    };

    var validatePass2 = (rule, value, callback) => {
      if (value === "") {
        callback(new Error("请再次输入密码"));
      } else if (value !== this.ruleForm.pass) {
        callback(new Error("两次输入密码不一致!"));
      } else {
        callback();
      }
    };

    return {
      activeName: "second",
      ruleForm: {
        name: "",
        pass: "",
        checkPass: "",
      },
      rules: {
        name: [
          { required: true, message: "请输入您的名称", trigger: "blur" },
          { min: 2, max: 5, message: "长度在 2 到 5 个字符", trigger: "blur" },
        ],
        pass: [{ required: true, validator: validatePass, trigger: "blur" }],
        checkPass: [
          { required: true, validator: validatePass2, trigger: "blur" },
        ],
      },
    };
  },

  methods: {
    submitForm(formName) {
      this.$refs[formName].validate((valid) => {
        if (valid) {
          this.$message({
            type: "success",
            message: "注册成功",
          });
          // this.activeName: 'first',
        } else {
          console.log("error submit!!");
          return false;
        }
      });
    },

    resetForm(formName) {
      this.$refs[formName].resetFields();
    },
  },
};
</script>
<style scoped lang="less">
.btns {
      display: flex;
      justify-content: flex-end;
    }
</style>