toggleSelection(rows) {
    if (rows) {
     rows.forEach(row => {
      this.$refs.multipleTable.toggleRowSelection(row);
     });
    } else {
     this.$refs.multipleTable.clearSelection();
    }
   }

<el-dialog class="contract_modal" title="信息" :visible.sync="glht_modal" width="80%" :modal="false" @close="cancel">
 <el-form :inline="true" :model="searchData" label-width="90px">
  <el-form-item label="名称：">
   <el-input v-model.trim="searchData.mc_" size="small" class="contract_input"></el-input>
  </el-form-item>
  <span class="list_btns">
   <el-button type="primary" size="small" @click="listSearch(page, 1)" class="con_btn">搜索</el-button>
   <el-button size="small" @click="searchData = {}" class="con_btn">清空</el-button>
  </span>
 </el-form>
 <div id="list_body" class="list-body" style="padding-left: 0;">
  <el-table :data="tableData" stripe border style="width: 100%" max-height="480" ref="multipleTable" @select-all="handleSelectionAll" @select="handleSelectionChange">
   <el-table-column type="selection" width="26" align="right"></el-table-column>
   <el-table-column type="index" width="50" label="序号" align="left" header-align="left"></el-table-column>
   <el-table-column prop="mc_" label="名称" width="180" show-overflow-tooltip align="left"></el-table-column>
   
  </el-table>
  <div class="list-pagination">
   <el-pagination background @size-change="handleSizeChange" @current-change="handleCurrentChange"
           :current-page.sync="page.page" :page-sizes="[10, 20, 50, 100]":page-size="page.pageCount"
           layout="total, sizes, prev, pager, next, jumper, ->"
           :total="page.total"></el-pagination>
  </div>
 </div>
 <div slot="footer" class="dialog-footer">
  <el-button type="primary" @click="save" size="small">确定</el-button>
  <el-button @click="cancel" size="small">取消</el-button>
 </div>
</el-dialog>

// 全选  当val有数据，即为全选；为空数组，即为取消全选
handleSelectionAll (val) {
 // 获取所有选中的数据 
 this.records = JSON.parse(localStorage.getItem('glht'))
 if(val.length !== 0) {  
  //全选
  // this.records = Array.from(new Set(val.concat(this.records)))  发现去重不好用！只能手动push了
  // 全选选中的一定是本页所有数据，所以循环本页
  this.tableData.forEach((v) => {
   if(this.records.find((e,index) => { return v.id_ === e.id_})){}else {
    // 如果数组中没有就把选中的push进去
    this.records.push(v)
   }
  })
 } else {   
  // 取消全选，在选中的所有信息中把本页列表有的删除
  this.tableData.forEach((v) => {
   this.records.forEach((e,index) => {
    if (e.id_ === v.id_) {
     this.records.splice(index, 1)
    }
   })
  })
 }
 // 每次选的数据暂时存一下
 localStorage.setItem('glht', JSON.stringify(this.records))
},
// 单选 
handleSelectionChange(val, row) {
 // 获取所有选中的数据 
 this.records = JSON.parse(localStorage.getItem('glht'))
 if (this.records.length === 0) {
  // 还没有选中任何数据
  this.records = [row]
 } else {
  if (this.records.filter(i => { return i.id_ === row.id_ }).length === 0) {
    // 已选中的数据里没有本条(取消)，把这条加进来
   this.records.push(row)
  } else {
    // 已选中的数据里有本条(取消选中)，把这条删除
   this.records.forEach((e,index) => {
    if (e.id_ === row.id_) {
     this.records.splice(index, 1)
    }
   })
  }
 }
 // 每次选的数据暂时存一下
 localStorage.setItem('glht', JSON.stringify(this.records))
},

listGet() {
  this.$axios.post("interface", {}, { params: searchData }).then(res => {
   if (res.data.success) {
    this.tableData = res.data.data.rows;
    this.page.total = res.data.data.total;
    this.records = JSON.parse(localStorage.getItem('yglht'))
    this.toggleSelection(JSON.parse(localStorage.getItem('yglht')));  // 反选操作
   } else {
    this.$message.error(res.data.message)
   }
  })
 .catch(err => console.log(err));
},
// 反选处理
toggleSelection(rows) {
 let arr =[]
 this.tableData.forEach((e, index) => {
  rows.forEach((i, ind) => {
   if (e.id_ === i.id_) {
     arr.push(this.tableData[index])
   }
  })
 })
 if (arr) {
  this.$nextTick(() => {
   arr.forEach(row => {
    this.$refs.multipleTable.toggleRowSelection(row);
   });
  })
 } else {
  this.$refs.multipleTable.clearSelection();
 }
},

save () {
 this.glht_modal = false
 localStorage.setItem('yglht', localStorage.getItem('glht'))
 this.yglht()
},
cancel () {
 this.glht_modal = false
 // 取消时 取在页面上的值
 localStorage.setItem('glht', localStorage.getItem('yglht'))
 // this.toggleSelection(JSON.parse(localStorage.getItem('yglht')));  直接写不好用
 this.listGet({})  // 获取弹出框列表数据，这里调用一次是因为防止再次打开弹出框闪现之前选择的内容
 this.yglht()
},
yglht() {
  this.list = JSON.parse(localStorage.getItem('yglht'))
  // 处理this.list中地址、时间等页面显示问题
}