为了解决这个问题，我们可以在Ag-grid表格中创建一个自定义表头，并将搜索框添加到其中。为了解决焦点问题，我们可以在搜索框的input上绑定事件，以确保每次聚焦时都会使网格重新设置焦点。

以下是代码示例：

// Create custom header component
class CustomHeader extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      searchTerm: ''
    };
  }

  onSearchTermChanged = (event) => {
    this.setState({searchTerm: event.target.value});
    this.props.onSearchTermChanged(event.target.value);
  }

  onFocus = () => {
    this.props.gridOptions.api.setFocusedCell(null);
  }

  render() {
    return (
      

        My Custom Header
        
      
    );
  }
}

// Define column definitions
const columnDefs = [
  {headerName: 'Make', field: 'make'},
  {headerName: 'Model', field: 'model'},
  {headerName: 'Price', field: 'price'}
];

// Define row data
const rowData = [
  {make: 'Toyota', model: 'Celica', price: 35000},
  {make: 'Ford', model: 'Mondeo', price: 32000},
  {make: 'Porsche', model: 'Boxter', price: 72000}
];

// Define grid options
const gridOptions = {
  columnDefs: columnDefs,
  rowData: rowData,
  headerHeight: 80,
  frameworkComponents: {
    customHeader: CustomHeader
  },
  components: {
    agColumnHeader: CustomHeader
  },
  onGridReady: (params) => {
    params.api.sizeColumnsToFit();
  }
};

// Render grid