Angular4 标签设置style背景图片

HTML页面：

[style.background-image]="bgpictrue"

component.ts页面：

import{ DomSanitizer }from'@angular/platform-browser';

constructor(

    privatesanitizer: DomSanitizer

){}

this.bgpictrue=this.sanitizer.bypassSecurityTrustStyle("url('"+image_str+"')");