My Spring Boot controller sends String "hello Angular" as a simple response to http request.
@Controller
@RequestMapping(path = "/u")
public class UController {
@RequestMapping("/greet")
public @ResponseBody String greet() {
System.out.println("you are in the method greet() ");
return "hello Angular";
}
}
I see at console (System.out) that Angular has requested right method and the response should have been sent to client.
I would like to print this message by Angular on the web site, so I subscribe the Observable from http client, but it does not appear on the screen.
Here is my Angular component:
import { Component, OnInit } from '@angular/core';
import { HttpClientModule } from '@angular/common/http';
import { HttpClient, HttpHeaders } from '@angular/common/http';
@Component({
selector: 'app-root',
template: `
<div style="text-align:center">
<h1> {{greeting}} </h1>
</div>
<router-outlet></router-outlet>
`,
styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit{
greeting : string;
constructor(private http: HttpClient){ }
ngOnInit() {
this.http.get<string>('http://localhost:8080/u/greet').subscribe(data => { this.greeting = data; });
}
}
I really have no idea how can I fix it.
The error is happening because HttpClient
assumes content to be valid JSON, not a simple string. It effectively attempts to parse JSON internally. If you try to do JSON.parse("hello Angular")
, it will show the exact same error:
JSON.parse("hello Angular");
To retrieve non-JSON content , you can do the following by specifying the response type to be text
as well as removing the generic typing of <string>
:
this.http.get('http://localhost:8080/u/greet', {responseType: 'text'})
.subscribe(data => { this.greeting = data; });
Otherwise, for any actual JSON ( application/json
) data being returned from the server, you do not need to provide responseType
and can/should use the generic typing mechanism.
Hopefully that helps!
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.