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Angular数据请求之HttpClient

Httpclient引入

模块引入

import { NgModule }         from '@angular/core';
import { BrowserModule }    from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http';

@NgModule({
  imports: [
    BrowserModule,
    // import HttpClientModule after BrowserModule.
    HttpClientModule,
  ],
  declarations: [
    AppComponent,
  ],
  bootstrap: [ AppComponent ]
})
export class AppModule {}复制代码

httpclient 注入

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Injectable()
export class ConfigService {
  constructor(private http: HttpClient) { }
}复制代码

get请求

ts定义数据类型

export interface Config {
  heroesUrl: string;
  textfile: string;
}复制代码

定义service

configUrl = 'assets/config.json';

getConfig() {
  // now returns an Observable of Config
  return this.http.get<Config>(this.configUrl);
}
//等效于
getConfig():Observable<Config> {
  // now returns an Observable of Config
  return this.http.get<Config>(this.configUrl);
}复制代码

调用service

config: Config;
 showConfig() {
  this.configService.getConfig()
    .subscribe((data: Config) => this.config = {
        heroesUrl: data['heroesUrl'],
        textfile:  data['textfile']
    });
    // or 
     .subscribe((data: Config) => this.config = { ...data });
}复制代码

修改返回数据类型

getConfigResponse(): Observable<HttpResponse<Config>> {
  return this.http.get<Config>(
    this.configUrl, { observe: 'response' });
}复制代码

返回类型修改 HttpResponse<Config >
请求参数添加，{ observe: 'response' }

showConfigResponse() {
  this.configService.getConfigResponse()
    // resp is of type `HttpResponse<Config>`
    .subscribe(resp => {
      // display its headers
      const keys = resp.headers.keys();
      this.headers = keys.map(key =>
        `${key}: ${resp.headers.get(key)}`);

      // access the body directly, which is typed as `Config`.
      this.config = { ... resp.body };
    });
}复制代码

返回文本

getTextFile(filename: string) {
  // The Observable returned by get() is of type Observable<string>
  // because a text response was specified.
  // There's no need to pass a <string> type parameter to get().
  return this.http.get(filename, {responseType: 'text'})
    .pipe(
      tap( // Log the result or error
        data => this.log(filename, data),
        error => this.logError(filename, error)
      )
    );
}复制代码

jsonp请求

import { NgModule }         from '@angular/core';
import { BrowserModule }    from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http';
import {HttpClientJsonpModule} from  '@angular/common/http';
@NgModule({
  imports: [
    BrowserModule,
    // import HttpClientModule after BrowserModule.
    HttpClientModule,
    HttpClientJsonpModule
  ],
  declarations: [
    AppComponent,
  ],
  bootstrap: [ AppComponent ]
})
export class AppModule {}复制代码

searchHeroes(term: string): Observable {  // 利用subscribe订阅成功数据
  term = term.trim();

  let heroesURL = `${this.heroesURL}?${term}`;
  return this.http.jsonp(heroesUrl, 'callback').pipe(
      catchError(this.handleError('searchHeroes', []) // then handle the error
    );
};复制代码

post请求

添加数据

addHero (hero: Hero): Observable<Hero> {
  return this.http.post<Hero>(this.heroesUrl, hero, httpOptions)
    .pipe(
      catchError(this.handleError('addHero', hero))
    );
}复制代码

调动触发

this.heroesService
  .addHero(newHero)
  .subscribe(hero => this.heroes.push(hero));复制代码

put请求

更新数据

updateHero (hero: Hero): Observable<Hero> {
  return this.http.put<Hero>(this.heroesUrl, hero, httpOptions)
    .pipe(
      catchError(this.handleError('updateHero', hero))
    );
}复制代码

调用更新

this.heroesService.updateHero(hero);复制代码

delete请求

删除数据

deleteHero (id: number): Observable<{}> {
  const url = `${this.heroesUrl}/${id}`; // DELETE api/heroes/42
  return this.http.delete(url, httpOptions)
    .pipe(
      catchError(this.handleError('deleteHero'))
    );
}复制代码

方法调用触发请求

this.heroesService
  .deleteHero(hero.id)
  .subscribe();复制代码

拦截器配置

headers配置

初始化

import { HttpHeaders } from '@angular/common/http';

const httpOptions = {
  headers: new HttpHeaders({
    'Content-Type':  'application/json',
    'Authorization': 'my-auth-token'
  })
};复制代码

更新header

httpOptions.headers =
  httpOptions.headers.set('Authorization', 'my-new-auth-token');复制代码

错误处理

pipe提前处理

getConfig() {
  return this.http.get<Config>(this.configUrl)
    .pipe(
      catchError(this.handleError)
    );
}复制代码

getConfig() {
  return this.http.get<Config>(this.configUrl)
    .pipe(
      retry(3), // retry a failed request up to 3 times
      catchError(this.handleError) // then handle the error
    );
}复制代码

subscribe处理

showConfig() {
  this.configService.getConfig()
    .subscribe(
      (data: Config) => this.config = { ...data }, // success path
      error => this.error = error // error path
    );
}复制代码