1、新增一个模块，代码如下：

export const ROUTES: Routes = [
  {
    path: '',component: ArticleComponent,}
];

@NgModule({
  imports: [
    CommonModule,RouterModule.forChild(ROUTES)
  ],declarations: [
    ArticleComponent,]
})
export class AdminModule { }

报错为：

ERROR Error: Uncaught (in promise): Error: Type ArticleComponent is part of the declarations of 2 modules: AppModule and AdminModule! Please consider moving ArticleComponent to a higher module that imports AppModule and AdminModule. You can also create a new NgModule that exports and includes ArticleComponent then import that NgModule in AppModule and AdminModule.
Error: Type ArticleComponent is part of the declarations of 2 modules: AppModule and AdminModule! Please consider moving ArticleComponent to a higher module that imports AppModule and AdminModule. You can also create a new NgModule that exports and includes ArticleComponent then import that NgModule in AppModule and AdminModule.
    at SyntaxError (compiler.js:466)
    at CompileMetadataResolver._addTypeToModule (compiler.js:15255)
    at eval (compiler.js:15127)
    at Array.forEach (<anonymous>)
    at CompileMetadataResolver.getNgModuleMetadata (compiler.js:15118)
    at JitCompiler._loadModules (compiler.js:33486)
    at JitCompiler._compileModuleAndComponents (compiler.js:33447)
    at JitCompiler.compileModuleAsync (compiler.js:33363)
    at CompilerImpl.compileModuleAsync (platform-browser-dynamic.js:230)
    at eval (core.js:6441)
    at SyntaxError (compiler.js:466)
    at CompileMetadataResolver._addTypeToModule (compiler.js:15255)
    at eval (compiler.js:15127)
    at Array.forEach (<anonymous>)
    at CompileMetadataResolver.getNgModuleMetadata (compiler.js:15118)
    at JitCompiler._loadModules (compiler.js:33486)
    at JitCompiler._compileModuleAndComponents (compiler.js:33447)
    at JitCompiler.compileModuleAsync (compiler.js:33363)
    at CompilerImpl.compileModuleAsync (platform-browser-dynamic.js:230)
    at eval (core.js:6441)
    at resolvePromise (zone.js:824)
    at resolvePromise (zone.js:795)
    at eval (zone.js:873)
    at ZoneDelegate.invokeTask (zone.js:425)
    at Object.onInvokeTask (core.js:4620)
    at ZoneDelegate.invokeTask (zone.js:424)
    at Zone.runTask (zone.js:192)
    at drainMicroTaskQueue (zone.js:602)
    at <anonymous>

2、新增的模块代码修改如下，还是报错：

Error: Uncaught (in promise): Error: Component ArticleComponent is not part of any NgModule or the module has not been imported into your module.
Error: Component ArticleComponent is not part of any NgModule or the module has not been imported into your module.
    at JitCompiler._createCompiledHostTemplate (webpack-internal:///../../../compiler/esm5/compiler.js:33839)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:33792)
    at Array.forEach (<anonymous>)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:33789)
    at Array.forEach (<anonymous>)
    at JitCompiler._compileComponents (webpack-internal:///../../../compiler/esm5/compiler.js:33778)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:33666)
    at Object.then (webpack-internal:///../../../compiler/esm5/compiler.js:673)
    at JitCompiler._compileModuleAndComponents (webpack-internal:///../../../compiler/esm5/compiler.js:33665)
    at JitCompiler.compileModuleAsync (webpack-internal:///../../../compiler/esm5/compiler.js:33581)
    at JitCompiler._createCompiledHostTemplate (webpack-internal:///../../../compiler/esm5/compiler.js:33839)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:33792)
    at Array.forEach (<anonymous>)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:33789)
    at Array.forEach (<anonymous>)
    at JitCompiler._compileComponents (webpack-internal:///../../../compiler/esm5/compiler.js:33778)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:33666)
    at Object.then (webpack-internal:///../../../compiler/esm5/compiler.js:673)
    at JitCompiler._compileModuleAndComponents (webpack-internal:///../../../compiler/esm5/compiler.js:33665)
    at JitCompiler.compileModuleAsync (webpack-internal:///../../../compiler/esm5/compiler.js:33581)
    at resolvePromise (webpack-internal:///../../../../zone.js/dist/zone.js:824)
    at resolvePromise (webpack-internal:///../../../../zone.js/dist/zone.js:795)
    at eval (webpack-internal:///../../../../zone.js/dist/zone.js:873)
    at ZoneDelegate.invokeTask (webpack-internal:///../../../../zone.js/dist/zone.js:425)
    at Object.onInvokeTask (webpack-internal:///../../../core/esm5/core.js:4815)
    at ZoneDelegate.invokeTask (webpack-internal:///../../../../zone.js/dist/zone.js:424)
    at Zone.runTask (webpack-internal:///../../../../zone.js/dist/zone.js:192)
    at drainMicroTaskQueue (webpack-internal:///../../../../zone.js/dist/zone.js:602)
    at <anonymous>

3、正确的写法是，新增一个组件，且这个组件不在appmodule中声明，错误分析和总结白天在弄。

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import {ArticleComponent} from "../article/article.component";
import {RouterModule,Routes} from "@angular/router";
import {TestComponent} from "../test/test.component";

export const ROUTES: Routes = [
  {
    path: '',component: TestComponent,declarations: [
    TestComponent
  ]
})
export class AdminModule { }