如何动态改变Retrofit的base url和rest版本详解

class HeaderInterceptor implements Interceptor {

  private static final String ENCODING_GZIP = "gzip" ;

  private static final String CONTENT_TYPE_JSON = "application/json;charset=UTF-8" ;

  private static final String HEADER_CONTENT_TYPE = "Content-Type" ;

  private static final String HEADER_ACCEPT_TYPE = "application/json" ;

  private static final String HEADER_CONTENT_ENCODING = "Content-Encoding" ;

  private final static String CHARSET = "UTF-8" ;

  @Override

  public Response intercept(Chain chain) throws IOException {

   Request originRequest = chain.request();

   Request.Builder newBuilder = originRequest.newBuilder();

   newBuilder.addHeader( "Accept" , HEADER_ACCEPT_TYPE);

   newBuilder.addHeader( "Accept-Charset" , CHARSET);

   newBuilder.addHeader( "Accept-Encoding" , ENCODING_GZIP);

   newBuilder.addHeader( "Accept-Language" , Locale.getDefault().toString().replace( "_" , "-" ));

   newBuilder.addHeader(HEADER_CONTENT_TYPE, CONTENT_TYPE_JSON);

   return chain.proceed(newBuilder.build());

  }

}

Request originRequest = chain.request();

if (paramsMap != null ) {

  HttpUrl originUrl = originRequest.url();

  HttpUrl.Builder newBuilder = originUrl.newBuilder();

  for (String key : paramsMap.keySet()) {

   newBuilder.addEncodedQueryParameter(key, paramsMap.get(key));

  }

  HttpUrl newUrl = newBuilder.build();

  Request newRequest = originRequest.newBuilder().url(newUrl).build();

  return chain.proceed(newRequest);

}

return chain.proceed(originRequest);

interface HostName {

  String CLOUD = "CLOUD" ;

  String PRIVATE = "PRIVATE" ;

  String DEV = "DEV" ;

}

interface HostValue {

  String CLOUD = "https://www.baidu.com" ;

  String PRIVATE = "https://private.bidu.com" ;

  String DEV = "https://dev.baidu.com" ;

}

interface RestVersionCode {

  String EMPTY = "EMPTY" ;

  String V1 = "V1" ;

  String V2 = "V2" ;

  String PRIVATE = "PRIVATE" ;

}

/**

  * path 前缀值

  */

interface RestVersionValue {

  String EMPTY = "" ;

  String V1 = "rest/v1" ;

  String V2 = "rest/v2" ;

  String PRIVATE = "rest/private" ;

}

interface BaiduApiService {

  @GET ( "s" )

  Observable<Response<Object>> search( @Query ( "wd" )String wd);

  @GET ( "s" )

  @Headers ({UrlConstants.Header.REST_VERSION_V1})

  Observable<Response<Object>> searchChangePath( @Query ( "wd" )String wd);

  @GET ( "s" )

  @Headers ({UrlConstants.Header.HOST_DEV})

  Observable<Response<Object>> searchChangeHost( @Query ( "wd" )String wd);

  @Headers ({UrlConstants.Header.HOST_PRIVATE, UrlConstants.Header.REST_VERSION_PRIVATE})

  @GET ( "s" )

  Observable<Response<Object>> searchChangeHostPath( @Query ( "wd" )String wd);

}

interface Header {

  String SPLIT_COLON = ":" ;

  String HOST = "HostName" ;

  String HOST_CLOUD = HOST + SPLIT_COLON + HostName.CLOUD;

  String HOST_PRIVATE = HOST + SPLIT_COLON + HostName.PRIVATE;

  String HOST_DEV = HOST + SPLIT_COLON + HostName.DEV;

  String REST_VERSION = "RestVersion" ;

  String REST_VERSION_V1 = REST_VERSION + SPLIT_COLON + RestVersionCode.V1;

  String REST_VERSION_V2 = REST_VERSION + SPLIT_COLON + RestVersionCode.V2;

  String REST_VERSION_PRIVATE = REST_VERSION + SPLIT_COLON + RestVersionCode.PRIVATE;

  String REST_VERSION_EMPTY = REST_VERSION + SPLIT_COLON + RestVersionCode.EMPTY;

}

class RequestInterceptor implements Interceptor {

  @Override

  public Response intercept(Chain chain) throws IOException {

   Request originRequest = chain.request();

   HttpUrl originUrl = originRequest.url();

   HttpUrl.Builder newBuilder;

   String hostType = originRequest.header(UrlConstants.Header.HOST);

   System.out.println( "hostType:" + hostType);

   if (hostType != null && hostType.length() > 0 ) {

    String hostValue = UrlManager.getInstance().getHost(hostType);

    HttpUrl temp = HttpUrl.parse(hostValue);

    if (temp == null ) {

     throw new IllegalArgumentException(hostType + "对应的host地址不合法:" + hostValue);

    }

    newBuilder = temp.newBuilder();

   } else {

    newBuilder = new HttpUrl.Builder()

      .scheme(originUrl.scheme())

      .host(originUrl.host())

      .port(originUrl.port());

   }

   String restVersion = originRequest.header(UrlConstants.Header.REST_VERSION);

   System.out.println( "restVersion:" + restVersion);

   if (restVersion == null ) {

    restVersion = UrlConstants.RestVersionCode.V2;

   }

   String restValue = UrlManager.getInstance().getRest(restVersion);

   if (restValue.contains( "/" )) {

    String[] paths = restValue.split( "/" );

    for (String path : paths) {

     newBuilder.addEncodedPathSegment(path);

    }

   } else {

    newBuilder.addEncodedPathSegment(restValue);

   }

   for ( int i = 0 ; i < originUrl.pathSegments().size(); i++) {

    newBuilder.addEncodedPathSegment(originUrl.encodedPathSegments().get(i));

   }

   newBuilder.encodedPassword(originUrl.encodedPassword())

     .encodedUsername(originUrl.encodedUsername())

     .encodedQuery(originUrl.encodedQuery())

     .encodedFragment(originUrl.encodedFragment());

   HttpUrl newUrl = newBuilder.build();

   System.out.println( "newUrl:" + newUrl.toString());

   Request newRequest = originRequest.newBuilder().url(newUrl).build();

   return chain.proceed(newRequest);

  }

}

private Map<String, String> hostMap;

private Map<String, String> restMap;

private UrlManager() {

  hostMap = new HashMap<>( 16 );

  for (UrlConstants.Host host : UrlConstants.Host.values()) {

   hostMap.put(host.getName(), host.getValue());

  }

  restMap = new HashMap<>();

  for (UrlConstants.Rest rest : UrlConstants.Rest.values()) {

   restMap.put(rest.getVersion(), rest.getValue());

  }

}

//更新host 的值

public void setHost(String name, String value) {

  if (hostMap.containsKey(name)) {

   HttpUrl httpUrl = HttpUrl.parse(value);

   if (httpUrl == null ) {

    throw new IllegalArgumentException( "要存入的Host " + name + "对应的value:"

      + value + "不合法!" );

   }

   hostMap.put(name, value);

  } else {

   throw new NoSuchElementException( "没有找到已经定义的Host名称:" + name + ",请先在" +

     "net.devwiki.manager.UrlConstants.Host中定义!" );

  }

}

//根据host 获取值

public String getHost(String name) {

  if (!hostMap.containsKey(name)) {

   throw new NoSuchElementException( "没有找到已经定义的Host名称:" + name + ",请先在" +

     "net.devwiki.manager.UrlConstants.Host中定义!" );

  }

  return hostMap.get(name);

}

private static void testRequest() {

  BaiduRest rest = new BaiduRest();

  testDefault(rest);

  testChangeHost(rest);

  testChangePath(rest);

  testChangeHostPath(rest);

}