动态改变Retrofit的 base url和 rest version-白红宇

动态改变Retrofit的 base url和 rest version

1. 需求与前提

base url

默认base url: https://cloud.devwiki.net

测试版 url : https://dev.devwiki.net

私有云版本url: https://private.devwiki.net

rest 版本

/rest/v1/

/rest/v2/

/rest/v3/

需求点

大部分接口使用 cloud host, 部分接口使用 private host

大部分接口使用 rest/v3 版本, 部分接口使用 v2, v1版本.

每个host 都有可能存在 rest v1, v2, v3的接口

2. 实现思路

okhttp 可以添加拦截器, 可在发起访问前进行拦截, 通常我们会在拦截器中统一添加 header, 比如:

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());    }}复制代码

同理我们也可以在所有请求中添加统一的uuid 或者 key 进行防劫持或者认证. 比如:

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);复制代码

那么, 同样我们可以再拦截器中进行host 和 path的替换, 那么怎么替换呢?

3. 实现过程

3.1 定义host 类型和 rest 版本

host类型:

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";}复制代码

rest 版本:

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";}复制代码

设置一个默认的 host 和 rest 版本, 然后在需要更改host和rest 版本的请求接口处添header, 根据header设置来变更.

interface BaiduApiService {    @GET("s")    Observable

header 的可选值:

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;}复制代码

然后是解析:

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);    }}复制代码

为了能动态设置host, 我们需要一个map来存储host 类型和值.

private Map
    
      hostMap;private Map
     
       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);}复制代码

这样就可以动态替换host 和 rest版本了.

4.测试运行

测试代码:

private static void testRequest() {    BaiduRest rest = new BaiduRest();    testDefault(rest);    testChangeHost(rest);    testChangePath(rest);    testChangeHostPath(rest);}复制代码

测试运行结果:

ostType:nullrestVersion:nullnewUrl:https://www.baidu.com/rest/v2/s?wd=123九月 07, 2018 11:36:58 上午 okhttp3.internal.platform.Platform log信息: --> GET https://www.baidu.com/rest/v2/s?wd=123 http/1.1九月 07, 2018 11:36:58 上午 okhttp3.internal.platform.Platform log信息: <-- 302 Found https://www.baidu.com/rest/v2/s?wd=123 (83ms, 154-byte body)九月 07, 2018 11:36:58 上午 okhttp3.internal.platform.Platform log信息: --> GET http://www.baidu.com/s?wd=123&tn=SE_PSStatistics_p1d9m0nf http/1.1九月 07, 2018 11:36:58 上午 okhttp3.internal.platform.Platform log信息: <-- 200 OK http://www.baidu.com/s?wd=123&tn=SE_PSStatistics_p1d9m0nf (46ms, unknown-length body)hostType:DEVrestVersion:nullnewUrl:https://dev.baidu.com/rest/v2/s?wd=123九月 07, 2018 11:36:58 上午 okhttp3.internal.platform.Platform log信息: --> GET https://dev.baidu.com/rest/v2/s?wd=123 http/1.1九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: <-- 302 Found https://dev.baidu.com/rest/v2/s?wd=123 (154ms, 154-byte body)九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: --> GET http://developer.baidu.com/error.html http/1.1九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: <-- 301 Moved Permanently http://developer.baidu.com/error.html (18ms, 73-byte body)九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: --> GET https://developer.baidu.com/error.html http/1.1hostType:nullrestVersion:V1newUrl:https://www.baidu.com/rest/v1/s?wd=123九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: <-- 200 OK https://developer.baidu.com/error.html (157ms, unknown-length body)九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: --> GET https://www.baidu.com/rest/v1/s?wd=123 http/1.1九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: <-- 302 Found https://www.baidu.com/rest/v1/s?wd=123 (46ms, 154-byte body)九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: --> GET http://www.baidu.com/s?wd=123&tn=SE_PSStatistics_p1d9m0nf http/1.1九月 07, 2018 11:36:59 上午 okhttp3.internal.platform.Platform log信息: <-- 200 OK http://www.baidu.com/s?wd=123&tn=SE_PSStatistics_p1d9m0nf (54ms, unknown-length body)hostType:PRIVATErestVersion:PRIVATEnewUrl:https://private.bidu.com/rest/private/s?wd=123复制代码

结果按照设置进行了host 和 rest 的变更.

5. 项目代码

项目代码地址:

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