一、什么是UA

User-Agent就是告诉网站服务器，访问者是通过什么工具来请求的，或者自定义信息、例如手机型号、系统版本、app版本、渠道号、便于我们对数据的统计

二、客户端如何设置UA

1.如果APP的网络请求时okhttp。

Request request = new Request.Builder().url(url)                             .removeHeader("User-Agent")                             .addHeader("User-Agent", WebSettings.getDefaultUserAgent(Context)                              .build();            httpClient.newCall(request).enqueue(handler);

2.如果是okhttp+retrofit。

public static MusicApi getInfoApi() {        if (musicApi == null) {            Retrofit retrofit = new Retrofit.Builder()                    .client(getOkHttpClient())//获取后的okhttp头部                    .baseUrl("http://tingapi.ting.baidu.com/v1/restserver/")                    .addConverterFactory(gsonConverterFactory)                    .addCallAdapterFactory(rxJavaCallAdapterFactory)                    .build();            musicApi = retrofit.create(MusicApi.class);        }        return musicApi;    }    /**     *  构造okhttp头部     *     * */    private static OkHttpClient getOkHttpClient() {        OkHttpClient httpClient = new OkHttpClient.Builder()                .addInterceptor(new Interceptor() {                    @Override                    public Response intercept(Chain chain) throws IOException {                        Request request = chain.request()                                .newBuilder()                                .removeHeader("User-Agent")//移除旧的                                .addHeader("User-Agent", WebSettings.getDefaultUserAgent(Context))//添加真正的头部                                .build();                        return chain.proceed(request);                    }                }).build();        return httpClient;    }

兼容版本的获取UA

private static String getUAInfo() {        String userAgent = "";        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {            try {                userAgent = WebSettings.getDefaultUserAgent(context);            } catch (Exception e) {                userAgent = System.getProperty("http.agent");            }        } else {            userAgent = System.getProperty("http.agent");        }        StringBuffer sb = new StringBuffer();        for (int i = 0, length = userAgent.length(); i < length; i++) {            char c = userAgent.charAt(i);            if (c <= '\u001f' || c >= '\u007f') {                sb.append(String.format("\\u%04x", (int) c));            } else {                sb.append(c);            }        }        return sb.toString();    }

以上的UA获取都是系统级的日志信息、那么我们如何自定义UA呢？