在实际项目中,对于有需要统一进行公共参数添加的网络请求,可以使用下面的代码来实现:
RestAdapter restAdapter = new RestAdapter.Builder()
.setEndpoint(ctx).setRequestInterceptor(new RequestInterceptor() {
@Override
public void intercept(RequestFacade request) {
request.addQueryParam("publicParams", "1");
}
}).setConverter(new BaseConverter())
.build();
在RestAdapter的实例化对象的时候,为其指定一个RequestInterceptor接口的实现类即可,在该类中,可以对请求体的相关参数进行设置,如addHeader、addQueryParam等。
不过遗憾的是Retrofit2.0已经没有了该类,该怎么做呢?通过Interceptor实现。
Interceptor是拦截器, 在发送之前, 添加一些参数, 或者获取一些信息。
/**
* 封装公共参数(Key和密码)
*
*/
public class CommonInterceptor implements Interceptor {
private final String mApiKey;
private final String mApiSecret;
public CommonInterceptor(String apiKey, String apiSecret) {
mApiKey = apiKey;
mApiSecret = apiSecret;
}
@Override public Response intercept(Interceptor.Chain chain) throws IOException {
String marvelHash = ApiUtils.generateMarvelHash(mApiKey, mApiSecret);
Request oldRequest = chain.request();
// 添加新的参数
HttpUrl.Builder authorizedUrlBuilder = oldRequest.url()
.newBuilder()
.scheme(oldRequest.url().scheme())
.host(oldRequest.url().host())
.addQueryParameter(MarvelService.PARAM_API_KEY, mApiKey)
.addQueryParameter(MarvelService.PARAM_TIMESTAMP, ApiUtils.getUnixTimeStamp())
.addQueryParameter(MarvelService.PARAM_HASH, marvelHash);
// 新的请求
Request newRequest = oldRequest.newBuilder()
.method(oldRequest.method(), oldRequest.body())
.url(authorizedUrlBuilder.build())
.build();
return chain.proceed(newRequest);
}
}
Okhttp3使用了装饰者模式, 使用Builder添加Interceptor。
CommonInterceptor commonInterceptor = new CommonInterceptor(
"key", "Secret");
OkHttpClient client = new OkHttpClient.Builder()
.addInterceptor(commonInterceptor)
.build();
// 适配器
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("url")
.addConverterFactory(GsonConverterFactory.create()
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.client(client)
.build();
有时候你找到了一条线,就能顺着线找到更多。
背景
在 Android Http API 请求开发中经常遇到这样的需求:每一次请求带上一个或者多个固定不变的参数,例如:
设备唯一标识:device_id = 7a4391e28f309c21
业务唯一标识:uid = 2231001
平台类型:platform = android
客户端版本号:version_code = 6
…
这些参数是每一次发生请求都需要的,我们姑且称他们为公共参数(或者基础参数)。公共参数一般以 header line、url query 或者 post body(较少) 这些形式插入请求。
实现
如果使用 OkHttp 作为 http request client, 这件事情就变得简单多了。OkHttp 提供了强大的拦截器组件 (Interceptor):
Interceptors are a powerful mechanism that can monitor, rewrite, and retry calls.
也就是说,OkHttp 的拦截器功能之一就是对将要发出的请求进行拦截、改造然后再发出。这正是我们想要的。BasicParamsInterceptor 实现了 okhttp3.Interceptor 接口。
实现 public Response intercept(Chain chain) throws IOException 方法。使用 Builder 模式,暴露以下接口:
addParam(String key, String value)
post 请求,且 body type 为 x-www-form-urlencoded 时,键值对公共参数插入到 body 参数中,其他情况插入到 url query 参数中。
addParamsMap(Map paramsMap)
同上,不过这里用键值对 Map 作为参数批量插入。
addHeaderParam(String key, String value)
在 header 中插入键值对参数。
addHeaderParamsMap(Map headerParamsMap)
在 header 中插入键值对 Map 集合,批量插入。
addHeaderLine(String headerLine)
在 header 中插入 headerLine 字符串,字符串需要符合 -1 != headerLine.indexOf(“:”) 的规则,即可以解析成键值对。
addHeaderLinesList(List headerLinesList)
同上,headerLineList: List 为参数,批量插入 headerLine。
addQueryParam(String key, String value)
插入键值对参数到 url query 中。
addQueryParamsMap(Map queryParamsMap)
插入键值对参数 map 到 url query 中,批量插入。
示例
使用 Buider 模式创建 Interceptor 对象,然后调用 OkHttp 的 addInterceptor(Interceptor i) 方法将 interceptor 对象添加至 client 中:
BasicParamsInterceptor basicParamsInterceptor =
new OkPublicParamsInterceptor.Builder()
.addHeaderParam("device_id", DeviceUtils.getDeviceId())
.addParam("uid", UserModel.getInstance().getUid())
.addQueryParam("api_version", "1.1")
.build();
OkHttpClient client = new OkHttpClient.Builder()
.addInterceptor(basicParamsInterceptor)
.build();
TODO
自动时间戳公共参数的支持
动态参数的支持(例如登录后插入服务器返回的 uid)
源码
basicparamsinterceptor应用
配置基本提交参数
我们可以建一个拦截器,这里我举例加些简单的系统参数,如下:
class HttpBaseParamsLoggingInterceptor implements Interceptor{
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Request.Builder requestBuilder = request.newBuilder();
RequestBody formBody = new FormBody.Builder()
.add("userId", "10000")
.add("sessionToken", "E34343RDFDRGRT43RFERGFRE")
.add("q_version", "1.1")
.add("device_id", "android-344365")
.add("device_os", "android")
.add("device_osversion","6.0")
.add("req_timestamp", System.currentTimeMillis() + "")
.add("app_name","forums")
.add("sign", "md5")
.build();
String postBodyString = Utils.bodyToString(request.body());
postBodyString += ((postBodyString.length() > 0) ? "&" : "") + Utils.bodyToString(formBody);
request = requestBuilder
.post(RequestBody.create(MediaType.parse("application/x-www-form-urlencoded;charset=UTF-8"),
postBodyString))
.build();
return chain.proceed(request);
}
}
上面Utils类是使用的okio.Buffer里面的工具类。通过RequestBody构建要上传的一些基本公共的参数,然后通过”&”符号在http 的body里面其他要提交参数拼接。然后再通过requestBuilder重新创建request对象,然后再通过chain.proceed(request)返回Response 。
接下来在创建OkHttpClient对象的时候修改为如下代码:
mOkHttpClient = new OkHttpClient.Builder()
.addInterceptor(interceptor)
.addInterceptor(new HttpBaseParamsLoggingInterceptor())
.build();
这样就添加好了一些基本的公共参数。
下面我们借助BasicParamsInterceptor实现,代码如下:
public class BasicParamsInterceptor implements Interceptor {
Map queryParamsMap = new HashMap<>();
Map paramsMap = new HashMap<>();
Map headerParamsMap = new HashMap<>();
List headerLinesList = new ArrayList<>();
private BasicParamsInterceptor() {
}
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Request.Builder requestBuilder = request.newBuilder();
// process header params inject
Headers.Builder headerBuilder = request.headers().newBuilder();
if (headerParamsMap.size() > 0) {
Iterator iterator = headerParamsMap.entrySet().iterator();
while (iterator.hasNext()) {
Map.Entry entry = (Map.Entry) iterator.next();
headerBuilder.add((String) entry.getKey(), (String) entry.getValue());
}
}
if (headerLinesList.size() > 0) {
for (String line: headerLinesList) {
headerBuilder.add(line);
}
}
requestBuilder.headers(headerBuilder.build());
// process header params end
// process queryParams inject whatever it's GET or POST
if (queryParamsMap.size() > 0) {
injectParamsIntoUrl(request, requestBuilder, queryParamsMap);
}
// process header params end
// process post body inject
if (request.method().equals("POST") && request.body().contentType().subtype().equals("x-www-form-urlencoded")) {
FormBody.Builder formBodyBuilder = new FormBody.Builder();
if (paramsMap.size() > 0) {
Iterator iterator = paramsMap.entrySet().iterator();
while (iterator.hasNext()) {
Map.Entry entry = (Map.Entry) iterator.next();
formBodyBuilder.add((String) entry.getKey(), (String) entry.getValue());
}
}
RequestBody formBody = formBodyBuilder.build();
String postBodyString = bodyToString(request.body());
postBodyString += ((postBodyString.length() > 0) ? "&" : "") + bodyToString(formBody);
requestBuilder.post(RequestBody.create(MediaType.parse("application/x-www-form-urlencoded;charset=UTF-8"), postBodyString));
} else { // can't inject into body, then inject into url
injectParamsIntoUrl(request, requestBuilder, paramsMap);
}
request = requestBuilder.build();
return chain.proceed(request);
}
// func to inject params into url
private void injectParamsIntoUrl(Request request, Request.Builder requestBuilder, Map paramsMap) {
HttpUrl.Builder httpUrlBuilder = request.url().newBuilder();
if (paramsMap.size() > 0) {
Iterator iterator = paramsMap.entrySet().iterator();
while (iterator.hasNext()) {
Map.Entry entry = (Map.Entry) iterator.next();
httpUrlBuilder.addQueryParameter((String) entry.getKey(), (String) entry.getValue());
}
}
requestBuilder.url(httpUrlBuilder.build());
}
private static String bodyToString(final RequestBody request){
try {
final RequestBody copy = request;
final Buffer buffer = new Buffer();
if(copy != null)
copy.writeTo(buffer);
else
return "";
return buffer.readUtf8();
}
catch (final IOException e) {
return "did not work";
}
}
public static class Builder {
BasicParamsInterceptor interceptor;
public Builder() {
interceptor = new BasicParamsInterceptor();
}
public Builder addParam(String key, String value) {
interceptor.paramsMap.put(key, value);
return this;
}
public Builder addParamsMap(Map paramsMap) {
interceptor.paramsMap.putAll(paramsMap);
return this;
}
public Builder addHeaderParam(String key, String value) {
interceptor.headerParamsMap.put(key, value);
return this;
}
public Builder addHeaderParamsMap(Map headerParamsMap) {
interceptor.headerParamsMap.putAll(headerParamsMap);
return this;
}
public Builder addHeaderLine(String headerLine) {
int index = headerLine.indexOf(":");
if (index == -1) {
throw new IllegalArgumentException("Unexpected header: " + headerLine);
}
interceptor.headerLinesList.add(headerLine);
return this;
}
public Builder addHeaderLinesList(List headerLinesList) {
for (String headerLine: headerLinesList) {
int index = headerLine.indexOf(":");
if (index == -1) {
throw new IllegalArgumentException("Unexpected header: " + headerLine);
}
interceptor.headerLinesList.add(headerLine);
}
return this;
}
public Builder addQueryParam(String key, String value) {
interceptor.queryParamsMap.put(key, value);
return this;
}
public Builder addQueryParamsMap(Map queryParamsMap) {
interceptor.queryParamsMap.putAll(queryParamsMap);
return this;
}
public BasicParamsInterceptor build() {
return interceptor;
}
}
}
只要像上面一样配置就行了。