Retrofit2自定义拦截器和ConverterFactory实现客户端与服务端加密通信
网络请求框架使用的retrofit，客户端与服务端之间需要加密通信并且请求需要gzip压缩。为完成这一需求，需要拦截请求和响应。特此记录下修改请求的过程，希望可以帮助有需要的人。
处理request
retrofit2使用okhttp3.x，请求上的处理只需要给okhttp添加拦截器即可
这里与服务端通信相互之间对称加密，并且需要开启gzip压缩，因此这里定义了三个拦截器完成这一需求
1.修改请求头
public class RequestHeaderInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
Request originalRequest = chain.request();
Request updateRequest = originalRequest.newBuilder()
.header("Content-Type", "text/plain; charset=utf-8")
.header("Accept", "*/*")
.header("Accept-Encoding", "gzip")
.build();
return chain.proceed(updateRequest);
}
}
2.加密请求内容
public class RequestEncryptInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
RequestBody body = request.body();
Buffer buffer = new Buffer();
body.writeTo(buffer);
Charset charset = Charset.forName("UTF-8");
MediaType contentType = body.contentType();
if (contentType != null) {
charset = contentType.charset(charset);
}
String paramsStr = buffer.readString(charset);
try {
paramsStr = EncryptUtils.encryptParams(paramsStr);
} catch (Exception e) {
LogUtils.e(e);
}
RequestBody requestBody = RequestBody.create(MediaType.parse("text/plain; charset=utf-8"), paramsStr);
request = request.newBuilder()
.post(requestBody)
.build();
return chain.proceed(request);
}
}
3.启用Gzip压缩
public class GzipRequsetInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
Request originalRequest = chain.request();
if (originalRequest.body() == null || originalRequest.header("Content-Encoding") != null) {
return chain.proceed(originalRequest);
}
Request compressedRequest = originalRequest.newBuilder()
.header("Content-Encoding", "gzip")
.method(originalRequest.method(), gzip(originalRequest.body()))
.build();
return chain.proceed(compressedRequest);
}
private RequestBody gzip(final RequestBody body) {
return new RequestBody() {
@Override
public MediaType contentType() {
return body.contentType();
}
@Override
public long contentLength() throws IOException {
return -1;
}
@Override
public void writeTo(BufferedSink sink) throws IOException {
BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
body.writeTo(gzipSink);
gzipSink.close();
}
};
}
}
处理response
对response处理需要未retrofit设置自定义的ConverterFactory，因客户端与服务端使用json通信，因此我们参考官方提供GsonConverterFactory编写
自定义GsonConverterFactory，其实相对于原版只修改了responseBodyConverter方法的内容，requestBodyConverter依旧用的原版内容。
注意,GsonRequestBodyConverter类的修饰符不是public，需要将其代码拷贝出来
public final class CustomGsonConverterFactory extends Converter.Factory {
private final Gson gson;
public static CustomGsonConverterFactory create() {
return create(new Gson());
}
@SuppressWarnings("ConstantConditions") // Guarding public API nullability.
public static CustomGsonConverterFactory create(Gson gson) {
if (gson == null) throw new NullPointerException("gson == null");
return new CustomGsonConverterFactory(gson);
}
private CustomGsonConverterFactory(Gson gson) {
this.gson = gson;
}
@Override
public Converter responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) {
TypeAdapter adapter = gson.getAdapter(TypeToken.get(type));
return new CustomGsonResponseConverter<>(gson, adapter);
}
@Override
public Converter requestBodyConverter(Type type, Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
TypeAdapter adapter = gson.getAdapter(TypeToken.get(type));
return new GsonRequestBodyConverter<>(gson, adapter);
}
}
修改GsonResponseConverter，使其解密后再处理内容。
注意：这里预处理json的过程并非通用步骤，因我的json格式是 { “code”: 0, “message”: “success”,
“data”: { … } }这样的，如果你的不同请换一种方式。
class CustomGsonResponseConverter implements Converter {
private final Gson gson;
private final TypeAdapter adapter;
CustomGsonResponseConverter(Gson gson, TypeAdapter adapter) {
this.gson = gson;
this.adapter = adapter;
}
@Override
public T convert(ResponseBody value) throws IOException {
try {
String originalBody = value.string();
// 解密
String body = EncryptUtils.decryptParams(originalBody);
// 获取json中的code，对json进行预处理
JSONObject json = new JSONObject(body);
int code = json.optInt("code");
// 当code不为0时，设置data为{}，这样转化就不会出错了
if (code != 0) {
json.put("data", new JSONObject());
body = json.toString();
}
return adapter.fromJson(body);
} catch (Exception e) {
throw new RuntimeException(e.getMessage());
} finally {
value.close();
}
}
这里也贴一下原版的GsonRequestBodyConverter：
class GsonRequestBodyConverter implements Converter {
private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8");
private static final Charset UTF_8 = Charset.forName("UTF-8");
private final Gson gson;
private final TypeAdapter adapter;
GsonRequestBodyConverter(Gson gson, TypeAdapter adapter) {
this.gson = gson;
this.adapter = adapter;
}
@Override public RequestBody convert(T value) throws IOException {
Buffer buffer = new Buffer();
Writer writer = new OutputStreamWriter(buffer.outputStream(), UTF_8);
JsonWriter jsonWriter = gson.newJsonWriter(writer);
adapter.write(jsonWriter, value);
jsonWriter.close();
return RequestBody.create(MEDIA_TYPE, buffer.readByteString());
}
}
这样build.gradle中就可以删掉引入的GsonConverterFactory了
整合使用
使用方式如下
Retrofit retrofit = new Retrofit.Builder()
.client(getOkHttpClient())
.addConverterFactory(CustomGsonConverterFactory.create())
.baseUrl(BASE_URL)
.build();
其中，okhttpClient方法：
@NonNull
private OkHttpClient getOkHttpClient() {
OkHttpClient.Builder okHttpClientBuilder = new OkHttpClient.Builder();
okHttpClientBuilder.connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS)
.writeTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS)
.readTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS)
.addInterceptor(new RequestHeaderInterceptor())
.addInterceptor(new RequestEncryptInterceptor())
.addInterceptor(new GzipRequsetInterceptor());
return okHttpClientBuilder.build();
}
就酱
喜欢的话请帮忙转发一下能让更多有需要的人看到吧，有些技术上的问题大家可以多探讨一下。
