OkHttp 拦截器应用

  1. URL重定向
  2. 请求体数据加密
  3. HEAD动态添加
  4. 请求日志抓取

URL重定向

如何重定向,说白了就是更换个新的url,但是一般服务端做比较好,客户端就显得有些鸡肋。但是这个东西日常也会有用到,比如一些场景,测试生成环境的切换。业务多了,几个人混合开发的后台,每个人的代码不同意导致了baseurl还不同,这时候可以通过一个入口来修改就行,不然每个地方都去修改,接口量大的话会很麻烦。

  • 自定义一个Interceptor(TestInterceptor后面都是基于这个来讲解),直接创建个类实现Interceptor接口即可,然后在Okhttp初始化的是添加这个拦截器即可
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public class TestInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {

return null;
}
}


然后在你需要初始化的okhttp的地方添加这个拦截器

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public class TestActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

OkHttpClient build = new OkHttpClient.Builder()
.addInterceptor(new TestInterceptor())
.build();
}
}


那么接下来我们需要干什么呢,拦截器已经写好了,既然定义是拦截器,肯定请求体信息都在那里。我们可以在接口Interceptor里面的方法intercept给了我们一个参数Chain,一切的源头都在这里面。来看看接下来如何进行骚操作来改变初始的URL达到重定向的功能

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public class TestInterceptor implements Interceptor {
private String newHost = "127.0.0.1";
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
HttpUrl url = request.url();
//http://127.0.0.1/test/upload/img?userName=xiaoming&userPassword=12345
String scheme = url.scheme();// http https
String host = url.host();// 127.0.0.1
String path = url.encodedPath();// /test/upload/img
String query = url.encodedQuery();// userName=xiaoming&userPassword=12345

StringBuffer sb = new StringBuffer();
String newUrl = sb.append(scheme).append(newHost).append(path).append("?").append(query).toString();

Request.Builder builder = request.newBuilder()
.url(newUrl);

return chain.proceed(builder.build());
}
}


上面只是简单的换了一下host retrofit可以轻易做到,在构造retrofit的时候可以修改baseUrl,但是如果要换path呢,这时候可能retrofit不是那么好做,而且你需要每个地方都要换,这时候你可以在这里当成一个统一的入口new一个新的path即可。简单吧,对于后面的每个字段说明意思我在后面也有备注,可以看到拆分后的样子

请求体数据加密

既然要对请求体加密,那肯定要知道请求体在哪里,然后才能加密,其实都一样不论是加密url里面的query内容还是加密body体里面的都一样,只要拿到了对应的数据我们想怎么做怎么,有的接口比较奇葩,他需要根据请求体的内容进行签名认证。不论如何我们拿到了请求体当然想怎么样就怎么样,看下嘛的操作

  1. 加密query内容
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public class TestInterceptor implements Interceptor {
private String newHost = "127.0.0.1";

@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
HttpUrl url = request.url();

//http://127.0.0.1/test/upload/img?userName=xiaoming&userPassword=12345
String scheme = url.scheme();// http https
String host = url.host();// 127.0.0.1
String path = url.encodedPath();// /test/upload/img
String query = url.encodedQuery();// userName=xiaoming&userPassword=12345

StringBuffer sb = new StringBuffer();
sb.append(scheme).append(newHost).append(path).append("?");
Set<String> queryList = url.queryParameterNames();
Iterator<String> iterator = queryList.iterator();

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

String queryName = iterator.next();
sb.append(queryName).append("=");
String queryKey = url.queryParameter(queryName);
//对query的key进行加密
sb.append(CommonUtils.getMD5(queryKey));
if (iterator.hasNext()) {
sb.append("&");
}
}

String newUrl = sb.toString();

Request.Builder builder = request.newBuilder()
.url(newUrl);

return chain.proceed(builder.build());
}
}


这样拼接的query内容就可以直接统一加密了。我这里只是简单的md5加密 如果说服务端和客户端定义了一套加密解密协议,就可以在这里进行特定的加密方式进行加密

  1. 加密body体内容
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public class TestInterceptor implements Interceptor {
private String newHost = "127.0.0.1";

public static String requestBodyToString(RequestBody requestBody) throws IOException {
Buffer buffer = new Buffer();
requestBody.writeTo(buffer);
return buffer.readUtf8();
}

@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
HttpUrl url = request.url();

//http://127.0.0.1/test/upload/img?userName=xiaoming&userPassword=12345
String scheme = url.scheme();// http https
String host = url.host();// 127.0.0.1
String path = url.encodedPath();// /test/upload/img
String query = url.encodedQuery();// userName=xiaoming&userPassword=12345

StringBuffer sb = new StringBuffer();
sb.append(scheme).append(newHost).append(path).append("?");
Set<String> queryList = url.queryParameterNames();
Iterator<String> iterator = queryList.iterator();

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

String queryName = iterator.next();
sb.append(queryName).append("=");
String queryKey = url.queryParameter(queryName);
//对query的key进行加密
sb.append(CommonUtils.getMD5(queryKey));
if (iterator.hasNext()) {
sb.append("&");
}
}

String newUrl = sb.toString();

RequestBody body = request.body();
String bodyToString = requestBodyToString(body);
TestBean testBean = GsonTools.changeGsonToBean(bodyToString, TestBean.class);
String userPassword = testBean.getUserPassword();
//加密body体中的用户密码
testBean.setUserPassword(CommonUtils.getMD5(userPassword));

String testGsonString = GsonTools.createGsonString(testBean);
RequestBody requestBody = RequestBody.create(MediaType.parse("application/json"), testGsonString);

Request.Builder builder = request.newBuilder()
.post(requestBody)
.url(newUrl);

return chain.proceed(builder.build());
}
}


从上面可以看出我们先拿到body体的内容然后解析后,拿到对应的实体类,然后进行加密,再次创建一个新的body体里面然后post过去,即可达到body体加密,我这只是一种body加密方法,也有可能是拿到body然后进行加密然后对加密后的东西加入head 当成签名使用。

最终这种拦截器方式的加密也是一种统一代码入口的方式。

HEAD动态添加

在日常的开发中,可能每个接口对应的header不同有的多有的少。不可能说每个接口都写一个拦截器进行添加头部。这时候我们可以换个思维来考虑这个问题。怎么做呢,其实也是为了统一代码,同一种操作不要再多个地方进行,这样修改起来很麻烦。统一入口,统一出口。

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public class TestInterceptor implements Interceptor {
private String newHost = "127.0.0.1";
private String path1 = "/test/upload/img";
private String path2 = "/test/upload/voice";

public static String requestBodyToString(RequestBody requestBody) throws IOException {
Buffer buffer = new Buffer();
requestBody.writeTo(buffer);
return buffer.readUtf8();
}

@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
HttpUrl url = request.url();

//http://127.0.0.1/test/upload/img?userName=xiaoming&userPassword=12345
String scheme = url.scheme();// http https
String host = url.host();// 127.0.0.1
String path = url.encodedPath();// /test/upload/img
String query = url.encodedQuery();// userName=xiaoming&userPassword=12345

StringBuffer sb = new StringBuffer();
sb.append(scheme).append(newHost).append(path).append("?");
Set<String> queryList = url.queryParameterNames();
Iterator<String> iterator = queryList.iterator();

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

String queryName = iterator.next();
sb.append(queryName).append("=");
String queryKey = url.queryParameter(queryName);
//对query的key进行加密
sb.append(CommonUtils.getMD5(queryKey));
if (iterator.hasNext()) {
sb.append("&");
}
}

String newUrl = sb.toString();

RequestBody body = request.body();
String bodyToString = requestBodyToString(body);
TestBean testBean = GsonTools.changeGsonToBean(bodyToString, TestBean.class);
String userPassword = testBean.getUserPassword();
//加密body体中的用户密码
testBean.setUserPassword(CommonUtils.getMD5(userPassword));

String testGsonString = GsonTools.createGsonString(testBean);
RequestBody requestBody = RequestBody.create(MediaType.parse("application/json"), testGsonString);

Request.Builder builder = request.newBuilder()
.post(requestBody)
.url(newUrl);

switch (path) {
case path1:
builder.addHeader("token","token");
break;
case path2:
builder.addHeader("token","token");
builder.addHeader("uid","uid");
break;
}

return chain.proceed(builder.build());
}
}


骚不骚,根据url中path的不同来动态的添加header,其实写代码吗?每个人实现的方式不同,只要路子对,怎么撸都行,看个人。

请求日志抓取

这个其实已经有现成的log拦截器了,大家日常开发中已经有用过,但是如果说我们只想看到我想要的,过滤那些不要的东西。怎么办呢。只能自己来自定义了。把自己需要的东西打印出来。以免太多每次看很乱。这时候怎么通过拦截器完成这样的一个骚操作呢。也很简单,基于上面的基础我们应该该拿到的都拿到了。

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public class TestInterceptor implements Interceptor {
private String newHost = "127.0.0.1";
private String path1 = "/test/upload/img";
private String path2 = "/test/upload/voice";
private String TAG = "TestInterceptor";
public static String requestBodyToString(RequestBody requestBody) throws IOException {
Buffer buffer = new Buffer();
requestBody.writeTo(buffer);
return buffer.readUtf8();
}

@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Response response = chain.proceed(request);

HttpUrl url = request.url();
//http://127.0.0.1/test/upload/img?userName=xiaoming&userPassword=12345
String scheme = url.scheme();// http https
String host = url.host();// 127.0.0.1
String path = url.encodedPath();// /test/upload/img
String query = url.encodedQuery();// userName=xiaoming&userPassword=12345

RequestBody body = request.body();
String bodyToString = requestBodyToString(body);

Log.e(TAG,scheme);
Log.e(TAG,host);
Log.e(TAG,path);
Log.e(TAG,query);

if (response != null) {
ResponseBody responseBody = response.body();
long contentLength = responseBody.contentLength();
String bodySize = contentLength != -1 ? contentLength + "-byte" : "unknown-length";

Log.e(TAG,response.code() + ' '
+ response.message() + ' '
+ response.request().url()+' '
+ bodySize
);

Headers headers = response.headers();
for (int i = 0, count = headers.size(); i < count; i++) {
Log.e(TAG,headers.name(i) + ": " + headers.value(i));
}

}

return chain.proceed(request);
}
}



OkHttp 拦截器应用
https://blog.ityet.com/2017/12/17/2017-12-17-okhttp-interceptor/
作者
Leo
发布于
2017年12月17日
许可协议