拦截器调用顺序一般为顺序调用，将上一个拦截器的返回作为下一个拦截器的输入，直到所有拦截器执行完毕，返回最终结果。这里通过for循环先模拟一个简单的拦截器调用过程，再模拟okhttp拦截器工作过程
简单顺序拦截器调用
模拟屏蔽词：
public static Response execute() {
//模拟所有拦截器
List<Interceptor> mInterceptorList = new ArrayList<Interceptor>() {{
add(new FatherInterceptor());
add(new GrandpaInterceptor());
}};
Chain chain = new RealInterceptor("我是你爸爸，我是你爷爷");
Response response = null;
for (Interceptor interceptor : mInterceptorList) {
response = interceptor.intercept(chain);
chain = new RealInterceptor(response.result);
}
return response;
}
public static class RealInterceptor implements Chain {
private String params;
public RealInterceptor(String params) {
this.params = params;
}
@Override
public Request request() {
return new Request(params);
}
}
public static class FatherInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) {
Response response = new Response(chain.request().params.replace("爸爸", "**"));
return response;
}
}
public static class GrandpaInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) {
Response response = new Response(chain.request().params.replace("爷爷", "**"));
return response;
}
}
public static interface Interceptor {
Response intercept(Chain chain) throws RuntimeException;
interface Chain {
Request request();
}
}
public static class Response {
public Response(String result) {
this.result = result;
}
public String result;
}
public static class Request {
public Request(String params) {
this.params = params;
}
public String params;
}
当调用execute()将得到以下reponse:
image.png
模拟OKhttp模拟器拦截调用
okhttp拦截器调用核心步骤
- 构建
Request，在当前调用链Chain中获取当前要执行的拦截器Interceptor - 创建下一个调用链
RealInterceptor,将该调用链作为当前拦截器的参数Chain - 在当前拦截器中执行拦截动作
intercept(Chain chain)，并调用下一个拦截器的proceed - 在下一个调用链的
proceed(Request request)判断是否所有拦截器执行完毕，如果没有执行完毕重复继续以上步骤,如果全部执行完毕抛出特定Exception，拦截器中捕捉该异常并构建最终返回结果。
public static Response execute() {
Chain chain = new RealInterceptor(0, new Request("request params"));
Response response = chain.proceed(chain.request());
return response;
}
public static class RealInterceptor implements Interceptor.Chain {
//请求拦截器位置
int index = 0;
//请求体
Request mRequest;
public RealInterceptor(int count, Request request) {
this.index = count;
this.mRequest = request;
}
//模拟所有拦截器
private List<Interceptor> mInterceptorList = new ArrayList<Interceptor>() {{
add(new BridgeInterceptor());
add(new CacheInterceptor());
add(new ConnectionInterceptor());
add(new ServerInterceptor());
}};
@Override
public Request request() {
return mRequest;
}
@Override
public Response proceed(Request request) {
if (index >= mInterceptorList.size()) {
//所有拦截器执行结束，抛出特定异常
throw new RuntimeException("interceptors execute finish");
}
//执行当前下标的拦截器
Interceptor interceptor = mInterceptorList.get(index);
//创建下一个调用链
RealInterceptor next = new RealInterceptor(index + 1, request);
//获取调用链结果
Response response = interceptor.intercept(next);
return response;
}
}
public static class BridgeInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) {
chain.request().params += "-" + "BridgeInterceptor";
Response response = null;
try {
response = chain.proceed(chain.request());
} catch (Exception e){
}
if (response == null) {
//执行结束构建最后的Response
return new Response(chain.request().params);
}
return response;
}
}
public static class CacheInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) {
chain.request().params += "-" + "CacheInterceptor";
Response response = null;
try {
response = chain.proceed(chain.request());
} catch (Exception e){
}
if (response == null) {
//执行结束构建最后的Response
return new Response(chain.request().params);
}
return response;
}
}
public static class ConnectionInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) {
chain.request().params += "-" + "ConnectionInterceptor";
Response response = null;
try {
response = chain.proceed(chain.request());
} catch (Exception e){
}
if (response == null) {
//执行结束构建最后的Response
return new Response(chain.request().params);
}
return response;
}
}
public static class ServerInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) {
chain.request().params += "-" + "Reponse";
Response response = null;
try {
response = chain.proceed(chain.request());
} catch (Exception e){
}
if (response == null) {
//执行结束构建最后的Response
return new Response(chain.request().params);
}
return response;
}
}
public static interface Interceptor {
Response intercept(Chain chain) throws RuntimeException;
interface Chain {
Request request();
Response proceed(Request request) throws RuntimeException;
}
}
public static class Response {
public Response(String result) {
this.result = result;
}
public String result;
}
public static class Request {
public Request(String params) {
this.params = params;
}
public String params;
}
当调用execute()将得到以下reponse:
image.png
