攔截器調用順序一般為順序調用，將上一個攔截器的返回作為下一個攔截器的輸入，直到所有攔截器執(zhí)行完畢，返回最終結果。這里通過for循環(huán)先模擬一個簡單的攔截器調用過程，再模擬okhttp攔截器工作過程
簡單順序攔截器調用
模擬屏蔽詞：
public static Response execute() {
//模擬所有攔截器
List<Interceptor> mInterceptorList = new ArrayList<Interceptor>() {{
add(new FatherInterceptor());
add(new GrandpaInterceptor());
}};
Chain chain = new RealInterceptor("我是你爸爸，我是你爺爺");
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("爺爺", "**"));
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;
}
當調用execute()將得到以下reponse:
image.png
模擬OKhttp模擬器攔截調用
okhttp攔截器調用核心步驟
- 構建
Request，在當前調用鏈Chain中獲取當前要執(zhí)行的攔截器Interceptor - 創(chuàng)建下一個調用鏈
RealInterceptor,將該調用鏈作為當前攔截器的參數(shù)Chain - 在當前攔截器中執(zhí)行攔截動作
intercept(Chain chain)，并調用下一個攔截器的proceed - 在下一個調用鏈的
proceed(Request request)判斷是否所有攔截器執(zhí)行完畢，如果沒有執(zhí)行完畢重復繼續(xù)以上步驟,如果全部執(zhí)行完畢拋出特定Exception，攔截器中捕捉該異常并構建最終返回結果。
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 {
//請求攔截器位置
int index = 0;
//請求體
Request mRequest;
public RealInterceptor(int count, Request request) {
this.index = count;
this.mRequest = request;
}
//模擬所有攔截器
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()) {
//所有攔截器執(zhí)行結束，拋出特定異常
throw new RuntimeException("interceptors execute finish");
}
//執(zhí)行當前下標的攔截器
Interceptor interceptor = mInterceptorList.get(index);
//創(chuàng)建下一個調用鏈
RealInterceptor next = new RealInterceptor(index + 1, request);
//獲取調用鏈結果
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) {
//執(zhí)行結束構建最后的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) {
//執(zhí)行結束構建最后的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) {
//執(zhí)行結束構建最后的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) {
//執(zhí)行結束構建最后的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;
}
當調用execute()將得到以下reponse:
image.png
