學(xué)習(xí)資料：
沒有網(wǎng)絡(luò)，讀取本地緩存
在手機(jī)狀態(tài)欄中，并沒有流量和WIFI聯(lián)網(wǎng)的標(biāo)志
1. 無網(wǎng)絡(luò)，使用本地緩存
完整Activity代碼：
public class NoNetworkActivity extends AppCompatActivity implements ResultCallback<String> {
private TextView tv_info;
private String cachePath;
private Platform mPlatform;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_no_network);
//緩存路徑
String path = Environment.getExternalStorageDirectory().getPath()
+ File.separator + Strings.FILE_PATH + File.separator + Strings.CACHE_PATH;
File directory = new File(path);
if (!directory.exists()) {
if (directory.mkdirs()) ToastUtils.show(NoNetworkActivity.this, "緩存文件夾創(chuàng)建成功");
}
cachePath = directory.getPath();
init();
}
/**
* 初始化
*/
private void init() {
mPlatform = Platform.get();
tv_info = (TextView) findViewById(R.id.no_network_activity_tv);
request();
}
private void request() {
OkHttpClient okHttpClient = new OkHttpClient
.Builder()
.connectTimeout(10, TimeUnit.SECONDS)
.readTimeout(10, TimeUnit.SECONDS)
.addNetworkInterceptor(new Interceptor() {//添加網(wǎng)絡(luò)攔截器
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Response response = chain.proceed(request);
if (isNetworkConnected()) {
int maxAge = 60 * 60;// 有網(wǎng) 就1個(gè)小時(shí)可用
return response.newBuilder()
.header("Cache-Control", "public, max-age=" + maxAge)
.build();
} else {
int maxStale = 60 * 60 * 24 * 7;// 沒網(wǎng) 就1周可用
return response.newBuilder()
.header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
.build();
}
}
})
.cache(new Cache(new File(cachePath), 30 * 1024 * 1024))//最大 30m
.build();
Request request = new Request.Builder().url(Urls.GET_URL).build();
Call call = okHttpClient.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
sendFailResultCallback(e);//失敗回調(diào)
}
@Override
public void onResponse(Call call, Response response) throws IOException {
//請求結(jié)果
ResponseBody responseBody = null;
try {
//判斷請求是否取消
if (call.isCanceled()) {
sendFailResultCallback(new IOException("Request Canceled"));
return;
}
//獲取請求結(jié)果 ResponseBody
responseBody = response.body();
//獲取字符串
String json = responseBody.string();
Log.e("activity", json);
//成功回調(diào)
sendSuccessResultCallback(json);
} catch (Exception e) {//發(fā)生異常，失敗回調(diào)
sendFailResultCallback(e);
} finally {//記得關(guān)閉操作
if (null != responseBody) {
responseBody.close();
}
}
}
});
}
/**
* 手機(jī)是否聯(lián)網(wǎng)
*/
private boolean isNetworkConnected() {
//6.0 之后得使用 getApplicationContext()..getSystemService(...)
//否則會內(nèi)存泄漏
ConnectivityManager manager = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = manager.getActiveNetworkInfo();
return activeNetworkInfo.isConnected();
}
/**
* 網(wǎng)絡(luò)請求失敗
*/
@Override
public void sendFailResultCallback(final Exception e) {
doSomething(new Runnable() {
@Override
public void run() {
String info = "Fail Message --> " + e.getMessage();
tv_info.setText(info);
}
});
}
/**
* 請求成功
*/
@Override
public void sendSuccessResultCallback(final String result) {
doSomething(new Runnable() {
@Override
public void run() {
tv_info.setText(JsonFormatUtils.formatJson(result));
}
});
}
/**
* UI線程回調(diào)
*/
private void doSomething(Runnable runnable) {
mPlatform.execute(runnable);
}
}
cache(Cache,Size):添加緩存，指定緩存路徑和空間大小
當(dāng)設(shè)備斷網(wǎng)時(shí)，通過Interceptor攔截器來進(jìn)行網(wǎng)絡(luò)訪問,可以直接讀取之前本地緩存
使用addNetworkInterceptor(Interceptor)為OkHttpCLient添加一個(gè)網(wǎng)絡(luò)攔截器
重寫Interceptor內(nèi)的intercept(Chain)方法，根據(jù)網(wǎng)絡(luò)狀態(tài)，設(shè)置緩存有效期
-
Cache-Control，緩存控制 -
public，所有網(wǎng)頁信息都緩存 -
max-age，緩存有效期限，在這個(gè)期限內(nèi)，不去再去進(jìn)行網(wǎng)絡(luò)訪問 -
only-if-cached，只接受緩存的內(nèi)容 -
max-stale，在設(shè)置期限內(nèi)，客戶端可以接受過去的內(nèi)容
百度百科中Cache-control說得挺簡單明了
2. Interceptor攔截器
Interceptor是一個(gè)接口
源碼：
/*
* Copyright (C) 2014 Square, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package okhttp3;
import java.io.IOException;
/**
* Observes, modifies, and potentially short-circuits requests going out and the corresponding
* responses coming back in. Typically interceptors add, remove, or transform headers on the request
* or response.
*/
public interface Interceptor {
Response intercept(Chain chain) throws IOException;
interface Chain {
Request request();
Response proceed(Request request) throws IOException;
Connection connection();
}
}
代碼不多，但感覺接口的使用方式，可以學(xué)習(xí)
攔截器作用：
Interceptors are a powerful mechanism that can monitor, rewrite, and retry
calls. Here's a simple interceptor that logs the outgoing request and the
incoming response
攔截器是一個(gè)強(qiáng)大的機(jī)制，可以監(jiān)控，修改，重試 Call請求
個(gè)人理解：可以看作是海關(guān)，高速收費(fèi)站，對進(jìn)出的船或車，進(jìn)行把控
interceptors
貼個(gè)圖，不為別的，就是感覺這個(gè)圖：簡潔，優(yōu)雅，大方，逼格
攔截有兩種：Application Interceptor和Network Interceptor
一個(gè)灰色矩形塊塊就是一個(gè)Interceptor，一個(gè)OkHttpClient可以添加多個(gè)Interceptor攔截器
Application Interceptor：主要多用于查看請求信息或者返回信息，如鏈接地址，頭信息，參數(shù)等Network Interceptor：多用于對請求體Request或者響應(yīng)體Response的改變，緩存處理用這個(gè)
暫時(shí)也就知道這么多了，Interceptor.Chain中3個(gè)方法具體做了啥，到了后面學(xué)習(xí)OkHttp工程流程，再學(xué)習(xí)了解
2.1 Application Interceptor 簡單使用
代碼：直接加在OkHttpClient中的addNetworkInterceptor前就可以
.addInterceptor(new Interceptor() {
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
long t1 = System.nanoTime();
String info_1 = String.format("Sending request %s on %s%n%s", request.url(),
chain.connection(), request.headers());
Log.e("info1", "-->" + info_1);
Response response = chain.proceed(request);
long t2 = System.nanoTime();
String info_2 = String.format("Received response for %s in %.1fms%n%s".toLowerCase(),
response.request().url(), (t2 - t1) / 1e6d, response.headers());
Log.e("info2", "-->" + info_2);
return response;
}
})
輸出Log信息：
Application Interceptor 攔截信息
3. 最后
有錯(cuò)誤，請指出
共勉 ：）
