Android Okhttp缓存：Cache，创建OkHttpClient实现（一）

心已赠人 2024-02-18 16:01 29阅读 0赞

**Android Okhttp缓存Cache，创建OkHttpClient实现**

Android Okhttp使用缓存通过Cache实现。在创建OkHttpClient实现。构造Cache需要传递一个缓存文件目录已经缓存的大小尺寸。

下面演示一个简单功能，加载一张图片到一个ImageView，如果该连接下图片已经存在，那么即便在断网时候，也能使用缓存加载出来。

package zhangphil.app;
    
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.os.Bundle;
    import android.support.annotation.Nullable;
    import android.support.v7.app.AppCompatActivity;
    import android.widget.ImageView;
    
    import java.io.File;
    import java.io.IOException;
    import java.util.concurrent.TimeUnit;
    
    import okhttp3.Cache;
    import okhttp3.Call;
    import okhttp3.Callback;
    import okhttp3.OkHttpClient;
    import okhttp3.Request;
    import okhttp3.Response;
    
    public class MainActivity extends AppCompatActivity {
    
        private OkHttpClient mOkHttpClient;
    
        @Override
        public void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            final ImageView image = (ImageView) findViewById(R.id.image);
    
            File cacheDir = new File(this.getCacheDir(), "zhangphilcache");
            Cache mCache = new Cache(cacheDir, 8 * 1024 * 1024);
            OkHttpClient.Builder mBuilder = new OkHttpClient.Builder();
    
            mOkHttpClient = mBuilder
                    .connectTimeout(10, TimeUnit.SECONDS) //连接超时阈值
                    .writeTimeout(10, TimeUnit.SECONDS) //写超时阈值
                    .readTimeout(10, TimeUnit.SECONDS)  //读超时阈值
                    .retryOnConnectionFailure(true) //当失败后重试
                    .cache(mCache)
                    .build();
    
            String url = "https://www.baidu.com/img/bd_logo1.png";
            Request mRequest = new Request.Builder().url(url).build();
    
            mOkHttpClient.newCall(mRequest).enqueue(new Callback() {
    
                @Override
                public void onFailure(Call call, IOException e) {
    
                }
    
                @Override
                public void onResponse(Call call, Response response) throws IOException {
                    if (response.isSuccessful()) {
                        byte[] bytes = response.body().bytes();
                        final Bitmap bmp = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
    
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                image.setImageBitmap(bmp);
                            }
                        });
                    }
                }
            });
        }
    
        @Override
        protected void onDestroy() {
            super.onDestroy();
    
            //取消所有Okhttp的网络请求
            mOkHttpClient.dispatcher().cancelAll();
        }
    }