Java tutorial
/* * Copyright 2014 Google 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 com.google.android.apps.muzei.util; import android.annotation.TargetApi; import android.content.Context; import android.content.res.AssetManager; import android.net.Uri; import android.os.Build; import android.os.Environment; import android.text.TextUtils; import com.squareup.okhttp.OkHttpClient; import org.json.JSONException; import org.json.JSONObject; import org.json.JSONTokener; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.UnsupportedEncodingException; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.List; public class IOUtil { private static final int DEFAULT_READ_TIMEOUT = 30 * 1000; // 30s private static final int DEFAULT_CONNECT_TIMEOUT = 15 * 1000; // 15s public static InputStream openUri(Context context, Uri uri, String reqContentTypeSubstring) throws OpenUriException { if (uri == null) { throw new IllegalArgumentException("Uri cannot be empty"); } String scheme = uri.getScheme(); InputStream in = null; if ("content".equals(scheme)) { try { in = context.getContentResolver().openInputStream(uri); } catch (FileNotFoundException e) { throw new OpenUriException(false, e); } catch (SecurityException e) { throw new OpenUriException(false, e); } } else if ("file".equals(scheme)) { List<String> segments = uri.getPathSegments(); if (segments != null && segments.size() > 1 && "android_asset".equals(segments.get(0))) { AssetManager assetManager = context.getAssets(); StringBuilder assetPath = new StringBuilder(); for (int i = 1; i < segments.size(); i++) { if (i > 1) { assetPath.append("/"); } assetPath.append(segments.get(i)); } try { in = assetManager.open(assetPath.toString()); } catch (IOException e) { throw new OpenUriException(false, e); } } else { try { in = new FileInputStream(new File(uri.getPath())); } catch (FileNotFoundException e) { throw new OpenUriException(false, e); } } } else if ("http".equals(scheme) || "https".equals(scheme)) { OkHttpClient client = new OkHttpClient(); HttpURLConnection conn = null; int responseCode = 0; String responseMessage = null; try { conn = client.open(new URL(uri.toString())); conn.setConnectTimeout(DEFAULT_CONNECT_TIMEOUT); conn.setReadTimeout(DEFAULT_READ_TIMEOUT); responseCode = conn.getResponseCode(); responseMessage = conn.getResponseMessage(); if (!(responseCode >= 200 && responseCode < 300)) { throw new IOException("HTTP error response."); } if (reqContentTypeSubstring != null) { String contentType = conn.getContentType(); if (contentType == null || contentType.indexOf(reqContentTypeSubstring) < 0) { throw new IOException("HTTP content type '" + contentType + "' didn't match '" + reqContentTypeSubstring + "'."); } } in = conn.getInputStream(); } catch (MalformedURLException e) { throw new OpenUriException(false, e); } catch (IOException e) { if (conn != null && responseCode > 0) { throw new OpenUriException(500 <= responseCode && responseCode < 600, responseMessage, e); } else { throw new OpenUriException(false, e); } } } return in; } public static String getCacheFilenameForUri(Uri uri) { StringBuilder filename = new StringBuilder(); filename.append(uri.getScheme()).append("_").append(uri.getHost()).append("_"); String encodedPath = uri.getEncodedPath(); if (!TextUtils.isEmpty(encodedPath)) { int length = encodedPath.length(); if (length > 60) { encodedPath = encodedPath.substring(length - 60); } encodedPath = encodedPath.replace('/', '_'); filename.append(encodedPath).append("_"); } try { MessageDigest md = MessageDigest.getInstance("MD5"); md.update(uri.toString().getBytes("UTF-8")); byte[] digest = md.digest(); for (byte b : digest) { if ((0xff & b) < 0x10) { filename.append("0").append(Integer.toHexString((0xFF & b))); } else { filename.append(Integer.toHexString(0xFF & b)); } } } catch (NoSuchAlgorithmException e) { filename.append(uri.toString().hashCode()); } catch (UnsupportedEncodingException e) { filename.append(uri.toString().hashCode()); } return filename.toString(); } public static class OpenUriException extends Exception { private boolean mRetryable; public OpenUriException(boolean retryable, String message, Throwable cause) { super(message, cause); mRetryable = retryable; } public OpenUriException(boolean retryable, Throwable cause) { super(cause); mRetryable = retryable; } public boolean isRetryable() { return mRetryable; } } public static JSONObject fetchJsonObject(String url) throws IOException, JSONException { return readJsonObject(fetchPlainText(new URL(url))); } public static JSONObject readJsonObject(String json) throws IOException, JSONException { JSONTokener tokener = new JSONTokener(json); Object val = tokener.nextValue(); if (!(val instanceof JSONObject)) { throw new JSONException("Expected JSON object."); } return (JSONObject) val; } public static void readFullyWriteToFile(InputStream in, File file) throws IOException { readFullyWriteToOutputStream(in, new FileOutputStream(file)); } public static void readFullyWriteToOutputStream(InputStream in, OutputStream out) throws IOException { try { byte[] buffer = new byte[1024]; int bytesRead; while ((bytesRead = in.read(buffer)) > 0) { out.write(buffer, 0, bytesRead); } out.flush(); } finally { out.close(); } } public static String readFullyPlainText(InputStream in) throws IOException { ByteArrayOutputStream out = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int bytesRead; while ((bytesRead = in.read(buffer)) > 0) { out.write(buffer, 0, bytesRead); } return new String(out.toByteArray(), "UTF-8"); } @TargetApi(Build.VERSION_CODES.KITKAT) public static File getBestAvailableCacheRoot(Context context) { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { // In KitKat we can query multiple devices. // TODO: optimize for stability instead of picking first one File[] roots = context.getExternalCacheDirs(); if (roots != null) { for (File root : roots) { if (root == null) { continue; } if (Environment.MEDIA_MOUNTED.equals(Environment.getStorageState(root))) { return root; } } } } else if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) { // Pre-KitKat, only one external storage device was addressable return context.getExternalCacheDir(); } // Worst case, resort to internal storage return context.getCacheDir(); } @TargetApi(Build.VERSION_CODES.KITKAT) public static File getBestAvailableFilesRoot(Context context) { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { // In KitKat we can query multiple devices. // TODO: optimize for stability instead of picking first one File[] roots = context.getExternalFilesDirs(null); if (roots != null) { for (File root : roots) { if (root == null) { continue; } if (Environment.MEDIA_MOUNTED.equals(Environment.getStorageState(root))) { return root; } } } } else if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) { // Pre-KitKat, only one external storage device was addressable return context.getExternalFilesDir(null); } // Worst case, resort to internal storage return context.getFilesDir(); } static String fetchPlainText(URL url) throws IOException { InputStream in = null; try { OkHttpClient client = new OkHttpClient(); HttpURLConnection conn = client.open(url); conn.setConnectTimeout(DEFAULT_CONNECT_TIMEOUT); conn.setReadTimeout(DEFAULT_READ_TIMEOUT); in = conn.getInputStream(); return readFullyPlainText(in); } finally { if (in != null) { in.close(); } } } }