public class Utils {
public static List<Message> getMessages() {
//File file = new File("file:///android_asset/helloworld.txt");
AssetManager assetManager = getAssets();
InputStream ims = assetManager.open("helloworld.txt");
}
}
我正在使用这段代码试图从资产读取文件。我尝试了两种方法。首先，当使用文件时，我收到FileNotFoundException，当使用资产管理器getAssets()方法不被识别。 有什么解决办法吗?
当前回答
下面是一个在资产中读取文件的方法:
/**
* Reads the text of an asset. Should not be run on the UI thread.
*
* @param mgr
* The {@link AssetManager} obtained via {@link Context#getAssets()}
* @param path
* The path to the asset.
* @return The plain text of the asset
*/
public static String readAsset(AssetManager mgr, String path) {
String contents = "";
InputStream is = null;
BufferedReader reader = null;
try {
is = mgr.open(path);
reader = new BufferedReader(new InputStreamReader(is));
contents = reader.readLine();
String line = null;
while ((line = reader.readLine()) != null) {
contents += '\n' + line;
}
} catch (final Exception e) {
e.printStackTrace();
} finally {
if (is != null) {
try {
is.close();
} catch (IOException ignored) {
}
}
if (reader != null) {
try {
reader.close();
} catch (IOException ignored) {
}
}
}
return contents;
}
其他回答
这里是一种方法来获得一个InputStream的文件在资产文件夹没有上下文，活动，片段或应用程序。如何从InputStream中获取数据取决于您。在这里的其他答案中有很多关于这个问题的建议。
科特林
val inputStream = ClassLoader::class.java.classLoader?.getResourceAsStream("assets/your_file.ext")
Java
InputStream inputStream = ClassLoader.class.getClassLoader().getResourceAsStream("assets/your_file.ext");
如果正在使用自定义ClassLoader，那么所有的赌注都是无效的。
下面是一个在资产中读取文件的方法:
/**
* Reads the text of an asset. Should not be run on the UI thread.
*
* @param mgr
* The {@link AssetManager} obtained via {@link Context#getAssets()}
* @param path
* The path to the asset.
* @return The plain text of the asset
*/
public static String readAsset(AssetManager mgr, String path) {
String contents = "";
InputStream is = null;
BufferedReader reader = null;
try {
is = mgr.open(path);
reader = new BufferedReader(new InputStreamReader(is));
contents = reader.readLine();
String line = null;
while ((line = reader.readLine()) != null) {
contents += '\n' + line;
}
} catch (final Exception e) {
e.printStackTrace();
} finally {
if (is != null) {
try {
is.close();
} catch (IOException ignored) {
}
}
if (reader != null) {
try {
reader.close();
} catch (IOException ignored) {
}
}
}
return contents;
}
读取和写入文件总是冗长且容易出错。避免这些答案，使用Okio即可:
public void readLines(File file) throws IOException {
try (BufferedSource source = Okio.buffer(Okio.source(file))) {
for (String line; (line = source.readUtf8Line()) != null; ) {
if (line.contains("square")) {
System.out.println(line);
}
}
}
}
getAssets()
它只适用于其他任何类的活动，你必须为它使用上下文。
让Utils类的构造函数将活动引用(丑陋的方式)或应用程序上下文作为参数传递给它。在Utils类中使用getAsset()。
ExceptionProof
It maybe too late but for the sake of others who look for the peachy answers.loadAssetFile()方法返回资产的纯文本，如果有任何错误，则返回defaultValue参数。
public static String loadAssetFile(Context context, String fileName, String defaultValue) {
String result=defaultValue;
InputStreamReader inputStream=null;
BufferedReader bufferedReader=null;
try {
inputStream = new InputStreamReader(context.getAssets().open(fileName));
bufferedReader = new BufferedReader(inputStream);
StringBuilder out= new StringBuilder();
String line = bufferedReader.readLine();
while (line != null) {
out.append(line);
line = bufferedReader.readLine();
}
result=out.toString();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
Objects.requireNonNull(inputStream).close();
} catch (Exception e) {
e.printStackTrace();
}
try {
Objects.requireNonNull(bufferedReader).close();
} catch (Exception e) {
e.printStackTrace();
}
}
return result;
}
