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
cityfile.txt
public void getCityStateFromLocal() {
AssetManager am = getAssets();
InputStream inputStream = null;
try {
inputStream = am.open("city_state.txt");
} catch (IOException e) {
e.printStackTrace();
}
ObjectMapper mapper = new ObjectMapper();
Map<String, String[]> map = new HashMap<String, String[]>();
try {
map = mapper.readValue(getStringFromInputStream(inputStream), new TypeReference<Map<String, String[]>>() {
});
} catch (IOException e) {
e.printStackTrace();
}
ConstantValues.arrayListStateName.clear();
ConstantValues.arrayListCityByState.clear();
if (map.size() > 0)
{
for (Map.Entry<String, String[]> e : map.entrySet()) {
CityByState cityByState = new CityByState();
String key = e.getKey();
String[] value = e.getValue();
ArrayList<String> s = new ArrayList<String>(Arrays.asList(value));
ConstantValues.arrayListStateName.add(key);
s.add(0,"Select City");
cityByState.addValue(s);
ConstantValues.arrayListCityByState.add(cityByState);
}
}
ConstantValues.arrayListStateName.add(0,"Select States");
}
// Convert InputStream to String
public String getStringFromInputStream(InputStream is) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb + "";
}
其他回答
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);
}
}
}
}
AssetManager assetManager = getAssets();
InputStream inputStream = null;
try {
inputStream = assetManager.open("helloworld.txt");
}
catch (IOException e){
Log.e("message: ",e.getMessage());
}
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;
}
如果你用的是Activity以外的类，你可能会想，
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader( YourApplication.getInstance().getAssets().open("text.txt"), "UTF-8"));
getAssets()方法将在Activity类内部调用时工作。
如果你在非Activity类中调用这个方法，那么你需要从Context中调用这个方法，这个Context是从Activity类中传递过来的。下面是可以访问该方法的行。
ContextInstance.getAssets();
ContextInstance可以作为Activity类的this传递。
