迟到总比不到好。

在某些情况下，我很难逐行阅读文件。 下面的方法是到目前为止我发现的最好的方法，我推荐它。

使用:字符串yourData = LoadData(“YourDataFile.txt”);

YourDataFile.txt假定驻留在资产/

 public String LoadData(String inFile) {
        String tContents = "";

    try {
        InputStream stream = getAssets().open(inFile);

        int size = stream.available();
        byte[] buffer = new byte[size];
        stream.read(buffer);
        stream.close();
        tContents = new String(buffer);
    } catch (IOException e) {
        // Handle exceptions here
    }

    return tContents;

 }

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 + "";

    }

AssetManager assetManager = getAssets();
InputStream inputStream = null;
try {
    inputStream = assetManager.open("helloworld.txt");
}
catch (IOException e){
    Log.e("message: ",e.getMessage());
}

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()。

在MainActivity.java

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TextView tvView = (TextView) findViewById(R.id.tvView);

        AssetsReader assetsReader = new AssetsReader(this);
        if(assetsReader.getTxtFile(your_file_title)) != null)
        {
            tvView.setText(assetsReader.getTxtFile(your_file_title)));
        }
    }

此外，您还可以创建单独的类来完成所有工作

public class AssetsReader implements Readable{

    private static final String TAG = "AssetsReader";


    private AssetManager mAssetManager;
    private Activity mActivity;

    public AssetsReader(Activity activity) {
        this.mActivity = activity;
        mAssetManager = mActivity.getAssets();
    }

    @Override
    public String getTxtFile(String fileName)
    {
        BufferedReader reader = null;
        InputStream inputStream = null;
        StringBuilder builder = new StringBuilder();

        try{
            inputStream = mAssetManager.open(fileName);
            reader = new BufferedReader(new InputStreamReader(inputStream));

            String line;

            while((line = reader.readLine()) != null)
            {
                Log.i(TAG, line);
                builder.append(line);
                builder.append("\n");
            }
        } catch (IOException ioe){
            ioe.printStackTrace();
        } finally {

            if(inputStream != null)
            {
                try {
                    inputStream.close();
                } catch (IOException ioe){
                    ioe.printStackTrace();
                }
            }

            if(reader != null)
            {
                try {
                    reader.close();
                } catch (IOException ioe)
                {
                    ioe.printStackTrace();
                }
            }
        }
        Log.i(TAG, "builder.toString(): " + builder.toString());
        return builder.toString();
    }
}

在我看来，最好创建一个界面，但这不是必要的

public interface Readable {
    /**
     * Reads txt file from assets
     * @param fileName
     * @return string
     */
    String getTxtFile(String fileName);
}

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。