67

我是 Android 开发的新手。

我需要从 SD 卡中读取一个文本文件并显示该文本文件。有什么方法可以直接在 Android 中查看文本文件，或者如何读取和显示文本文件的内容？

4

6 回答 6

128

在您的布局中，您需要一些东西来显示文本。ATextView是显而易见的选择。所以你会有这样的东西：

<TextView 
    android:id="@+id/text_view" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"/>

您的代码将如下所示：

//Find the directory for the SD Card using the API
//*Don't* hardcode "/sdcard"
File sdcard = Environment.getExternalStorageDirectory();

//Get the text file
File file = new File(sdcard,"file.txt");

//Read text from file
StringBuilder text = new StringBuilder();

try {
    BufferedReader br = new BufferedReader(new FileReader(file));
    String line;

    while ((line = br.readLine()) != null) {
        text.append(line);
        text.append('\n');
    }
    br.close();
}
catch (IOException e) {
    //You'll need to add proper error handling here
}

//Find the view by its id
TextView tv = (TextView)findViewById(R.id.text_view);

//Set the text
tv.setText(text);

这可以onCreate()采用您的方法，也可以采用其他方法，Activity具体取决于您想要做什么。

于 2010-05-25T09:27:12.113 回答
7

In response to

Don't hardcode /sdcard/

Sometimes we HAVE TO hardcode it as in some phone models the API method returns the internal phone memory.

Known types: HTC One X and Samsung S3.

Environment.getExternalStorageDirectory().getAbsolutePath() gives a different path - Android

于 2013-06-21T06:16:19.410 回答
3

您应该具有读取 sdcard 的 READ_EXTERNAL_STORAGE 权限。在 manifest.xml 中添加权限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

从 android 6.0 或更高版本开始，您的应用程序必须要求用户在运行时授予危险权限。请参阅此链接 权限概述

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
    if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 0);
    }
}
于 2018-08-21T09:23:22.077 回答
2 
package com.example.readfilefromexternalresource;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.os.Bundle;
import android.os.Environment;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import android.os.Build;

public class MainActivity extends Activity {
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        textView = (TextView)findViewById(R.id.textView);
        String state = Environment.getExternalStorageState();

        if (!(state.equals(Environment.MEDIA_MOUNTED))) {
            Toast.makeText(this, "There is no any sd card", Toast.LENGTH_LONG).show();


        } else {
            BufferedReader reader = null;
            try {
                Toast.makeText(this, "Sd card available", Toast.LENGTH_LONG).show();
                File file = Environment.getExternalStorageDirectory();
                File textFile = new File(file.getAbsolutePath()+File.separator + "chapter.xml");
                reader = new BufferedReader(new FileReader(textFile));
                StringBuilder textBuilder = new StringBuilder();
                String line;
                while((line = reader.readLine()) != null) {
                    textBuilder.append(line);
                    textBuilder.append("\n");

                }
                textView.setText(textBuilder);

            } catch (FileNotFoundException e) {
                // TODO: handle exception
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            finally{
                if(reader != null){
                    try {
                        reader.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }

        }
    }
}
于 2014-08-07T06:04:23.867 回答
1 
BufferedReader br = null;
try {
        String fpath = Environment.getExternalStorageDirectory() + <your file name>;
        try {
            br = new BufferedReader(new FileReader(fpath));
        } catch (FileNotFoundException e1) {
            e1.printStackTrace();
        }
        String line = "";
        while ((line = br.readLine()) != null) {
         //Do something here 
        }
于 2015-05-13T11:11:27.910 回答
1

注意：有些手机有 2 个 SD 卡，一个内部固定的和一个可移动的卡。您可以通过标准应用程序找到最后一个的名称：“Mijn Bestanden”（英文：“MyFiles”？）当我打开这个应用程序（项目：所有文件）时，打开文件夹的路径是“/sdcard”，向下滚动有一个条目 "external-sd" ，单击它会打开文件夹 "/sdcard/external_sd/" 。假设我想打开一个文本文件“MyBooks.txt”，我会使用以下内容：

   String Filename = "/mnt/sdcard/external_sd/MyBooks.txt" ;
   File file = new File(fname);...etc...
于 2017-10-14T08:53:11.720 回答