Question

我是Android开发的新手，我需要你的帮助。我正在锁定与我的开发相似的主题，但不支持我。到目前为止，我创建的函数可以从我的SD卡中获取文件并向我显示当时的列表。这是有效的

这是在sdcard上获取路径的代码：

package com.seminarskirad;

import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.app.ListActivity;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FilenameFilter;
import java.io.IOException;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;

public class LoadActivity extends ListActivity{

     private enum DISPLAYMODE{ ABSOLUTE, RELATIVE; }
     private final DISPLAYMODE displayMode = DISPLAYMODE.ABSOLUTE;
     private List<String> directoryEntries = new ArrayList<String>();
     private File currentDirectory = new File("/");

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            Browse(Environment.getExternalStorageDirectory());

        }

        private void upOneLevel(){
                if(this.currentDirectory.getParent() != null)
                        this.Browse(this.currentDirectory.getParentFile());
        }

        private void Browse(final File aDirectory){
                if (aDirectory.isDirectory()){
                        this.currentDirectory = aDirectory;
                        fill(aDirectory.listFiles());

              }
        }

        private void fill(File[] files) {
                this.directoryEntries.clear();
                if(this.currentDirectory.getParent() != null)
                        this.directoryEntries.add("..");

                switch(this.displayMode){
                        case ABSOLUTE:
                                for (File file : files){
                                        this.directoryEntries.add(file.getPath());
                                }
                                break;
                        case RELATIVE: // On relative Mode, we have to add the current-path to the beginning
                                int currentPathStringLenght = this.currentDirectory.getAbsolutePath().length();
                                for (File file : files){
                                        this.directoryEntries.add(file.getAbsolutePath().substring(currentPathStringLenght));
                                }
                                break;
                }

        ArrayAdapter<String> directoryList = new ArrayAdapter<String>(this, R.layout.load, this.directoryEntries);
        this.setListAdapter(directoryList);
        }

        protected void onListItemClick(ListView l, View v, int position, long id) {
                int selectionRowID = position;
                String selectedFileString = this.directoryEntries.get(selectionRowID);
                if(selectedFileString.equals("..")){
                        this.upOneLevel();
                }else if(selectedFileString.equals()){   /// what to write here ???
                        this.readFile();    ///what to write here???
                } else {
                        File clickedFile = null;
                        switch(this.displayMode){
                                case RELATIVE:
                                        clickedFile = new File(this.currentDirectory.getAbsolutePath()
                                                                                                + this.directoryEntries.get(selectionRowID));
                                        break;
                                case ABSOLUTE:
                                        clickedFile = new File(this.directoryEntries.get(selectionRowID));
                                        break;
                        }
                        if(clickedFile.isFile())
                            this.Browse(clickedFile);
                }
        }

        private void readFile() {
// what to write here???
        }

很抱歉我放不上图片，因为我没有声望，但是当我在我的模拟器上运行时，得到这样的东西：

 /mnt/sdcard/kuzmanic.c
/mnt/sdcard/text.txt
/mnt/sdcard/DCIM
/mnt/sdcard/LOST.DIR

所以我想要做的就是当我点击text.txt或kuzmanic.c文件时我要在同一个布局文件中打开，那就是我的load.xml文件：

This is the code for the xml file:
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
    android:textSize="18sp">    


</TextView>

我需要在代码中编写什么，是否必须在清单中写任何内容？

Answer 1

试试这段代码：

package com.javasamples;
import java.io.*;
import android.app.Activity;
import android.os.Bundle;
import android.view.*;
import android.view.View.OnClickListener;
import android.widget.*;

public class FileDemo2 extends Activity {
    // GUI controls
    EditText txtData;
    Button btnWriteSDFile;
    Button btnReadSDFile;
    Button btnClearScreen;
    Button btnClose;

    @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    // bind GUI elements with local controls
    txtData = (EditText) findViewById(R.id.txtData);
    txtData.setHint("Enter some lines of data here...");

    btnWriteSDFile = (Button) findViewById(R.id.btnWriteSDFile);
    btnWriteSDFile.setOnClickListener(new OnClickListener() {

    public void onClick(View v) {
        // write on SD card file data in the text box
        try {
            File myFile = new File("/sdcard/mysdfile.txt");
            myFile.createNewFile();
            FileOutputStream fOut = new FileOutputStream(myFile);
            OutputStreamWriter myOutWriter = 
                                    new OutputStreamWriter(fOut);
            myOutWriter.append(txtData.getText());
            myOutWriter.close();
            fOut.close();
            Toast.makeText(getBaseContext(),
                    "Done writing SD 'mysdfile.txt'",
                    Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            Toast.makeText(getBaseContext(), e.getMessage(),
                    Toast.LENGTH_SHORT).show();
        }
    }// onClick
    }); // btnWriteSDFile

        btnReadSDFile = (Button) findViewById(R.id.btnReadSDFile);
        btnReadSDFile.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            // write on SD card file data in the text box
        try {
            File myFile = new File("/sdcard/mysdfile.txt");
            FileInputStream fIn = new FileInputStream(myFile);
            BufferedReader myReader = new BufferedReader(
                    new InputStreamReader(fIn));
            String aDataRow = "";
            String aBuffer = "";
            while ((aDataRow = myReader.readLine()) != null) {
                aBuffer += aDataRow + "\n";
            }
            txtData.setText(aBuffer);
            myReader.close();
            Toast.makeText(getBaseContext(),
                    "Done reading SD 'mysdfile.txt'",
                    Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            Toast.makeText(getBaseContext(), e.getMessage(),
                    Toast.LENGTH_SHORT).show();
        }
        }// onClick
        }); // btnReadSDFile

        btnClearScreen = (Button) findViewById(R.id.btnClearScreen);
        btnClearScreen.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // clear text box
                txtData.setText("");
            }
        }); // btnClearScreen

        btnClose = (Button) findViewById(R.id.btnClose);
        btnClose.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // clear text box
                finish();
            }
        }); // btnClose

    }// onCreate

}// AndSDcard

布局文件是

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="@+id/widget28"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ff0000ff"
android:orientation="vertical"
xmlns:android="http://schemas.android.com/apk/res/android"
>
<EditText
android:id="@+id/txtData"
android:layout_width="fill_parent"
android:layout_height="180px"
android:textSize="18sp"  />

<Button
android:id="@+id/btnWriteSDFile"
android:layout_width="143px"
android:layout_height="44px"
android:text="1. Write SD File"  />

<Button
android:id="@+id/btnClearScreen"
android:layout_width="141px"
android:layout_height="42px"
android:text="2. Clear Screen"  />

<Button
android:id="@+id/btnReadSDFile"
android:layout_width="140px"
android:layout_height="42px"
android:text="3. Read SD File"  />

<Button
android:id="@+id/btnClose"
android:layout_width="141px"
android:layout_height="43px"
android:text="4. Close" />

</LinearLayout>

enter image description here

Answer 2

我用这段代码读取SD卡中的文本文件，

public class ReadFileSDCardActivity extends Activity {  
    /** Called when the activity is first created. */  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  

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

        File dir = Environment.getExternalStorageDirectory();  
        //File yourFile = new File(dir, "path/to/the/file/inside/the/sdcard.ext");  

        //Get the text file  
        File file = new File(dir,"text.txt");  
        // i have kept text.txt in the sd-card  

        if(file.exists())   // check if file exist  
        {  
              //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');  
                }  
            }  
            catch (IOException e) {  
                //You'll need to add proper error handling here  
            }  
            //Set the text  
            tv.setText(text);  
        }  
        else  
        {  
            tv.setText("Sorry file doesn't exist!!");  
        }  
     }  
}

Answer 3

首先，您必须将textview的id赋予load.xml文件，并在线性布局中定义textview。像这样

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
<TextView android:id="@+id/tv1
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" 
        android:textSize="18sp"/>

现在您必须设置活动的布局。您只能在onCreate（）方法中执行此操作。

setContentView(R.layout.load);

现在创建一个像这样的TextVew对象。

TextView tview = (TextView) findViewById(R.id.tv1);

现在您必须使用 FileInputStream 读取文本文件并将其保存为字符串变量。

之后，您可以将字符串分配给文本视图。

tview.setText(string variable name);

如何从android上的sdcard读取选定的文本文件

3 个答案: