SD卡读写文件 代码学习

把文件存入SD卡中

首先加入读写权限

SD卡创建与删除文件权限

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

SD卡写入数据权限

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

 

点击保存前：



点击保存：




 

SD卡根目录多了123.txt文件

 


 点击读取：



 

读取成功。

代码：

[java]
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.os.Environment; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 
import android.widget.Toast; 
 
import com.luku.file.service.FileService; 
 
public class fileActivity extends Activity 
{ 
    private EditText editText=null; 
    private Button   button =null; 
    private TextView content =null; 
    private Button   read=null; 
    private TextView textView1=null; 
    private Button   exit=null; 
     
    @Override 
    public void onCreate(Bundle savedInstanceState) 
    { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
         
        textView1=(TextView)findViewById(R.id.textView1); 
        content=(TextView)findViewById(R.id.content); 
        editText=(EditText)findViewById(R.id.filename); 
        button=(Button)findViewById(R.id.baocun); 
        read=(Button)findViewById(R.id.read); 
        exit=(Button)findViewById(R.id.exit); 
         
        button.setOnClickListener(listener); 
        read.setOnClickListener(listener);       
        exit.setOnClickListener(listener); 
    } 
     
    private OnClickListener listener=new OnClickListener() 
    { 
        int resId = R.string.success; 
        @Override 
        public void onClick(View v) 
        { 
            Button btn=(Button)v;            
            File file=new File(Environment.getExternalStorageDirectory(),//得到SD卡根目录  
                    editText.getText().toString());                      //保存文件的文件名  
             
            switch (btn.getId()) 
            { 
                case R.id.baocun: 
                if(Environment.getExternalStorageState(). 
                        equals(Environment.MEDIA_MOUNTED)) //判断SD卡是否存在，并且可以可以读写  
                {        
                    try 
                    { 
                        FileOutputStream stream=new FileOutputStream(file); 
                        FileService.save(stream, content.getText().toString()); 
                    }  
                    catch (IOException e) 
                    { 
                        e.printStackTrace(); 
                        resId = R.string.error; 
                        Toast.makeText(fileActivity.this, resId, Toast.LENGTH_LONG).show(); 
                    }            
                    Toast.makeText(fileActivity.this, resId, Toast.LENGTH_LONG).show(); 
                } 
                else  
                { 
                    Toast.makeText(fileActivity.this, "SD卡不存在或写保护", Toast.LENGTH_LONG).show(); 
                } 
                    break; 
                     
                case R.id.read: 
                    try 
                    { 
                        InputStream instream=new FileInputStream(file); 
                        String string=FileService.read(instream); 
                        System.out.println(string); 
                        textView1.setText(string.toString()); 
                    } catch (Exception e) 
                    { 
                        e.printStackTrace(); 
                        Toast.makeText(fileActivity.this, "读取失败", Toast.LENGTH_LONG).show(); 
                    } 
                    break; 
                 
                case R.id.exit: 
                    android.os.Process.killProcess(android.os.Process.myPid()); 
                    break; 
                     
                default: 
                    break; 
            } 
             
             
        } 
    }; 
} 
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.luku.file.service.FileService;

public class fileActivity extends Activity
{
 private EditText editText=null;
 private Button   button =null;
 private TextView content =null;
 private Button   read=null;
 private TextView textView1=null;
 private Button   exit=null;
 
 @Override
 public void onCreate(Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  
  textView1=(TextView)findViewById(R.id.textView1);
  content=(TextView)findViewById(R.id.content);
  editText=(EditText)findViewById(R.id.filename);
  button=(Button)findViewById(R.id.baocun);
  read=(Button)findViewById(R.id.read);
  exit=(Button)findViewById(R.id.exit);
  
  button.setOnClickListener(listener);
  read.setOnClickListener(listener);  
  exit.setOnClickListener(listener);
 }
 
 private OnClickListener listener=new OnClickListener()
 {
  int resId = R.string.success;
  @Override
  public void onClick(View v)
  {
   Button btn=(Button)v;   
   File file=new File(Environment.getExternalStorageDirectory(),//得到SD卡根目录
     editText.getText().toString());                      //保存文件的文件名
   
   switch (btn.getId())
   {
    case R.id.baocun:
    if(Environment.getExternalStorageState().
      equals(Environment.MEDIA_MOUNTED)) //判断SD卡是否存在，并且可以可以读写
    {  
     try
     {
      FileOutputStream stream=new FileOutputStream(file);
      FileService.save(stream, content.getText().toString());
     }
     catch (IOException e)
     {
      e.printStackTrace();
      resId = R.string.error;
      Toast.makeText(fileActivity.this, resId, Toast.LENGTH_LONG).show();
     }   
     Toast.makeText(fileActivity.this, resId, Toast.LENGTH_LONG).show();
    }
    else
    {
     Toast.makeText(fileActivity.this, "SD卡不存在或写保护", Toast.LENGTH_LONG).show();
    }
     break;
     
    case R.id.read:
     try
     {
      InputStream instream=new FileInputStream(file);
      String string=FileService.read(instream);
      System.out.println(string);
      textView1.setText(string.toString());
     } catch (Exception e)
     {
      e.printStackTrace();
      Toast.makeText(fileActivity.this, "读取失败", Toast.LENGTH_LONG).show();
     }
     break;
    
    case R.id.exit:
     android.os.Process.killProcess(android.os.Process.myPid());
     break;
     
    default:
     break;
   }
   
   
  }
 };
}

 

FileService文件

 

 

[java]
import java.io.ByteArrayOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 
 
public class FileService 
{ 
    /**
     * 保存数据
     * @param stream
     * @param content
     * @throws IOException
     */ 
    public static void save(OutputStream stream , String content) throws IOException 
    { 
        stream.write(content.getBytes()); 
        stream.close(); 
    } 
    /**
     * 读取数据
     * @param inStream
     * @return
     * @throws IOException
     */ 
    public static String read(InputStream inStream) throws IOException 
    { 
        ByteArrayOutputStream outputStream=new ByteArrayOutputStream(); 
        int len=-1; 
        byte[] buffer =new byte[1024];       
        while( (len=inStream.read(buffer))!=-1 ) 
        { 
            outputStream.write(buffer, 0, len); 
        } 
        byte[] data = outputStream.toByteArray(); 
        inStream.close(); 
        outputStream.close(); 
        return new String(data); 
         
    } 
     
} 
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class FileService
{
 /**
  * 保存数据
  * @param stream
  * @param content
  * @throws IOException
  */
 public static void save(OutputStream stream , String content) throws IOException
 {
  stream.write(content.getBytes());
  stream.close();
 }
 /**
  * 读取数据
  * @param inStream
  * @return
  * @throws IOException
  */
 public static String read(InputStream inStream) throws IOException
 {
  ByteArrayOutputStream outputStream=new ByteArrayOutputStream();
  int len=-1;
  byte[] buffer =new byte[1024];  
  while( (len=inStream.read(buffer))!=-1 )
  {
   outputStream.write(buffer, 0, len);
  }
  byte[] data = outputStream.toByteArray();
  inStream.close();
  outputStream.close();
  return new String(data);
  
 }
 
}

 

 

 

main.xml文件

 

 

[java]
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    > 
     
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
        android:orientation="vertical" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content"> 
             
            <TextView   
                android:layout_width="90px"  
                android:layout_height="wrap_content"  
                android:text="文件名称:" 
                android:textSize="21px" 
                android:id="@+id/filenamelebal" 
                /> 
             
            <EditText 
                 android:layout_width="fill_parent" 
                 android:layout_height="wrap_content"  
                 android:layout_toRightOf="@id/filenamelebal" 
                 android:layout_alignTop="@id/filenamelebal" 
                 android:id="@+id/filename" 
            ></EditText> 
        ></RelativeLayout> 
         
        <TextView   
                android:layout_width="90px"  
                android:layout_height="wrap_content"  
                android:text="内容:" 
                android:textSize="21px" 
                /> 
        <EditText 
                 android:layout_width="fill_parent"  
                 android:layout_height="wrap_content"  
                 android:minLines="3" 
                 android:id="@+id/content" 
            ></EditText> 
        <LinearLayout android:id="@+id/linearLayout1" android:layout_width="match_parent" android:layout_height="wrap_content"> 
            <Button  
                android:layout_height="wrap_content"  
                android:id="@+id/baocun"  
                android:text="保存"  
                android:layout_width="wrap_content"></Button> 
            <Button  
                android:text="读取"  
                android:id="@+id/read"  
                android:layout_width="wrap_content"  
                android:layout_height="wrap_content"></Button> 
            <Button  
                android:text="退出"  
                android:id="@+id/exit"  
                android:layout_width="wrap_content"  
                android:layout_height="wrap_content"></Button> 
                 
        </LinearLayout> 
        <TextView  
                android:text="读取内容显示"  
                android:id="@+id/textView1"  
                android:layout_width="wrap_content"  
                android:layout_height="wrap_content"> 
                </TextView> 
        
         
        
</LinearLayout> 
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
 
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content">
      
      <TextView 
       android:layout_width="90px"
       android:layout_height="wrap_content"
       android:text="文件名称:"
       android:textSize="21px"
       android:id="@+id/filenamelebal"
       />
      
      <EditText
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/filenamelebal"
        android:layout_alignTop="@id/filenamelebal"
        android:id="@+id/filename"
      ></EditText>
     ></RelativeLayout>
     
     <TextView 
       android:layout_width="90px"
       android:layout_height="wrap_content"
       android:text="内容:"
       android:textSize="21px"
       />
  <EditText
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:minLines="3"
        android:id="@+id/content"
      ></EditText>
     <LinearLayout android:id="@+id/linearLayout1" android:layout_width="match_parent" android:layout_height="wrap_content">
         <Button
          android:layout_height="wrap_content"
          android:id="@+id/baocun"
          android:text="保存"
          android:layout_width="wrap_content"></Button>
         <Button
          android:text="读取"
          android:id="@+id/read"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"></Button>
         <Button
          android:text="退出"
          android:id="@+id/exit"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"></Button>
          
     </LinearLayout>
     <TextView
       android:text="读取内容显示"
       android:id="@+id/textView1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content">
       </TextView>
   
    
   
</LinearLayout>

 

 

 

配置文件

[java]
<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
      package="com.luku.file" 
      android:versionCode="1" 
      android:versionName="1.0"> 
    <uses-sdk android:minSdkVersion="8" /> 
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission> 
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission> 
     
    <application android:icon="@drawable/icon" android:label="@string/app_name"> 
        <uses-library android:name="android.test.runner"></uses-library> 
        <activity android:name=".fileActivity" 
                  android:label="@string/app_name"> 
            <intent-filter> 
                <action android:name="android.intent.action.MAIN" /> 
                <category android:name="android.intent.category.LAUNCHER" /> 
            </intent-filter> 
        </activity> 
 
    </application> 
     
    <instrumentation  
        android:name="android.test.InstrumentationTestRunner" 
        android:targetPackage="com.luku.file" 
        android:label="Test for my app" 
    ></instrumentation> 
     
</manifest> 
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.luku.file"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>
 
    <application android:icon="@drawable/icon" android:label="@string/app_name">
     <uses-library android:name="android.test.runner"></uses-library>
        <activity android:name=".fileActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
   
    <instrumentation
     android:name="android.test.InstrumentationTestRunner"
     android:targetPackage="com.luku.file"
     android:label="Test for my app"
    ></instrumentation>
   
</manifest>

摘自 奔跑的蜗牛