将数据存储到SD卡中

     一、整体运行效果图片

  

                                                                   主要代码：

1.MainActivity.java

                                    

import java.io.BufferedReader;    
    import java.io.File;    
    import java.io.FileInputStream;    
    import java.io.FileOutputStream;    
    import java.io.InputStreamReader;    
    import android.os.Bundle;    
    import android.os.Environment;    
    import android.app.Activity;    
    import android.view.View;    
    import android.view.View.OnClickListener;    
    import android.widget.Button;    
    import android.widget.Toast;    
        
    public class MainActivity extends Activity {    
        private Button button1;    
        private Button button2;    
        
        @Override    
        protected void onCreate(Bundle savedInstanceState) {    
            super.onCreate(savedInstanceState);    
            setContentView(R.layout.activity_main);    
            button1 = (Button) this.findViewById(R.id.button1);    
            button2 = (Button) this.findViewById(R.id.button2);    
            button1.setOnClickListener(new OnClickListener() {    
                @Override    
                public void onClick(View arg0) {    
                    writeSDcard("Hello，恭喜您数据读取了！");    
                }    
            });    
            button2.setOnClickListener(new OnClickListener() {    
                @Override    
                public void onClick(View arg0) {    
                    readSDcard();    
        
                }    
            });    
        }    
        
        // 向SD卡写入数据    
        private void writeSDcard(String str) {    
            try {    
                // 判断是否存在SD卡    
                if (Environment.getExternalStorageState().equals(    
                        Environment.MEDIA_MOUNTED)) {    
                    // 获取SD卡的目录    
                    File sdDire = Environment.getExternalStorageDirectory();    
                    FileOutputStream outFileStream = new FileOutputStream(    
                            sdDire.getCanonicalPath() + "/test.txt");    
                    outFileStream.write(str.getBytes());    
                    outFileStream.close();    
                    Toast.makeText(this, "数据保存到text.txt文件了", Toast.LENGTH_LONG)    
                            .show();    
                }    
            } catch (Exception e) {    
                e.printStackTrace();    
            }    
        }    
        
        // 从SD卡中读取数据    
        private void readSDcard() {    
            StringBuffer strsBuffer = new StringBuffer();    
            try {    
                // 判断是否存在SD    
                if (Environment.getExternalStorageState().equals(    
                        Environment.MEDIA_MOUNTED)) {    
                    File file = new File(Environment.getExternalStorageDirectory()    
                            .getCanonicalPath() + "/test.txt");    
                    // 判断是否存在该文件    
                    if (file.exists()) {    
                        // 打开文件输入流    
                        FileInputStream fileR = new FileInputStream(file);    
                        BufferedReader reads = new BufferedReader(    
                                new InputStreamReader(fileR));    
                        String st = null;    
                        while ((st = reads.readLine()) != null) {    
                            strsBuffer.append(st);    
                        }    
                        fileR.close();    
                    } else {    
                        Toast.makeText(this, "该目录下文件不存在", Toast.LENGTH_LONG).show();    
                    }    
                }    
            } catch (Exception e) {    
                e.printStackTrace();    
            }    
            Toast.makeText(this, "读取到的数据是：" + strsBuffer.toString() + "",    
                    Toast.LENGTH_LONG).show();    
        }    
    }  

2.布局文件    activity_main.xml

    <Button    
        android:id="@+id/button1"    
        android:layout_width="match_parent"    
        android:layout_height="wrap_content"   
           
        android:text="将数据写入SD卡"   
        android:textColor="#ff9900"  
        />    
    
    <Button    
        android:id="@+id/button2"    
        android:layout_width="match_parent"    
        android:layout_height="wrap_content"    
        android:text="从SD卡里读取数据"   
          
        android:textColor="#ff9900"  
        />  
</LinearLayout> 

3. . AndroidManifest.xml（注册文件代码）

package="com.example.filesd"    
    android:versionCode="1"    
    android:versionName="1.0" >    
    
    <uses-sdk    
        android:minSdkVersion="8"    
        android:targetSdkVersion="18" />    
    <!-- 在SDCard中创建与删除文件权限 -->    
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />    
    <!-- 往SDCard写入数据权限 -->    
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />    
    <!-- 从SDCard读取数据权限 -->    
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />    
    
    <application    
        android:allowBackup="true"    
        android:icon="@drawable/ic_launcher"    
        android:label="@string/app_name"    
        android:theme="@style/AppTheme" >    
        <activity    
            android:name="com.example.filesd.MainActivity"    
            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>    
    
</manifest>