将数据存储到SD卡上

来源：互联网发布：软件自动化研究生编辑：程序博客网时间：2024/05/16 18:12

一、运行效果图

二、核心代码

1.MainActivity的代码：

public class MainActivity extends Activity implements OnClickListener{    private Button read_btn;private Button write_btn;private TextView show;private EditText editText;private String FILE_NAME;@Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        read_btn = (Button)findViewById(R.id.read);        write_btn = (Button)findViewById(R.id.write);        show = (TextView)findViewById(R.id.show);        editText = (EditText)findViewById(R.id.editText);        read_btn.setOnClickListener(this);        write_btn.setOnClickListener(this);    }public void onClick(View v){switch(v.getId()){case R.id.read:String str=read(FILE_NAME);if(str!=null){show.setText(str);}else{show.setText("未读取到内容");}break;case R.id.write:String content=editText.getText().toString();write(content,FILE_NAME);break;default:break;}}/** * 写入方法 * @param content 写入的内容 * @param fileName 写入文件的文件名称 */private void write(String content,String fileName){try{//手机是否插入了SD卡if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){//获取SD卡的目录File sdCardDir=Environment.getExternalStorageDirectory();File file=new File(sdCardDir.getCanonicalPath()+"/"+fileName);//创建RandomAccessFile对象RandomAccessFile raf=new RandomAccessFile(file,"rw");//将文件记录指针移动到最后raf.seek(file.length());//写入文件raf.write(content.getBytes());raf.close();}}catch(Exception e){e.printStackTrace();}}/** * 读取文件 * @param fileName 文件名称 * @return 读取的字符串 */private String read(String fileName){try{//手机是否插入了SD卡if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){//获取SD卡的目录File sdCardDir=Environment.getExternalStorageDirectory();FileInputStream fis=new FileInputStream(sdCardDir.getCanonicalPath()+"/"+fileName);BufferedReader bf=new BufferedReader(new InputStreamReader(fis));StringBuffer sb=new StringBuffer("");String line=null;while((line=bf.readLine())!=null){sb.append(line);}bf.close();return sb.toString();}return null;}catch(Exception e){e.printStackTrace();return null;}}    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    }

2.activity_main的代码：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >  <EditText      android:id="@+id/editText"      android:layout_width="fill_parent"      android:layout_height="wrap_content"      android:text=""/>  <Button      android:id="@+id/read"      android:layout_width="fill_parent"      android:layout_height="wrap_content"      android:layout_below="@id/editText"      android:text="读取文件"/>   <Button      android:id="@+id/write"      android:layout_width="fill_parent"      android:layout_height="wrap_content"      android:layout_below="@id/read"      android:text="写入文件"/>       <TextView       android:id="@+id/show"       android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:layout_below="@id/write"       android:text=""/> </RelativeLayout>

三、遇到的问题

在安卓自带的模拟器上无法写入数据，没有SD卡，只有新下载的模拟器才能运行出效果

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