Android 读取和保存文件（手机内置存储器）

1:activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView 
        android:id="@+id/tv_filename"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="文件名称"/>
    <EditText 
        android:id="@+id/et_filename"
        android:layout_below="@id/tv_filename"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    
    <TextView 
        android:id="@+id/tv_content"
        android:layout_below="@id/et_filename"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="文件内容"/>
    <EditText 
        android:id="@+id/et_content"
        android:layout_below="@id/tv_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    
    <Button 
        android:id="@+id/btn_save"
        android:layout_below="@id/et_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="保存"/>
    
    <Button 
        android:id="@+id/btn_read"
        android:layout_below="@id/btn_save"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="读取"/>
</RelativeLayout>

2:文件操作类:FileService.java

public class FileService {
	private Context context=null;
	
	public FileService(Context context){
		this.context=context;
	}
	
	//save file
	public void saveFile(String filename,String content) throws Exception{
		FileOutputStream out=context.openFileOutput(filename, Context.MODE_PRIVATE);
		out.write(content.getBytes());
		out.close();
	}
	
	//read file
	public String readFile(String filename)throws Exception{
		FileInputStream is=context.openFileInput(filename);
		byte b[]=new byte[1024];
		int len=0;
		ByteArrayOutputStream baos=new ByteArrayOutputStream();
		//先把数据写入内存
		while((len=is.read(b))!=-1){
			baos.write(b,0,len);
		}
		//从内存中读取数据
		byte data[]=baos.toByteArray();
		
		baos.close();
		is.close();
		
		return new String(data);
	}
}

3:MainActivity.java

public class MainActivity extends Activity {
	private FileService fileService=null;
	private Button btnSave=null,btnRead=null;
	private EditText etFilename=null;
	private EditText etContent=null;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		btnSave=(Button)findViewById(R.id.btn_save);
		btnRead=(Button)findViewById(R.id.btn_read);
		etFilename=(EditText)findViewById(R.id.et_filename);
		etContent=(EditText)findViewById(R.id.et_content);
		
		fileService=new FileService(MainActivity.this);
		
		btnSave.setOnClickListener(new OnClickListener(){
			public void onClick(View view){
				String filename=etFilename.getText().toString();
				String content=etContent.getText().toString();
				try {
					fileService.saveFile(filename, content);
					Toast.makeText(MainActivity.this, "Save file success!", Toast.LENGTH_SHORT).show();
				} catch (Exception e) {
					Toast.makeText(MainActivity.this, "Save file error!", Toast.LENGTH_SHORT).show();
				}
			}
		});
		
		btnRead.setOnClickListener(new OnClickListener(){
			public void onClick(View view){
				String filename=etFilename.getText().toString();
				try {
					String text=fileService.readFile(filename);
					etContent.setText(text);
				} catch (Exception e) {
					Toast.makeText(MainActivity.this, "Read file error!", Toast.LENGTH_SHORT).show();
				}
			}
		});
	}

}

　　

4:运行结果