Files保存数据和资源的引用技术

1,文件保存数据  

  输出流:OpenFileOutput

  输入流:OpenFileInput

 

2,将数据报讯到内存卡里面

操作内存卡需要一下三个权限

 

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

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

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />读取权限

    

//获得外部存储卡

//File file = Environment.getExternalStorageDirectory();

    

//获取制定文件sdcard位置的目录

File file =Environment.getExternalStoragePublicDirectory("DCIM");

 

 

3,android工程中获取资源的引用;

 

 

使用文件的方式保存数据

 1,创建布局文件 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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
    <EditText 
        android:id="@+id/text_v1"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:gravity="center_horizontal"
        android:hint="输入框"
        />

    <Button
        android:id="@+id/Save"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/text_v1"
        android:onClick="show"
        android:text="保            存" />
    
      <Button
         android:id="@+id/clear"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/Save"
         android:layout_below="@id/text_v1"
        android:onClick="show"
        android:text="清除输入框" />
     <Button
         android:id="@+id/Read"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/Save"
        android:onClick="show"
        android:text="          读                           取               " />

    
    
</RelativeLayout>

 

FileDemo操作数据,并显示

public class FileDemo extends Activity {

	private EditText text_v1;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
      text_v1=(EditText)this.findViewById(R.id.text_v1);
	}

	// 按钮的监听器方法
	public void show(View view) {
		switch (view.getId()) {
		case R.id.Save:// 保存
			try {
				//将数据写到文件中
				//参数一:文件名
				//参数二:文件创建的模式;私有模式
			FileOutputStream fos=this.openFileOutput("FileDemo", MODE_PRIVATE);
			ObjectOutputStream oos = new ObjectOutputStream(fos);
			oos.writeObject("保存成内部文件的方式操作");
			oos.flush();
			oos.close();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();
			break;

		case R.id.Read:
			//读取保存的文件的数据
	         try {
	        	 //读取文件的数据
	        	 FileInputStream fis=this.openFileInput("FileDemo");
	        	 ObjectInputStream ois =new ObjectInputStream(fis);
	        	 String str =(String)ois.readObject();
	        	 text_v1.setText(str);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			break;
			
		case R.id.clear:
			//清空
			text_v1.setText("");	
			break;
		}

	}
}

 

 

数据保存到内存卡  关键代码

1,创建布局文件acivity_main.xml ,

 <Button
        android:id="@+id/Save"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/text_v1"
        android:onClick="show"
        android:text="保            存" />

 

操作布局的文件

// 按钮的监听器方法
	public void show(View view) {
		switch (view.getId()) {
		case R.id.Save:// 保存
			//获得外部存储卡
			//File file = Environment.getExternalStorageDirectory();
			
			//获得制定sdcard位置的目录
			File file =Environment.getExternalStoragePublicDirectory("DCIM");
			//在DCIM的目录下创建文件C++++++++++++++
			File files= new File(file,"C++++++++++++++");
			
			if(!files.exists()){
				Boolean b=file.mkdir();
				if(!b){
					Toast.makeText(this, "不能创建", Toast.LENGTH_SHORT).show();
				
				}
			}
			
			if(!files.canWrite()){
				Toast.makeText(this, "不能写文件", Toast.LENGTH_SHORT).show();
			}
			
			//在C++++++++++++++的目录下创建文件abc
			File file1 = new File(files,"abc");
			try {
				FileOutputStream fos = new FileOutputStream(file1);
				fos.write("长沙".getBytes());
				fos.flush();
				fos.close();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			
			Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();
			break;
}

 

 

 

3,android工程中使用静态资源的方式

 读取assets和res文件下的raw资源

 

 

text.txt文件的内容

 

raw文件下的text1.txt

 

运行效果:

 
 

详细代码:

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
    <EditText 
        android:id="@+id/text_v1"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:gravity="center_horizontal"
        android:hint="输入框"
        />

    <Button
        android:id="@+id/Save"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/text_v1"
        android:onClick="show"
        android:text="保            存" />
    
      <Button
         android:id="@+id/clear"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/Save"
         android:layout_below="@id/text_v1"
        android:onClick="show"
        android:text="清除输入框" />
     <Button
         android:id="@+id/Read"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/Save"
        android:onClick="show"
        android:text="          读                           取               " />

     <ImageView
         android:id="@+id/imageView1"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_alignLeft="@+id/Read"
         android:layout_below="@+id/Read"
         android:layout_marginLeft="56dp"
         android:layout_marginTop="154dp"
         android:ems="10"
        android:inputType="textMultiLine"/>
    
</RelativeLayout>

 Dmo操作数据的显示,读取assets和res文件下的raw资源

public class Demo extends Activity{

	private ImageView img;
	private EditText text_v1;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		img=(ImageView)this.findViewById(R.id.imageView1);
		 text_v1=(EditText)this.findViewById(R.id.text_v1);
	}
	public void show(View v){
		switch (v.getId()) {
		case R.id.Save:
			//读取assets资源文件中的文件,使用流读取
			try {
				//使用流读取Assets中的资源
				InputStream is	=this.getResources().getAssets().open("text.txt");
	         	byte[] by= new byte[is.available()];
		        is.read(by);
		        String str = EncodingUtils.getString(by,"GBK");
		        text_v1.setText(str);
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			break;

       case R.id.Read:
    	 //读取assets资源文件中的图片
			try {
				InputStream ism	=this.getResources().getAssets().open("img_1.jpg");
				byte[] bs = new byte[ism.available()];
				ism.read(bs);
				//将荼毒到的字节转化成bmp格式的图片
				Bitmap bmp=BitmapFactory.decodeByteArray(bs, 0, bs.length);
				//设置图片显示
				img.setImageBitmap(bmp);
			} catch (IOException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
    	   
    	   
			break;
       case R.id.clear:
			//res文件中创建的raw文件下的文件
    	   InputStream is1=this.getResources().openRawResource(R.raw.text1);
			byte[] by;
			try {
				by = new byte[is1.available()];
				  is1.read(by);
			        String str1 = EncodingUtils.getString(by,"GBK");
			        text_v1.setText(str1);
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
	      
			break;
		}
	}
}