Android Development stores data to file instances

The first step, rewrite Androidmanifest.xml, give the mobile phone SCard card Authorization

<!--add SCard card Read and write authorization-->
<uses-permission android:name= "Android.permission.WRITE_EXTERNAL_STORAGE"/>

Then add unit test instrumentation

<instrumentation
Android:name= "Android.test.InstrumentationTestRunner"
Android:targetpackage= "Com.example.androidsdcard" >
</instrumentation>

And under the application, add <uses-library android:name= "Android.test.runner"/>


<application
Android:allowbackup= "true"
android:icon= "@drawable/ic_launcher"
Android:label= "@string/app_name"
Android:theme= "@style/apptheme" >
<uses-library android:name= "Android.test.runner"/>
<activity
Android:name= ". 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>


The second step is to write the FileStream of writing the document

Package Com.example.androidsdcard;

Import Java.io.ByteArrayOutputStream;
Import Java.io.File;
Import Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import Java.io.FileOutputStream;
Import java.io.IOException;
Import Java.io.OutputStream;

Import Android.content.Context;
Import android.os.Environment;

public class FileStream {
private context;

Public FileStream {
This.context = context;
}

Public FileStream () {

}
Read the contents of the SD card file
public string ReadFile (string filename) {
FileInputStream Inputstream=null;
Character Buffer stream
Bytearrayoutputstream outputstream=new Bytearrayoutputstream ();
Get the path to the SD card via environment
File File=new file (environment.getexternalstoragedirectory (), filename);
To determine whether SDcard exists
if (Environment.MEDIA_MOUNTED.equals (Environment.getexternalstoragestate ())) {
try {
Inputstream=new fileinputstream (file);
int len=0;
Creating a byte array
Byte[]data=new byte[2048];
Read by size of byte array
while ((Len=inputstream.read (data))!=-1) {
Outputstream.write (data, 0, Len);
}
catch (FileNotFoundException e) {
TODO auto-generated Catch block
E.printstacktrace ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}finally{
if (inputstream!=null) {
try {
Inputstream.close ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}
}
}
return new String (Outputstream.tobytearray ());

}

public boolean savafile (string filename, string content) {
Boolean flag = false;
FileOutputStream outputstream = null;
File File = new file (Environment.getexternalstoragedirectory (),
filename);
if (Environment.MEDIA_MOUNTED.equals (environment
. Getexternalstoragestate ()) {
try {
OutputStream = new FileOutputStream (file);
Outputstream.write (Content.getbytes ());
Flag = true;
catch (FileNotFoundException e) {
TODO auto-generated Catch block
E.printstacktrace ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
finally {
if (OutputStream!= null) {
try {
Outputstream.close ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}
}

}

return flag;
}

}


Part III, write test class for unit test, read and write files

Package Com.example.androidsdcard;

Import Android.content.Context;
Import Android.test.AndroidTestCase;
Import Android.util.Log;

public class MyTest extends Androidtestcase {
Private final String tag= "MyTest";
Public MyTest () {

}
public void SaveFile () {//test file Write
Context Context=getcontext ();
FileStream filestream=new FileStream (context);
Boolean Flag=filestream.savafile ("Hello.txt", "How are You?") ");
LOG.I (TAG, "--->" +flag);

}
public void ReadFile () {//test file content Read
Context Context=getcontext ();
FileStream filestream=new FileStream (context);
String filename= "Hello.txt";
String flag=filestream.readfile (filename);
LOG.I (TAG, "--->" +flag);

}

}