Implementation content:
Write an interface. There are three lines of content are student number, name, class. There are five buttons required: write sd, read sd, clear interface content, write sp, and read sp.
As shown in the figure:
1, activity_main.xml page layout file
<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" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="36dp"
android:layout_marginTop="34dp"
android:text="学号" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/textView1"
android:layout_marginLeft="34dp"
android:layout_toRightOf="@+id/textView1"
android:ems="10" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView1"
android:layout_below="@+id/textView1"
android:layout_marginTop="38dp"
android:text="姓名" />
<EditText
android:id="@+id/editText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/textView2"
android:layout_alignLeft="@+id/editText1"
android:ems="10" >
<requestFocus />
</EditText>
<Button
android:id="@+id/button4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginBottom="20dp"
android:layout_toLeftOf="@+id/button3"
android:text="写sp" />
<Button
android:id="@+id/button5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/button4"
android:layout_alignLeft="@+id/button2"
android:text="读sp" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/button4"
android:layout_marginBottom="89dp"
android:layout_toLeftOf="@+id/editText2"
android:text="write to sd" />
<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/button4"
android:layout_alignLeft="@+id/editText2"
android:layout_marginBottom="17dp"
android:text="Clear" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button1"
android:layout_alignBottom="@+id/button1"
android:layout_toRightOf="@+id/button3"
android:text="读出sd" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button4"
android:layout_below="@+id/textView2"
android:layout_marginTop="44dp"
android:text="class" />
<EditText
android:id="@+id/editText3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/textView3"
android:layout_alignRight="@+id/editText2"
android:layout_toRightOf="@+id/button1"
android:ems="10" />
</RelativeLayout>
The specific layout content is as above, the layout is not perfect, and the interface content is basically realized.
2, MainActivity.java file content
package com.ligang;
//import com.dxxy.lab3.R;
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 com.dxxy.lab2.R;
import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
private Button loginBt,loginBt1,Rdsp,RdBt,clear;
private EditText qqNo,qqPsw,banji;
SharedPreferences sp;//Data read and write variables
Editor edit; //Editor edit object
private File sdCardDir;//sd card path
private File saveFile;//File name
private FileOutputStream outStream;//input file stream
private FileInputStream inStream;//input file
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate (savedInstanceState);
setContentView(R.layout.activity_main);
loginBt1 = (Button) findViewById(R.id.button1);
RdBt = (Button) findViewById(R.id.button2);
clear =(Button) findViewById(R.id.button3);
loginBt = (Button)findViewById(R.id.button4);
Rdsp = (Button)findViewById(R.id.button5);
qqNo = (EditText)findViewById(R.id.editText1);
qqPsw = (EditText)findViewById(R.id.editText2);
banji = (EditText)findViewById(R.id.editText3);
sp = this.getSharedPreferences("201521111012",MODE_WORLD_READABLE);
//Use the edit() method to get the Editor object.
edit = sp.edit();
//Monitor the write sp button to complete the xml file writing function
loginBt.setOnClickListener(new OnClickListener(){
public void onClick(View v){
if(qqNo.getText().toString().equals("")||qqPsw.getText().toString().equals("")){
Toast toast = Toast.makeText(getApplicationContext(), "Please enter student number and name", Toast.LENGTH_SHORT);
toast.show();
}
else{
//Store key-value key-value pair data through the Editor object
edit.putString("学号",qqNo.getText().toString());
edit.putString("姓名",qqPsw.getText().toString());
edit.putString("班级",banji.getText().toString());
// Submit data through the commit() method
edit.commit();
Toast toast = Toast.makeText(getApplicationContext(),
"sp write successfully", Toast.LENGTH_SHORT);
toast.show();
}
}
});
//3 Complete the reading function of user name and password
Rdsp.setOnClickListener(new OnClickListener(){
public void onClick(View v){
if(null!=sp.getString("学号",""))
{
qqNo.setText(sp.getString("学号",""));
}
if(null!=sp.getString("姓名",""))
{
qqPsw.setText(sp.getString("姓名",""));
}
if(null!=sp.getString("班级",""))
{
banji.setText(sp.getString("班级",""));
}
Toast toast = Toast.makeText(getApplicationContext(),
"sp read successfully", Toast.LENGTH_SHORT);
toast.show();
}
});
//Monitor the write file button to complete the file writing function
loginBt1.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if (qqNo.getText().toString().equals("")
|| qqPsw.getText().toString().equals("")) {
Toast toast = Toast.makeText(getApplicationContext(),
"Please enter student number name", Toast.LENGTH_SHORT);
toast.show();
} else {
Toast toast = Toast.makeText(getApplicationContext(),
"Start writing to file", Toast.LENGTH_SHORT);
toast.show();
Write_Files("201521111012.txt",qqNo.getText().toString());
Write_Files("ligang.txt",qqPsw.getText().toString());
Write_Files("dianxin.txt",banji.getText().toString());
/*Toast toast = Toast.makeText(getApplicationContext(),
"Write to file successful", Toast.LENGTH_SHORT);
toast.show();*/
}
}
});
//5 Complete the reading function of user name and password
RdBt.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if(null!=Read_Files("201521111012.txt"))
{
qqNo.setText(Read_Files("201521111012.txt"));
}
if(null!=Read_Files("ligang.txt"))
{
qqPsw.setText(Read_Files("ligang.txt"));
}
if(null!=Read_Files("dianxin.txt"))
{
banji.setText(Read_Files("dianxin.txt"));
}
}
});
//Complete the interface content clearing function
clear.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
qqNo.setText("");
qqPsw.setText("");
banji.setText("");
Toast toast = Toast.makeText(getApplicationContext(),
"Interface content successfully cleared", Toast.LENGTH_SHORT);
toast.show();
}
});
}
@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;
}
private void Write_Files(String fileName, String strContent) {
sdCardDir = Environment.getExternalStorageDirectory();
saveFile = new File(sdCardDir, fileName);
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
// create initialization stream object
try {
outStream = new FileOutputStream(saveFile);
} catch (FileNotFoundException e) {
Toast.makeText(this, "The file does not exist!", Toast.LENGTH_SHORT).show();
return;
}
try {
// write content to file
outStream.write(strContent.getBytes());
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
Toast.makeText(this, "No exception found in file!", Toast.LENGTH_SHORT).show();
} catch (IOException e) {
// TODO Auto-generated catch block
Toast.makeText(this, "File read and write exception!", Toast.LENGTH_SHORT).show();
} catch (NullPointerException e) {
Toast.makeText(this, "File read and write null pointer exception!", Toast.LENGTH_SHORT).show();
} finally {
try {
// close the file output stream
outStream.close();
} catch (IOException e) {
// TODO Auto-generated catch block
Toast.makeText(this, "File read and write exception!", Toast.LENGTH_SHORT).show();
}
Toast.makeText(this, "The file was written successfully!", Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(this, "The memory card does not exist!", Toast.LENGTH_SHORT).show();
return;
}
}
// 3 Complete the file read operation function
private String Read_Files(String fileName) {
sdCardDir = Environment.getExternalStorageDirectory();
saveFile = new File(sdCardDir, fileName);
int len;
// Then create a byte array output stream
byte[] buffer = new byte[1024];
ByteArrayOutputStream ostream = new ByteArrayOutputStream();
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
// create initialization stream object
try {
inStream = new FileInputStream(saveFile);
Log.v("Instance inStream", "实例化inStream！");
} catch (FileNotFoundException e) {
Toast.makeText(this, "The file does not exist!", Toast.LENGTH_SHORT).show();
return null;
}
try {
Log.v("Read", "Read data!");
Toast.makeText(this, "The file was read successfully!", Toast.LENGTH_SHORT).show();
while ((len = inStream.read(buffer)) != -1) {
ostream.write(buffer, 0, len);
}
Log.v("Read", "读成功！");
} catch (IOException e) {
Toast.makeText(this, "读 异常！", Toast.LENGTH_SHORT).show();
}
try {
// Finally close the input stream and output stream
inStream.close();
ostream.close();
Log.v("Read", "读成功！");
} catch (IOException e) {
Toast.makeText(this, "读 异常！", Toast.LENGTH_SHORT).show();
}
String str = new String(ostream.toByteArray());
Log.v("Disp", "Text display!");
return str;
} else {
Toast.makeText(this, "The memory card does not exist!", Toast.LENGTH_SHORT).show();
return null;
}
}
}
