Android--文件读写

package com.zx.filedemo2;

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {
private TextView textView;
private Button btnButton;
private EditText editText;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

textView=(TextView) findViewById(R.id.textView1);
btnButton=(Button) findViewById(R.id.button1);
editText=(EditText) findViewById(R.id.editText1);

btnButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
// TODO 自动生成的方法存根
writeDate(editText.getText().toString());
textView.setText(readDate());
}
});
}

public void writeDate(String contentString) {
try {
FileOutputStream stream = openFileOutput("a.txt", MODE_PRIVATE);
stream.write(contentString.getBytes());
stream.close();
} catch (FileNotFoundException e) {
// TODO 自动生成的 catch 块
e.printStackTrace();
} catch (IOException e) {
// TODO 自动生成的 catch 块
e.printStackTrace();
}
}

public String readDate() {
String str=null;
try {
FileInputStream stream = openFileInput("a.txt");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = stream.read(buffer))!=-1) {
baos.write(buffer,0,len);
}
str = baos.toString();
baos.close();
stream.close();
} catch (FileNotFoundException e) {
// TODO 自动生成的 catch 块
e.printStackTrace();
} catch (IOException e) {
// TODO 自动生成的 catch 块
e.printStackTrace();
}

return str;
}

@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;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}