这里会用到三个android包:File, FileInputStream, FIleOutputStream.
package com.example.filetest; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import android.os.Bundle; import android.app.Activity; import android.util.Log; import android.view.Menu; import android.widget.TextView; public class MainActivity extends Activity { final String FILE_PATH = "data/data/com.example.filetest/"; final String FILE_NAME = "test.txt"; final String TAG = "MainActivity"; final String TEXT_ENCODING = "UTF-8"; File file; FileOutputStream out; FileInputStream in; TextView tv = null; String display; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //创建文件 file = new File(FILE_PATH, FILE_NAME); try { file.createNewFile(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } //打开文件file的out try { out = new FileOutputStream(file); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } String infoTowrite = "This is my file test, thanks!"; //将字符串转换成byte数组 try { out.write(infoTowrite.getBytes()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } //关闭IO try { out.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } /**************将刚刚写入的数据显示到textview中**************/ //打开文件的FileInputStream; try { in = new FileInputStream(file); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } //将文件全部读取出来 byte[] temp =new byte[(int) file.length()]; try { in.read(temp); in.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } //将byte数组的内容转换成string类型 display = new String(temp); Log.e(TAG, "应该显示的为:" + display); setContentView(R.layout.activity_main); tv = (TextView)findViewById(R.id.textView); tv.setText(display); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.activity_main, menu); return true; } }