/**

     * 创建各种文件

     * @throws IOException

     *

     */

    @SuppressLint({ "WorldWriteableFiles", "WorldReadableFiles" })

    @SuppressWarnings("resource")

    private void createFile() throws IOException {

        Log.i(TAG, "开始创建文件");

        FileOutputStream fos;

        //创建私有文件

        fos = this.openFileOutput("private.txt", Context.MODE_PRIVATE);

        fos.write("private".getBytes());

        fos.close();

        //创建公有文件

        fos = this.openFileOutput("public.txt", Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE);

        fos.write("public".getBytes());

        fos.close();

        //创建默认文件

        File file = new File(this.getFilesDir(), "default.txt");

        fos = new FileOutputStream(file);

        fos.write("default".getBytes());

        fos.close();

        //创建只读文件

        fos = this.openFileOutput("readable.txt", Context.MODE_WORLD_READABLE);

        fos.write("readable".getBytes());

        fos.close();

        //创建只写文件

        fos = this.openFileOutput("writeable.txt", Context.MODE_WORLD_WRITEABLE);

        fos.write("writeable".getBytes());

        fos.close();

        Toast.makeText(this, "文件创建成功", Toast.LENGTH_LONG).show();

        Log.i(TAG, "创建文件完成");

    }

package com.example.other;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import android.annotation.SuppressLint;

import android.os.Bundle;

import android.support.v7.app.ActionBarActivity;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.Toast;

public class MainActivity extends ActionBarActivity implements OnClickListener{

    private String TAG = "MainActivity";

    /** 读写私有文件 */

    private Button btnWritePrivate, btnReadPrivate;

    /** 读写共有文件 */

    private Button btnWritePublic, btnReadPublic ;

    /** 读写默认文件 */

    private Button btnWriteDefalut, btnReadDefault;

    /** 读写只读文件 */

    private Button btnWriteReadable, btnReadReadable;

    /** 读写只写文件 */

    private Button btnWriteWriteable, btnReadWriteable;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        //组件获取

        btnWritePrivate = (Button)findViewById(R.id.btn_writePrivate);

        btnReadPrivate = (Button)findViewById(R.id.btn_readPrivate);

        btnWritePublic = (Button)findViewById(R.id.btn_writePublic);

        btnReadPublic = (Button)findViewById(R.id.btn_readPublic);

        btnWriteDefalut = (Button)findViewById(R.id.btn_writeDefault);

        btnReadDefault = (Button)findViewById(R.id.btn_readDefault);

        btnWriteReadable = (Button)findViewById(R.id.btn_writeReadable);

        btnReadReadable = (Button)findViewById(R.id.btn_readReadable);

        btnWriteWriteable = (Button)findViewById(R.id.btn_writeWriteable);

        btnReadWriteable = (Button)findViewById(R.id.btn_readWriteable);

        //设置监听事件

        btnWritePrivate.setOnClickListener(this);

        btnReadPrivate.setOnClickListener(this);

        btnWritePublic.setOnClickListener(this);

        btnReadPublic.setOnClickListener(this);

        btnWriteDefalut.setOnClickListener(this);

        btnReadDefault.setOnClickListener(this);

        btnWriteReadable.setOnClickListener(this);

        btnReadReadable.setOnClickListener(this);

        btnWriteWriteable.setOnClickListener(this);

        btnReadWriteable.setOnClickListener(this);

    }

    @Override

    public void onClick(View v) {

        switch (v.getId()) {

        case R.id.btn_readPrivate:

            readFile("private.txt");

            break;

        case R.id.btn_readPublic:

            readFile("public.txt");

            break;

        case R.id.btn_readDefault:

            readFile("default.txt");

            break;

        case R.id.btn_readReadable:

            readFile("readable.txt");

            break;

        case R.id.btn_readWriteable:

            readFile("writeable.txt");

            break;

        case R.id.btn_writePrivate:

            writeFile("private.txt");

            break;

        case R.id.btn_writePublic:

            writeFile("public.txt");

            break;

        case R.id.btn_writeDefault:

            writeFile("default.txt");

            break;

        case R.id.btn_writeReadable:

            writeFile("readable.txt");

            break;

        case R.id.btn_writeWriteable:

            writeFile("writeable.txt");

            break;

        default:

            break;

        }

    }

    @SuppressLint("SdCardPath")

    public void readFile(String fileName) {

        Log.i(TAG, "读文件"+fileName);

        File file = new File("/data/data/com.example.filepower/files/"+fileName);

        try {

            @SuppressWarnings("resource")

            BufferedReader br = new BufferedReader(new FileReader(file));

            String context = br.readLine();

            Toast.makeText(this, context, Toast.LENGTH_SHORT).show();

        } catch (Exception e) {

            Toast.makeText(this, "读取失败", Toast.LENGTH_SHORT).show();

        }

    }

    @SuppressLint("SdCardPath")

    @SuppressWarnings("resource")

    public void writeFile(String fileName) {

        Log.i(TAG, "写文件"+fileName);

        File file = new File("/data/data/com.example.filepower/files/", fileName);

        try {

            FileOutputStream fos = new FileOutputStream(file);

            fos.write("xxx".getBytes());

        } catch (Exception e) {

            Toast.makeText(this, "写文件失败", Toast.LENGTH_SHORT).show();

        }

    }

}