sd卡文件存储和读取

package com.example.filedemo1;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;

import android.os.Bundle;
import android.app.Activity;

public class MainActivity extends Activity {
    private static final String FILENAME = "/mnt/sdcard/neusoft/jmz.txt";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        File file = new File(FILENAME);
        //判断文件是否存在，如果不存在创建
        if(!file.getParentFile().exists()){
            file.getParentFile().mkdirs();
        }
        PrintStream out = null;
        try {
            out = new PrintStream(new FileOutputStream(file));
            out.println("中国吉林长春");
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            if(out!=null){
                out.close();
            }
        }
    }

}

必须配置权限 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

tv = (TextView) findViewById(R.id.tv);
        // 判断sd卡是否挂载
        if (Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)) {
            // 得到sd卡名称
            File file = new File(Environment.getExternalStorageDirectory()
                    + File.separator + DIR + File.separator + FILENAME);
            Scanner sc = null;
            try {
                //判断文件是否存在
                if (file.getParentFile().exists()) {
                    sc = new Scanner(new FileInputStream(file));
                    while (sc.hasNext()) {
                        tv.append(sc.next());
                    }
                }else{
                    Toast.makeText(this, "不存在", 0).show();
                }
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } finally {
                if (sc != null) {
                    sc.close();
                }
            }

        } else {
            Toast.makeText(this, "不存在sd卡", 0).show();
        }