安卓学习-文件管理

 

 

 

案例：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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"

    tools:context="com.example.administrator.filemanager.MainActivity"
    android:id="@+id/读取私有文件">


    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="写入私有文件"
        android:onClick="writePrivateFileClick"
        android:id="@+id/button"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="读取私有文件"
        android:onClick="readPrivateFileClick"
        android:id="@+id/button2"
        android:layout_below="@+id/button"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="读取res/raw文件"
        android:id="@+id/button3"
        android:onClick="readRAWFileClick"
        android:layout_below="@+id/button2"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="150dp"
        android:text=""
        android:id="@+id/textView"
        android:scrollbars = "vertical"
        android:layout_below="@+id/button3"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="写入私有缓存数据"
        android:onClick="writePrivateCacheDataClick"
        android:id="@+id/button4"
        android:layout_below="@+id/textView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="判断是否有外部存储设备"
        android:id="@+id/button5"
        android:onClick="isSDCardClick"
        android:layout_below="@+id/button4"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="写入外部存储的私有文件"
        android:onClick="writeSDcardPrivateFileClick"
        android:id="@+id/button6"
        android:layout_below="@+id/button5"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="写入外部存储私有缓存文件"
        android:id="@+id/button7"
        android:onClick="writeSDcardPrivateCacheFileClick"
        android:layout_below="@+id/button6"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

</RelativeLayout>

MainActivity.java

package com.example.administrator.filemanager;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.ActionBarActivity;
import android.text.method.ScrollingMovementMethod;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;

public class MainActivity extends Activity {

    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.textView);
        textView.setTextSize(14);
    }

    /*写入私有文件*/
    public void writePrivateFileClick(View view) {
        try {
            //Context.MODE.PRIVATE 创建私有文件 APPEND是增加内容
            OutputStream out = openFileOutput("xfei.txt", Context.MODE_APPEND);
            String info = "我是中国人";
            byte[] bytes = info.getBytes();
            out.write(bytes, 0, bytes.length);
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /*读取私有文件*/
    public void readPrivateFileClick(View view) {
        try {
            InputStream in = openFileInput("xfei.txt");
            byte[] bytes = new byte[1024];
            StringBuffer sb = new StringBuffer();
            int len = -1;
            while ((len = in.read(bytes)) != -1) {
                sb.append(new String(bytes, 0, len));
            }
            in.close();
            textView.setText("  " + sb);
            //  Toast.makeText(this,sb,Toast.LENGTH_SHORT).show();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //读取目录raw下的文件
    public void readRAWFileClick(View view) {

        try {
            InputStream in = getResources().openRawResource(R.raw.xfei);
            byte[] bytes = new byte[1024];
            StringBuffer sb = new StringBuffer();
            int len = -1;
            while ((len = in.read(bytes)) != -1) {
                sb.append(new String(bytes, 0, len));
            }
            in.close();
            // Toast.makeText(this,sb,Toast.LENGTH_SHORT).show();
            textView.setText("  " + sb);
            textView.setMovementMethod(ScrollingMovementMethod.getInstance());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //写入一个内部私有缓存文件
    public void writePrivateCacheDataClick(View view) {
        //创建一个缓存的文件
        //String temp= getCacheDir()+"/temp.tmp";
        //System.out.println();
        try {
            File temp = File.createTempFile("temp", null, getCacheDir());
            FileOutputStream out = new FileOutputStream(temp);
            PrintStream ps = new PrintStream(out);
            ps.print("我可是要成为编程王的男人");
            ps.close();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    public void isSDCardClick(View view) {
        //判断是否有SD卡
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            Toast.makeText(this, "有SD卡", Toast.LENGTH_SHORT).show();
            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED_READ_ONLY)) {
                Toast.makeText(this, "SDCard只读", Toast.LENGTH_SHORT).show();
            } else {//sdcard路径
                System.out.println(Environment.getExternalStorageDirectory().getPath());
                //访问android内置的文件夹
                System.out.println(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS));
            }
        } else {
            Toast.makeText(this, "没有SD卡", Toast.LENGTH_SHORT).show();
        }
    }

    //写SD卡私有文件
    public void writeSDcardPrivateFileClick(View view) {
        //获得路径
        File file = getExternalFilesDir(null);
        if (file != null) {
            try {
                FileOutputStream out = new FileOutputStream(file + "/xfei.txt");
                PrintStream ps = new PrintStream(out);
                ps.print("今天吃药没？");
                ps.close();
                out.close();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }
      //写入SD卡 私有缓存文件
    public void writeSDcardPrivateCacheFileClick(View v) {
        try {
           File temp= File.createTempFile("xfei",null,getExternalCacheDir());

            if (temp != null) {

                    FileOutputStream out = new FileOutputStream(temp);
                    PrintStream ps = new PrintStream(out);
                    ps.print("今天吃药没？给你药吃");
                    ps.close();
                    out.close();

            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}