android开发积累5-操作sd卡

android中操作sd卡相关说明：

1、判断sd卡是否存在

if (Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)==false) {
            text.setText("sd卡不存在");
            return;
        }

 

2、获取sd卡根目录

Environment.getExternalStorageDirectory().getPath()

 

3、操作sd卡的权限

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

 

 

下面是一个操作sd卡，创建、删除目录、文件的例子：

CardActivity.java

package Test.wangfu;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.widget.TextView;

public class CardActivity extends Activity {

    private TextView text = null;
    private String directory = "/sdcard/wangfu";
    private String fileName = "/sdcard/wangfu/text.txt";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.card);
        text = (TextView) this.findViewById(R.id.cardLabel);

        if (Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)==false) {
            text.setText("sd卡不存在");
            return;
        }
        File path = new File(directory);
        if (path.exists() == false) {
            path.mkdir();
            text.setText("创建sd卡目录完成");
            // 创建文件
            try {
                java.io.OutputStreamWriter fw = new OutputStreamWriter(
                        new FileOutputStream(new File(fileName)), "UTF-8");

                //写入wangfu writer test
                fw.write("wangfu writer test");
                fw.flush();
                fw.close();
            } catch (java.lang.Exception ex) {
                text.setText(ex.getMessage());
                ex.printStackTrace();
            }
        } else {
            String sContent = "";
            java.io.InputStreamReader rd;
            try {
                rd = new java.io.InputStreamReader(new java.io.FileInputStream(
                        new File(fileName)), "UTF-8");
                java.io.BufferedReader reader = new java.io.BufferedReader(rd);
                String s = null;
                s = reader.readLine();

                while (s != null) {
                    sContent += s + "\r\n";
                    s = reader.readLine();
                }
                reader.close();
            } catch (java.lang.Exception e) {
               
                e.printStackTrace();
            }
            text.setText(sContent);
            File file = new File(fileName);
            file.delete();
            path.delete();
        }

    }

 

card.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
   
 <TextView
        android:id="@+id/cardLabel"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Enter Number to Dial:" />
   
</LinearLayout>

 

 

需要在AndroidManifest.xml添加权限

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