android读取sd卡文件的工具类

package com.guanjia.global;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import android.os.Environment;

public class FileUtils {

private String SDCardRoot;

private String SDStateString ;

public FileUtils() {

//得到当前外部存储设备的目录

SDCardRoot = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator;

// 获取扩展SD卡设备状态

SDStateString = Environment.getExternalStorageState();

}

/**

* 在SD卡上创建文件

* @param dir 目录路径

* @param fileName

* @return

* @throws IOException

/

public File createFileInSDCard(String dir ,String fileName) throws IOException {

File file = new File(SDCardRoot+ dir + File.separator + fileName);

file.createNewFile();

return file;

}

/**

* 在SD卡上创建目录

* @param dir 目录路径

* @return

/

public File creatSDDir(String dir) {

File dirFile = new File(SDCardRoot + dir + File.separator);

if( !dirFile.exists() ){

dirFile.mkdirs();

}

return dirFile;

}

/**

* 判断SD卡上的文件夹是否存在

* @param dir 目录路径

* @param fileName 文件名称

* @return

/

public boolean isFileExist(String dir ,String fileName){

File file = new File(SDCardRoot + dir + File.separator + fileName);

return file.exists();

}

/***

* 获取文件的路径

* @param dir

* @param fileName

* @return

/

public String getFilePath(String dir,String fileName){

return SDCardRoot + dir + File.separator + fileName;

}

/***

* 获取SD卡的剩余容量,单位是Byte

* @return

/

public long getSDAvailableSize(){

if (SDStateString.equals(android.os.Environment.MEDIA_MOUNTED)) {

// 取得sdcard文件路径

File pathFile = android.os.Environment.getExternalStorageDirectory();

android.os.StatFs statfs = new android.os.StatFs(pathFile.getPath());

// 获取SDCard上每个block的SIZE

long nBlocSize = statfs.getBlockSize();

// 获取可供程序使用的Block的数量

long nAvailaBlock = statfs.getAvailableBlocks();

// 计算 SDCard 剩余大小Byte

long nSDFreeSize = nAvailaBlock * nBlocSize ;

return nSDFreeSize;

}

return 0;

}

/**

* 将一个字节数组数据写入到SD卡中

/

public boolean write2SD(String dir,String fileName,byte[] bytes){

if(bytes == null ){

return false;

}

OutputStream output = null;

try {

// 拥有可读可写权限，并且有足够的容量

if (SDStateString.equals(android.os.Environment.MEDIA_MOUNTED) && bytes.length < getSDAvailableSize() ) {

File file = null;

creatSDDir(dir);

file = createFileInSDCard(dir,fileName);

output = new BufferedOutputStream(new FileOutputStream(file));

output.write(bytes);

output.flush();

return true;

}

} catch (IOException e1) {

// TODO Auto-generated catch block

e1.printStackTrace();

}finally{

try{

if( output != null ){

output.close();

}

}

catch(Exception e){

e.printStackTrace();

}

}

return false;

}

/***

* 从sd卡中读取文件，并且以字节流返回

* @param dir

* @param fileName

* @return

/

public byte[] readFromSD(String dir,String fileName){

File file = new File(SDCardRoot + dir + File.separator + fileName);

if( !file.exists() ){

return null;

}

InputStream inputStream = null;

try {

inputStream = new BufferedInputStream(new FileInputStream(file));

byte[] data = new byte[inputStream.available()];

inputStream.read(data);

return data;

} catch (FileNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally{

try {

if( inputStream != null ){

inputStream.close();

}

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

return null;

}

/**

* 将一个InputStream里面的数据写入到SD卡中 ,从网络上读取图片

/

public File write2SDFromInput(String dir,String fileName,InputStream input){

File file = null;

OutputStream output = null;

try {

int size = input.available();

// 拥有可读可写权限，并且有足够的容量

if (SDStateString.equals(android.os.Environment.MEDIA_MOUNTED) && size < getSDAvailableSize() ) {

creatSDDir(dir);

file = createFileInSDCard(dir,fileName);

output = new BufferedOutputStream(new FileOutputStream(file));

byte buffer [] = new byte[4*1024];

int temp ;

while((temp = input.read(buffer)) != -1){

output.write(buffer,0,temp);

}

output.flush();

}

} catch (IOException e1) {

// TODO Auto-generated catch block

e1.printStackTrace();

}finally{

try{

if( output != null ){

output.close();

}

}

catch(Exception e){

e.printStackTrace();

}

}

return file;

}

}