[转载]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;
}
}