Android SdCard 新建文件夹并在文件夹中读、写文件

From:http://blog.csdn.net/llp1992/article/details/41786993

首先你要获取SdCard的读写权限：

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

我们现在SdCard中新建一个文件夹：名字为 datas

File sd = Environment.getExternalStorageDirectory(); String mPath = sd.getPath() + "/datas"; File file = new File(mPath); if (!file.exists()) { file.mkdir(); }

File sd = Environment.getExternalStorageDirectory();
String mPath = sd.getPath() + "/datas";
File file = new File(mPath);
if (!file.exists()) {
file.mkdir();
}

然后定义一个FileService类用于存放那些读写的函数：

首先我们还是要定义一下我们的文件路径：

private String mPath = Environment.getExternalStorageDirectory().getPath()+
"/datas";

private String mPath = Environment.getExternalStorageDirectory().getPath()+ "/datas";

接下来是保存文件到SdCard中某个目录下的函数：保存类型是txt文本

public void write2Path(String fileName, String content) {

File f = new File(mPath + "/" + fileName +
".txt");
try {
FileOutputStream fileOS = new FileOutputStream(f);

try {
fileOS.write(content.getBytes());
fileOS.close();
BufferedWriter buf = new BufferedWriter(new OutputStreamWriter(

fileOS));
buf.write(content, 0, content.length());
buf.flush();
buf.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

public void write2Path(String fileName, String content) {
File f = new File(mPath + "/" + fileName + ".txt");
try {
FileOutputStream fileOS = new FileOutputStream(f);
try {
fileOS.write(content.getBytes());
fileOS.close();
BufferedWriter buf = new BufferedWriter(new OutputStreamWriter(
fileOS));
buf.write(content, 0, content.length());
buf.flush();
buf.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

接着是从保存文件的那个路径读取我们保存的文件的函数：

public String readFromPath(String fileName) {

byte[] data = new
byte[1024];
try {
FileInputStream fileIS = new FileInputStream(mPath +
"/" + fileName
+ ".txt");
// BufferedReader buf = new BufferedReader(new
// InputStreamReader(in))
byte[] buffer = new
byte[1024];
ByteArrayOutputStream byteArrayOutputStream =
new ByteArrayOutputStream();
int len = -1;
while ((len = fileIS.read(buffer)) != -1) {// 读取文件到缓冲区

byteArrayOutputStream.write(buffer, 0, len);// 写入到内存

}
data = byteArrayOutputStream.toByteArray();// 将内存中的二进制数据转为数组

byteArrayOutputStream.close();
fileIS.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return new String(data);

}

public String readFromPath(String fileName) {
byte[] data = new byte[1024];
try {
FileInputStream fileIS = new FileInputStream(mPath + "/" + fileName
+ ".txt");
// BufferedReader buf = new BufferedReader(new
// InputStreamReader(in))
byte[] buffer = new byte[1024];
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
int len = -1;
while ((len = fileIS.read(buffer)) != -1) {// 读取文件到缓冲区
byteArrayOutputStream.write(buffer, 0, len);// 写入到内存
}
data = byteArrayOutputStream.toByteArray();// 将内存中的二进制数据转为数组
byteArrayOutputStream.close();
fileIS.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return new String(data);
}

完整的FileService类如下：

FileService.Java：

package com.llp.classdifine;

import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;

import android.content.Context;
import android.os.Environment;

public class FileService {

private Context context;
private String mPath = Environment.getExternalStorageDirectory().getPath()

+ "/datas";

public FileService(Context context) {
this.context = context;
}
/**
* 保存文件到sdcard中某个路径下
* @param fileName
* @param content
*/
public void write2Path(String fileName, String content) {

File f = new File(mPath +
"/" + fileName + ".txt");
try {
FileOutputStream fileOS = new FileOutputStream(f);

try {
fileOS.write(content.getBytes());
fileOS.close();
BufferedWriter buf = new BufferedWriter(new OutputStreamWriter(

fileOS));
buf.write(content, 0, content.length());

buf.flush();
buf.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

/**
* 从sdcard中的某个路径下读取文件
* @param fileName
* @return
*/
public String readFromPath(String fileName) {

byte[] data = new
byte[1024];
try {
FileInputStream fileIS = new FileInputStream(mPath +
"/" + fileName
+ ".txt");
// BufferedReader buf = new BufferedReader(new
// InputStreamReader(in))
byte[] buffer = new
byte[1024];
ByteArrayOutputStream byteArrayOutputStream =
new ByteArrayOutputStream();
int len = -1;
while ((len = fileIS.read(buffer)) != -1) {// 读取文件到缓冲区

byteArrayOutputStream.write(buffer, 0, len);// 写入到内存

}
data = byteArrayOutputStream.toByteArray();// 将内存中的二进制数据转为数组

byteArrayOutputStream.close();
fileIS.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return new String(data);

}
}

package com.llp.classdifine;

import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;

import android.content.Context;
import android.os.Environment;

public class FileService {
private Context context;
private String mPath = Environment.getExternalStorageDirectory().getPath()
+ "/datas";

public FileService(Context context) {
this.context = context;
}
/**
* 保存文件到sdcard中某个路径下
* @param fileName
* @param content
*/
public void write2Path(String fileName, String content) {
File f = new File(mPath + "/" + fileName + ".txt");
try {
FileOutputStream fileOS = new FileOutputStream(f);
try {
fileOS.write(content.getBytes());
fileOS.close();
BufferedWriter buf = new BufferedWriter(new OutputStreamWriter(
fileOS));
buf.write(content, 0, content.length());
buf.flush();
buf.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

/**
* 从sdcard中的某个路径下读取文件
* @param fileName
* @return
*/
public String readFromPath(String fileName) {
byte[] data = new byte[1024];
try {
FileInputStream fileIS = new FileInputStream(mPath + "/" + fileName
+ ".txt");
// BufferedReader buf = new BufferedReader(new
// InputStreamReader(in))
byte[] buffer = new byte[1024];
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
int len = -1;
while ((len = fileIS.read(buffer)) != -1) {// 读取文件到缓冲区
byteArrayOutputStream.write(buffer, 0, len);// 写入到内存
}
data = byteArrayOutputStream.toByteArray();// 将内存中的二进制数据转为数组
byteArrayOutputStream.close();
fileIS.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return new String(data);
}
}

MainActivity.java代码如下：

package com.example.sdcard;

import java.io.File;
import com.example.sdcard.FileService;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity
extends Activity {
/** Called when the activity is first created. */

private static
final String TAG = "MainActivity";
private FileService fileService;
String fileName;
String content;

@Override
public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
File sd = Environment.getExternalStorageDirectory(); String mPath = sd.getPath() + "/datas"; File file = new File(mPath); if (!file.exists()) { file.mkdir(); }
Log.v("test", "file.getPath()" + file.getPath());

Button button = (Button) findViewById(R.id.btnsave);
Button read = (Button) findViewById(R.id.btnread);
fileService = new FileService(this);

// File file = this.getFilesDir();// 快速得到文件夹

// this.getCacheDir();// 获得缓存文件夹
final EditText fileNameText = (EditText) findViewById(R.id.fileName);

final EditText contenText = (EditText) findViewById(R.id.content);

final EditText readtext = (EditText) findViewById(R.id.contentread);

button.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {

fileName = fileNameText.getText().toString();
content = contenText.getText().toString();
try {
// 判断sd卡是否存在手机上并且可以进行读写
if (Environment.getExternalStorageState().equals(

Environment.MEDIA_MOUNTED)) {
fileService.write2Path(fileName, content);
} else {
}
} catch (Exception e) {
Log.e(TAG, e.toString());
}
}
});
read.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {

// TODO Auto-generated method stub

try {
// 判断sd卡是否存在手机上并且可以进行读写
if (Environment.getExternalStorageState().equals(

Environment.MEDIA_MOUNTED)) {
fileName = fileNameText.getText().toString();
Log.v("test", "fileName" + fileName);

readtext.setText(fileService.readFromPath(fileName));
} else {
}
} catch (Exception e) {
Log.e(TAG, e.toString());
}
}
});
}
}