android > SDcard读写文件

package sp.mft;import java.io.BufferedReader;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.InputStreamReader;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.io.UnsupportedEncodingException;import android.app.Activity;import android.content.Context;import android.content.SharedPreferences;import android.os.Bundle;import android.os.Environment;import android.util.Log;public class SpActivity extends Activity {    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                         String filePath = "ip_sensor";//sdcartpath/ipsensor/        String fileName = "sensor_list.xml";                //写文件        writeToXml(SpActivity.this,"i want write in",getSdcardPath()+filePath,fileName);                //读文件         String readXml = ReadTxtFile(getSdcardPath()+filePath+"/"+fileName);        System.out.println(readXml);            }    ////写文件      public static int writeToXml(Context context, String str,String file_path,String file_name){        int result = 0;    File path = new File(file_path);        File file = new File(file_path+"/"+file_name);        if (!path.exists()) {            // 路径不存在? Just 创建            path.mkdirs();        }        if (!file.exists()) {            // 文件不存在、 Just创建            try {                file.createNewFile();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        OutputStreamWriter osw = null;        try {            osw = new OutputStreamWriter(new FileOutputStream(                    file));        } catch (FileNotFoundException e1) {            // TODO Auto-generated catch block            e1.printStackTrace();        }        try {            osw.write(str);            osw.close();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }                return result;    }              /// 读文件    public static String ReadTxtFile(String strFilePath)    {        String path = strFilePath;        String content = ""; //文件内容字符串            //打开文件            File file = new File(path);            //如果path是传递过来的参数，可以做一个非目录的判断            if (file.isDirectory())            {                Log.d("TestFile", "The File doesn't not exist.");            }            else            {                try {                    InputStream instream = new FileInputStream(file);                     if (instream != null)                     {                        InputStreamReader inputreader = new InputStreamReader(instream);                        BufferedReader buffreader = new BufferedReader(inputreader);                        String line;                        //分行读取                        while (( line = buffreader.readLine()) != null) {                            content += line + "\n";                        }                                        instream.close();                    }                }                catch (java.io.FileNotFoundException e)                 {                    Log.d("TestFile", "The File doesn't not exist.");                }                 catch (IOException e)                 {                     Log.d("TestFile", e.getMessage());                }            }            return content;    }        // 获取sdCard路径    public static String getSdcardPath()    {        // 定义一个空字符串，存储sdcard路径        String sdcardPath = "";        // 定义一个File类型的变量，存储sdcard的路径        File sdcardPathFile = null;        // 判断sdcard是否存在        boolean isSdcardExist = Environment.getExternalStorageState().equals(                                                   Environment.MEDIA_MOUNTED);        if (isSdcardExist)        {            // 将路径值赋给变量sdcardPath            sdcardPathFile = Environment.getExternalStorageDirectory();            sdcardPath = sdcardPathFile.toString() + "/";        }        else        {            // 将路径值赋给变量sdcardPath            sdcardPathFile = Environment.getRootDirectory();            sdcardPath = sdcardPathFile.toString() + "/";        }        // 最后返回一个保存sdcard路径的字符串        return sdcardPath;    }        //\\    }

然后是是 xml 加入权限

<!-- 在SDCard中创建与删除文件权限 --><uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/><!-- 往SDCard写入数据权限 --><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

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