1 public class MainActivity extends Activity implements OnClickListener {
  2     
  3      /** 存储后的文件路径：/data/data/<package name>/shares_prefs + 文件名.xml */ 
  4     public static final String PATH = "/data/data/com.example.datademo/shared_prefs/preferences.xml";
  5     private SharedPreferences userInfo;
  6 
  7     private Button button1;
  8     private Button button2;
  9     private Button button3;
 10     private Button button4;
 11     private Button button5;
 12     private Button button6;
 13     private Button button7;
 14     private Button button8;
 15     private Button button9;
 16     private Button button10;
 17     private TextView textView;
 18     private EditText editText;
 19 
 20     @Override
 21     protected void onCreate(Bundle savedInstanceState) {
 22         super.onCreate(savedInstanceState);
 23         setContentView(R.layout.activity_main);
 24 
 25         // 获得界面的控件
 26         textView = (TextView) findViewById(R.id.textView1);
 27         editText = (EditText) findViewById(R.id.editText1);
 28         button1 = (Button) findViewById(R.id.button1);
 29         button1.setOnClickListener(this);
 30         button2 = (Button) findViewById(R.id.button2);
 31         button2.setOnClickListener(this);
 32         button3 = (Button) findViewById(R.id.button3);
 33         button3.setOnClickListener(this);
 34         button4 = (Button) findViewById(R.id.button4);
 35         button4.setOnClickListener(this);
 36         button5 = (Button) findViewById(R.id.button5);
 37         button5.setOnClickListener(this);
 38         button6 = (Button) findViewById(R.id.button6);
 39         button6.setOnClickListener(this);
 40         button7 = (Button) findViewById(R.id.button7);
 41         button7.setOnClickListener(this);
 42         button8 = (Button) findViewById(R.id.button8);
 43         button8.setOnClickListener(this);
 44         button9 = (Button) findViewById(R.id.button9);
 45         button9.setOnClickListener(this);
 46         button10 = (Button) findViewById(R.id.button10);
 47         button10.setOnClickListener(this);
 48         
 49         //在界面组件或服务组件中调用，构造应用默认的设置文件，默认文件名字为_preferences.xml
 50         //userInfo = PreferenceManager.getDefaultSharedPreferences(this);  
 51         //或获取指定名字的SharedPreferences对象  参数分别为存储的文件名和存储模式。
 52         userInfo = getSharedPreferences("preferences.xml", Activity.MODE_PRIVATE); 
 53         
 54         //读取数据，如果无法找到则会使用默认值
 55         String username = userInfo.getString("name", "未定义姓名");  
 56         String msg = userInfo.getString("msg", "未定义信息");
 57         //显示文本
 58         textView.setText(username+","+msg);
 59     }
 60 
 61     @Override
 62     public void onClick(View v) {
 63         // TODO Auto-generated method stub
 64         switch (v.getId()) {
 65         case R.id.button1: {
 66             Log.d("TEST", "sdcard?"+FileUtil.isSdcardAvailable());
 67             Log.d("TEST", "全部容量"+(float)FileUtil.getSDAllSizeKB()/1024/1024);
 68             Log.d("TEST", "可用容量"+(float)FileUtil.getSDAvalibleSizeKB()/1024/1024);
 69             Toast.makeText(this, "status", Toast.LENGTH_SHORT).show();
 70             break;
 71         }
 72         case R.id.button2: {
 73             Log.d("TEST", "example文件夹存在?"+FileUtil.isFileExist("example"));
 74             Log.d("TEST", "创建forexample文件夹"+FileUtil.createFile("forexample"));
 75             Toast.makeText(this, "IsFile", Toast.LENGTH_SHORT).show();
 76             break;
 77         }  
 78         case R.id.button3: {
 79             FileUtil.writeToSDCardFile("forexample", "test.txt",   
 80                     editText.getText().toString(), "UTF-8", true);
 81             Toast.makeText(this, "WriteFile", Toast.LENGTH_SHORT).show();
 82             break;
 83         } 
 84         case R.id.button4: {
 85             textView.setText(FileUtil.ReadFromSDCardFile("forexample", "test.txt"));
 86             Toast.makeText(this, "ReadFile", Toast.LENGTH_SHORT).show();
 87             break;
 88         } 
 89         case R.id.button5: {
 90             writeFile("test2.txt",editText.getText().toString());
 91             Toast.makeText(this, "WritePrivateFile", Toast.LENGTH_SHORT).show();
 92             break;
 93         } 
 94         case R.id.button6: {
 95             textView.setText(readFile("test2.txt"));
 96             Toast.makeText(this, "ReadPrivateFile", Toast.LENGTH_SHORT).show();
 97             break;
 98         } 
 99         case R.id.button7: {
100             //获得SharedPreferences的编辑器
101             SharedPreferences.Editor editor = userInfo.edit();
102             //将信息存入相应的键值中
103             editor.putString("name", editText.getText().toString()).commit();
104             Toast.makeText(this, "SetName", Toast.LENGTH_SHORT).show();
105             break;
106         } 
107         case R.id.button8: {
108             //获得SharedPreferences的编辑器
109             SharedPreferences.Editor editor = userInfo.edit();
110             //将信息存入相应的键值中ss
111             editor.putString("msg", editText.getText().toString()).commit();
112             Toast.makeText(this, "SetMessage", Toast.LENGTH_SHORT).show();
113             break;
114         } 
115         case R.id.button9: {
116             userInfo = getSharedPreferences("preferences.xml", Activity.MODE_PRIVATE);
117             String username = userInfo.getString("name", "未定义姓名");  
118             String msg = userInfo.getString("msg", "未定义信息");
119             textView.setText(username+","+msg);
120             Toast.makeText(this, "ShowMsg", Toast.LENGTH_SHORT).show();
121             break;
122         } 
123         case R.id.button10: {
124             textView.setText(print());
125             Toast.makeText(this, "ShowXML", Toast.LENGTH_SHORT).show();
126             break;
127         } 
128         }
129     }
130     
131     public void writeFile(String fileName,String writestr){ 
132         try{ 
133                 FileOutputStream fout =openFileOutput(fileName,MODE_PRIVATE); 
134                 byte [] bytes = writestr.getBytes(); 
135                 fout.write(bytes); 
136                 fout.close(); 
137               } 
138                 catch(Exception e){ 
139                 e.printStackTrace(); 
140                } 
141         } 
142 
143         //读数据
144     public String readFile(String fileName){ 
145       String res=""; 
146       try{ 
147              FileInputStream fin = openFileInput(fileName); 
148              int length = fin.available(); 
149              byte [] buffer = new byte[length]; 
150              fin.read(buffer);     
151              res = EncodingUtils.getString(buffer, "UTF-8"); 
152              fin.close();     
153          } 
154          catch(Exception e){ 
155              e.printStackTrace(); 
156          } 
157          return res; 
158     }
159     
160     private String print() {  
161         StringBuffer buff = new StringBuffer();  
162         try {  
163             BufferedReader reader = new BufferedReader(new InputStreamReader(  
164                     new FileInputStream(PATH)));  
165             String str;  
166             while ((str = reader.readLine()) != null) {  
167                 buff.append(str + "/n");  
168             }  
169         } catch (Exception e) {  
170             e.printStackTrace();  
171         }  
172         return buff.toString();  
173     }
174 
175 }

  1 package com.example.datademo;
  2 
  3 import java.io.File;
  4 import java.io.FileInputStream;
  5 import java.io.FileNotFoundException;
  6 import java.io.FileOutputStream;
  7 import java.io.IOException;
  8 import java.io.InputStream;
  9 import java.io.OutputStream;
 10 
 11 import org.apache.http.util.EncodingUtils;
 12 
 13 import android.os.Environment;
 14 import android.os.StatFs;
 15 import android.util.Log;
 16 
 17 public class FileUtil {
 18     private static int bufferd = 1024;
 19 
 20     private FileUtil() {
 21     }
 22 
 23     /*
 24      * <!-- 在SDCard中创建与删除文件权限 --> <uses-permission
 25      * android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/> <!--
 26      * 往SDCard写入数据权限 --> <uses-permission
 27      * android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 28      */
 29 
 30     // =================get SDCard information===================
 31     public static boolean isSdcardAvailable() {
 32         String status = Environment.getExternalStorageState();
 33         //Environment.MEDIA_MOUNTED表示SD卡正常挂载
 34         //sd卡   http://blog.csdn.net/yuzhiboyi/article/details/8645730
 35         if (status.equals(Environment.MEDIA_MOUNTED)) {
 36             return true;
 37         }
 38         return false;
 39     }
 40 
 41     public static long getSDAllSizeKB() {
 42         // get path of sdcard
 43         File path = Environment.getExternalStorageDirectory();
 44         //StatFs获取的都是以block为单位的   http://blog.csdn.net/pang3510726681/article/details/6969557
 45         StatFs sf = new StatFs(path.getPath());
 46         // get single block size(Byte)
 47         long blockSize = sf.getBlockSize();
 48         // 获取所有数据块数
 49         long allBlocks = sf.getBlockCount();
 50         // 返回SD卡大小
 51         return (allBlocks * blockSize) / 1024; // KB
 52     }
 53 
 54     /**
 55      * free size for normal application
 56      * 
 57      * @return
 58      */
 59     public static long getSDAvalibleSizeKB() {
 60         File path = Environment.getExternalStorageDirectory();
 61         StatFs sf = new StatFs(path.getPath());
 62         long blockSize = sf.getBlockSize();
 63         long avaliableSize = sf.getAvailableBlocks();
 64         return (avaliableSize * blockSize) / 1024;// KB
 65     }
 66 
 67     // =====================File Operation==========================
 68     /**
 69      * @param director 文件夹名称
 70      * @return
 71      */
 72     public static boolean isFileExist(String director) {
 73         File file = new File(Environment.getExternalStorageDirectory()
 74                 + File.separator + director);
 75         return file.exists();
 76     }
 77 
 78     /**
 79      * create multiple director
 80      * 
 81      * @param path
 82      * @return
 83      */
 84     public static boolean createFile(String director) {
 85         if (isFileExist(director)) {
 86             return true;
 87         } else {
 88             File file = new File(Environment.getExternalStorageDirectory()
 89                     + File.separator + director);
 90             if (!file.mkdirs()) {
 91                 return false;
 92             }
 93             return true;
 94         }
 95     }
 96 
 97     public static File writeToSDCardFile(String directory, String fileName,
 98             String content, boolean isAppend) {
 99         return writeToSDCardFile(directory, fileName, content, "", isAppend);
100     }
101 
102     /**
103      * 
104      * @param director
105      *            (you don‘t need to begin with
106      *            Environment.getExternalStorageDirectory()+File.separator)
107      * @param fileName
108      * @param content
109      * @param encoding
110      *            (UTF-8...)
111      * @param isAppend
112      *            : Context.MODE_APPEND
113      * @return
114      */
115     public static File writeToSDCardFile(String directory, String fileName,
116             String content, String encoding, boolean isAppend) {
117         // mobile SD card path +path
118         File file = null;
119         OutputStream os = null;
120         try {
121             if (!createFile(directory)) {
122                 return file;
123             }
124             file = new File(Environment.getExternalStorageDirectory()
125                     + File.separator + directory + File.separator + fileName);
126             os = new FileOutputStream(file, isAppend);
127             if (encoding.equals("")) {
128                 os.write(content.getBytes());
129             } else {
130                 os.write(content.getBytes(encoding));
131             }
132             os.flush();
133         } catch (IOException e) {
134             Log.e("FileUtil", "writeToSDCardFile:" + e.getMessage());
135         } finally {
136             try {
137                 if (os != null) {
138                     os.close();
139                 }
140             } catch (IOException e) {
141                 e.printStackTrace();
142             }
143         }
144         return file;
145     }
146 
147     /**
148      * write data from inputstream to SDCard
149      */
150     public static File writeToSDCardFromInput(String directory, String fileName,
151             InputStream input) {
152         File file = null;
153         OutputStream os = null;
154         try {
155             if (createFile(directory)) {
156                 return file;
157             }
158             file = new File(Environment.getExternalStorageDirectory()
159                     + File.separator + directory + File.separator + fileName);
160             os = new FileOutputStream(file);
161             byte[] data = new byte[bufferd];
162             int length = -1;
163             while ((length = input.read(data)) != -1) {
164                 os.write(data, 0, length);
165             }
166             // clear cache
167             os.flush();
168         } catch (Exception e) {
169             Log.e("FileUtil", "" + e.getMessage());
170             e.printStackTrace();
171         } finally {
172             try {
173                 os.close();
174             } catch (Exception e) {
175                 e.printStackTrace();
176             }
177         }
178         return file;
179     }
180     
181     public static String ReadFromSDCardFile(String directory,String fileName){
182         String res=""; 
183         File file = null;
184         file = new File(Environment.getExternalStorageDirectory()
185                 + File.separator + directory + File.separator + fileName);
186         try {
187             FileInputStream fis = new FileInputStream(file);
188             int length = fis.available();
189             byte [] buffer = new byte[length]; 
190             fis.read(buffer);
191             res = EncodingUtils.getString(buffer, "UTF-8");
192             fis.close();
193             return res;
194         }catch (FileNotFoundException  e) {
195             // TODO Auto-generated catch block
196             Log.d("TEST", "FileNotFound");
197             e.printStackTrace();
198         }catch (Exception  e) {
199             Log.d("TEST", "Can Not Open File");
200             e.printStackTrace();
201         }
202         return null;     
203     }
204 }