android本地、sd卡保存对象或集合，以及读取该对象

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

存储

 /**      * 将对象保存到本地      * @param context      * @param fileName 文件名      * @param bean  对象      * @return true 保存成功      */      public boolean writeObjectIntoLocal(Context context,String fileName,T bean){          try {              // 通过openFileOutput方法得到一个输出流，方法参数为创建的文件名（不能有斜杠），操作模式              @SuppressWarnings("deprecation")              FileOutputStream fos = context.openFileOutput(fileName, Context.MODE_WORLD_READABLE);              ObjectOutputStream oos = new ObjectOutputStream(fos);              oos.writeObject(bean);//写入              fos.close();//关闭输入流              oos.close();              return true;          } catch (FileNotFoundException e) {                e.printStackTrace();                //Toast.makeText(WebviewTencentActivity.this, "出现异常1",Toast.LENGTH_LONG).show();                return false;          } catch (IOException e) {                e.printStackTrace();                //Toast.makeText(WebviewTencentActivity.this, "出现异常2",Toast.LENGTH_LONG).show();                return false;          }       }      /**      * 将对象写入sd卡      * @param fileName 文件名      * @param bean  对象      * @return true 保存成功      */      public boolean writObjectIntoSDcard(String fileName,T bean){          if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){                File sdCardDir = Environment.getExternalStorageDirectory();//获取sd卡目录              File sdFile  = new File(sdCardDir, fileName);              try {                  FileOutputStream fos = new FileOutputStream(sdFile);                  ObjectOutputStream oos = new ObjectOutputStream(fos);                  oos.writeObject(bean);//写入                  fos.close();                  oos.close();                  return true;              } catch (FileNotFoundException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return false;              } catch (IOException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return false;              }          }          else {              return false;          }      }      /**      * 将集合写入sd卡      * @param fileName 文件名      * @param list  集合      * @return true 保存成功      */      public boolean writeListIntoSDcard(String fileName,List<T> list){          if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){                File sdCardDir = Environment.getExternalStorageDirectory();//获取sd卡目录              File sdFile  = new File(sdCardDir, fileName);              try {                  FileOutputStream fos = new FileOutputStream(sdFile);                  ObjectOutputStream oos = new ObjectOutputStream(fos);                  oos.writeObject(list);//写入                  fos.close();                  oos.close();                  return true;              } catch (FileNotFoundException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return false;              } catch (IOException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return false;              }          }          else {              return false;          }      }  }

读取

  /**      * 读取本地对象      * @param context      * @param fielName 文件名      * @return      */      @SuppressWarnings("unchecked")      public T readObjectFromLocal(Context context,String fielName){          T bean;          try {              FileInputStream fis = context.openFileInput(fielName);//获得输入流                ObjectInputStream ois = new ObjectInputStream(fis);              bean = (T) ois.readObject();              fis.close();              ois.close();              return bean;          } catch (StreamCorruptedException e) {                //Toast.makeText(ShareTencentActivity.this,"出现异常3",Toast.LENGTH_LONG).show();//弹出Toast消息                e.printStackTrace();                return null;          } catch (OptionalDataException e) {                //Toast.makeText(ShareTencentActivity.this,"出现异常4",Toast.LENGTH_LONG).show();//弹出Toast消息                e.printStackTrace();              return null;          } catch (FileNotFoundException e) {                //Toast.makeText(ShareTencentActivity.this,"出现异常5",Toast.LENGTH_LONG).show();//弹出Toast消息                e.printStackTrace();                return null;          } catch (IOException e) {                e.printStackTrace();                return null;          } catch (ClassNotFoundException e) {                //Toast.makeText(ShareTencentActivity.this,"出现异常6",Toast.LENGTH_LONG).show();//弹出Toast消息                e.printStackTrace();                return null;          }        }      /**      * 读取sd卡对象      * @param fileName 文件名      * @return      */      @SuppressWarnings("unchecked")      public T readObjectFromSdCard(String fileName){          if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){  //检测sd卡是否存在              T bean;              File sdCardDir = Environment.getExternalStorageDirectory();              File sdFile = new File(sdCardDir,fileName);              try {                  FileInputStream fis = new FileInputStream(sdFile);                  ObjectInputStream ois = new ObjectInputStream(fis);                  bean = (T) ois.readObject();                  fis.close();                  ois.close();                  return bean;              } catch (StreamCorruptedException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              } catch (OptionalDataException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              } catch (FileNotFoundException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                   return null;               } catch (IOException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              } catch (ClassNotFoundException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              }            }          else {              return null;          }      }      /**      * 读取sd卡对象      * @param fileName 文件名      * @return      */      @SuppressWarnings("unchecked")      public List<T> readListFromSdCard(String fileName){          if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){  //检测sd卡是否存在              List<T> list;              File sdCardDir = Environment.getExternalStorageDirectory();              File sdFile = new File(sdCardDir,fileName);              try {                  FileInputStream fis = new FileInputStream(sdFile);                  ObjectInputStream ois = new ObjectInputStream(fis);                  list = (List<T>) ois.readObject();                  fis.close();                  ois.close();                  return list;              } catch (StreamCorruptedException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              } catch (OptionalDataException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              } catch (FileNotFoundException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                   return null;               } catch (IOException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              } catch (ClassNotFoundException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    return null;              }            }          else {              return null;          }      }  }

补充判断是否存在

// 判断文件是否存在    public boolean fileIsExists(String strFile) {        try {            if (Environment.getExternalStorageState().equals(                    Environment.MEDIA_MOUNTED)) { // 检测sd卡是否存在                File sdCardDir = Environment.getExternalStorageDirectory();// 获取sd卡目录                File sdFile = new File(sdCardDir, strFile);                if (sdFile.exists()) {                    return true;                }            }        } catch (Exception e) {            return false;        }        return false;    }

原文地址

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