对SD读写的接口以及实现

为什么要写一个SD的读写接口呢？

最近在看一本书叫做《大话设计模式》，里面的各种设计模式，让我感觉到代码要写的好是要经过很多次的修改的，整合出来的思想，或者好的代码，要复用，这样子开发的效率才能提高。

以前在写对SD的读写时，都是需要什么就用什么，这样子每一次都要写相同的代码。

所以今天总结一下对SD读写的接口

public abstract class SDEngine {
	protected File dirFile = null;    //保存的文件夹
	protected File file = null;   //保存的文件
	
	
	public boolean createFile(String str_dir_name, String str_file_name) {
		String str_dir_path = Environment.getExternalStorageDirectory() + "/" + str_dir_name + "/" ;
		dirFile = new File(str_dir_path);
		if(!dirFile.exists()) {
			dirFile.mkdirs();
		}
		file = new File(str_dir_path + str_file_name);
		if (file.exists()) {
			return true;
		} else {
			try {
				if(file.createNewFile()) {
					return true;
				} 
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
		return false;
	}
	
	public abstract boolean writeData(Object object); 
	public abstract Object readData();
}

这是继承上面的抽象类的类，用来读写ArrayList：

public class MsgDataListEngine extends SDEngine {
	
	
	public MsgDataListEngine() {
		this.createFile(CampusConstants.SD_DIR_NAME, CampusConstants.SD_FILE_NAME_MSG);
	}
	@Override
	public boolean writeData(Object object) {
		// TODO Auto-generated method stub
		FileOutputStream output = null;
		ObjectOutputStream objectOutputStream = null;
		try {
			if(this.createFile(CampusConstants.SD_DIR_NAME, CampusConstants.SD_FILE_NAME_MSG)) {
				output = new FileOutputStream(this.file);
				objectOutputStream = new ObjectOutputStream(output);
				//ArrayList<String> list = (ArrayList<String>)object;
				objectOutputStream.writeObject(object);
				return true;
			} else {
				return false;
			}
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		} finally {
			try {
				if (objectOutputStream!=null) {
					objectOutputStream.close();
				}
				if(output!=null) {
					output.close();
				}
			} catch (Exception e2) {
				// TODO: handle exception
				e2.printStackTrace();
			}
			
		}
		return false;
	}
	@Override
	public Object readData() {
		// TODO Auto-generated method stub
		FileInputStream inputStream = null;
		ObjectInputStream objectInputStream = null;
		try {
			if (!this.file.exists()) {
				return null;
			} else {
				inputStream = new FileInputStream(this.file);
				objectInputStream = new ObjectInputStream(inputStream);
				return objectInputStream.readObject();
			}
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		} finally {
			try {
				if (objectInputStream != null) {
					objectInputStream.close();
				}
				if (inputStream != null) {
					inputStream.close();
				}
			} catch (Exception e2) {
				// TODO: handle exception
				e2.printStackTrace();
			}
		}
		return null;
	}

}