Android中的文件的读取方法

在Android中根据文件位置的不同，可分为四种文件读取方式，具体如下；

//方法：从resource中的raw文件夹中获取文件并读取数据,注意：只能读取不能写入数据

 public String getFromRaw(int fileId) {
    		InputStream in = null;
    		String result = "";
    		ByteArrayOutputStream baos=null;

    		try {
    			// 获取Resources资源文件流
    			in = getResources().openRawResource(fileId);
    			// 文件大小
    			int length = in.available();
    			// 创建byte数组
    			byte[] buf = new byte[length];
    			// 创建内存流加快效率
    			baos = new ByteArrayOutputStream();
    			int count = 0;
    			while ((count = in.read(buf)) != -1) {
    				baos.write(buf, 0, count);
    			}
    			
    			result=new String(baos.toByteArray(), "UTF-8");
    		//	result = EncodingUtils.getString(buf, "UTF-8");
    		} catch (IOException e) {
    			Toast.makeText(this, "找不到文件", 2000).show();
    		} finally{
    			if(baos!=null)
    				try {
    					baos.close();
    				} catch (IOException e) {
    					e.printStackTrace();
    				}
    			if(in!=null)
    				try {
    					in.close();
    				} catch (IOException e) {
    					e.printStackTrace();
    				}
    		}
    		return result;
    	}

  
    //方法：从asset中获取文件并读取数据,只能读取不能写入数据
  

 public String getFromAsset(String fileName){//fileName="read_asset.txt"
        	InputStream in = null;
    		String result = "";
    		ByteArrayOutputStream baos=null;
    		
            try{
            in = getAssets().open(fileName);
            int size = in.available();
            
            byte[] buffer = new byte[size];
            baos = new ByteArrayOutputStream();
            
            while(in.read(buffer)!=-1){
            	baos.write(buffer);
            }
            // Convert the buffer into a string.
         //   result = new String(baos.toByteArray(),"UTF-8");
              result = EncodingUtils.getString(baos.toByteArray(), "UTF-8");
            }catch(IOException e){
            	Toast.makeText(this, "找不到文件", 2000).show();
            } finally{
    			if(baos!=null)
    				try {
    					baos.close();
    				} catch (IOException e) {
    					e.printStackTrace();
    				}
    			if(in!=null)
    				try {
    					in.close();
    				} catch (IOException e) {
    					e.printStackTrace();
    				}
    		}
            return result;
       }

//方法：向指定系统文件中写入指定的数据
  

	public void writeFileData(String fileName, String message) {
		FileOutputStream fos = null;
		try {
			fos = openFileOutput(fileName, Context.MODE_PRIVATE);
			byte[] bytes = message.getBytes();
			fos.write(bytes);
			fos.flush();
		} catch (IOException e) {
			Toast.makeText(this, "文件写入错误", 2000).show();
		} finally {
			if (fos != null) {
				try {
					fos.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}

	}

   //方法：打开指定系统文件读取其数据，
   

 public String readFileData(String fileName){
    	FileInputStream fis=null;
        String result="";
        try{
        fis = openFileInput(fileName);
        int size = fis.available();
        byte [] buffer = new byte[size];
        fis.read(buffer);
        result=new String(buffer,"UTF-8");
        }catch(IOException e){
        	Toast.makeText(this, "文件没有找到", 2000).show();
        }finally{
        	if(fis!=null){
        		try {
					fis.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
        	}
        }
        return result;//返回读到的数据字符串
       }    

ok,下写到这里，待续