【DataStructure】A useful util class for reading and writing files

Faced with the upcoming exam, Some useful methods referred to file operation drew tremenous attention. Now I make a summary to reading file.

 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.OutputStreamWriter;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 public class FileUtil
 {

     public static final String SEP = "：";

     public static final String ENCODING = "UTF-8";

     /**
      * Read the content from file, the format of content is like "Key：Value"
      * TODO
      *
      * @time Jul 17, 2014 11:21:50 AM
      * @param filePath
      * @return
      * @throws Exception
      * @return Map<String,String>
      */
     public static Map<String, String> readFileToMap(String filePath)
             throws Exception
     {
         System.out.println("读文件[" + filePath + "]开始...");

         Map<String, String> contents = new HashMap<String, String>();

         File file = new File(filePath);
         BufferedReader reader = null;

         try
         {
             reader = new BufferedReader(new InputStreamReader(
                     new FileInputStream(file), ENCODING));
             String info = null;

             while ((info = reader.readLine()) != null)
             {
                 contents.put(info.split(SEP)[0], info.split(SEP)[1]);
             }
         }
         catch (FileNotFoundException e)
         {
             System.out.println("文件[" + filePath + "]未找到.");
             throw e;
         }
         catch (IOException e)
         {
             System.out.println("文件IO操作出错, 异常信息: " + e.getMessage());
             throw e;
         }
         catch (Exception e)
         {
             System.out.println("读文件出错, 异常信息: " + e.getMessage());
             throw e;
         }
         finally
         {
             if (reader != null)
             {
                 try
                 {
                     reader.close();
                 }
                 catch (IOException e)
                 {
                     System.out.println("关闭IO流出错, 异常信息: " + e.getMessage());
                     throw e;
                 }
             }
         }

         System.out.println("读文件[" + filePath + "]结束.");

         return contents;
     }

     /**
      * Read the content from file, every line will be an element of list.
      *
      * @time Jul 17, 2014 11:39:07 AM
      * @param fileName
      * @return
      * @return List<String>
      */
     public static List<String> readFileToList(String fileName) throws Exception
     {
         List<String> infos = new ArrayList<String>();

         BufferedReader reader = null;

         try
         {
             reader = new BufferedReader(new InputStreamReader(
                     new FileInputStream(new File(fileName)), "utf-8"));
             String info = null;
             while ((info = reader.readLine()) != null)
             {
                 infos.add(info);
             }
         }
         catch (FileNotFoundException e)
         {
             System.out.println("文件[" + fileName + "]未找到.");
             throw e;
         }
         catch (IOException e)
         {
             System.out.println("文件IO操作出错, 异常信息: " + e.getMessage());
             throw e;
         }
         finally
         {
             try
             {
                 if (reader != null)
                 {
                     reader.close();
                 }
             }
             catch (IOException e)
             {
                 e.printStackTrace();
             }
         }

         return infos;
     }

     /**
      * Read all the content from filePath at a time.
      *
      * @time Jul 17, 2014 11:45:55 AM
      * @param filePathOrFileName
      * @return
      * @return String
      */
     public static String readFileToString(String filePath) throws Exception
     {
         InputStreamReader isReder = null;
         BufferedReader br = null;
         StringBuffer sb = new StringBuffer();
         try
         {
             File f = new File(filePath);
             if (f.isFile() && f.exists())
             {
                 isReder = new InputStreamReader(new FileInputStream(f), "UTF-8");
                 br = new BufferedReader(isReder);
                 String line;
                 while ((line = br.readLine()) != null)
                 {
                     sb.append(line).append("\r\n");
                 }
             }
         }
         catch (Exception e)
         {
             System.out.println("exception when reading the file" + filePath);
             throw e;
         }
         finally
         {
             if (isReder != null)
             {
                 try
                 {
                     isReder.close();
                 }
                 catch (IOException e)
                 {
                     e.getMessage();
                 }
             }
             if (br != null)
             {
                 try
                 {
                     br.close();
                 }
                 catch (IOException e)
                 {
                     e.getMessage();
                 }
             }
         }
         return sb.toString();
     }

     /**
      * Write result to the fileName
      *
      * @time Jul 17, 2014 4:57:57 PM
      * @param result
      * @param fileName
      * @return void
      */
     public static void writeFile(String result, String fileName)
     {
         File f = new File(fileName);
         OutputStreamWriter osw = null;
         BufferedWriter bw = null;
         try
         {
             if (!f.exists())
             {
                 f.createNewFile();
             }
             osw = new OutputStreamWriter(new FileOutputStream(f), "UTF-8"); //"gbk"

             bw = new BufferedWriter(osw);
             bw.write(result);
         }
         catch (IOException e)
         {
             System.out.println("IOException when writing result, "
                     + e.getMessage());
         }
         catch (Exception e)
         {
             System.out.println("Exception when writing result, "
                     + e.getMessage());
         }
         finally
         {
             if (bw != null)
             {
                 try
                 {
                     bw.close();
                 }
                 catch (IOException e)
                 {
                     System.out.println("IOException when closing FileWriter, "
                             + e.getMessage());
                 }
             }

             if (osw != null)
             {
                 try
                 {
                     osw.close();
                 }
                 catch (IOException e)
                 {
                     System.out.println("IOException when closing bufferwriter, "
                             + e.getMessage());
                 }
             }
         }
     }

     public static void main(String[] args) throws Exception
     {
         Map<String, String> testMap = FileUtil.readFileToMap("input.txt");
         System.out.println("---------------------");
         for (Map.Entry<String, String> entry : testMap.entrySet())
         {
             System.out.println(entry.getKey() + ":" + entry.getValue());
         }

         System.out.println("---------------------");

         List<String> testList = FileUtil.readFileToList("input.txt");

         for (String str : testList)
         {
             System.out.println(str);
         }
         System.out.println("---------------------");
         String test = FileUtil.readFileToString("input.txt");
         FileUtil.writeFile(test, "output.txt");
     }
 }