Faced with the upcoming exam, Some useful methods referred to file operation drew tremenous attention. Now I make a summary to reading file.
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import java.io.BufferedReader;
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import java.io.BufferedWriter;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileNotFoundException;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.io.OutputStreamWriter;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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public class FileUtil
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{
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public static final String SEP = "：";
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public static final String ENCODING = "UTF-8";
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public static Map<String, String> readFileToMap(String filePath)
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throws Exception
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{
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System.out.println("读文件[" + filePath + "]开始...");
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Map<String, String> contents = new HashMap<String, String>();
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File file = new File(filePath);
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BufferedReader reader = null;
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try
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{
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reader = new BufferedReader(new InputStreamReader(
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new FileInputStream(file), ENCODING));
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String info = null;
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while ((info = reader.readLine()) != null)
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{
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contents.put(info.split(SEP)[0], info.split(SEP)[1]);
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}
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}
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catch (FileNotFoundException e)
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{
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System.out.println("文件[" + filePath + "]未找到.");
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throw e;
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}
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catch (IOException e)
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{
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System.out.println("文件IO操作出错, 异常信息: " + e.getMessage());
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throw e;
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}
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catch (Exception e)
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{
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System.out.println("读文件出错, 异常信息: " + e.getMessage());
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throw e;
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}
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finally
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{
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if (reader != null)
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{
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try
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{
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reader.close();
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}
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catch (IOException e)
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{
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System.out.println("关闭IO流出错, 异常信息: " + e.getMessage());
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throw e;
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}
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}
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}
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System.out.println("读文件[" + filePath + "]结束.");
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return contents;
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}
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public static List<String> readFileToList(String fileName) throws Exception
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{
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List<String> infos = new ArrayList<String>();
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BufferedReader reader = null;
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try
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{
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reader = new BufferedReader(new InputStreamReader(
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new FileInputStream(new File(fileName)), "utf-8"));
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String info = null;
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while ((info = reader.readLine()) != null)
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{
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infos.add(info);
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}
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}
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catch (FileNotFoundException e)
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{
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System.out.println("文件[" + fileName + "]未找到.");
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throw e;
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}
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catch (IOException e)
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{
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System.out.println("文件IO操作出错, 异常信息: " + e.getMessage());
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throw e;
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}
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finally
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{
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try
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{
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if (reader != null)
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{
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reader.close();
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}
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}
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catch (IOException e)
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{
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e.printStackTrace();
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}
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}
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return infos;
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}
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public static String readFileToString(String filePath) throws Exception
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{
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InputStreamReader isReder = null;
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BufferedReader br = null;
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StringBuffer sb = new StringBuffer();
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try
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{
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File f = new File(filePath);
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if (f.isFile() && f.exists())
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{
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isReder = new InputStreamReader(new FileInputStream(f), "UTF-8");
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br = new BufferedReader(isReder);
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String line;
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while ((line = br.readLine()) != null)
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{
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sb.append(line).append("\r\n");
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}
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}
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}
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catch (Exception e)
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{
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System.out.println("exception when reading the file" + filePath);
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throw e;
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}
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finally
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{
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if (isReder != null)
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{
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try
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{
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isReder.close();
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}
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catch (IOException e)
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{
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e.getMessage();
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}
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}
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if (br != null)
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{
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try
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{
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br.close();
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}
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catch (IOException e)
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{
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e.getMessage();
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}
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}
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}
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return sb.toString();
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}
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public static void writeFile(String result, String fileName)
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{
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File f = new File(fileName);
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OutputStreamWriter osw = null;
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BufferedWriter bw = null;
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try
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{
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if (!f.exists())
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{
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f.createNewFile();
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}
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osw = new OutputStreamWriter(new FileOutputStream(f), "UTF-8");
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bw = new BufferedWriter(osw);
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bw.write(result);
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}
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catch (IOException e)
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{
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System.out.println("IOException when writing result, "
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+ e.getMessage());
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}
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catch (Exception e)
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{
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System.out.println("Exception when writing result, "
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+ e.getMessage());
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}
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finally
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{
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if (bw != null)
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{
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try
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{
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bw.close();
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}
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catch (IOException e)
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{
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System.out.println("IOException when closing FileWriter, "
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+ e.getMessage());
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}
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}
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if (osw != null)
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{
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try
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{
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osw.close();
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}
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catch (IOException e)
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{
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System.out.println("IOException when closing bufferwriter, "
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+ e.getMessage());
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}
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}
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}
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}
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public static void main(String[] args) throws Exception
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{
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Map<String, String> testMap = FileUtil.readFileToMap("input.txt");
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System.out.println("---------------------");
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for (Map.Entry<String, String> entry : testMap.entrySet())
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{
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System.out.println(entry.getKey() + ":" + entry.getValue());
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}
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System.out.println("---------------------");
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List<String> testList = FileUtil.readFileToList("input.txt");
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for (String str : testList)
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{
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System.out.println(str);
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}
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System.out.println("---------------------");
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String test = FileUtil.readFileToString("input.txt");
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FileUtil.writeFile(test, "output.txt");
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}
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}
【DataStructure】A useful util class for reading and writing files,布布扣,bubuko.com
【DataStructure】A useful util class for reading and writing files
原文：http://blog.csdn.net/sxb0841901116/article/details/38548945
