用Java修改现有文件内容

如对类似问题的公认答案中所建议：

同时以写入模式打开一个临时文件，对于每一行，读取它，必要时进行修改，然后写入该临时文件。最后，删除原始文件并重命名临时文件。

根据您的实现，类似于以下内容：

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;public class ReplaceFileContents {   public static void main(String[] args) {     new ReplaceFileContents().replace();   }   public void replace() {      String oldFileName = "try.dat";      String tmpFileName = "tmp_try.dat";      BufferedReader br = null;      BufferedWriter bw = null;      try {         br = new BufferedReader(new FileReader(oldFileName));         bw = new BufferedWriter(new FileWriter(tmpFileName));         String line;         while ((line = br.readLine()) != null) { if (line.contains("1313131"))    line = line.replace("1313131", ""+System.currentTimeMillis()); bw.write(line+"n");         }      } catch (Exception e) {         return;      } finally {         try { if(br != null)    br.close();         } catch (IOException e) { //         }         try { if(bw != null)    bw.close();         } catch (IOException e) { //         }      }      // once everything is complete, delete old file..      File oldFile = new File(oldFileName);      oldFile.delete();      // And rename tmp file's name to old file name      File newFile = new File(tmpFileName);      newFile.renameTo(oldFile);   }}