java实现写入并保存txt文件的代码详解

package TEST;

import java.io.BufferedWriter;

import java.io.FileWriter;

import java.io.IOException;

public class BufferedWriterDemo {

  public static void main(String[] args) throws IOException {

 

    write("E:\\1.txt"); //运行主方法

  }

  public static void write(String path)

      throws IOException {

    //将写入转化为流的形式

    BufferedWriter bw = new BufferedWriter(new FileWriter(path));

    //一次写一行

    String ss = "测试数据";

     bw.write(ss);

      bw.newLine(); //换行用

 

    //关闭流

    bw.close();

    System.out.println("写入成功");

    }

 

 

  }

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
  
public class txtExport {
  
 private static String path = "D:/";
 private static String filenameTemp;
  
 public static void main(String[] args) throws IOException {
 txtExport.creatTxtFile("你好");
 txtExport.writeTxtFile("你好");
 }
  
  
 /**
 * 创建文件
 * 
 * @throws IOException
 */
 public static boolean creatTxtFile(String name) throws IOException {
 boolean flag = false;
 filenameTemp = path + name + ".txt";
 File filename = new File(filenameTemp);
 if (!filename.exists()) {
  filename.createNewFile();
  flag = true;
 }
 return flag;
 }
  
 /**
 * 写文件
 * 
 * @param newStr
 *      新内容
 * @throws IOException
 */
 public static boolean writeTxtFile(String newStr) throws IOException {
 // 先读取原有文件内容，然后进行写入操作
 boolean flag = false;
 String filein = newStr + "\r\n";
 String temp = "";
  
 FileInputStream fis = null;
 InputStreamReader isr = null;
 BufferedReader br = null;
  
 FileOutputStream fos = null;
 PrintWriter pw = null;
 try {
  // 文件路径
  File file = new File(filenameTemp);
  // 将文件读入输入流
  fis = new FileInputStream(file);
  isr = new InputStreamReader(fis);
  br = new BufferedReader(isr);
  StringBuffer buf = new StringBuffer();
  
  // 保存该文件原有的内容
  for (int j = 1; (temp = br.readLine()) != null; j++) {
  buf = buf.append(temp);
  // System.getProperty("line.separator")
  // 行与行之间的分隔符 相当于“\n”
  buf = buf.append(System.getProperty("line.separator"));
  }
  buf.append(filein);
  
  fos = new FileOutputStream(file);
  pw = new PrintWriter(fos);
  pw.write(buf.toString().toCharArray());
  pw.flush();
  flag = true;
 } catch (IOException e1) {
  // TODO 自动生成 catch 块
  throw e1;
 } finally {
  if (pw != null) {
  pw.close();
  }
  if (fos != null) {
  fos.close();
  }
  if (br != null) {
  br.close();
  }
  if (isr != null) {
  isr.close();
  }
  if (fis != null) {
  fis.close();
  }
 }
 return flag;
 }
  
}