给定二个文本文件1.txt，2.txt，编写程序新建文件3.txt，依次将1.txt，2.txt文件的内容写入3.txt。
/* * 题目描述给定二个文本文件1.txt，2.txt，编写程序新建文件3.txt，依次将1.txt，2.txt文件的内容写入3.txt。 输入描述无 输出描述无 输入样例无 */package exam2;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.FileReader;import java.io.FileWriter;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;/** * * @author Administrator */public class Test5 { public static String readFile(String filePathAndName) { String fileContent = ""; try { File f = new File(filePathAndName); if(f.isFile()&&f.exists()){ InputStreamReader read = new InputStreamReader(new FileInputStream(f),"UTF-8"); BufferedReader reader=new BufferedReader(read); String line; while ((line = reader.readLine()) != null) { fileContent += line; } read.close(); } } catch (Exception e) { System.out.println("读取文件内容操作出错"); e.printStackTrace(); } return fileContent;}public static void writeFile(String filePathAndName, String fileContent) { try { File f = new File(filePathAndName); if (!f.exists()) { f.createNewFile(); } OutputStreamWriter write = new OutputStreamWriter(new FileOutputStream(f),"UTF-8"); BufferedWriter writer=new BufferedWriter(write); //PrintWriter writer = new PrintWriter(new BufferedWriter(new FileWriter(filePathAndName))); //PrintWriter writer = new PrintWriter(new FileWriter(filePathAndName)); writer.write(fileContent); writer.close(); } catch (Exception e) { System.out.println("写文件内容操作出错"); e.printStackTrace(); }} public static void main(String[] args) throws FileNotFoundException, IOException { Test5 test= new Test5(); String s1=test.readFile("D:\\1.txt"); String s2=test.readFile("D:\\2.txt"); test.writeFile( "D:\\3.txt",s1+s2); }}/* public String readTXT(String path) throws FileNotFoundException, IOException{ String txt; File file = new File(path); FileInputStream fis = new FileInputStream(file); InputStreamReader isr= new InputStreamReader(fis,"UTF-8"); BufferedReader br = new BufferedReader(isr); txt=br.readLine(); try { if (br != null) br.close(); if (isr != null) isr.close(); if (fis != null) fis.close();// 关闭文件 } catch (Exception e) { System.out.println(e);} return txt; } private void writeStr(String str,String path){ File f=new File(path); BufferedWriter bw=null; try { bw=new BufferedWriter(new FileWriter(f)); bw.write(str); bw.flush(); } catch (Exception e) { System.out.println(e.getMessage()); }finally{ try { if(bw!=null){ bw.close(); } } catch (Exception e) { } }}private void writeTxt(){ File f1=new File("D:\\test1.txt"); File f2=new File("D:\\test2.txt"); FileReader fr=null; FileWriter fw=null; BufferedReader br=null; BufferedWriter bw=null; try { fr=new FileReader(f1); fw=new FileWriter(f2); br=new BufferedReader(fr); bw=new BufferedWriter(fw); String read=""; while((read=br.readLine())!=null){ bw.write(read); bw.write("\r\n"); } bw.flush(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (IOException e) { e.printStackTrace(); }finally{ try { if(fr!=null){ br.close(); fr.close(); } if(fw!=null){ bw.close(); fw.close(); } } catch (Exception e) { }}}*/