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) {

    }


}
}*/