上面我们讲了Hello World!，我们完成了一个程序，得到的结果该如何保存，总不能每次开机都要运行一次吧？所以我们需要一个载体把我们的结果记录下来。下面我就介绍一个方便的记录方式，文件读写。

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.RandomAccessFile;

public class TestFile {
	
	 public TestFile(){
		 
		 
	 }
	
	 
	 
	 public void appendWriterFile(String fileName,String content){	 
		 try {
			FileWriter writer = new FileWriter(fileName,true);
			writer.write(content);
			writer.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		 
	 }
	 
	 public void writerFile(String fileName,String content){
				 
		 try {
			FileWriter writer = new FileWriter(fileName);
			writer.write(content);
			writer.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		 
	 }
	 

	 public String readFile(String fileName){
		 StringBuffer results = new StringBuffer();
		 File file = new File(fileName);  
		 BufferedReader reader = null;
	     try {
			reader = new BufferedReader(new FileReader(file));
			String tempString = null;
			 while ((tempString = reader.readLine()) != null) { 
				 results.append(tempString+"\r\n");
			 }
			 reader.close();
			
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {  
            if (reader != null) {  
                try {  
                    reader.close();  
                } catch (IOException e1) {  
                }  
            }  
        }
		return results.toString();    
         	 
	 }
	 
	 public void randomWriterFile(String fileName,String content){
		 
		 try {
			RandomAccessFile writer = new RandomAccessFile(fileName, "rw"); 
			long length = writer.length();
			writer.seek(length);
			writer.writeBytes(content);
			writer.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		 
	 }
	 
	 public String randomReadFile(String fileName){
		 StringBuffer results = new StringBuffer();
		 RandomAccessFile reader = null; 
	     try {
			reader = new RandomAccessFile(fileName, "r"); 
			long length = reader.length();  
            // 读文件的起始位置  
            int index = (length > 4) ? 4 : 0;  
            // 将读文件的开始位置移到beginIndex位置。  
            reader.seek(index);  
			String tempString = null;
			 while ((tempString = reader.readLine()) != null) { 
				 results.append(tempString+"\r\n");
			 }
			 reader.close();
			
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {  
            if (reader != null) {  
                try {  
                    reader.close();  
                } catch (IOException e1) {  
                }  
            }  
        }
		return results.toString();    
         	 
	 }
	
	 public static void main(String[] args) { 
		 String fileName="/Users/victor/test.txt";
		 String content="Hello World!\r\n";   // 加入换行符 \r\n
		 
		 TestFile test =new TestFile();
		 //写入文件
		 test.writerFile(fileName, content);
		 test.appendWriterFile(fileName, content);  //追加写入
		 //读取文件
		 String results = test.readFile(fileName);
		 System.out.println(results);		  
		 
	 }

}


	快速的学会文件的读写，这些能满足大家大部分需求，如果要对流操作请查api。
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