FileReader、FileWriter--对文件操作

直接读取：

import java.io.File;
import java.io.FileReader;
import java.io.Reader;

public class Test8 {

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

		File file=new File("D://a.txt");
		Reader reader=new FileReader(file);
		char []c=new char[1024];
		int len=reader.read(c);
		reader.close();
		System.out.println("内容："+new String(c,0,len));
	}

}

一个字符 一个字符地读取：

import java.io.File;
import java.io.FileReader;
import java.io.Reader;

public class Test8 {

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

		File file=new File("D://a.txt");
		Reader reader=new FileReader(file);
		char []c=new char[1024];
		int len=0;
		int temp=0;
		while((temp=reader.read())!=-1) {
			c[len++]=(char) temp;
		}
		reader.close();
		System.out.println("内容："+new String(c,0,len));
	}

}

运行结果：

FileWriter写入文件（覆盖写入）：

import java.io.File;
import java.io.FileWriter;
import java.io.Writer;

public class Test9 {

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

		File file=new File("D://b.txt");
		Writer writer=new FileWriter(file);
		String str="jifie减肥哦九分二分个人";
		writer.write(str);
		writer.close();
	}

}

FileWriter实例化时加上参数可以追加写入：

import java.io.File;
import java.io.FileWriter;
import java.io.Writer;

public class Test9 {

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

		File file=new File("D://b.txt");
		Writer writer=new FileWriter(file,true);
		String str="jifidf得分分个人";
		writer.write(str);
		writer.close();
	}

}