java IO流相关

1.体系图解

2.代码

2.1 字符流读取文件

package com.fjh;

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

public class CharStream {

	public static void main(String[] args) throws IOException {
		//System.getProperty("user.dir")读取用户当前工作环境目录
		File file = new File(System.getProperty("user.dir")+"/1.txt");
		if(!file.exists()){
			try {
				file.createNewFile();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		//字符流
		Reader read = new FileReader(file);
		//读内容
		char[] cbuf = new char[1024];//每次读取的字符数
		int len = 0;
		String content = null;
		//将字节数组转化为字符串
		while((len = read.read(cbuf)) != -1){//返回-1代表的是已经读取完毕
			 content =new String(cbuf, 0, len);
			
		}
		System.out.println("读取的内容为:"+content);
		 if(null != read){
			 read.close();
		 }
	}

}

package com.fjh;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public class BufferReaderStream {

	public static void main(String[] args) throws IOException {
		File file = new File(System.getProperty("user.dir") + "/1.txt");
		if (!file.exists()) {
			try {
				file.createNewFile();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		Reader read = new FileReader(file);
		
		BufferedReader bf = new BufferedReader(read);
		String str = null;
		while ((str = bf.readLine()) != null){
			System.out.println(str);
		}
		bf.close();

	}

}

2.2 字节流读取文件，字符流写入文件

package com.fjh;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Writer;

public class ByteStream {
	public static void main(String[] args) throws IOException {
		File file = new File(System.getProperty("user.dir") + "/1.txt");
		if (!file.exists()) {
			try {
				file.createNewFile();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		// 字节流
		InputStream is = new FileInputStream(file);
		// 读内容,按字节读取
		byte[] b = new byte[1024];// 每次读取的字节数
		int len = 0;
		String content = null;
		// 将字节数组转化为字符串
		while ((len = is.read(b)) != -1) {// 返回-1代表的是已经读取完毕
			content = new String(b, 0, len);

		}
		System.out.println("读取的内容为:" + content);
		if (null != is) {
			is.close();
		}

		// 字节流写入文件
		File file2 = new File(System.getProperty("user.dir") + "/2.txt");
		if (!file2.exists()) {
			try {
				file2.createNewFile();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

		OutputStream os = new FileOutputStream(file2);
		String str = "fsdf看发生";
		os.write(str.getBytes());
		os.close();
		// 字符流写入内容
		Writer write = new FileWriter(file2, true);// true表示从文件后面接着写入

		String str2 = "发生纠纷好看fsdaf";

		write.write(str2);

		// 关闭
		write.close();
	}

}