IO流之缓冲流
处理流之一:缓冲流
BufferedReader br = null;
BufferedWriter bw = null;
try {
//step1:创建缓冲流对象:它是过滤流,是对节点流的包装
br = new BufferedReader(new FileReader("d:\\IOTest\\source.txt"));
bw = new BufferedWriter(new FileWriter("d:\\IOTest\\destBF.txt"));
String str = null;
while ((str = br.readLine()) != null) { //一次读取字符文本文件的一行字符
bw.write(str); //一次写入一行字符串
bw.newLine(); //写入行分隔符
} bw.flush(); //step2:刷新缓冲区
} catch (IOException e) {
e.printStackTrace();
}
finally {
// step3: 关闭IO流对象
try {
if (bw != null) {
bw.close(); //关闭过滤流时,会自动关闭它所包装的底层节点流
}
} catch (IOException e) {
e.printStackTrace();
}
try {
if (br != null) {
br.close();
} } catch (IOException e) {
e.printStackTrace();
}
}
package fifteen;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import org.junit.Test;
/*
* 抽象基类 节点流(文件流) 缓冲流(处理流的一种,可以提升文件操作的效率)
* InputStream FileInputStream BufferedInputStream
* OutputStream FileOutputStream BufferedOutputStream (flush())
* Reader FileReader BufferedReader (readLine())
* Writer FileWriter BufferedWriter (flush())
*/
public class TestBuffered {
@Test
public void testBufferedReader(){
BufferedReader br = null;
BufferedWriter bw = null;
try {
File file = new File("dbcp.txt");
File file1 = new File("dbcp3.txt");
FileReader fr = new FileReader(file);
FileWriter fw = new FileWriter(file1);
br = new BufferedReader(fr);
bw = new BufferedWriter(fw);
// char[] c = new char[1024];
// int len;
// while((len = br.read(c))!= -1){
// String str = new String(c, 0, len);
// System.out.print(str);
// }
String str;
while((str = br.readLine()) != null){
// System.out.println(str);
bw.write(str + "\n");
// bw.newLine();
bw.flush();
}
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(bw != null){
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(br != null){
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
@Test
public void testCopyFile(){
long start = System.currentTimeMillis();
// String src = "C:\\Users\\shkstart\\Desktop\\1.avi";
// String dest = "C:\\Users\\shkstart\\Desktop\\3.avi";
String src = "C:\\Users\\shkstart\\Desktop\\实验.doc";
String dest = "C:\\Users\\shkstart\\Desktop\\实验1.doc";
copyFile(src,dest);
long end = System.currentTimeMillis();
System.out.println("花费的时间为:" + (end - start));//746
}
//使用缓冲流实现文件的复制的方法
public void copyFile(String src,String dest){
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
try {
//1.提供读入、写出的文件
File file1 = new File(src);
File file2 = new File(dest);
//2.想创建相应的节点流:FileInputStream、FileOutputStream
FileInputStream fis = new FileInputStream(file1);
FileOutputStream fos = new FileOutputStream(file2);
//3.将创建的节点流的对象作为形参传递给缓冲流的构造器中
bis = new BufferedInputStream(fis);
bos = new BufferedOutputStream(fos);
//4.具体的实现文件复制的操作
byte[] b = new byte[1024];
int len;
while((len = bis.read(b)) != -1){
bos.write(b, 0, len);
bos.flush();
}
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
//5.关闭相应的流
if(bos != null){
try {
bos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(bis != null){
try {
bis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
//使用BufferedInputStream和BufferedOutputStream实现非文本文件的复制
@Test
public void testBufferedInputOutputStream(){
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
try {
//1.提供读入、写出的文件
File file1 = new File("1.jpg");
File file2 = new File("2.jpg");
//2.想创建相应的节点流:FileInputStream、FileOutputStream
FileInputStream fis = new FileInputStream(file1);
FileOutputStream fos = new FileOutputStream(file2);
//3.将创建的节点流的对象作为形参传递给缓冲流的构造器中
bis = new BufferedInputStream(fis);
bos = new BufferedOutputStream(fos);
//4.具体的实现文件复制的操作
byte[] b = new byte[1024];
int len;
while((len = bis.read(b)) != -1){
bos.write(b, 0, len);
bos.flush();
}
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
//5.关闭相应的流
if(bos != null){
try {
bos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(bis != null){
try {
bis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
韧桂 2020-01-04