本节课程将学习以下内容:
特点:
第一种:
输入流;输出流。
第二种:
字节流;字符流。
第三种:
节点流;处理流。
特点:
1.新建txt文件分别名为from.txt和to.txt;在from.txt中写上字符串abcd,然后新建一个名为Demo01.java的源文件:
// 1.导入类;
import java.io.*;
class Demo01 {
public static void main(String[] args) {
// 2.声明输入流引用、生成输出流的引用
FileInputStream fis = null;
FileOutputStream fos = null;
try {
// 3.生成代表输入流的对象、生成代表输出流的对象
fis = new FileInputStream("e:/src/from.txt");
fos = new FileOutputStream("e:/src/to.txt");
// 4.生成一个字节数组
byte[] buffer = new byte[100];
// 5.调用输入流对象的read方法,读取数据;调用输出流对象的write方法,写入数据;
int temp = fis.read(buffer, 0, buffer.length);
fos.write(buffer, 0, temp);
} catch (Exception e) {
}
}
}
1.新建txt文件分别名为from2.txt和to2.txt;在from2.txt中写上一篇很长(几万字,网上copy)的纯英文文章,然后新建一个名为Demo02.java的源文件:
import java.io.*;
class Demo02 {
public static void main(String[] args) {
FileInputStream fis = null;
FileOutputStream fos = null;
try {
fis = new FileInputStream("e:/src/from2.txt");
fos = new FileOutputStream("e:/src/to2.txt");
byte[] buffer = new byte[1024];
while (true) {
int temp = fis.read(buffer, 0, buffer.length);
// temp是-1的时候,说明read函数已经读完
// 这时跳出循环
if (temp == -1) {
break;
}
fos.write(buffer, 0, temp);
}
} catch (Exception e) {
System.out.println(e);
} finally {
try {
// 一定要执行输入输出流的关闭
fis.close();
fos.close();
} catch (Exception e) {
System.out.println(e);
}
}
}
}
例子3:(请动手)
使用前面的from.txt和to.txt来进行操作。
import java.io.*;
class Demo03 {
public static void main(String[] args) {
FileReader fr = null;
FileWriter fw = null;
try {
fr = new FileReader("e:/src/from.txt");
fw = new FileWriter("e:/src/to.txt");
char[] buffer = new char[100];
int temp = fr.read(buffer, 0, buffer.length);
fw.write(buffer, 0, temp);
} catch (Exception e) {
System.out.println(e);
} finally {
try {
fr.close();
fw.close();
} catch (Exception e) {
System.out.println(e);
}
}
}
}
例子4:BufferedReader的使用
import java.io.*;
class Demo04 {
public static void main(String[] args) {
FileReader fr = null;
BufferedReader br = null;
try {
fr = new FileReader("e:/src/from.txt");
br = new BufferedReader(fr);
String line = null;
while (true) {
line = br.readLine();
if (line == null) {
break;
}
System.out.println(line);
}
} catch (Exception e) {
System.out.println(e);
} finally {
try {
fr.close();
br.close();
} catch (Exception e) {
System.out.println(e);
}
}
}
}
1.定义一个Worker接口
interface Worker {
public void doSomeWork();
}
2.定义一个A公司的类AWorker,文件名为AWorker.java:
class AWorker implements Worker {
private Worker worker;
public AWorker (Worker worker) {
this.worker = worker;
}
public void doSomeWork() {
System.out.println("你好。我是A公司");
worker.doSomeWork();
}
}
3.新建两个文件名为Plumber.java和Carpenter.java的源文件:
class Plumber implements Worker {
public void doSomeWork() {
System.out.println("修水管");
}
}
class Carpenter implements Worker {
public void doSomeWork() {
System.out.println("修门窗");
}
}
4.新建一个名为Demo05.java的Java源文件:
class Demo05 {
public static void main(String[] args) {
// 生成一个A公司水管工对象
Plumber plumber = new Plumber();
AWorker aWorker1 = new AWorker(plumber);
aWorker1.doSomeWork();
Carpenter carpenter = new Carpenter();
AWorker aWorker2 = new AWorker(carpenter);
aWorker2.doSomeWork();
}
}