最近又复习了下JavaIO写了些实例代码都很简单但是能体现大部分方法的用法。
IO流实现文件的拷贝 几种不同的方法：
package com.wxisme.TestIO; import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream; /**
* 字节流拷贝文本文件
* @author wxisme
*
*/ public class StreamOne { public static void main(String[] args) {
String path = "E:" + File.separator + "test.txt";
File file = new File(path);
try {
file.createNewFile();
} catch (IOException e) {
System.out.println("创建文件失败");
e.printStackTrace();
}
InputStream is = null;
try {
is = new FileInputStream(file);
} catch (FileNotFoundException e1) {
e1.printStackTrace();
}
String fileName = "E:" + File.separator + "Bullet.java";
OutputStream os = null;
try {
os = new FileOutputStream(fileName,true);
} catch (FileNotFoundException e1) {
e1.printStackTrace();
}
byte[] b = new byte[10];
int len = 0;
try {
while((len = is.read(b)) != -1) {
os.write(b, 0, len);
}
os.flush();//强制刷出缓冲区
} catch (IOException e) { e.printStackTrace();
}finally {
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
} System.exit(0); } }
package com.wxisme.TestIO; import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer; /**
* 字节流拷贝文件
* @author wxisme
*
*/ public class StreamTwo { public static void main(String[] args) {
String path = "E:" + File.separator + "test.txt";
String name = "E:" + File.separator + "Bullet.java";
Reader r = null;
try {
r = new FileReader(name);
} catch (FileNotFoundException e) {
System.out.println("创建字符输入流失败");
e.printStackTrace();
}
Writer w = null;
try {
w = new FileWriter(path);
} catch (IOException e) {
System.out.println("创建字符输出流失败");
e.printStackTrace();
}
char[] cbuf = new char[10];
int len = 0;
try {
while((len = r.read(cbuf)) != -1) {
//w.write(cbuf);
w.write(cbuf, 0, len);
}
w.flush();//强制刷出
} catch (IOException e) {
e.printStackTrace();
}finally {
try {
w.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
r.close();
} catch (IOException e) {
e.printStackTrace();
}
} } }
package com.wxisme.TestIO; import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;
import java.util.Scanner; /**
* 重定向输入输出 实现文件的拷贝
* @author wxisme
*
*/ public class Reset { public static void main(String[] args) throws FileNotFoundException {
String src = "E:" + File.separator + "Bullet.java";
String path = "E:" + File.separator + "test.txt";
FileInputStream fis = new FileInputStream(src);
System.setIn(fis); PrintStream ps = new PrintStream(new FileOutputStream(path));
System.setOut(ps); Scanner scan = new Scanner(System.in);
scan.useDelimiter("\n");//以换行符为分隔符
while(scan.hasNext()) {
System.out.println(scan.next());
}
} }
处理流PrintStrream PrintWriter
package com.wxisme.TestIO; import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter; /**
* 使用处理流printStream printWriter
* @author wxisme
*
*/ public class StreamFour { public static void main(String[] args) throws IOException {
String path = "E:" + File.separator + "test.txt";
PrintStream ps = new PrintStream(new FileOutputStream(path,true));
ps.print("PrintStream");
PrintWriter pw = new PrintWriter(new FileWriter(path));
pw.print("PrintWriter");
pw.close();
ps.close();
} }
读取单个字符
package com.wxisme.TestIO; import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.Scanner; /**
* 读取单个字符
* @author wxisme
*
*/ public class ReaderOne { public static void main(String[] args) throws IOException {
Scanner scan = new Scanner(System.in);
String str = scan.next();
Reader r = new StringReader(str);
char[] cbuf = new char[10];
while(r.read(cbuf,0,1) != -1) {
char c = cbuf[0];
System.out.println(c);
}
r.close(); } }
转换流
package com.wxisme.TestIO; import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException; /**
* 使用转换流
* @author wxisme
*
*/ public class StreamThree { public static void main(String[] args) throws IOException { /*
* 输入流底层使用字节流，然后使用转换流把字节流转换成字符流，并且指定解码字符集。
* 然后把字符流包装成缓冲流，按行读取文件。
* 乱码问题的两个主要原因：
* 1. 解码字符集与编码字符集不统一
* 2. 读取字节缺少，长度丢失。
*/
String path = "E:" + File.separator + "Bullet.java";
BufferedReader br = new BufferedReader(
new InputStreamReader(
new FileInputStream(
new File(path)),"utf-8"));
String str;
while((str = br.readLine()) != null) {
System.out.println(str);
}
br.close(); } }
关闭文件的工具方法的两种写法：
package com.wxisme.TestIO; import java.io.Closeable;
import java.io.IOException; /**
* 关闭文件资源的工具类 有两种实现方法 可以实现一次关闭多个文件，先打开的文件后关闭
* @author wxisme
*
*/ public class CloseAll { /**
* 使用多态 可变参数 可以有多个形参以数组的形式 可变形参必须在所有参数的最后
* @param io
*/
public static void closeAll1(Closeable ... io) {
for(Closeable temp : io) {
if(temp != null) {
try {
temp.close();
} catch (IOException e) {
System.out.println("文件关闭失败");
e.printStackTrace();
}
}
}
} /**
* 泛型方法 使用泛型方法和可变参数
* @param io
*/ public static <T extends Closeable> void closeAll2(Closeable ... io) {
for(Closeable temp : io) {
if(temp != null) {
try {
temp.close();
} catch (IOException e) {
System.out.println("文件关闭失败");
e.printStackTrace();
}
}
}
} }