| 彻底明白 Java 语言中的IO系统 |
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| 来源： 作者： 添加日期：2007-11-16 19:33:11 点击次数： |
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4) PushbackInputStream：很少用到，一般用于编译器开发
2.2.2 用于封装以字符为导向的InputStream
1) 没有与DataInputStream对应的类。除非在要使用readLine()时改用BufferedReader，否则使用DataInputStream
2) BufferedReader：与BufferedInputStream对应
3) LineNumberReader：与LineNumberInputStream对应
4) PushBackReader：与PushbackInputStream对应
2.3 FilterOutStream的各种类型
2.2.3 用于封装以字节为导向的OutputStream
1) DataIOutStream：往stream中输出基本类型（int、char等）数据。
2) BufferedOutStream：使用缓冲区
3) PrintStream：产生格式化输出
2.2.4 用于封装以字符为导向的OutputStream
1) BufferedWrite：与对应
2) PrintWrite：与对应
3. RandomAccessFile
1) 可通过RandomAccessFile对象完成对文件的读写操作
2) 在产生一个对象时，可指明要打开的文件的性质：r，只读；w，只写；rw可读写
3) 可以直接跳到文件中指定的位置
4. I/O应用的一个例子
java 代码
import java.io.*;
public class TestIO{
public static void main(String[] args)
throws IOException{
//1.以行为单位从一个文件读取数据
BufferedReader in = new BufferedReader(
new FileReader("F:\\nepalon\\TestIO.java"));
String s, s2 = new String();
while((s = in.readLine()) != null)
s2 += s + "\n";
in.close();
//1b. 接收键盘的输入
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a line:");
System.out.println(stdin.readLine());
//2. 从一个String对象中读取数据
StringReader in2 = new StringReader(s2);
int c;
while((c = in2.read()) != -1)
System.out.println((char)c);
in2.close();
//3. 从内存取出格式化输入
try{
DataInputStream in3 =new DataInputStream(new ByteArrayInputStream(s2.getBytes()));
while(true)
System.out.println((char)in3.readByte());
}
catch(EOFException e){
System.out.println("End of stream");
}
//4. 输出到文件
try{
BufferedReader in4 =new BufferedReader(new StringReader(s2));
PrintWriter out1 =new PrintWriter(new BufferedWriter(new FileWriter("F:\\nepalon\\ TestIO.out")));
int lineCount = 1;
while((s = in4.readLine()) != null)
out1.println(lineCount++ + "：" + s);
out1.close();
in4.close();
}
catch(EOFException ex){
System.out.println("End of stream");
}
//5. 数据的存储和恢复
try{
DataOutputStream out2 =new DataOutputStream(new BufferedOutputStream(
new FileOutputStream("F:\\nepalon\\ Data.txt")));
out2.writeDouble(3.1415926);
out2.writeChars("\nThas was pi:writeChars\n");
out2.writeBytes("Thas was pi:writeByte\n");
out2.close();
DataInputStream in5 =new DataInputStream(
new BufferedInputStream(new FileInputStream("F:\\nepalon\\ Data.txt")));
BufferedReader in5br =new BufferedReader(new InputStreamReader(in5));
System.out.println(in5.readDouble());
System.out.println(in5br.readLine());
System.out.println(in5br.readLine());
}
catch(EOFException e){
System.out.println("End of stream");
}
//6. 通过RandomAccessFile操作文件
RandomAccessFile rf = new RandomAccessFile("F:\\nepalon\\ rtest.dat", "rw");
for(int i=0; i <10; i++)
rf.writeDouble(i*1.414);
rf.close();
rf = new RandomAccessFile("F:\\nepalon\\ rtest.dat", "r");
for(int i=0; i <10; i++)
System.out.println("Value " + i + "：" + rf.readDouble());
rf.close();
rf = new RandomAccessFile("F:\\nepalon\\ rtest.dat", "rw");
rf.seek(5*8);
rf.writeDouble(47.0001);
rf.close();
rf = new RandomAccessFile("F:\\nepalon\\ rtest.dat", "r");
for(int i=0; i <10; i++)
System.out.println("Value " + i + "：" + rf.readDouble());
rf.close();
}
} |
关于代码的解释（以区为单位）： |
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