Java 文本文件和二进制文件的读取(转)

一,文本文件的读取?

1，FileInputStream：按字节读取文件?
1.1，导入包?
import java.io.FileInputStream;?
java.io.InputStream;?
import java.io.*;?
1.2，生成一个InputStream对象?
InputStream in = new FileInputStream("myfile//a.txt");//("myfile//a.txt",true),写入的内容追加在原有内容的后面，不覆盖?
1.3，一个一个字节地读取文件内容?
try {?
????? int size = in.available();?
????? char x[] = new char[200];?
????? for (int i = 0; i < size; i++) {?
??????? x[i] = (char)in.read();?
??????? System.out.print(x[i]);?
????? }?
??? }?
??? catch (IOException ex1) {?
????? ex1.printStackTrace();?
??? }?
1.4，关闭对象?
finally{?
????? try {?
??????? in.close();?
????? }?
????? catch (IOException ex2) {?
??????? ex2.printStackTrace();?
????? }?
??? }?
=================================================?

2，FileOutputStream：按字节写入文件?
2.1，导入包?
import java.io.*;?
2.2，声明一个OutputStream引用?
OutputStream out =null;?
2.3，构造一个OutputStream对象，并在其中写入内容?
try {?
???? out = new FileOutputStream("b.txt");?
??? String str ="java终于完了";?
??? byte[] b = str.getBytes();?
??? try {?
????? out.write(b, 0, b.length);?
??? }?
??? catch (IOException ex1) {?
????? ex1.printStackTrace();?
??? }?
2.4，关闭对象?
finally{?
??? try {?
????? out.close();?
??? }?
??? catch (IOException ex2) {?
????? ex2.printStackTrace();?
??? }?
? }?

=================================?

3，BufferedReader：按字符读取内容?
3.1，导入包?
import java.io.*;?
3.2，声明一个FileReader和BufferedReader的引用?
FileReader fr? = null;?
BufferedReader buf =null;?
3.3，构造一个FileReader和BUfferedReader的对象?
fr = new FileReader("myfile//a.txt");?
buf = new BufferedReader(fr);?
3.4，按行读取文件内容?
try {?
??? String s = buf.readLine();?
??? while(s!=null)?
??? {?
????? System.out.println(s);?
????? s =buf.readLine();?

??? }?
? }?
? catch (IOException ex1) {?
??? ex1.printStackTrace();?
? }?
3.5，关闭对象连接?
finally{?
??? try {?
????? buf.close();?
????? fr.close();?
??? }?
??? catch (IOException ex2) {?
????? ex2.printStackTrace();?
??? }?
? }?

====================================?

4，BufferWriter：按字符写入内容?
4.1，导入包?
import java.io.*;?
4.2，声明一个FileWriter和BufferedWriter的引用?
FileWriter fw? = null;?
????? BufferedWriter buf = null;?
4.3，构造一个FileWriter和BUfferedWriter的对象，并写入内容?
try {?
???? fw = new FileWriter("c.txt");?
???? buf = new BufferedWriter(fw);?
??? buf.write("你好!!");?
? }?
? catch (IOException ex) {?
??? ex.printStackTrace();?
? }?
4.4，关闭对象连接?
finally{?
??? try {?
????? buf.close();?
????? fw.close();?
??? }?
??? catch (IOException ex1) {?
????? ex1.printStackTrace();?
??? }?
? }?

====================================?

二，二进制文件的读写?
1，导入包?
import java.io.*;?
2，生成FileInputStream,DataInputStream,FileOutputStream,DataOutputStream的对象?
FileInputStream fin = new FileInputStream("d://x.jpg");?
???? DataInputStream da = new DataInputStream(fin);?
???? FileOutputStream fout = new FileOutputStream("e://b.jpg");?
???? DataOutputStream dout = new DataOutputStream(fout);?
3，写入数据?
?? int temp ;?
??? try {?
????? while ( (temp = da.read()) != -1) {?
?????????????????? dout.write(temp);?
????? }?
??? }?
??? catch (IOException ex1) {?
????? ex1.printStackTrace();?
??? }?
4，关闭连接?
finally{?
??? try {?
fin.close();?
?????? da.close();?
?? fout.close();?
dout.close();?
??? }?
??? catch (IOException ex2) {?
????? ex2.printStackTrace();?
??? }?
? }

5 将文件转成二进制流，然后进行写入数据操作

public class IOTest

{

public static void main(String[] args) throws FileNotFoundException

{

FileOutputStream fout = new FileOutputStream("e:\\2.xls");

DataOutputStream dout = new DataOutputStream(fout);

byte[] buffer = getByteFromFile("c:\\1.xls");

int count, i;

try

{

for (i = 0; i < buffer.length; i++)

{

dout.write(buffer[i]);

}

}

catch (IOException e)

{

e.printStackTrace();

}

finally

{

try

{

fout.close();

dout.close();

}

catch (IOException ex2)

{

ex2.printStackTrace();

}

}

?

}

?

private static byte[] getByteFromFile(String file)

{

File f = new File(file);

if (f == null)

{

return null;

}

try

{

FileInputStream stream = new FileInputStream(f);

ByteArrayOutputStream out = new ByteArrayOutputStream(1024);

byte[] b = new byte[1024];

int n;

while ((n = stream.read(b)) != -1)

out.write(b, 0, n);

stream.close();

out.close();

return out.toByteArray();

}

catch (IOException e)

{

}

return null;

?

}

}