本文共 2613 字,大约阅读时间需要 8 分钟。
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(); } }转载地址:http://beivi.baihongyu.com/