J2SE代码例子收集（IO）

package io;
import java.io.*;
public class FileCopy {
  public static void main(String[] args) {
	  int b = 0;
	  FileReader in = null;
	  FileWriter out = null;
	  try {
	    in = new FileReader("d:/share/java/HelloWorld.java");
	    out = new FileWriter("d:/share/java/io/HW.java");
	    while((b=in.read())!=-1){
	      out.write(b);
	    }
	    out.close();
	    in.close(); 
	    
	  } catch (FileNotFoundException e2) {
	    System.out.println("找不到指定文件"); System.exit(-1);
	  } catch (IOException e1) {
	    System.out.println("文件读写错误"); System.exit(-1);
	  }
	  System.out.println("文件复制完成");
  }
}

//ByteArrayOutputStream and ByteArrayInputStream belongs to node stream(节点流)
//两者通过字节数组来实现数据的传输，例如new ByteArrayInputStream(baos.toByteArray())

//ByteArrayInputStream以内存中的一个缓冲区作为InputStream使用
//JDK1.6源码中数据存储在protected byte buf[]
//该程序动作皆在内存中进行，不用flush()
package io;
import java.io.*;
public class TestDataStream {
  public static void main(String[] args) {
    ByteArrayOutputStream baos = 
                        new ByteArrayOutputStream(); 
    DataOutputStream dos = 
                        new DataOutputStream(baos);
    try {
      dos.writeDouble(Math.random());
      dos.writeBoolean(true);
      ByteArrayInputStream bais = 
          new ByteArrayInputStream(baos.toByteArray());
      System.out.println(bais.available());	//Returns the number of remaining bytes that 
      										//can be read (or skipped over) from this input stream.
      DataInputStream dis = new DataInputStream(bais);
      System.out.println(dis.readDouble());
      System.out.println(dis.readBoolean());
      dos.close();  dis.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}   

package io;
import java.io.*;
public class TestBufferStream1 {
  public static void main(String[] args) {
    try {
      FileInputStream fis = 
              new FileInputStream("F:\\111213zidian.sql");
      BufferedInputStream bis = 
              new BufferedInputStream(fis);
      int c = 0;
      System.out.println(bis.read());
      System.out.println(bis.read());
      System.out.println(bis.markSupported());
      bis.mark(10);//?没有效果
      for(int i=0;i<=100&& (c=bis.read())!=-1;i++){
        System.out.print((char)c+" ");
      }
      System.out.println(); 
      bis.reset();
      for(int i=0;i<=100 && (c=bis.read())!=-1;i++){
        System.out.print((char)c+" ");
      }
      bis.close();
    } catch (IOException e) {e.printStackTrace();}
  }
}

package io;
import java.io.*;
public class TestBufferStream2 {
  public static void main(String[] args) {
    try {
      BufferedWriter bw = new BufferedWriter(new FileWriter("d:\\share\\java\\dat2.txt"));
      BufferedReader br = new BufferedReader(
             new FileReader("d:\\share\\java\\dat2.txt"));
      String s = null;
      for(int i=1;i<=100;i++){
        s = String.valueOf(Math.random());
        bw.write(s);
        bw.newLine();
      }
      bw.flush();
      while((s=br.readLine())!=null){
        System.out.println(s);
      }
      bw.close(); 
      br.close();
    } catch (IOException e) { e.printStackTrace();}
  }
}

package io;
import java.io.*;
public class TestFileInputStream {
  public static void main(String[] args) {
    int b = 0;
    FileInputStream in = null;
    try {
      in = new FileInputStream("f:\\java学习路线.txt");
    } catch (FileNotFoundException e) {
      System.out.println("文件未找到！"); 
      System.exit(-1);
    }
    try {
      long num = 0;
      while((b=in.read())!=-1){
        System.out.print((char)b); 
        num++;
      }
      in.close();  
      System.out.println();
      System.out.println("有"+num+"字节");
    } catch (IOException e1) {
      System.out.println("读文件错误"); System.exit(-1);
    }
  }
}

import java.io.*;
public class TestFileOutputStream {
  public static void main(String[] args) {
	  int b = 0;
	  FileInputStream in = null;
	  FileOutputStream out = null;
	  try {
	    in = new FileInputStream("d:/share/java/HelloWorld.java");
	    out = new FileOutputStream("d:/share/java/io/HW.java");
	    while((b=in.read())!=-1){
	      out.write(b);
	    }
	    in.close(); 
	    out.close();
	  } catch (FileNotFoundException e2) {
	    System.out.println("文件未找到"); System.exit(-1);
	  } catch (IOException e1) {
	    System.out.println("读写错误"); System.exit(-1);
	  }
	  System.out.println(" ");
  }
}

package io;
import java.io.*;
public class TestFileReader {
  public static void main(String[] args) {
    FileReader fr = null; 
    int c = 0;
    try {
      fr = new FileReader("f:\\java学习路线.txt");
      int ln = 0;
      while ((c = fr.read()) != -1) {
        //char ch = (char) fr.read();
        System.out.print((char)c);//FileReader为节点 字符流
        //if (++ln >= 100) { System.out.println(); ln = 0;}
      }
      fr.close();
    } catch (FileNotFoundException e) {
      System.out.println("文件未找到！");
    } catch (IOException e) {
      System.out.println("读写错误！");
    }

  }
}//FileWriter out = new FileWriter("output.txt");

//相当于FileWriter out = new FileWriter(new FileOutputStream("output.txt"));

package io;
import java.io.*;
public class TestFileWriter {
  public static void main(String[] args) {
    FileWriter fw = null;
    try {
      fw = new FileWriter("f:\\unicode.dat");
      for(int c=0;c<=50000;c++){
        fw.write(c);
      }
      fw.close();
    } catch (IOException e1) {
    	e1.printStackTrace();
      System.out.println("写文件错误");
      System.exit(-1);
    }
  }
}

package io;
import java.io.*;

public class TestFileWriter2 {
	public static void main(String[] args) throws Exception {
		FileReader fr = new FileReader("d:/java/io/TestFileWriter2.java");
		FileWriter fw = new FileWriter("d:/java/io/TestFileWriter2.bak");
		int b;
		while((b = fr.read()) != -1) {
			fw.write(b);
		}
		fr.close();
		fw.close();
	}
}

package io;
import java.io.*;

public class TestObjectIO {
	public static void main(String args[]) throws Exception {
		T t = new T();
		t.k = 8;
		FileOutputStream fos = new FileOutputStream("f:/testobjectio.dat");
		ObjectOutputStream oos = new ObjectOutputStream(fos);
		oos.writeObject(t);
		oos.flush();
		oos.close();
		
		FileInputStream fis = new FileInputStream("f:/testobjectio.dat");
		ObjectInputStream ois = new ObjectInputStream(fis);
		T tReaded = (T)ois.readObject();
		System.out.println(tReaded.i + ", " + tReaded.j + ", " 
				+ tReaded.d + ", " + tReaded.k);
	}
}

class T implements Serializable
{
	int i = 10;
	int j = 9;
	double d = 2.3;
	transient int k = 15;//如果用transient声明一个实例变量，当对象存储时，它的值不需要维持。
}

10, 9, 2.3, 0

package io;
import java.io.*;
public class TestPrintStream1 { 
  public static void main(String[] args) {
    PrintStream ps = null;
    try {
      FileOutputStream fos = 
              new FileOutputStream("f:\\log.dat");
      ps = new PrintStream(fos);
    } catch (IOException e) {
      e.printStackTrace();
    }
    if(ps != null){
      System.setOut(ps);//Reassigns the "standard" output stream.
    }
    int ln = 0;
    for(char c = 0; c <= 60000; c++){
      System.out.print(c+ " ");
      if(ln++ >=100){ System.out.println(); ln = 0;}//默认是控制台输出，现在为输出到文件
    }
  }
}

package io;
import java.io.*;
public class TestPrintStream2 {
  public static void main(String[] args) {
    String filename = "f:\\logfile.log";
    if(filename!=null){list(filename,System.out);}
  }
  public static void list(String f,PrintStream fs){
    try {
      BufferedReader br = new BufferedReader(new FileReader(f));
      String s = null; 
      while((s=br.readLine())!=null){
        fs.println(s);            
      }
      br.close();
    } catch (IOException e) {
      fs.println(" ");
    }
  }
}

package io;
import java.util.*; 
import java.io.*;
public class TestPrintStream3 {
  public static void main(String[] args) {
    String s = null;
    BufferedReader br = new BufferedReader(
                        new InputStreamReader(System.in));
    try {
      FileWriter fw = new FileWriter
                           ("f:\\logfile.log", true); 
      PrintWriter log = new PrintWriter(fw);
      while ((s = br.readLine())!=null) {
        if(s.equalsIgnoreCase("exit")) break;
        System.out.println(s.toUpperCase());
        log.println("-----");
        log.println(s.toUpperCase()); 
        log.flush();
      }
      log.println("==="+new Date()+"==="); 
      log.flush();
      log.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

package io;
import java.io.*;
public class TestTransForm2 {
  public static void main(String args[]) {
    InputStreamReader isr = 
            new InputStreamReader(System.in);
    BufferedReader br = new BufferedReader(isr);
    String s = null;
    try {
      s = br.readLine();//阻塞式
      while(s!=null){
        if(s.equalsIgnoreCase("exit")) break;
        System.out.println(s.toUpperCase());
        s = br.readLine();
      }
      br.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
} 

package io;
import java.io.*;
public class TestTransForm1 {
  public static void main(String[] args) {
    try {
      OutputStreamWriter osw = new OutputStreamWriter(
           new FileOutputStream("f:\\char.txt"));
      osw.write("mircosoftibmsunapplehp");
      System.out.println(osw.getEncoding());//GBK
      osw.close();
      osw = new OutputStreamWriter(new FileOutputStream("f:\\char.txt", true),
    		  "ISO8859_1"); // latin-1
      osw.write("mircosoftibmsunapplehp");
      System.out.println(osw.getEncoding());
      osw.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}