UsingRandomAccessFile.java

package org.javacore.io;

import java.io.IOException;
import java.io.RandomAccessFile;

/*
 * Copyright [2015] [Jeff Lee]
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @author Jeff Lee
 * @since 2015-9-28 18:50:22
 * RandomAccessFile的使用案例
 */
public class UsingRandomAccessFile {
	// 文件名
	static String file = "rtest.bat";
	
	static void display() throws IOException {
		// 创建随机访问类，只读模式
		RandomAccessFile rf = new RandomAccessFile(file, "r");
		for (int i = 0; i < 7; i++)
			System.out.println("Value "  + i + ": " + rf.readDouble());// 读取一个Double
		System.out.println(rf.readUTF());// 读取一个字符串
		rf.close();
	}
	
	public static void main(String[] args) throws IOException {
		// 创建随机访问类，读写模式
		RandomAccessFile rf = new RandomAccessFile(file, "rw");
		for (int i = 0; i < 7; i++)
			rf.writeDouble( i * 1.123);// 写入一个Double
		rf.writeUTF("文件结束");// 写入一个字符串
		rf.close();
		
		display();
		
		rf = new RandomAccessFile(file, "rw");
		rf.seek(5 * 8);// 设置文件指针偏移量，设置到第5个双精度字节
		rf.writeDouble(47.003);
		rf.close();
		
		display();
	}
}