Java文件读写简单方法

本文章提供一个简单的文件读取方法：

具体代码如下：

package com.wrh.java.microblg.io;

/*
 * FileOperate.java 2012/03/20
 * Copyright (c) wrh
 * Beijing, Chaoyang, 100101
 * China
 * All rights reserved
 * 
 */

import java.io.*;
import java.util.ArrayList;

/**
 * The interface of file operate include read files and write files etc.
 * 
 * @version 1.0 2011/12
 * @author wrh
 * 
 */
public interface FileOperate {
    /* the interface of the file operate */

    /**
     * read the directories under the file path.
     * 
     * @param filePath
     *            the path you want to read from
     * @return ArrayList<String> to store the directories
     * @throws FileNotFoundException
     *             if the file does not find
     * @throws IOException
     *             if io has some exceptions
     */
    public ArrayList<String> readDirs(String filePath)
            throws FileNotFoundException, IOException;

    /**
     * read the file content from file path
     * 
     * @param file
     *            like D:\\a.txt
     * @return the file content
     * @throws UnsupportedEncodingException
     *             if the encoding exception
     * @throws FileNotFoundException
     *             if the file does not find
     * @throws IOException
     *             if io has some exceptions
     */
    public String readFileContent(String file)
            throws UnsupportedEncodingException, FileNotFoundException,
            IOException;

    /**
     * read the file content from file path
     * 
     * @param file
     *            like D:\\a.txt
     * @return the file content
     * @throws UnsupportedEncodingException
     *             if the encoding exception
     * @throws FileNotFoundException
     *             if the file does not find
     * @throws IOException
     *             if io has some exceptions
     */
    public ArrayList<String> readFileContentByLine(String file)
            throws UnsupportedEncodingException, FileNotFoundException,
            IOException;

    /**
     * save content to the file in path
     * 
     * @param content
     *            the be saved content
     * @param path
     *            the saved path
     * @param b 
     *             append or not
     * @throws IOException
     */
    public void saveToFile(String content, String path, boolean b) throws IOException;

    /**
     * save content to the ../className/keyword.txt
     * 
     * @param content
     *            the saved file content
     * @param className
     *            the part of the file directory
     * @param keyWords
     *            the file name
     * @throws FileNotFoundException
     */
    public void saveToFile(String content, String className, String keyWord)
            throws FileNotFoundException;
}

其实现代码为：

package com.wrh.java.microblog.io.impl;

import com.wrh.java.microblg.io.FileOperate;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;

public class FileOperateImpl implements FileOperate{

    /**
     * the implement of com.wrh.java.study.fileoperate.FileOperate
     * 
     * @version 1.0 Mar 2012
     * @author wrh
     * 
     */
        private ArrayList<String> fileList = new ArrayList<String>();

        /**
         * read the directories of file path
         */
        @Override
        public ArrayList<String> readDirs(String filePath)
                throws FileNotFoundException, IOException {
            File file = new File(filePath);

            if (!file.isDirectory()) {
                System.out.println("The parameter you give is not a directory!");
            } else {
                String[] list = file.list();

                for (int i = 0; i < list.length; i++) {
                    File readFile = new File(filePath + "\\" + list[i]);

                    if (!readFile.isDirectory()) {
                        fileList.add(readFile.getAbsolutePath());
                    } else {
                        readDirs(filePath + "\\" + list[i]);
                    }
                }
            }

            return fileList;
        }

        /**
         * read the file content and return
         */
        @Override
        public String readFileContent(String file)
                throws UnsupportedEncodingException, FileNotFoundException,
                IOException {
            StringBuffer sb = new StringBuffer();
            InputStreamReader is = new InputStreamReader(new FileInputStream(file),
                    "utf-8");
            BufferedReader br = new BufferedReader(is);
            String line = br.readLine();
            while (line != null) {
                sb.append(line).append("\r\n");
                line = br.readLine();
            }
            br.close();
            is.close();

            return sb.toString();
        }

        /**
         * read the content and save to arrayList by line
         */
        @Override
        public ArrayList<String> readFileContentByLine(String file)
                throws UnsupportedEncodingException, FileNotFoundException,
                IOException {
            ArrayList<String> content = new ArrayList<String>();
            InputStreamReader is = new InputStreamReader(new FileInputStream(file),
                    "gb2312");
            BufferedReader br = new BufferedReader(is);
            String line = br.readLine();
            while (line != null) {
                content.add(line);
                line = br.readLine();
            }
            br.close();
            is.close();
            return content;
        }

        /**
         * save content to the specified path
         */
        @Override
        public void saveToFile(String content, String path, boolean b) throws IOException {
            // get the path
            String dir = path.substring(0, path.lastIndexOf("\\"));
            File file = new File(dir);
            if (!file.exists()) {
                file.mkdir();
            }

            file = new File(path);
            if (!file.exists()) {
                file.createNewFile();
            }

            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(
                    new FileOutputStream(file, b)));
            bw.write(content);
            bw.flush();
            bw.close();
        }

        @Override
        public void saveToFile(String content, String className, String keyWord)
                throws FileNotFoundException {

        }

        public static void main(String[] args) throws IOException {
            FileOperateImpl f = new FileOperateImpl();
            System.out.println(f.readDirs("D:\\result"));
            //f.saveToFile("aaa", "D:\\a.txt");
            System.out.println(f.readFileContent("D:\\a.txt"));
        }

}