import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;

public class IOUtil {
    /**
     * 将文件读入到一个String，利用FileReader+BufferedReader(提供readLine方法)
     *
     * @param fileName
     * @return String
     */
    public static String fileReaderStringHandle(String fileName) {
       StringBuilder sb = new StringBuilder();
       try {
           BufferedReader in = new BufferedReader(new FileReader(new File(
                  fileName).getAbsoluteFile()));
           try {
              String s;
              while ((s = in.readLine()) != null) {
                  sb.append(s);
                  sb.append("\n");
              }
           } finally {
              in.close();
           }
       } catch (IOException e) {
           throw new RuntimeException(e);
       }
       return sb.toString();
    }

    /**
     * 使用FileInputStream+BufferedInputStream以byte的方式处理文件
     *
     * @param fileName
     * @return byte[]
     */
    public static byte[] fileReaderByteHandle(String fileName) {
       byte[] data = null;
       try {
           BufferedInputStream bf = new BufferedInputStream(
                  new FileInputStream(fileName));
           try {
              data = new byte[bf.available()];
              bf.read(data);

           } finally {
              bf.close();
           }
       } catch (IOException e) {
           throw new RuntimeException(e);
       }
       return data == null ? new byte[] {} : data;
    }

    /**
     * 将指定的text写入到文件名为fileName的文件中
     *
     * @param fileName
     * @param text
     */
    public static void fileWriterHandle(String fileName, String text) {
       try {
           PrintWriter out = new PrintWriter(new File(fileName)
                  .getAbsoluteFile());
           try {
              out.print(text);
           } finally {
              out.close();
           }
       } catch (IOException e) {
           throw new RuntimeException(e);
       }
    }

    public static void main(String[] args) throws IOException {
       System.out.print(fileReaderStringHandle("src/IOUtil.java"));
    
       for (byte b : fileReaderByteHandle("src/IOUtil.java"))
           System.out.print(b);

       fileWriterHandle("zj.txt",
              fileReaderStringHandle("src/IOUtil.java"));
    }
}