java的I/O操作，读取和写入文件

package up.down.file;

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.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.OutputStreamWriter;

import java.io.UnsupportedEncodingException;

import java.nio.Buffer;

import java.util.Date;

import org.apache.axis.message.InputStreamBody;

import org.apache.commons.fileupload.FileItemFactory;

import org.apache.commons.fileupload.FileUpload;

import org.apache.commons.fileupload.ProgressListener;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

import org.apache.struts.upload.DiskFile;

public class Test {

public static void main(String[] args) {

File file = new File("./build/期 日 未 収 入 金 内 訳 帳.xml");

File writefile = new File("./build/writefile.txt");

String upload="F:/期 日 未 収 入 金 内 訳 帳.xml.bak";

if(file.exists()){

System.out.println("--->文件存在");

try {

readfile(file); //读取

writfile(writefile,readfile(file)); //创建文件写入

//uploadfile(upload); //上传文件

} catch (Exception e) {

e.printStackTrace();

}

}else{

System.out.println("-->文件不存在exists");

}

}

//读取文件

public static StringBuffer readfile(File file) throws IOException{

System.out.println("读取开始时间:"+new Date());

BufferedReader br = new BufferedReader(new FileReader(file));

System.out.println("文件大小:"+file.length()/1000+"KB");

StringBuffer line = new StringBuffer();

String str = null;

while((str=br.readLine())!=null){

line.append(str);

line.append("\n");

}

System.out.println("--->"+line);

System.out.println("读取结束时间="+new Date());

br.close();

return line;

}

//写入文件将读取的文件内容保存在制定的工程目录下

public static void writfile(File file,StringBuffer sb) throws Exception{

FileWriter fw = new FileWriter(file);

fw.getEncoding().getBytes("utf-8");

fw.write(sb.toString());

System.out.println("------->写入成功！");

System.out.println("写入了一个大小为"+file.length()/1000+"KB的文件");

fw.close();

}