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org.apache.commons.io.FileUtils快速读写文件

String fileName = "C://11.txt";
File file = new File(fileName);
String fileContent = "";
try {
    fileContent = org.apache.commons.io.FileUtils.readFileToString(file, "GBK");
} catch (IOException e) {
    e.printStackTrace();
}
fileContent += "Helloworld";
try {
    org.apache.commons.io.FileUtils.writeStringToFile(file, fileContent, "GBK");
} catch (IOException e) {
    e.printStackTrace();
}

其他参考

Commons IO方便读写文件的工具类:

Commons IO是apache的一个开源的工具包,封装了IO操作的相关类,使用Commons IO可以很方便的读写文件,url源代码等.

普通地读取一个网页的源代码的代码可能如下

InputStream in = new URL("http://laoyu.info").openStream();
try {
    InputStreamReader inR = new InputStreamReader(in);
    BufferedReader buf = new BufferedReader(inR);
    String line;
    while ((line = buf.readLine()) != null) {
        System.out.println(line);
    }
} finally {
    in.close();
}

使用了Commons IO,则可以大大简化代码.如下:

InputStream in = new URL("http://laoyu.info").openStream();
try {
    System.out.println(IOUtils.toString(in));
} finally {
    IOUtils.closeQuietly(in);
}

Commons IO里的常用类

FileUtils包含了文件操作的相关方法.

下面的代码用于读取磁盘上的某个文件:

1. File file = new File("c:/test.txt");
2. List lines = FileUtils.readLines(file, "UTF-8");

FileSystemUtils 可以获得指定磁盘路径的可用空间

1. long freeSpace = FileSystemUtils.freeSpace("d:/");

文件复制代码:

1. File src = new File("src.txt");
2. File dest = new File("dest.txt");
3. FileUtils.copyFile(src, dest);

补充:

方便地下载文 件到本地

InputStream in = new URL("http://www.baidu.com/img/baidu_logo.gif").openStream();
byte[] gif = IOUtils.toByteArray(in);
//IOUtils.write(gif,new FileOutputStream(new File("c:/test.gif")));
FileUtils.writeByteArrayToFile(new File("c:/test.gif"), gif);
IOUtils.closeQuietly(in);

分享 commons io 工具类 代码

输入流复制到 输出流

Writer write = new FileWriter("c:\\kk.dat");
InputStream ins = new FileInputStream(new File("c:\\text.txt"));
IOUtils.copy(ins, write);
write.close();
ins.close();

文本写入指定文件

String name = "my name is panxiuyan";
File file = new File("c:\name.txt");
FileUtils.writeStringToFile(file, name);  

将输入流转换成文本

URL url = new URL("http://www.dimurmill.com");
InputStream ins = url.openStream();
String contents = IOUtils.toString(ins, "UTF-8");
System.out.println("Slashdot: " + contents);

文件复制指定的目录

File srcfile = new File("c:\\Test.java");
File destDir = new File("D:\\");
FileUtils.copyFileToDirectory(srcfile, destDir);

网络流保存为文件

URL url = new URL("http://www.163.com");
File file = new File("c:\163.html");
FileUtils.copyURLToFile(url, file);

文件目录操作

File dir = new File("c:\test");
FileUtils.cleanDirectory(dir);//清空目录下的文件
FileUtils.deleteDirectory(dir);//删除目录和目录下的文件
//目录大小 
long size = FileUtils.sizeOfDirectory(dir);  

目录操作

File testFile = new File("testFile.txt");
//如果不存在,新建
// 如果存在,修改文件修改时间
FileUtils.touch(testFile);

记录流的读取写入字节数

File test = new File("test.dat");
//输出流的统计
CountingOutputStream countStream = null;
//输入流的统计
//CountingInputStream countStream = null;
try {
    FileOutputStream fos = new FileOutputStream(test);
    countStream = new CountingOutputStream(fos);
    countStream.write("Hello".getBytes());
} catch (IOException ioe) {
    System.out.println("Error writing bytes to file.");
} finally {
    IOUtils.closeQuietly(countStream);
}
if (countStream != null) {
    int bytesWritten = countStream.getCount();
    System.out.println("Wrote " + bytesWritten + " bytes to test.dat");
}

相同的内容写入不同的文本

File test1 = new File("split1.txt");
File test2 = new File("split2.txt");
OutputStream outStream = null;
try {
    FileOutputStream fos1 = new FileOutputStream(test1);
    FileOutputStream fos2 = new FileOutputStream(test2);
    //包含不同的文本
    outStream = new TeeOutputStream(fos1, fos2);
    outStream.write("One Two Three, Test".getBytes());
    outStream.flush();
} catch (IOException ioe) {
    System.out.println("Error writing to split output stream");
} finally {
    IOUtils.closeQuietly(outStream);
}

文件删除

File file = new File(("io/project.properties"));
String display = FileUtils.byteCountToDisplaySize(file.length());
System.out.println("project.xml is " + display);
FileUtils.forceDelete(file);

读取取文本中的每一行：

File file = new File((Test.class.getClass().getResource("/io/web.xml")).getFile());
List lines = FileUtils.readLines(file, "UTF-8");
for (int i = 0; i < lines.size(); i++)
    System.out.println(lines.get(i));