JDK7的文件操作

向右看齐 2022-08-24 14:12 95阅读 0赞

`` `添加删除文件的代码：`

//创建新路径
    Path newFile = Paths.get("test1");
    try {
      Files.deleteIfExists(newFile);
      newFile = Files.createFile(newFile);
    } catch (IOException ex) {
      System.out.println("Error creating file");
    }
    System.out.println(Files.exists(newFile));

读写文件：

代码片段如下：

import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.nio.charset.Charset;
    import java.nio.file.FileSystems;
    import java.nio.file.Files;
    import java.nio.file.Path;
    import java.nio.file.StandardOpenOption;
    import java.util.ArrayList;
    import java.util.List;
     
    /**
     *
     * @author Eric Bruno
     */
    public class Java7FileIO {
        String myXML =  "<Configuration>\n" +
                        "   <Server>\n" +
                        "       <Name>MyServer</Name>\n" +
                        "       <Address>192.168.0.1</Address>\n" +
                        "   </Server>\n" +
                        "   <RetryCount>10</RetryCount>\n" +
                        "   <Logs>\n"+
                        "       <FilePath>/logs/out.txt</FilePath>\n"+
                        "       <Level>INFO</Level>\n"+
                        "   </Logs>\n"+
                        "</Configuration>";
     
        public static void main(String[] args) {
            Java7FileIO j7fio = new Java7FileIO();
            List<String> lines = null;
             
            // 写文件
            j7fio.writeFileBytes("config.xml", j7fio.myXML);
     
            // 一次性读取小文件
            System.out.println("\n-- TEST 1 ---------------------------");
            String config = new String(j7fio.readSmallFileBytes("config.xml"));
            System.out.println(config);
     
            // 一次性读取小文件的所有行
            System.out.println("\n-- TEST 2 ---------------------------");
            lines = j7fio.readSmallFileLines("config.xml");
            for ( String line: lines )
                System.out.println(line);
            
            // 读取大文件的所有行
            System.out.println("\n-- TEST 3 ---------------------------");
            lines = j7fio.readLargeFileLines("log.txt");
            for ( String line: lines )
                System.out.println(line);
     
            // 读取大文件的所有行
            System.out.println("\n-- TEST 4 ---------------------------");
            lines = j7fio.readLargeFileLinesMixed("log.txt");
            for ( String line: lines )
                System.out.println(line);
        }
         
        public Java7FileIO() {
        }
         
        public byte[] readSmallFileBytes(String name) {
            byte[] filearray = null;
            try {
                Path path = FileSystems.getDefault().getPath(".", name);
                return Files.readAllBytes(path);
            }
            catch ( IOException ioe ) {
                ioe.printStackTrace();
            }
            return filearray;
        }
         //读取小文件的所有行
        public List<String> readSmallFileLines(String name) {
          
              try {
                      return Files.readAllLines(
                                FileSystems.getDefault().getPath(".", name),
                                Charset.defaultCharset() );
            }
            catch ( IOException ioe ) {
                ioe.printStackTrace();
            }
            return null;
        }
         //读取大文件的所有行，为了性能，使用了bufferedreader
        public List<String> readLargeFileLines(String name) {
            try {
                BufferedReader reader =
                    Files.newBufferedReader(
                        FileSystems.getDefault().getPath(".", name),
                        Charset.defaultCharset() );
     
                List<String> lines = new ArrayList<>();
                String line = null;
                while ( (line = reader.readLine()) != null )
                    lines.add(line);
     
                return lines;
            }
            catch (IOException ioe) {
                ioe.printStackTrace();
            }       
            return null;
        }
         
        public List<String> readLargeFileLinesMixed(String name) {
            try {
                Path path = FileSystems.getDefault().getPath(".", name);
                InputStream in = Files.newInputStream(path);
                BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                 
                List<String> lines = new ArrayList<>();
                String line = null;
                while ( (line = reader.readLine()) != null )
                    lines.add(line);
     
                return lines;
            }
            catch ( IOException ioe ) {
                ioe.printStackTrace();
            }
             
            return null;
        }
         
        //写文件
        void writeFileBytes(String filename, String content) {
            try {
                Files.write( FileSystems.getDefault().getPath(".", filename),
                             content.getBytes(),
                             StandardOpenOption.CREATE);
            }
            catch ( IOException ioe ) {
                ioe.printStackTrace();
            }
        }
         
       //写文件，可以设置字符集
        void writeFileBytesBuffered(String filename, String content) {
            try {
                BufferedWriter writer =
                    Files.newBufferedWriter(
                            FileSystems.getDefault().getPath(".", filename),
                            Charset.forName("US-ASCII"),
                            StandardOpenOption.CREATE);
     
                writer.write(content, 0, content.length());
            }
            catch ( IOException ioe ) {
                ioe.printStackTrace();
            }
        }
    }

原文链接：http://www.drdobbs.com/jvm/java-se-7-new-file-io/231600403