Java读写文件方法总结
Java的读写文件方法在工作中相信有很多的用处的，本人在之前包括现在都在使用Java的读写文件方法来处理数据方面的输入输出，确实很方便。奈何我的记性实在是叫人着急，很多时候既然都会想不起来怎么写了，不过我的Java代码量也实在是少的可怜，所以应该多多练习。这里做一个总结，集中在一起方面今后查看。
Java读文件
1 package 天才白痴梦; 2 3 import java.io.BufferedReader; 4 import java.io.File; 5 import java.io.FileInputStream; 6 import java.io.FileReader; 7 import java.io.IOException; 8 import java.io.InputStream; 9 import java.io.InputStreamReader; 10 import java.io.RandomAccessFile; 11 import java.io.Reader; 12 13 public class JavaIO { 14 15 /** 16 * 采用的是操作系统底层默认的编码方式，GBK等，非UTF8 17 * */ 18 19 /** 20 * 以字节为单位读取文件内容，常用于读取二进制文件，比如图片、影像、声音等文件 21 * */ 22 public static void readFileByBytes(String filename) { 23 File file=new File(filename); 24 FileInputStream in=null; 25 try { 26 System.out.println("以字节为单位读取文件,一次读一个字节: "); 27 in=new FileInputStream(file); 28 int temp=0; 29 while ((temp=in.read()) != -1) { 30 System.out.println(temp); 31 } 32 in.close(); 33 } catch (IOException e) { 34 e.printStackTrace(); 35 return ; 36 } 37 try { 38 System.out.println("以字节为单位读取文件，一次读多个字节： "); 39 byte[] temp=new byte[100]; 40 int byteread=0; 41 in=new FileInputStream(file); 42 JavaIO.showAvailableBytes(in); 43 while ((byteread=in.read(temp)) != -1) { 44 System.out.write(temp,0,byteread); 45 } 46 } catch (Exception e1) { 47 e1.printStackTrace(); 48 } finally { 49 if (in != null) { 50 try { 51 in.close(); 52 } catch (IOException e1) { 53 54 } 55 } 56 } 57 } 58 /** 59 * 以字符为单位读取文件，常用于读文本，数字等类型的文件 60 * */ 61 public static void readFileByChar(String filename) { 62 File file=new File(filename); 63 Reader reader=null; 64 try { 65 System.out.println("以字符为单位读取文件内容，一次一个字节："); 66 //InputStreamReader类:是字节向字符转换的桥梁 67 reader=new InputStreamReader(new FileInputStream(file)); 68 int temp; 69 while ((temp=reader.read()) != -1) { 70 if (((char)temp) != '\r') { 71 System.out.println((char)temp); 72 } 73 } 74 reader.close(); 75 } catch (Exception e) { 76 e.printStackTrace(); 77 } 78 try { 79 System.out.println("以字符为单位读取文件内容，一次读多个字节： "); 80 char[] temp=new char[30]; 81 int charread=0; 82 reader=new InputStreamReader(new FileInputStream(filename)); 83 while ((charread=reader.read(temp)) != -1) { 84 if ((charread == temp.length) && (temp[temp.length-1]!='\r')) { 85 System.out.println(temp); 86 } else { 87 for (int i=0; i 4 ? 4 : 0);146 randomfile.seek(beginIndex);147 byte[] bytes=new byte[10];148 int byteread=0;149 while ((byteread=randomfile.read(bytes)) != -1) {150 System.out.write(bytes,0,byteread);151 }152 } catch (IOException e) {153 e.printStackTrace();154 } finally {155 if (randomfile != null) {156 try {157 randomfile.close();158 } catch (IOException e) {159 160 }161 }162 }163 }164 private static void showAvailableBytes(InputStream in) {165 try {166 System.out.println("当前字节输入流中的字节数为：" + in.available());167 } catch (IOException e) {168 e.printStackTrace();169 }170 }171 public static void main(String[] args) {172 String filename="E:\\BaiYiShaoNian.txt";173 JavaIO.readFileByBytes(filename);174 JavaIO.readFileByChar(filename);175 JavaIO.readFileByLine(filename);176 JavaIO.readFileByRandomAccess(filename);177 }178 } Java写文件
1 package 天才白痴梦; 2 3 import java.io.BufferedWriter; 4 import java.io.File; 5 import java.io.FileNotFoundException; 6 import java.io.FileOutputStream; 7 import java.io.FileWriter; 8 import java.io.IOException; 9 import java.io.OutputStreamWriter;10 11 public class JavaIO2 {12 13 public static void main(String[] args) throws IOException {14 String Path="E:\\天才白痴梦\\JAVA";15 File file=new File("E:\\天才白痴梦\\JAVA","BaiYiShaoNian.txt");16 if (!file.exists()) {17 try {18 file.createNewFile();19 } catch (IOException e) {20 e.printStackTrace();21 }22 }23 /**24 * Java写入文件的三种方法25 * */26 FileOutputStream fos=null;27 BufferedWriter bw=null;28 FileWriter fw=null;29 int value=1000;30 31 try {32 fos=new FileOutputStream(new File(Path+"fos.txt"));33 long begin=System.currentTimeMillis();34 for (int i=1; i<=value; i++) {35 fos.write(5);36 }37 long end=System.currentTimeMillis();38 System.out.println("TheCostTime of FileOutputStream is : " + (end-begin));39 fos.close();40 41 bw=new BufferedWriter(new OutputStreamWriter(new FileOutputStream(new File(Path+"br.txt")),"UTF8"));42 begin=System.currentTimeMillis();43 for (int i=1; i<=value; i++) {44 bw.write(5);45 bw.newLine();46 }47 bw.close();48 end=System.currentTimeMillis();49 System.out.println("TheCostTime of BufferedWriter is : " + (end-begin));50 51 fw=new FileWriter(Path+"fw.txt");52 begin=System.currentTimeMillis();53 for (int i=1; i<=value; i++) {54 fw.write(5); 55 }56 fw.close();57 end=System.currentTimeMillis();58 System.out.println("TheCostTime of FileWriter is : " + (end-begin));59 60 61 } catch (Exception e) {62 // TODO Auto-generated catch block63 e.printStackTrace();64 } finally {65 try {66 fos.close(); //FileOutputStream67 bw.close(); //BufferedWriter68 fw.close(); //FileWriter69 } catch (Exception e) {70 e.printStackTrace();71 }72 }73 74 }75 } 