1.读取文件
import java.io.BufferedInputStream; import java.io.BufferedReader; import java.io.DataInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileReader; import java.io.InputStream; import java.io.InputStreamReader; import java.io.LineNumberReader; import java.io.RandomAccessFile; import java.io.Reader; public class ReadFile { public static void readByBufferedInputStream(String fileName) throws Exception { File file = new File(fileName); InputStream is = new FileInputStream(file); BufferedInputStream bis = new BufferedInputStream(is); int length = bis.available(); byte[] buffer = new byte[length]; bis.read(buffer, 0, length); bis.close(); is.close(); System.out.println(new String(buffer)); } public static void readByBufferedReader(String fileName) throws Exception { File file = new File(fileName); BufferedReader br = new BufferedReader(new FileReader(file)); String line = null; while ((line = br.readLine()) != null) { System.out.println(line); } br.close(); } public static void readByDataInputStream(String fileName) throws Exception { File file = new File(fileName); DataInputStream dis = new DataInputStream(new FileInputStream(file)); int temp; while ((temp = dis.read()) != -1) { System.out.println((char) temp); } } public static void readByFileInputStream(String fileName) throws Exception { File file = new File(fileName); InputStream is = new FileInputStream(file); int temp; while ((temp = is.read()) != -1) { System.out.println((char) temp); } is.close(); } public static void readByFileInputStream_Buffer(String fileName) throws Exception { File file = new File(fileName); InputStream is = new FileInputStream(file); int temp; byte[] buffer = new byte[1024]; while ((temp = is.read(buffer, 0, buffer.length)) != -1) { System.out.write(buffer, 0, temp); } is.close(); } public static void readByFileReader(String fileName) throws Exception { File file = new File(fileName); Reader reader = new FileReader(file); int temp; while ((temp = reader.read()) != -1) { System.out.println((char) temp); } reader.close(); } public static void readByFileReader_Buffer(String fileName) throws Exception { File file = new File(fileName); Reader reader = new FileReader(file); int temp; char[] buffer = new char[1024]; while ((temp = reader.read(buffer, 0, buffer.length)) != -1) { if ((buffer.length == 0) && (buffer[buffer.length - 1] != '\r')) { System.out.print(buffer); } else { for (int i = 0; i < temp; i++) { if (buffer[i] == '\r') { continue; } else { System.out.print(buffer[i]); } } } } reader.close(); } public static void readByInputStreamReader(String fileName) throws Exception { File file = new File(fileName); Reader reader = new InputStreamReader(new FileInputStream(file)); int temp; while ((temp = reader.read()) != -1) { System.out.println((char) temp); } reader.close(); } public static void readByInputStreamReader_Buffer(String fileName) throws Exception { File file = new File(fileName); Reader reader = new InputStreamReader(new FileInputStream(file)); int temp = 0; char[] buffer = new char[1024]; while ((temp = reader.read(buffer)) != -1) { if ((buffer.length == 0) && (buffer[buffer.length - 1] != '\r')) { System.out.print(buffer); } else { for (int i = 0; i < temp; i++) { if (buffer[i] == '\r') { continue; } else { System.out.print(buffer[i]); } } } } reader.close(); } public static void readByLineNumberReader(String fileName) throws Exception { File file = new File(fileName); Reader reader = new FileReader(file); LineNumberReader lnr = new LineNumberReader(reader); String line = null; while ((line = lnr.readLine()) != null) { System.out.println(lnr.getLineNumber() + " " + line); } } public static void readByRandomAccessFile(String fileName) throws Exception { File file = new File(fileName); RandomAccessFile raf = new RandomAccessFile(file, "rw"); long fileLen = raf.length(); int begin = (fileLen > 4) ? 4 : 0; raf.seek(begin); byte[] buffer = new byte[1024]; int temp = 0; while ((temp = raf.read(buffer)) != -1) { System.out.write(buffer, 0, temp); } } }
2.写入文件
import java.io.BufferedWriter; import java.io.File; import java.io.FileOutputStream; import java.io.FileWriter; import java.io.OutputStreamWriter; import java.io.PrintWriter; public class WriteFile { public static void wirteByPrintWriter(String fileName, String content) throws Exception { File file = new File(fileName); PrintWriter pw = new PrintWriter(file); pw.write(content, 0, content.length()); pw.flush(); pw.close(); } public static void writeByBufferedWriter(String fileName, String content) throws Exception { File file = new File(fileName); FileWriter fw = new FileWriter(file); BufferedWriter bw = new BufferedWriter(fw); bw.write(content); bw.newLine(); bw.close(); fw.close(); } public static void writeByFileWriter(String fileName, String content) throws Exception { FileWriter fw = new FileWriter(new File(fileName)); fw.write(content, 0, content.length()); fw.flush(); fw.close(); } public static void writeByOutputStreamWriter(String fileName, String content) throws Exception { File file = new File(fileName); FileOutputStream fos = new FileOutputStream(file); OutputStreamWriter osw = new OutputStreamWriter(fos); osw.write(content, 0, content.length()); osw.flush(); osw.close(); fos.close(); } }
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