Không biết sau này viết được game nào như Flappy Bird không chứ giờ viết hết đóng code này thấy chuẩn bị có thêm 2 mắt hơn anh Dương Tiễn luôn đó :v import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOError; import java.io.IOException; import java.util.Arrays; public class SortLargeFile { public static final int MAX_ARRAY_SIZE = 100000; public static final int BUFFER_SIZE = 100000; public static void main(String[] args) throws Exception{ // Sort largedata.dat to sortedfile.dat sort(largedata.dat,sortedfile.dat); // Display the first 100 numbers in the sorted file displayFile(sortedfile.dat); } /** Sort data in source file into target file */ public static void sort(String sourceFile, String targetFile) throws Exception{ // Implement Phase 1: Create initial segments int numberOfSegments = initializeSegments(MAX_ARRAY_SIZE, sourceFile, f1.dat); // Implement Phase 2: Merge segments recursively merge(numberOfSegments, MAX_ARRAY_SIZE, f1.dat, f2.dat, f3.dat, targetFile); } /** Sort original file into sorted segments */ private static int initializeSegments(int segmentSize, String originalFile, String f1) throws Exception{ // Same as Listing 23.12, so omitted int[] list = new int[segmentSize]; DataInputStream input = new DataInputStream(new BufferedInputStream(new FileInputStream(originalFile))); DataOutputStream output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(f1))); int numberOfSegments = 0; while(input.available() > 0){ numberOfSegments++; int i = 0; for ( ; input.available() > 0 && i < segmentSize; i++) { list[i] = input.readInt(); } // Sort an array list[0..i-1] Arrays.sort(list, 0, i); // Write the array to f1.dat for (int j = 0; j < i; j++) { output.writeInt(list[j]); } } input.close(); output.close(); return numberOfSegments; } private static void merge(int numberOfSegments, int segmentSize, String f1, String f2, String f3, String targetFile) throws Exception{ if(numberOfSegments > 1){ mergeOneStep(numberOfSegments, segmentSize, f1, f2, f3); merge((numberOfSegments + 1) / 2, segmentSize * 2,f3, f1, f2, targetFile); }else{// Rename f1 as the final sorted file File sortedFile = new File(targetFile); if(sortedFile.exists()) sortedFile.delete(); new File(f1).renameTo(sortedFile); } } private static void mergeOneStep(int numberOfSegments, int segmentSize, String f1, String f2, String f3) throws Exception{ DataInputStream f1Input = new DataInputStream(new BufferedInputStream(new FileInputStream(f1), BUFFER_SIZE)); DataOutputStream f2Output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(f2), BUFFER_SIZE)); // Copy half number of segments from f1.dat to f2.dat copyHalfToF2(numberOfSegments, segmentSize, f1Input, f2Output); f2Output.close(); // Merge remaining segments in f1 with segments in f2 into f3 DataInputStream f2Input = new DataInputStream(new BufferedInputStream(new FileInputStream(f2),BUFFER_SIZE)); DataOutputStream f3Output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(f3), BUFFER_SIZE)); mergeSegments(numberOfSegments, segmentSize, f1Input, f2Input, f3Output); f1Input.close(); f2Input.close(); f3Output.close(); } /** Copy first half number of segments from f1.dat to f2.dat */ private static void copyHalfToF2(int numberOfSegments, int segmentSize, DataInputStream f1, DataOutputStream f2) throws Exception{ for (int i = 0; i < (numberOfSegments / 2) * segmentSize; i++) { f2.writeInt(f1.readInt()); } } /** Merge all segments */ private static void mergeSegments(int numberOfSegments, int segmentSize, DataInputStream f1, DataInputStream f2, DataOutputStream f3) throws Exception{ for (int i = 0; i < numberOfSegments; i++) { mergeTwoSegments(segmentSize, f1, f2, f3); } // If f1 has one extra segment, copy it to f3 while(f1.available() > 0){ f3.writeInt(f1.readInt()); } } /** Merges two segments */ private static void mergeTwoSegments(int segmentSize, DataInputStream f1, DataInputStream f2, DataOutputStream f3) throws Exception{ int intFromF1 = f1.readInt(); int intFromf2 = f2.readInt(); int f1Count = 1; int f2Count = 1; while(true){ if(intFromF1 < intFromf2){ f3.writeInt(intFromF1); if(f1.available() == 0 || f1Count++ >= segmentSize){ f3.writeInt(intFromf2); break; }else{ intFromF1 = f1.readInt(); } }else{ f3.writeInt(intFromf2); if(f2.available() == 0 || f2Count++ >= segmentSize){ f3.writeInt(intFromF1); break; }else{ intFromf2 = f2.readInt(); } } } while(f1.available() > 0 && f1Count++ < segmentSize){ f3.writeInt(f1.readInt()); } while(f2.available() > 0 && f2Count++ < segmentSize){ f3.writeInt(f2.readInt()); } } /** Display the first 100 numbers in the specified file */ public static void displayFile(String filename){ try { DataInputStream input = new DataInputStream(new FileInputStream(filename)); for (int i = 0; i < 100; i++) { System.out.print(input.readInt() + ); } input.close(); } catch (IOException e) { // TODO: handle exception e.printStackTrace(); } } }
Posted on: Wed, 09 Jul 2014 13:39:50 +0000
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