此代码将根据大型机排序参数对文件进行排序。
您将 3 个参数传递给类的main方法Sort。
- 输入文件路径。
- 输出文件路径。
- 大型机排序格式中的排序参数。在你的情况下，这个字符串将是
19,5,CH,A,1,1,CH,A
第一个类，即SortParameter类，保存排序参数的实例。排序参数字符串中的每组 4 个参数都有一个实例。这个类是一个基本的getter/setter类，除了getDifference方法。该getDifference方法将一些排序比较器代码引入到SortParameter类中，以简化类中的比较器代码Sort。
public class SortParameter {
protected int fieldStartByte;
protected int fieldLength;
protected String fieldType;
protected String sortDirection;
public SortParameter(int fieldStartByte, int fieldLength, String fieldType,
String sortDirection) {
this.fieldStartByte = fieldStartByte;
this.fieldLength = fieldLength;
this.fieldType = fieldType;
this.sortDirection = sortDirection;
}
public int getFieldStartPosition() {
return fieldStartByte - 1;
}
public int getFieldEndPosition() {
return getFieldStartPosition() + fieldLength;
}
public String getFieldType() {
return fieldType;
}
public String getSortDirection() {
return sortDirection;
}
public int getDifference(String a, String b) {
int difference = 0;
if (getFieldType().equals("CH")) {
String as = a.substring(getFieldStartPosition(),
getFieldEndPosition());
String bs = b.substring(getFieldStartPosition(),
getFieldEndPosition());
difference = as.compareTo(bs);
if (getSortDirection().equals("D")) {
difference = -difference;
}
}
return difference;
}
}
该类Sort包含读取输入文件、对输入文件进行排序和写入输出文件的代码。这个类可能会使用更多的错误检查。
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class Sort implements Runnable {
protected List<String> lines;
protected String inputFilePath;
protected String outputFilePath;
protected String sortParameters;
public Sort(String inputFilePath, String outputFilePath,
String sortParameters) {
this.inputFilePath = inputFilePath;
this.outputFilePath = outputFilePath;
this.sortParameters = sortParameters;
}
@Override
public void run() {
List<SortParameter> parameters = parseParameters(sortParameters);
lines = read(inputFilePath);
lines = sort(lines, parameters);
write(outputFilePath, lines);
}
protected List<SortParameter> parseParameters(String sortParameters) {
List<SortParameter> parameters = new ArrayList<SortParameter>();
String[] field = sortParameters.split(",");
for (int i = 0; i < field.length; i += 4) {
SortParameter parameter = new SortParameter(
Integer.parseInt(field[i]), Integer.parseInt(field[i + 1]),
field[i + 2], field[i + 3]);
parameters.add(parameter);
}
return parameters;
}
protected List<String> sort(List<String> lines,
final List<SortParameter> parameters) {
Collections.sort(lines, new Comparator<String>() {
@Override
public int compare(String a, String b) {
for (SortParameter parameter : parameters) {
int difference = parameter.getDifference(a, b);
if (difference != 0) {
return difference;
}
}
return 0;
}
});
return lines;
}
protected List<String> read(String filePath) {
List<String> lines = new ArrayList<String>();
BufferedReader reader = null;
try {
String line;
reader = new BufferedReader(new FileReader(filePath));
while ((line = reader.readLine()) != null) {
lines.add(line);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return lines;
}
protected void write(String filePath, List<String> lines) {
BufferedWriter writer = null;
try {
writer = new BufferedWriter(new FileWriter(filePath));
for (String line : lines) {
writer.write(line);
writer.newLine();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (writer != null) {
writer.flush();
writer.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
if (args.length < 3) {
System.err.println("The sort process requires 3 parameters.");
System.err.println(" 1. The input file path.");
System.err.println(" 2. The output file path.");
System.err.print (" 3. The sort parameters in mainframe ");
System.err.println("sort format. Example: 15,5,CH,A");
} else {
new Sort(args[0], args[1], args[2]).run();
}
}
}