由于沒有紙質書或pdf沒有代碼，不在編輯器里看代碼，實在難看懂。所以跟著寫了一遍。代碼不完全一樣，沒有單元測試，不保證沒問題。大概可以一用吧。

代碼14-9

package com.example.demo.args;import java.util.HashMap; import java.util.Map; import java.util.Set; import java.util.TreeSet;/*** 代碼清單 14-9 一個早期版本代碼，只支持Boolean 參數*/ public class Args149 {private String schema;private String[] args;private boolean valid;private Set<Character> unexpectArguments = new TreeSet<>();private Map<Character, Boolean> booleanArgs = new HashMap<>();private int numberOfArguments = 0;public Args149(String schema, String[] args) {this.schema = schema;this.args = args;valid = parse();}public boolean getBoolean(char arg) {return booleanArgs.get(arg);//TODO 校驗key是否存在，不存在：給提示（拋錯太不友好；了）}public int cardinality() {return numberOfArguments;}public String usage() {if (schema.length() > 0)return "-[" + schema + "]";elsereturn "";}public String errorMessage() {if (unexpectArguments.size() > 0)return unexpectArgumentsMessage();elsereturn "";}public boolean isValid() {return valid;}private boolean parse() {if (schema.length() == 0 && args.length == 0) return true;parseSchema();parseArguments();return unexpectArguments.size() == 0;}private boolean parseSchema() {for (String element : schema.split(",")) {parseSchemaElement(element);}return true;}private void parseSchemaElement(String element) {if (element.length() == 1) {parseBooleanSchemaElement(element);}}private void parseBooleanSchemaElement(String element) {char c = element.charAt(0);if (Character.isLetter(c)) {booleanArgs.put(c, false);}}private boolean parseArguments() {for (String arg : args)parseArgument(arg);return true;}private void parseArgument(String arg) {if (arg.startsWith("-")) {parseElements(arg);}}private void parseElements(String arg) {for (int i = 1; i < arg.length(); i++) {parseElement(arg.charAt(i));}}private void parseElement(char argChar) {if (isBoolean(argChar)) {numberOfArguments++;setBooleanArg(argChar, true);} elseunexpectArguments.add(argChar);}private void setBooleanArg(char argChar, boolean value) {booleanArgs.put(argChar, value);}private boolean isBoolean(char argChar) {return booleanArgs.containsKey(argChar);}private String unexpectArgumentsMessage() {StringBuffer message = new StringBuffer("Argument(s) -");for (Character c : unexpectArguments) {message.append(c);}message.append(" unexpected.");return message.toString();}}

代碼14-10

package com.example.demo.args;import java.text.ParseException; import java.util.*;/*** 代碼清單 14-10*/ public class Args1410 {private String schema;private String[] args;private boolean valid = true;private Set<Character> unexpectArguments = new TreeSet<>();private Map<Character, Boolean> booleanArgs = new HashMap<>();private Map<Character, String> stringArgs = new HashMap<>();private Set<Character> argsFound = new HashSet<>();private int currentArgument;private char errorArgument = '\0';enum ErrorCode {OK, MISSING_STRING}private ErrorCode errorCode = ErrorCode.OK;private int numberOfArguments = 0;public Args1410(String schema, String[] args) throws ParseException {this.schema = schema;this.args = args;valid = parse();}private boolean parse() throws ParseException {if (schema.length() == 0 && args.length == 0) return true;parseSchema();parseArguments();return valid;}private boolean parseSchema() throws ParseException {for (String element : schema.split(",")) {if (element.length() > 0) {String trimElement = element.trim();parseSchemaElement(trimElement);}}return true;}private void parseSchemaElement(String element) throws ParseException {char elementId = element.charAt(0);String elementTail = element.substring(1);validateSchemaElementId(elementId);if (isBooleanSchemaElement(elementTail))parseBooleanSchemaElement(elementId);else if (isStringSchemaElement(elementTail))parseStringSchemaElement(elementId);}private void validateSchemaElementId(char elementId) throws ParseException {if (!Character.isLetter(elementId)) {throw new ParseException("Bad character:" + elementId + "in Args format: " + schema, 0);}}private boolean isBooleanSchemaElement(String elementTail) {return elementTail.length() == 0;}private boolean isStringSchemaElement(String elementTail) {return "*".equals(elementTail);}private void parseBooleanSchemaElement(char elementId) {booleanArgs.put(elementId, false);}private void parseStringSchemaElement(char elementId) {stringArgs.put(elementId, "");}private boolean parseArguments() {for (currentArgument = 0; currentArgument < args.length; currentArgument++) {String arg = args[currentArgument];parseArgument(arg);}return true;}private void parseArgument(String arg) {if (arg.startsWith("-")) {parseElements(arg);}}private void parseElements(String arg) {for (int i = 1; i < arg.length(); i++) {parseElement(arg.charAt(i));}}private void parseElement(char argChar) {if (setArgument(argChar)) {argsFound.add(argChar);} else {unexpectArguments.add(argChar);valid = false;}}private boolean setArgument(char argChar) {boolean set = true;if (isBoolean(argChar))setBooleanArg(argChar, true);else if (isString(argChar))setStringArg(argChar);elseset = false;return set;}private void setBooleanArg(char argChar, boolean value) {booleanArgs.put(argChar, value);}private void setStringArg(char argChar) {currentArgument++;try {stringArgs.put(argChar, args[currentArgument]);} catch (ArrayIndexOutOfBoundsException e) {valid = false;errorArgument = argChar;errorCode = ErrorCode.MISSING_STRING;}}private boolean isBoolean(char argChar) {return booleanArgs.containsKey(argChar);}private boolean isString(char argChar) {return stringArgs.containsKey(argChar);}public int cardinality() {return argsFound.size();}public String usage() {if (schema.length() > 0)return "-[" + schema + "]";elsereturn "";}public String errorMessage() throws Exception {if (unexpectArguments.size() > 0)return unexpectArgumentsMessage();elseswitch (errorCode) {case MISSING_STRING:return String.format("Could not find string paramenter for -%c.", errorArgument);case OK:throw new Exception("TILT: should not get here.");}return "";}private String unexpectArgumentsMessage() {StringBuffer message = new StringBuffer("Argument(s) -");for (Character c : unexpectArguments) {message.append(c);}message.append(" unexpected.");return message.toString();}public boolean getBoolean(char arg) {return falseIfNull(booleanArgs.get(arg));}private boolean falseIfNull(Boolean b) {return b == null ? false : b;}public String getString(char arg) {return blankIfNull(stringArgs.get(arg));}public String blankIfNull(String s) {return s == null ? "" : s;}public boolean has(char arg) {return argsFound.contains(arg);}public boolean isValid() {return valid;}}

基本上算完成的代碼：
Args1411

package com.example.demo.args;import com.example.demo.args.marshaler.ArgumentMarshaler; import com.example.demo.args.marshaler.BooleanArgumentMarshaler; import com.example.demo.args.marshaler.IntegerArgumentMarshaler; import com.example.demo.args.marshaler.StringArgumentMarshaler;import java.text.ParseException; import java.util.*;public class Args1411 {private String schema;private List<String> argsList;private boolean valid = true;private Set<Character> unexpectArguments = new TreeSet<>();private Map<Character, ArgumentMarshaler> argumentMarshaler = new HashMap<>();private Set<Character> argsFound = new HashSet<>();private Iterator<String> currentArgument;private ArgsException.ErrorCode errorCode = ArgsException.ErrorCode.OK;public Args1411(String schema, String[] args) throws ParseException {this.schema = schema;this.argsList = Arrays.asList(args);valid = parse();}private boolean parse() throws ParseException {if (schema.length() == 0 && argsList.size() == 0) return true;parseSchema();parseArguments();return valid;}private boolean parseSchema() throws ParseException {for (String element : schema.split(",")) {if (element.length() > 0) {String trimElement = element.trim();parseSchemaElement(trimElement);}}return true;}private void parseSchemaElement(String element) throws ParseException {char elementId = element.charAt(0);String elementTail = element.substring(1);validateSchemaElementId(elementId);if (elementTail.length() == 0)argumentMarshaler.put(elementId, new BooleanArgumentMarshaler());else if ("*".equals(elementTail))argumentMarshaler.put(elementId, new StringArgumentMarshaler());else if ("#".equals(elementTail))argumentMarshaler.put(elementId, new IntegerArgumentMarshaler());}private void validateSchemaElementId(char elementId) throws ParseException {if (!Character.isLetter(elementId)) {throw new ParseException("Bad character:" + elementId + "in Args format: " + schema, 0);}}private boolean parseArguments() {for (currentArgument = argsList.iterator(); currentArgument.hasNext(); ) {String arg = currentArgument.next();parseArgument(arg);}return true;}private void parseArgument(String arg) {if (arg.startsWith("-")) {parseElements(arg);}}private void parseElements(String arg) {for (int i = 1; i < arg.length(); i++) {parseElement(arg.charAt(i));}}private void parseElement(char argChar) {if (setArgument(argChar)) {argsFound.add(argChar);} else {unexpectArguments.add(argChar);valid = false;}}private boolean setArgument(char argChar) {boolean set = true;ArgumentMarshaler marshaler = this.argumentMarshaler.get(argChar);if (marshaler == null) return false;try {marshaler.set(currentArgument);} catch (ArgsException e) {errorCode = e.getErrorCode();valid = false;}return set;}public int cardinality() {return argsFound.size();}public String usage() {if (schema.length() > 0)return "-[" + schema + "]";elsereturn "";}public String errorMessage() throws Exception {if (unexpectArguments.size() > 0)return unexpectArgumentsMessage();elseswitch (errorCode) {case MISSING_STRING:return "Could not find string paramenter for -%c.";//其他的省略case OK:throw new Exception("TILT: should not get here.");}return "";}private String unexpectArgumentsMessage() {StringBuffer message = new StringBuffer("Argument(s) -");for (Character c : unexpectArguments) {message.append(c);}message.append(" unexpected.");return message.toString();}public boolean getBoolean(char arg) {ArgumentMarshaler am = argumentMarshaler.get(arg);boolean b;try {b = am != null && (boolean) am.get();} catch (ClassCastException e) {b = false;}return b;}public String getString(char arg) {ArgumentMarshaler am = argumentMarshaler.get(arg);return am == null ? "" : (String) am.get();}public String blankIfNull(String s) {return s == null ? "" : s;}public Integer getInteger(char arg) {ArgumentMarshaler am = argumentMarshaler.get(arg);return am == null ? 0 : (Integer) am.get();}public boolean has(char arg) {return argsFound.contains(arg);}public boolean isValid() {return valid;} }

ArgumentMarshaler

package com.example.demo.args.marshaler;import com.example.demo.args.ArgsException;import java.util.Iterator;public abstract class ArgumentMarshaler {public abstract void set(Iterator<String> integerValue) throws ArgsException;public abstract Object get(); }

BooleanArgumentMarshaler

package com.example.demo.args.marshaler;import java.util.Iterator;public class BooleanArgumentMarshaler extends ArgumentMarshaler {private boolean booleanValue = false;public void set(Iterator<String> currentArgument) {booleanValue = true;}public Object get() {return booleanValue;} }

IntegerArgumentMarshaler

package com.example.demo.args.marshaler;import com.example.demo.args.ArgsException;import java.util.Iterator;public class IntegerArgumentMarshaler extends ArgumentMarshaler {private Integer integerValue;public void set(Iterator<String> currentArgument) throws ArgsException {try {this.integerValue = Integer.valueOf(currentArgument.next());} catch (NumberFormatException e) {throw new ArgsException(ArgsException.ErrorCode.INALID_INTEGER);}}public Object get() {return integerValue == null ? 0 : integerValue;} }

StringArgumentMarshaler

package com.example.demo.args.marshaler;import com.example.demo.args.ArgsException;import java.util.Iterator;public class StringArgumentMarshaler extends ArgumentMarshaler {private String stringValue;public void set(Iterator<String> currentArgument) throws ArgsException {try {this.stringValue = currentArgument.next();} catch (ArrayIndexOutOfBoundsException e) {throw new ArgsException(ArgsException.ErrorCode.MISSING_STRING);} catch (ClassCastException e) {throw new ArgsException(ArgsException.ErrorCode.INALID_STRING);}}public String get() {return stringValue == null ? "" : stringValue;} }

ArgsException

package com.example.demo.args;public class ArgsException extends Exception {private char errorArgument = '\0';private String errorParameter = "TILT";private ErrorCode errorCode = ErrorCode.OK;public ErrorCode getErrorCode() {return errorCode;}public void setErrorCode(ErrorCode errorCode) {this.errorCode = errorCode;}public ArgsException() {}public ArgsException(String message) {super(message);}public ArgsException(ErrorCode errorCode) {this.errorCode = errorCode;}public enum ErrorCode {OK, MISSING_STRING, MISSING_INTEGER,INALID_INTEGER, INALID_STRING, UNEXPECTED_ARGUMENT;} }

Args1410Test

package com.example.demo.args;import java.text.ParseException;/*** description** @author lilei* @date 2022/4/12 16:32*/ public class Args1410Test {public static void main(String[] args) throws Exception {Args1410 args1410 = null;String[] args2 = new String[]{"-b", "-s", "A", "-S", "B", "c"};try {args1410 = new Args1410("b,s*,S*", args2);} catch (ParseException e) {System.out.println(e.getMessage());}System.out.printf("usage:%s", args1410.usage());System.out.println();System.out.printf("boolean:%b", args1410.getBoolean('b'));System.out.println();System.out.printf("String:%s", args1410.getString('s'));System.out.println();System.out.printf("String:%s", args1410.getString('S'));System.out.println();System.out.printf("isValid:%s", args1410.isValid());System.out.println();System.out.printf("errorMessage:%s", args1410.errorMessage());} }

總結

以上是生活随笔為你收集整理的《代码整洁之道》第14章 逐步改进 的代码片段的全部內容，希望文章能夠幫你解決所遇到的問題。

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