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如何用Java编写自己的库(3)

 2008-01-05 18:14:44 来源:WEB开发网   
核心提示:回忆一下,我在本文的开头,如何用Java编写自己的库(3),曾经提到过:"一个好的库必须是一个紧凑的关系紧密的整体,而不是一个分散的关系松散的对象的集合,它说明Matcher类的内部有一个指向Pattern实例的reference. this.re=regex; //int memregCount=(memr

  回忆一下,我在本文的开头,曾经提到过:"一个好的库必须是一个紧凑的关系紧密的整体,而不是一个分散的关系松散的对象的集合。"从API说明文档所显示的这个库的树形结构,并不能看出这些类之间的联系。而从源代码的角度,我们则可以清楚地看到这一点。在这一部分的讨论中,我们 也明白了两点:
  1、如何编写重载构造函数
  2、在一个类的实例中返回另外一个类的实例
  接下来,看看Matcher类。这个类实现了MatchResult interface. 看看MatchResult的定义:
  [games]$javap -classpath .. -s jregex.MatchResult
  Compiled from jregex/MatchResult.java
  public interface jregex.MatchResult
  /* ACC_SUPER bit NOT set */
  {
  public static final int MATCH;
  /* I */
  public static final int PREFIX;
  /* I */
  public static final int SUFFIX;
  /* I */
  public static final int TARGET;
  /* I */
  public abstract jregex.Pattern pattern();
  /* ()Ljregex/Pattern; */
  public abstract int groupCount();
  /* ()I */
  public abstract boolean isCaptured();
  /* ()Z */
  public abstract boolean isCaptured(int);
  /* (I)Z */
  public abstract boolean isCaptured(java.lang.String);
  /* (Ljava/lang/String;)Z */
  public abstract java.lang.String group(int);
  /* (I)Ljava/lang/String; */
  public abstract boolean getGroup(int, java.lang.StringBuffer);
  /* (ILjava/lang/StringBuffer;)Z */
  public abstract boolean getGroup(int, jregex.TextBuffer);
  /* (ILjregex/TextBuffer;)Z */
  public abstract java.lang.String group(java.lang.String);
  /* (Ljava/lang/String;)Ljava/lang/String; */
  public abstract boolean getGroup(java.lang.String, java.lang.StringBuffer);
  /* (Ljava/lang/String;Ljava/lang/StringBuffer;)Z */
  public abstract boolean getGroup(java.lang.String, jregex.TextBuffer);
  /* (Ljava/lang/String;Ljregex/TextBuffer;)Z */
  public abstract java.lang.String prefix();
  /* ()Ljava/lang/String; */
  public abstract java.lang.String suffix();
  /* ()Ljava/lang/String; */
  public abstract java.lang.String target();
  /* ()Ljava/lang/String; */
  public abstract int targetStart();
  /* ()I */
  public abstract int targetEnd();
  /* ()I */
  public abstract char targetChars()[];
  /* ()[C */
  public abstract int start();
  /* ()I */
  public abstract int end();
  /* ()I */
  public abstract int length();
  /* ()I */
  public abstract int start(int);
  /* (I)I */
  public abstract int end(int);
  /* (I)I */
  public abstract int length(int);
  /* (I)I */
  public abstract char charAt(int);
  /* (I)C */
  public abstract char charAt(int, int);
  /* (II)C */
  }
  jregex.MatchResult定义了一些abstract函数。有什么作用?在后面我们将会讨论到。
  再看看Matcher的实现。
  
  games]$javap -classpath .. -s jregex.Matcher
  Compiled from jregex/Matcher.java
  public class jregex.Matcher extends java.lang.Object implements jregex.MatchResult {
  public static final int ANCHOR_START;
  /* I */
  public static final int ANCHOR_LASTMATCH;
  /* I */
  public static final int ANCHOR_END;
  /* I */
  public static final int ACCEPT_INCOMPLETE;
  /* I */
  jregex.Matcher(jregex.Pattern);
  /* (Ljregex/Pattern;)V */
  public final void setTarget(jregex.Matcher, int);
  /* (Ljregex/Matcher;I)V */
  public void setTarget(java.lang.String);
  /* (Ljava/lang/String;)V */
  public void setTarget(java.lang.String, int, int);
  /* (Ljava/lang/String;II)V */
  public void setTarget(char[], int, int);
  /* ([CII)V */
  public final void setTarget(char[], int, int, boolean);
  /* ([CIIZ)V */
  public void setTarget(java.io.Reader, int) throws java.io.IOException;
  /* (Ljava/io/Reader;I)V */
  public final boolean isStart();
  /* ()Z */
  public final boolean matches();
  /* ()Z */
  public final boolean matches(java.lang.String);
  /* (Ljava/lang/String;)Z */
  public void setPosition(int);
  /* (I)V */
  public final boolean find();
  /* ()Z */
  public final boolean find(int);
  /* (I)Z */
  public jregex.MatchIterator findAll();
  /* ()Ljregex/MatchIterator; */
  public jregex.MatchIterator findAll(int);
  /* (I)Ljregex/MatchIterator; */
  public final boolean proceed();
  /* ()Z */
  public final boolean proceed(int);
  /* (I)Z */
  public final void skip();
  /* ()V */
  public java.lang.String toString();
  /* ()Ljava/lang/String; */
  public jregex.Pattern pattern();
  /* ()Ljregex/Pattern; */
  public java.lang.String target();
  /* ()Ljava/lang/String; */
  public char targetChars()[];
  /* ()[C */
  public int targetStart();
  /* ()I */
  public int targetEnd();
  /* ()I */
  public char charAt(int);
  /* (I)C */
  public char charAt(int, int);
  /* (II)C */
  public final int length();
  /* ()I */
  public final int start();
  /* ()I */
  public final int end();
  /* ()I */
  public java.lang.String prefix();
  /* ()Ljava/lang/String; */
  public java.lang.String suffix();
  /* ()Ljava/lang/String; */
  public int groupCount();
  /* ()I */
  public java.lang.String group(int);
  /* (I)Ljava/lang/String; */
  public java.lang.String group(java.lang.String);
  /* (Ljava/lang/String;)Ljava/lang/String; */
  public boolean getGroup(int, jregex.TextBuffer);
  /* (ILjregex/TextBuffer;)Z */
  public boolean getGroup(java.lang.String, jregex.TextBuffer);
  /* (Ljava/lang/String;Ljregex/TextBuffer;)Z */
  public boolean getGroup(int, java.lang.StringBuffer);
  /* (ILjava/lang/StringBuffer;)Z */
  public boolean getGroup(java.lang.String, java.lang.StringBuffer);
  /* (Ljava/lang/String;Ljava/lang/StringBuffer;)Z */
  public java.lang.String groups()[];
  /* ()[Ljava/lang/String; */
  public java.util.Vector groupv();
  /* ()Ljava/util/Vector; */
  public final boolean isCaptured();
  /* ()Z */
  public final boolean isCaptured(int);
  /* (I)Z */
  public final boolean isCaptured(java.lang.String);
  /* (Ljava/lang/String;)Z */
  public final int length(int);
  /* (I)I */
  public final int start(int);
  /* (I)I */
  public final int end(int);
  /* (I)I */
  public java.lang.String toString_d();
  /* ()Ljava/lang/String; */
  static {};
  /* ()V */
  
  
  先来看看它的构造函数,这个函数在Pattern中被调用用来构造Matcher类的实例。
  
  Matcher(Pattern regex){
  //注重下面这一行,它说明Matcher类的内部有一个指向Pattern实例的reference.
  this.re=regex;
  //int memregCount=(memregs=new MemReg[regex.memregs]).length;
  //for(int i=0;i // this.memregs[i]=new MemReg(-1); //unlikely to SearchEntry, in this case we know memreg indicies by d
  efinition
  //}
  //counters=new int[regex.counters];
  //int lookaheadCount=(lookaheads=new LAEntry[regex.lookaheads]).length;
  //for(int i=0;i // this.lookaheads[i]=new LAEntry();
  //}
  //定义了一些内部的数据,MemReg是一个有三个整数的类。类的声明见下。
  int memregCount,counterCount,lookaheadCount;
  if((memregCount=regex.memregs)>0){
  MemReg[] memregs=new MemReg[memregCount];
  for(int i=0;i memregs[i]=new MemReg(-1); //unlikely to SearchEntry, in this case we know memreg indicies by defin
  ition
  }
  this.m

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