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
