(File path, Analyzer a, boolean create)
IndexWriter(String path, Analyzer a, boolean create)
可见构造它需要一个索引文件目录，一个分析器(一般用标准的这个)，最后一个参数是标识是否清空索引目录
它有一些设置参数的功能如：设置Field的最大长度
看个例子：
[code]
public void IndexMaxField() throws IOException
{
        IndexWriter indexWriter= new IndexWriter("c:\\index",new StandardAnalyzer(),true);
        Document doc1 = new Document();
        doc1.add(new Field("name1","程序员之家",Field.Store.YES,Field.Index.TOKENIZED));
        Document doc2 = new Document();
        doc2.add(new Field("name2","Welcome to the Home of programers",Field.Store.YES,Field.Index.TOKENIZED));
        indexWriter.setMaxFieldLength(5);
        indexWriter.addDocument(doc1);
        indexWriter.setMaxFieldLength(3);
        indexWriter.addDocument(doc1);
        indexWriter.setMaxFieldLength(0);
        indexWriter.addDocument(doc2);
        indexWriter.setMaxFieldLength(3);
        indexWriter.addDocument(doc2);
        indexWriter.close();
}
public void SearcherMaxField() throws ParseException, IOException
{
        Query query = null;
        Hits hits = null;
        IndexSearcher indexSearcher= null;
        QueryParser queryParser= null;
        queryParser = new QueryParser("name1",new StandardAnalyzer());
        query = queryParser.parse("程序员");
        indexSearcher= new IndexSearcher("c:\\index");
        hits = indexSearcher.search(query);
        System.out.println("您搜的是：程序员");
        System.out.println("找到了"+hits.length()+"个结果");
        System.out.println("它们分别是：");
        for (int i = 0; i < hits.length(); i++)
        {
            Document doc = hits.doc(i);
            System.out.println(doc.get("name1"));
        }
        query = queryParser.parse("程序员之家");
        indexSearcher= new IndexSearcher("c:\\index");
        hits = indexSearcher.search(query);
        System.out.println("您搜的是：程序员之家");
        System.out.println("找到了"+hits.length()+"个结果");
        System.out.println("它们分别是：");
        for (int i = 0; i < hits.length(); i++)
        {
            Document doc = hits.doc(i);
            System.out.println(doc.get("name1"));
        }
        queryParser = new QueryParser("name2",new StandardAnalyzer());
        query = queryParser.parse("Welcome");
        indexSearcher= new IndexSearcher("c:\\index");
        hits = indexSearcher.search(query);
        System.out.println("您搜的是：Welcome");
        System.out.println("找到了"+hits.length()+"个结果");
        System.out.println("它们分别是：");
        for (int i = 0; i < hits.length(); i++)
        {
            Document doc = hits.doc(i);
            System.out.println(doc.get("name2"));
        }           
        query = queryParser.parse("the");
        indexSearcher= new IndexSearcher("c:\\index");
        hits = indexSearcher.search(query);
        System.out.println("您搜的是：the");
        System.out.println("找到了"+hits.length()+"个结果");
        System.out.println("它们分别是：");
        for (int i = 0; i < hits.length(); i++)
        {
            Document doc = hits.doc(i);
            System.out.println(doc.get("name2"));
        }
        query = queryParser.parse("home");
        indexSearcher= new IndexSearcher("c:\\index");
        hits = indexSearcher.search(query);
        System.out.println("您搜的是：home");
        System.out.println("找到了"+hits.length()+"个结果");
        System.out.println("它们分别是：");
        for (int i = 0; i < hits.length(); i++)
        {
            Document doc = hits.doc(i);
            System.out.println(doc.get("name2"));
        }
}
[/code]
它的运行结果为:
总结一下：
1.设置Field的长度限制只是限制了搜索。如果用了Field.Store.YES的话还是会
全部被保存进索引目录里的。
2.为什么搜the没有搜出来呢是因为lucene分析英文的时候不会搜索the to of 等无
用的词(搜这些词是无意义的)。
3.New StandardAnlayzer()对于英文的分词是按空格和一些无用的词，而中文呢是全部的单个
的字。
4.设置Field的最大长度是以0开头和数组一样。
程序员之家----------3--------程序员之
                                    0 1 2  3
Welcome to the home of programmers------3------Welcome to the home of programmers

                                                   0           1         2
大家还可以试一下别的，以便加深一下印象
(未完)