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用 lucene 建立索引不可能每次都重新开始建立,而是按照新增加的记录,一次次的递增
建立索引的IndexWriter类,有三个参数
IndexWriter writer = new IndexWriter(path, new StandardAnalyzer(),isEmpty);
其中第三个参数是bool型的,指定它可以确定是增量索引,还是重建索引.
对于从数据库中读取的记录,譬如要为文章建立索引,我们可以记录文章的id号,然后下次再次建立索引的时候读取存下的id号,从此id后往下继续增加索引,逻辑如下.
建立增量索引,主要代码如下
public void createIndex(String path)
{
Statement myStatement = null;
String articleId="0";
//读取文件,获得文章id号码,这里只存最后一篇索引的文章id
try {
FileReader fr = new FileReader("**.txt");
BufferedReader br = new BufferedReader(fr);
articleId=br.readLine();
if(articleId==null||articleId=="")
articleId="0";
br.close();
fr.close();
} catch (IOException e) {
System.out.println("error343!");
e.printStackTrace();
}
try {
//SQL语句,根据id读取下面的内容
String SQLText = "*****"+articleId;
myStatement = conn.createStatement();
ResultSet rs = myStatement.executeQuery(sqlText);
//写索引
while (rs.next()) {
Document doc = new Document();
doc.add(Field.Keyword("**", DateAdded));
doc.add(Field.Keyword("**", articleid));
doc.add(Field.Text("**", URL));
doc.add(Field.Text("**", Content));
doc.add(Field.Text("**", Title));
try{
writer.addDocument(doc);
}
catch(IOException e){
e.printStackTrace();
}
//将我索引的最后一篇文章的id写入文件
try {
FileWriter fw = new FileWriter("**.txt");
PrintWriter out = new PrintWriter(fw);
out.close();
fw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
ind.Close();
System.out.println("ok.end");
}
catch (SQLException e){
e.printStackTrace();
}
finally {
//数据库关闭操作
}
}
{
Statement myStatement = null;
String articleId="0";
//读取文件,获得文章id号码,这里只存最后一篇索引的文章id
try {
FileReader fr = new FileReader("**.txt");
BufferedReader br = new BufferedReader(fr);
articleId=br.readLine();
if(articleId==null||articleId=="")
articleId="0";
br.close();
fr.close();
} catch (IOException e) {
System.out.println("error343!");
e.printStackTrace();
}
try {
//SQL语句,根据id读取下面的内容
String SQLText = "*****"+articleId;
myStatement = conn.createStatement();
ResultSet rs = myStatement.executeQuery(sqlText);
//写索引
while (rs.next()) {
Document doc = new Document();
doc.add(Field.Keyword("**", DateAdded));
doc.add(Field.Keyword("**", articleid));
doc.add(Field.Text("**", URL));
doc.add(Field.Text("**", Content));
doc.add(Field.Text("**", Title));
try{
writer.addDocument(doc);
}
catch(IOException e){
e.printStackTrace();
}
//将我索引的最后一篇文章的id写入文件
try {
FileWriter fw = new FileWriter("**.txt");
PrintWriter out = new PrintWriter(fw);
out.close();
fw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
ind.Close();
System.out.println("ok.end");
}
catch (SQLException e){
e.printStackTrace();
}
finally {
//数据库关闭操作
}
}
然后控制是都建立增量索引的时候根据能否都到id值来设置IndexWriter的第三个参数为true 或者是false
boolean isEmpty = true;
try {
FileReader fr = new FileReader("**.txt");
BufferedReader br = new BufferedReader(fr);
if(br.readLine()!= null) {
isEmpty = false;
}
br.close();
fr.close();
} catch (IOException e) {
e.printStackTrace();
}
writer = new IndexWriter(Directory, new StandardAnalyzer(),isEmpty);
try {
FileReader fr = new FileReader("**.txt");
BufferedReader br = new BufferedReader(fr);
if(br.readLine()!= null) {
isEmpty = false;
}
br.close();
fr.close();
} catch (IOException e) {
e.printStackTrace();
}
writer = new IndexWriter(Directory, new StandardAnalyzer(),isEmpty);
