[英]Problems in Database Management - sqlite with Java (IDE: NetBeans)
我在通過查詢管理數據存儲時遇到一些問題(NetBeans-> Java-> Sqlite):
線程“主”中的異常java.sql.SQLException:無法在org.sqlite.DB.executeBatch(DB.java:236)處的org.sqlite.DB.throwex(DB.java:288)打開數據庫文件。 sqlite.PrepStmt.executeBatch(PrepStmt.java:83)
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public static void main(String[] args) throws ClassNotFoundException, SQLException, IOException, InterruptedException {
Class.forName("org.sqlite.JDBC");
Connection conn = DriverManager.getConnection("jdbc:sqlite:C:/Users/.../test.db");
Statement stmt;
stmt = conn.createStatement();
stmt.executeUpdate("DROP TABLE IF EXISTS words");
stmt.executeUpdate("CREATE TABLE words (words)");
String path_dir ="C:/Users/.../good";
File currentDIR = new File("C:/Users/.../good");
File files[]=currentDIR.listFiles();
String tmp="";
ArrayList app = new ArrayList();
//Search in DIR for Files
for( File f1 : files ){
String nameFile = f1.getName();
FileReader f = null;
BufferedReader fIN = null;
String s;
//Open the file xxx.txt
try{
f = new FileReader(path_dir+"/"+nameFile);
fIN = new BufferedReader(f);
s = fIN.readLine();
while(s != null) {
StringTokenizer st = new StringTokenizer(s);
while(st.hasMoreTokens()) {
String str = st.nextToken().toString().toLowerCase();
Pattern pattern =Pattern.compile("\\W", Pattern.MULTILINE);
String newAll = pattern.matcher(str).replaceAll("").trim();
tmp=newAll;
app.add(tmp); //Add all data in the ArrayList app
} // Close While 'hasMoreTokens'
s = fIN.readLine();
} //Close While on File
} //Close TRAY
catch (FileNotFoundException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
f.close(); //Close FileReader
} //Close Scan DIR for FILE
//Add all data in the Tbl od Database
PreparedStatement prep = conn.prepareStatement("insert into words values (?);");
for (int z=0; z<app.size();z++){
prep.setString(1,app.get(z).toString().toLowerCase());
prep.addBatch();
conn.setAutoCommit(false);
prep.executeBatch(); ***//Here I get the error although i use int [] Count =prep.executeBatch();***
conn.setAutoCommit(true);
}
prep.close();
} //Close MAIN
完成使用后,需要釋放正在使用的資源。 例如,執行該語句后的prepb.close()
。
您的文件句柄也一樣。
此外,如果您對每個插入都執行該語句,則批處理的點將丟失。
由於文件非常小,您最好在將其持久化到數據庫之前准備好內存中的所有數據。
package stackoverflow.wordanalysis;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.util.regex.*;
public class WordFrequencyImporter {
public static void main(String[] args) throws Exception {
List<String> words = readWords("the-directory-from-which-to-read-the-files");
Class.forName("org.sqlite.JDBC");
Connection conn = DriverManager.getConnection("jdbc:sqlite:test.db");
try {
createWordsTable(conn);
persistWords(words, conn);
} finally {
conn.close();
}
}
private static void persistWords(List<String> words, Connection conn)
throws SQLException {
System.out.println("Persisting " + words.size() + " words");
PreparedStatement prep = conn
.prepareStatement("insert into words values (?);");
try {
for (String word : words) {
prep.setString(1, word);
prep.addBatch();
}
conn.setAutoCommit(false);
prep.executeBatch();
conn.setAutoCommit(true);
} finally {
prep.close();
}
}
private static void createWordsTable(Connection conn) throws SQLException {
Statement stmt = conn.createStatement();
try {
stmt.executeUpdate("DROP TABLE IF EXISTS words");
stmt.executeUpdate("CREATE TABLE words (words)");
} finally {
stmt.close();
}
}
private static List<String> readWords(String path_dir) throws IOException {
Pattern pattern = Pattern.compile("\\W", Pattern.MULTILINE);
List<String> words = new ArrayList<String>();
for (File file : new File(path_dir).listFiles()) {
BufferedReader reader = new BufferedReader(new FileReader(file));
System.out.println("Reading " + file);
try {
String s;
while ((s = reader.readLine()) != null) {
StringTokenizer st = new StringTokenizer(s);
while (st.hasMoreTokens()) {
String token = st.nextToken().toString().toLowerCase();
String word = pattern.matcher(token).replaceAll("")
.trim();
words.add(word);
}
}
} finally {
reader.close();
}
}
return words;
}
}
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