你的Connection變量應(yīng)該在類之中,在使用ResultSet之前不可以把Statement和Connnection不應(yīng)該關(guān),你的ResultSet不應(yīng)被返回而是直接把結(jié)果拿到 []string 內(nèi)再返回import java.util.Arrays;

import java.lang.*;

import java.sql.*;

public class DatabaseConnectorTest {

private Connection connection = null;

private Statement statement = null;

public void connect(String connString) throws SQLException {

try {

Class.forName("org.sqlite.JDBC");

connection = DriverManager.getConnection(connString,"root", "root");

} catch (SQLException e) {

System.err.print("connect SQLException: ");

System.err.println(e.getMessage());

} catch (ClassNotFoundException e) {

System.err.print("ClassNotFoundException: ");

System.err.println(e.getMessage());

}

}

public String[] getUserName(String connString, String SQLString) {

ResultSet rs = null;

try {

if(null == connection)

connect(connString);

if(null == statement)

statement = connection.createStatement();

rs = statement.executeQuery(SQLString);

int rowcount = 0;

int i = 1;

while(rs.next()) {

rowcount = i++;

}

String[] retArray = new String[rowcount];

i=0;

rs = statement.executeQuery(SQLString);

while (rs.next()) {

retArray[i++] = rs.getString("user_name");

}

return retArray;

} catch (SQLException e ) {

System.err.print("getUserName SQLException: ");

System.err.println(e.getMessage());

} finally {

if (statement != null) {

try { statement.close(); }

catch(SQLException e) {

System.err.print("getUserName Final SQLException: ");

System.err.println(e.getMessage());

}

}

}

return null;

}

public static void main(String[] agrs){

String connString = "jdbc:sqlite:/tmp/test.db"; <<<< 用你自己的

String SQLString = "SELECT user_name FROM users";

DatabaseConnectorTest db = new DatabaseConnectorTest();

String[] user_name = db.getUserName(connString, SQLString);

System.out.println(Arrays.toString(user_name));

}

}

總結(jié)

以上是生活随笔為你收集整理的java sqlite3查询慢_java连接数据库进行查询优化跑不通谁能帮我调下通的全部?jī)?nèi)容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網(wǎng)站內(nèi)容還不錯(cuò)，歡迎將生活随笔推薦給好友。