你怎么读＆amp;从包含[x，y，z]形式的数据的文本文件中插入行，例如：
1 google com（由标签分隔）
进入数据库表（无需手动插入每一行）？
我是编程新手！
感谢您的时间，并帮助善良的先生和女士们！
import java.sql.*;
import java.util.Scanner;
import java.io.*;
public class Database {
public static Connection connectToDatabase(String user, String port, String database) {
System.out.println("-------- PostgreSQL " + "JDBC Connection Testing ------------");
try {
Class.forName("org.postgresql.Driver");
} catch (ClassNotFoundException e) {
System.out.println("Where is your PostgreSQL JDBC Driver? " + "Include in your library path!");
e.printStackTrace();
}
System.out.println("PostgreSQL JDBC Driver Registered!");
Connection connection = null;
try {
connection = DriverManager.getConnection("jdbc:postgresql://localhost:" + port + "/" + database, user,
"doesn't matter!");
} catch (SQLException e) {
System.out.println("Connection Failed! Check output console");
e.printStackTrace();
}
return connection;
}
public static ResultSet executeSelect(Connection connection, String query) {
Statement st = null;
try {
st = connection.createStatement();
} catch (SQLException e) {
e.printStackTrace();
return null;
}
ResultSet rs = null;
try {
rs = st.executeQuery(query);
st.close();
} catch (SQLException e) {
e.printStackTrace();
return null;
}
return rs;
}
public static void dropTable(Connection connection, String table) {
Statement st = null;
try {
st = connection.createStatement();
st.execute("DROP TABLE " + table);
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void createTable(Connection connection, String tableDescription) {
Statement st = null;
try {
st = connection.createStatement();
st.execute("CREATE TABLE " + tableDescription);
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static int insertIntoTableFromFile(Connection connection, String table, String file) {
BufferedReader br = null;
int numRows = 0;
try {
Statement st = connection.createStatement();
String sCurrentLine, brokenLine[], composedLine = "";
br = new BufferedReader(new FileReader(file));
while ((sCurrentLine = br.readLine()) != null) {
// Insert each line to the DB
brokenLine = sCurrentLine.split("\t");
composedLine = "INSERT INTO dotcom VALUES (";
int i;
for (i = 0; i < brokenLine.length - 1; i++) {
composedLine += "'" + brokenLine[i] + "',";
}
composedLine += "'" + brokenLine[i] + "')";
numRows = st.executeUpdate(composedLine);
}
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (br != null)
br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
return numRows;
}
public static void main(String[] argv) throws SQLException, FileNotFoundException {
@SuppressWarnings("resource")
Scanner input = new Scanner(System.in);
System.out.println("Please enter your Username:");
String user = input.next();
System.out.println("Please enter your Port ID:");
String port = input.next();
String database = "test";
Connection connection = connectToDatabase(user, port, database);
Statement st = connection.createStatement();
if (connection != null) {
System.out.println("You made it, take control your database now!");
} else {
System.out.println("Failed to make connection!");
return;
}
// Now we're ready to work on the DB
// read TopURLs file
try {
BufferedReader fileReader = new BufferedReader(new FileReader("TopURLs"));
while (fileReader.readLine() != null) {
st.execute("DROP TABLE IF EXISTS dotcom;");
st.execute("CREATE TABLE dotcom (rank integer PRIMARY KEY, domainName varchar(128), domainType varchar(128));");
st.execute("INSERT INTO dotcom VALUES(1, 'google', 'com');");
//st.execute("INSERT INTO dotcom VALUES(2, 'facebook', 'com');");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
}
/*
try {
BufferedReader fileReader = new BufferedReader(new FileReader("TopURLs"));
while (fileReader.readLine() != null) {
st.execute("DROP TABLE IF EXISTS dotcom;");
st.execute("CREATE TABLE dotcom (rank integer PRIMARY KEY, domainName varchar(128), domainType varchar(128));");
st.execute("INSERT INTO dotcom SELECT com, domainType FROM dotcom WHERE domainType = 'com'");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
}
*/
/*
Statement createStatement = null;
PreparedStatement insertStatement = null;
try {
BufferedReader fileReader = new BufferedReader(new FileReader("TopURLs"));
String line = null;
createStatement = connection.createStatement();
createStatement.executeUpdate("DROP TABLE IF EXISTS dotcom");
createStatement.executeUpdate("CREATE TABLE dotcom (rank integer PRIMARY KEY, domainName varchar(128), domainType varchar(128))");
connection.setAutoCommit(false);//commit whole batch at the end
insertStatement = connection.prepareStatement("INSERT INTO dotcom VALUES (?, ?, ?)");
while ( (line = fileReader.readLine()) != null) {
line = fileReader.readLine();
String[] urls = line.split("\t");//space or any other delimiter that you're using
insertStatement.setInt(1, Integer.parseInt(urls[0]));
insertStatement.setString(2, urls[1]);
insertStatement.setString(3, urls[2]);
//insertStatement.setString(4, urls[3]);
insertStatement.addBatch();
}
insertStatement.executeBatch();
connection.commit();
} catch (IOException e) {
e.printStackTrace();
} finally {
if(connection != null) {
connection.setAutoCommit(true);
}
if(createStatement != null) {
createStatement.close();
}
if(insertStatement != null) {
insertStatement.close();
}
}
*/
// connection is of type Connection (in JDBC)
DatabaseMetaData dbm = connection.getMetaData();
// check if table is there
ResultSet tables = dbm.getTables(null, null, "table name", null);
if (tables.next()) {
System.out.println("Table exists");
} else {
System.out.println("Table does not exist");
}
// check if view is there?
//"create view foo as select * from table;"
//"select * from foo;"
ResultSet views = dbm.getTables("catalog name", null, null, null);
if (views.next()) {
System.out.println("View exists");
} else {
System.out.println("View does not exist");
}
String query = "SELECT * FROM internet";
ResultSet rs = executeSelect(connection, query);
try {
while (rs.next()) {
System.out.print("Column 1 returned ");
System.out.println(rs.getString(1));
}
} catch (SQLException e) {
e.printStackTrace();
}
rs.close();
dropTable(connection, "dotcom");
createTable(connection,
"dotcom (id int primary key, name varchar(15), type varchar(15));");
int rows = insertIntoTableFromFile(connection, "dotcom", "TopURLs");
System.out.println(rows + " rows inserted.");
}
}
答案 0 :(得分：0)
评论太长了。
从文本文件加载数据时，我通常会加载到由字符列组成的临时表中。然后，我可以验证数据，转换为适当的数据类型，甚至在必要时重新分析一些列。
不可否认，Postgres COPY命令通常只能读取数据。
您似乎有两种选择：
因为我的SQL技能＆gt;＆gt;我的java技能，我会选择（SQL）。但这些似乎是你最合理的选择。