java错误（找不到合适的驱动程序）

public class ReportView extends JFrame { Connection con=null; void showReport() throws SQLException, ClassNotFoundException, JRException { con=DriverManager.getConnection("jdbc:postgresql://localhost:5432/Test"); JasperReport report=JasperCompileManager.compileReport("Testing.jrxml"); JasperPrint print=JasperFillManager.fillReport(report,null,con); JRViewer viewer=new JRViewer(print); viewer.setOpaque(true); viewer.setVisible(true); this.add(viewer); this.setSize(300, 200); this.setVisible(true); this.setDefaultCloseOperation(EXIT_ON_CLOSE); } 

这是错误：

线程“main”java.sql.SQLException中的exception：没有为jdbc找到合适的驱动程序：postgresql：// localhost：5432 / Test
     at java.sql.DriverManager.getConnection（Unknown Source）
     at java.sql.DriverManager.getConnection（Unknown Source）

怎么了？

Answer 1

1. 你需要在某个地方加载驱动程序。 Class.forName("org.postgresql.Driver");
2. 您将需要程序的类路径中的postgresql驱动程序.jar文件。

Answer 2

您需要将postgreSQL JDBC驱动程序放在类路径上。

有关说明 ，请参阅官方文档 。

Answer 3

你有没有将Postgresql驱动程序添加到类路径中？

http://jdbc.postgresql.org/

Answer 4

我不知道，但这对我来说非常合适。 我在本地运行Sun和PostgreSQL 8.1的JDK 1.6.0_21：

 package persistence; import java.sql.*; import java.util.*; /** * util.DatabaseUtils * User: Michael * Date: Aug 17, 2010 * Time: 7:58:02 PM */ public class DatabaseUtils { private static final String DEFAULT_DRIVER = "org.postgresql.Driver"; private static final String DEFAULT_URL = "jdbc:postgresql://localhost:5432/party"; private static final String DEFAULT_USERNAME = "pgsuper"; private static final String DEFAULT_PASSWORD = "pgsuper"; /* private static final String DEFAULT_DRIVER = "com.mysql.jdbc.Driver"; private static final String DEFAULT_URL = "jdbc:mysql://localhost:3306/party"; private static final String DEFAULT_USERNAME = "party"; private static final String DEFAULT_PASSWORD = "party"; */ public static void main(String[] args) { long begTime = System.currentTimeMillis(); String driver = ((args.length > 0) ? args[0] : DEFAULT_DRIVER); String url = ((args.length > 1) ? args[1] : DEFAULT_URL); String username = ((args.length > 2) ? args[2] : DEFAULT_USERNAME); String password = ((args.length > 3) ? args[3] : DEFAULT_PASSWORD); Connection connection = null; try { connection = createConnection(driver, url, username, password); DatabaseMetaData meta = connection.getMetaData(); System.out.println(meta.getDatabaseProductName()); System.out.println(meta.getDatabaseProductVersion()); String sqlQuery = "SELECT PERSON_ID, FIRST_NAME, LAST_NAME FROM PERSON ORDER BY LAST_NAME"; System.out.println("before insert: " + query(connection, sqlQuery, Collections.EMPTY_LIST)); connection.setAutoCommit(false); String sqlUpdate = "INSERT INTO PERSON(FIRST_NAME, LAST_NAME) VALUES(?,?)"; List parameters = Arrays.asList( "Foo", "Bar" ); int numRowsUpdated = update(connection, sqlUpdate, parameters); connection.commit(); System.out.println("# rows inserted: " + numRowsUpdated); System.out.println("after insert: " + query(connection, sqlQuery, Collections.EMPTY_LIST)); } catch (Exception e) { rollback(connection); e.printStackTrace(); } finally { close(connection); long endTime = System.currentTimeMillis(); System.out.println("wall time: " + (endTime - begTime) + " ms"); } } public static Connection createConnection(String driver, String url, String username, String password) throws ClassNotFoundException, SQLException { Class.forName(driver); if ((username == null) || (password == null) || (username.trim().length() == 0) || (password.trim().length() == 0)) { return DriverManager.getConnection(url); } else { return DriverManager.getConnection(url, username, password); } } public static void close(Connection connection) { try { if (connection != null) { connection.close(); } } catch (SQLException e) { e.printStackTrace(); } } public static void close(Statement st) { try { if (st != null) { st.close(); } } catch (SQLException e) { e.printStackTrace(); } } public static void close(ResultSet rs) { try { if (rs != null) { rs.close(); } } catch (SQLException e) { e.printStackTrace(); } } public static void rollback(Connection connection) { try { if (connection != null) { connection.rollback(); } } catch (SQLException e) { e.printStackTrace(); } } public static List> map(ResultSet rs) throws SQLException { List> results = new ArrayList>(); try { if (rs != null) { ResultSetMetaData meta = rs.getMetaData(); int numColumns = meta.getColumnCount(); while (rs.next()) { Map row = new HashMap(); for (int i = 1; i <= numColumns; ++i) { String name = meta.getColumnName(i); Object value = rs.getObject(i); row.put(name, value); } results.add(row); } } } finally { close(rs); } return results; } public static List> query(Connection connection, String sql, List 

这是结果：

 PostgreSQL 8.1.3 before insert: [{first_name=Foo, person_id=55, last_name=Bar}, {first_name=Foo, person_id=52, last_name=Bar}, {first_name=Foo, person_id=53, last_name=Bar}, {first_name=Foo, person_id=54, last_name=Bar}, {first_name=Foo, person_id=56, last_name=Bar}, {first_name=SEAMUS, person_id=2, last_name=DUFFY}, {first_name=MICHAEL, person_id=1, last_name=DUFFY}] # rows inserted: 1 after insert: [{first_name=Foo, person_id=56, last_name=Bar}, {first_name=Foo, person_id=52, last_name=Bar}, {first_name=Foo, person_id=53, last_name=Bar}, {first_name=Foo, person_id=54, last_name=Bar}, {first_name=Foo, person_id=55, last_name=Bar}, {first_name=Foo, person_id=57, last_name=Bar}, {first_name=SEAMUS, person_id=2, last_name=DUFFY}, {first_name=MICHAEL, person_id=1, last_name=DUFFY}] wall time: 344 ms