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java错误(未找到合适的驱动程序)_Java_Jdbc - Fatal编程技术网

java错误(未找到合适的驱动程序)

java错误(未找到合适的驱动程序),java,jdbc,Java,Jdbc,这是一个错误: public class ReportView extends JFrame { Connection con=null; void showReport() throws SQLException, ClassNotFoundException, JRException { con=DriverManager.getConnection("jdbc:postgresql://localhost:5432/Test"); JasperReport r

这是一个错误:

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);       
}
线程“main”java.sql.SQLException中的异常:未找到适合jdbc的驱动程序:postgresql://localhost:5432/Test 位于java.sql.DriverManager.getConnection(未知源) 位于java.sql.DriverManager.getConnection(未知源)
怎么了?

您是否将Postgresql驱动程序添加到了类路径中


您需要将postgreSQL JDBC驱动程序放在类路径上

有关说明,请参阅

  • 你需要在某个地方加载驱动程序<代码>Class.forName(“org.postgresql.Driver”)
  • 在程序的类路径中需要postgresql驱动程序.jar文件

  • 我不知道,但这对我来说非常有效。我在Sun和PostgreSQL 8.1本地运行JDK 1.6.021:

    Exception in thread "main" java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost:5432/Test at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source)
    为了添加更多细节,另一个问题是为什么我需要添加“Class.forName(“org.postgresql.Driver”);”,现在我知道这是必需的。
    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<String, Object>> map(ResultSet rs) throws SQLException
        {
            List<Map<String, Object>> results = new ArrayList<Map<String, Object>>();
    
            try
            {
                if (rs != null)
                {
                    ResultSetMetaData meta = rs.getMetaData();
                    int numColumns = meta.getColumnCount();
                    while (rs.next())
                    {
                        Map<String, Object> row = new HashMap<String, Object>();
                        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<Map<String, Object>> query(Connection connection, String sql, List<Object> parameters) throws SQLException
        {
            List<Map<String, Object>> results = null;
    
            PreparedStatement ps = null;
            ResultSet rs = null;
    
            try
            {
                ps = connection.prepareStatement(sql);
    
                int i = 0;
                for (Object parameter : parameters)
                {
                    ps.setObject(++i, parameter);
                }
    
                rs = ps.executeQuery();
                results = map(rs);
            }
            finally
            {
                close(rs);
                close(ps);
            }
    
            return results;
        }
    
        public static int update(Connection connection, String sql, List<Object> parameters) throws SQLException
        {
            int numRowsUpdated = 0;
    
            PreparedStatement ps = null;
    
            try
            {
                ps = connection.prepareStatement(sql);
    
                int i = 0;
                for (Object parameter : parameters)
                {
                    ps.setObject(++i, parameter);
                }
    
                numRowsUpdated = ps.executeUpdate();
            }
            finally
            {
                close(ps);
            }
    
            return numRowsUpdated;
        }
    }
    
    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