如何从Java连接到我的Heroku PostgreSQL数据库

Question

我有一个Heroku PostgreSQL数据库，无法从Java连接到该数据库。 我尝试了不同的方法，但没有成功。

下面是我的Java代码：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;



public class MainConfig {

    public static void main(String[] args) {

     try{
         dataSource();
         System.out.println("conected");
     }
    catch(Exception ex){
        ex.printStackTrace();
    }
    }

    public static Connection dataSource() throws URISyntaxException, SQLException {

        String ConnectionString ="jdbc:postgresql://l********n:cPd7VRjIhNVWOrZ4uWEeZWKYqV@ec2-184-73-251-115.compute-1.amazonaws.com:5432/dac36a93ohuvsd";
        String username = "****";
        String password = "***";

        return DriverManager.getConnection(ConnectionString, username, password);
    }

}

我在控制台中得到的错误是：

> org.postgresql.util.PSQLException: The connection attempt failed.
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:233)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:64)
    at org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:144)
    at org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:29)
    at org.postgresql.jdbc3g.AbstractJdbc3gConnection.<init>(AbstractJdbc3gConnection.java:21)
    at org.postgresql.jdbc4.AbstractJdbc4Connection.<init>(AbstractJdbc4Connection.java:31)
    at org.postgresql.jdbc4.Jdbc4Connection.<init>(Jdbc4Connection.java:24)
    at org.postgresql.Driver.makeConnection(Driver.java:410)
    at org.postgresql.Driver.connect(Driver.java:280)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at MainConfig.dataSource(MainConfig.java:34)
    at MainConfig.main(MainConfig.java:14)
Caused by: java.net.UnknownHostException: lxlrnhejlzmyun:cPd7VRjIhNVWOrZ4uWEeZWKYqV@ec2-184-73-251-115.compute-1.amazonaws.com
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at org.postgresql.core.PGStream.<init>(PGStream.java:61)
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:109)
    ... 12 more

我已将Java驱动程序postgresql-9.3-1102.jdbc41.jar添加到构建路径中

下面用错误消息描述了我尝试连接的另一种方法：

    import java.net.URI;
import java.net.URISyntaxException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;



public class MainConfig {

    public static void main(String[] args) {

     try{
         dataSource();
         System.out.println("conected");
     }
    catch(Exception ex){
        ex.printStackTrace();
    }
    }

    public static Connection dataSource() throws URISyntaxException, SQLException {
        URI dbUri = new URI(System.getenv("postgres://l**********n:cPd7VRjIhNVWOrZ4uWEeZWKYqV@ec2-184-73-251-115.compute-1.amazonaws.com:5432/dac36a93ohuvsd"));

        String username = dbUri.getUserInfo().split(":")[0];
        String password = dbUri.getUserInfo().split(":")[1];
        String ConnectionString = "jdbc:postgresql://" + dbUri.getHost() + ':' + dbUri.getPort() + dbUri.getPath();



        return DriverManager.getConnection(ConnectionString, username, password);
    }

}

错误

> java.lang.NullPointerException
    at java.net.URI$Parser.parse(Unknown Source)
    at java.net.URI.<init>(Unknown Source)
    at MainConfig.dataSource(MainConfig.java:23)
    at MainConfig.main(MainConfig.java:14)

我做错了什么？

Answer 1

为了连接到heroku的PostgreSQL（带有必需的ssl），您必须将以下内容附加到url：

?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory

因此，以上答案中提供的正确网址是：

jdbc:postgresql://host:port/database?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory

没有这些边界，您将得到描述的错误：

error: no pg_hba.conf entry for host 

Answer 2

格式应为： jdbc:postgresql://host:port/database ，而在您的代码中，请注意几个“：” jdbc:postgresql://l********n:cPd7VRjIhNVWOrZ4uWEeZWKYqV@ec2-184-73-251-115.compute-1.amazonaws.com:5432/dac36a93ohuvsd"

Answer 3

您的网址应类似于-jdbc：postgresql：// hostname：port / dbname？sslmode = require

复制heroku站点中提到的主机名（主机）端口和数据库名（数据库）

不要忘记在URL中附加？sslmode = require，否则您将无法连接