我在Heroku上部署了一个应用程序，它与Heroku数据库连接并执行简单的CRUD操作。
所以我写了以下程序： -
package com.auro.assignment.wallpostapi;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.URI;
import java.net.URISyntaxException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;
import java.util.Map;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
@Path("post_query")
public class PostQuery {
// private static final String DATABASE_URL = "DATABASE_URL";
// private static final String JDBC_POSTGRE = "jdbc:postgresql://" ;
private static final String JDBC_DATABASE_URL = "JDBC_DATABASE_URL";
private static final String POSTGRES_JDBC_DRIVER_NAME = "org.postgresql.Driver";
private String errorMessage = null;
public PostQuery() {
}
@GET
@Produces(MediaType.TEXT_PLAIN)
public String getPostedMessage() {
String[] array = new String[2];
String response = null;
Connection connection = null;
try {
connection = getConnection();
} catch (URISyntaxException e) {
e.printStackTrace();
}
if (connection != null) {
try {
Statement statement = connection.createStatement();
String sql = "DROP TABLE IF EXISTS user_info;";
statement.executeQuery(sql);
String sqlCreate = "CREATE TABLE user_info (user_id SERIAL PRIMARY KEY NOT NULL, user_name VARCHAR(30) NOT NULL, user_email VARCHAR(50) NOT NULL);";
// "CREATE TABLE userinfo" +
// "(user_id INT PRIMARY KEY NOT NULL AUTO_INCREMENT," +
// "user_name VARCHAR(30) NOT NULL," +
// "user_email VARChar(30) NOT NULL);";
PreparedStatement preparedStatement = connection.prepareStatement(sqlCreate);
errorMessage = String.valueOf(preparedStatement.execute());
String sqlInsert =
"INSERT INTO user_info (user_name, user_email) " +
"VALUES (\"AURO BAN ARI\",\" xyz.123@test.com\");";
statement.executeUpdate(sqlInsert);
String sqlQuery = "SELECT * FROM user_info;";
ResultSet resultSet = statement.executeQuery(sqlQuery);
statement.close();
connection.close();
errorMessage = String.valueOf(resultSet.wasNull());
while (resultSet.next()) {
response = resultSet.getString("user_id") +
resultSet.getString("user_name") +
resultSet.getString("user_email");
}
return response;
} catch (SQLException e) {
errorMessage = e.getMessage() + " -- " + e.toString() + " -- " + e.getErrorCode();
StringWriter stringWriter = new StringWriter();
PrintWriter printWriter = new PrintWriter(stringWriter);
e.printStackTrace(printWriter);
String stackTrace = stringWriter.toString();
errorMessage = stackTrace;
}
}
return "Oopsie Daisy" + errorMessage;
}
private Connection getConnection() throws URISyntaxException {
Connection connection = null;
try {
Class.forName(POSTGRES_JDBC_DRIVER_NAME);
} catch (ClassNotFoundException e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
final String dbURL = System.getenv(JDBC_DATABASE_URL);
try {
connection = DriverManager.getConnection(dbURL);
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
// public
//
// @GET
// @Produces(MediaType.TEXT_PLAIN)
// public String getPosts() {
//
// Connection conn = null;
// try {
// conn = tryAndConnectToDB();
// } catch (SQLException e) {
// connectionMsg = e.getMessage();
// } catch (URISyntaxException e) {
// connectionMsg = e.getMessage();
// e.printStackTrace();
// }
//
// if (conn != null)
// try {
// return "Oops!! No posts made yet!!" + conn.getSchema();
// } catch (SQLException e) {
// e.printStackTrace();
// }
// return connectionMsg;
// }
//
// private static Connection tryAndConnectToDB() throws URISyntaxException, SQLException {
//
// try {
// Class.forName(";");
// }
// catch (ClassNotFoundException e) {
//
// System.out.println(e.getMessage());
// connectionMsg = e.getMessage();
// }
//
// final String dbUrl = System.getenv(JDBC_DATABASE_URL);
//
// //URI dbURI = new URI(System.getenv(DATABASE_URL));
//
//// final String userName = dbURI.getUserInfo().split(":")[0];
//// final String userPassword = dbURI.getUserInfo().split(":")[1];
////
//// final String dbURL = JDBC_POSTGRE + dbURI.getHost() + ":" + dbURI.getPort() + dbURI.getPath();
//
// // return DriverManager.getConnection(dbURL,userName,userPassword);
//
// return DriverManager.getConnection(dbUrl);
//
//
// }
//
}
当我使用executeQuery语句执行SELECT时，它会返回以下异常： -
org.postgresql.util.PSQLException: No results were returned by the query.
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:287)
at com.auro.assignment.wallpostapi.PostQuery.getPostedMessage(PostQuery.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:205)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)