创建一个后端 java RESTful API 将与存储在云端的数据库进行通信
Creating a backend java RESTful API that will communicate with a database stored on the cloud
我目前正在学习 Java EE，我被要求开发一个后端 RESTful Java API 将与存储在云解决方案上的数据库进行通信（IBM Bluemix）。
我目前使用 Eclipse Photon 作为 IDE，我不是计算机的管理员用户。
我被要求使用 IBM Was Liberty 服务器插件测试我的代码，但我在设置服务器时遇到了一些问题。我想我可能不明白插件是如何工作的，不能让它像我想要的那样工作。
问题是我无法访问存储在该服务器上的数据库，无论是我的 api 还是管理中心（甚至无法登录管理中心）。
这是我使用（修改过）并在 this site
上找到的 java 代码
package connection;
//STEP 1. Import required packages
import java.sql.*;
public class FirstExample {
// JDBC driver name and database URL
static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3306/ibm/api/validator/dataSource/SAMPLEDB";
// Database credentials
static final String USER = "admin";
static final String PASS = "admin";
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try{
//STEP 2: Register JDBC driver
Class.forName(JDBC_DRIVER);
//STEP 3: Open a connection
System.out.println("Connecting to database...");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
//STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql;
sql = "SELECT * FROM *";
ResultSet rs = stmt.executeQuery(sql);
//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
String data = rs.getString("last");
//Display values
System.out.println("Data Retreived " + data);
}
//STEP 6: Clean-up environment
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
//Handle errors for JDBC
System.out.println("\nJDBC ERROR ! \n");
se.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
System.out.println("\nClass.forName ERROR ! \n");
e.printStackTrace();
}finally{
//finally block used to close resources
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){
System.out.println("\nSQL ERROR ! NOTHING TO DO \n");
}// nothing we can do
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
System.out.println("\nJDBC ERROR ! MAYBE SOMETHING TO DO \n");
se.printStackTrace();
}//end finally try
}//end try
System.out.println("\nGoodbye!");
}//end main
}//end FirstExample
至于我的 Server.xml 这是更新后的代码：
<server description="Liberty beta">
<featureManager>
<feature>webProfile-8.0</feature>
<feature>adminCenter-1.0</feature>
<feature>restConnector-2.0</feature>
<feature>transportSecurity-1.0</feature>
<feature>logstashCollector-1.1</feature>
<feature>validator-1.0</feature>
<feature>mpConfig-1.3</feature>
<feature>mpFaultTolerance-1.1</feature>
<feature>mpHealth-1.0</feature>
<feature>mpJwt-1.0</feature>
<feature>mpMetrics-1.1</feature>
<feature>mpOpenAPI-1.0</feature>
<feature>mpOpenTracing-1.0</feature>
<feature>mpRestClient-1.0</feature>
<feature>localConnector-1.0</feature>
<feature>jdbc-4.2</feature>
</featureManager>
<httpEndpoint id="defaultHttpEndpoint"
host="*"
httpPort="9080"
httpsPort="9443" />
<applicationManager autoExpand="true"/>
<keyStore id="defaultKeyStore"
password="Liberty" />
<basicRegistry id="userReg">
<user password="admin"
name="admin"
id="admin"></user>
</basicRegistry>
<administrator-role>
<user>admin</user>
</administrator-role>
<remoteFileAccess>
<writeDir>${server.config.dir}</writeDir>
</remoteFileAccess>
<dataSource id="DefaultDataSource" jndiName="jdbc/mySQL">
<jdbcDriver libraryRef="MySQLLib" />
<properties.microsoft.sqlserver databaseName="SAMPLEDB" serverName="localhost" portNumber="3306" user="admin" password="admin"/>
<connectionManager></connectionManager>
</dataSource>
<library id="MySQLLib">
<file name="C:/PUBLIC/tools/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12.jar" />
</library>
</server>
我现在遇到的问题是我似乎无法与我的服务器通信。
这是控制台错误：
Connecting to database...
JDBC ERROR !
Goodbye!
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:832)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at connection.FirstExample.main(FirstExample.java:23)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91)
at com.mysql.cj.NativeSession.connect(NativeSession.java:152)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:952)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:822)
... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:173)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65)
... 9 more
作为初学者，我试图盲目地遵循网上找到的教程，并没有想太多我到底在做什么。
我不明白 Was Liberty 不像设置一个包含您想要的服务的 VM，而且在 Liberty 中设置一个数据源 不是设置一个数据库。
由于缺乏信息、指导和严谨性，我在创建数据源时认为 Liberty 服务器实际上是 运行 一个 mySQL 服务器。事实上（如果我错了请纠正我）这部分代码，
<dataSource id="DefaultDataSource" jndiName="jdbc/mySQL">
<jdbcDriver libraryRef="MySQLLib" />
<properties.microsoft.sqlserver databaseName="SAMPLEDB"
serverName="localhost"
portNumber="3306"
user="admin"
password="admin"/>
<connectionManager></connectionManager>
</dataSource>
<library id="MySQLLib">
<file name="C:/PUBLIC/tools/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12.jar" />
</library>
旨在使用足够的驱动程序在服务器中设置服务以连接到您的远程数据库。在这种情况下，我设置了一个带有 mySQL 驱动程序的数据源。
当我使用 运行 本地 mySQL 服务器时，我能够通过我的 java 应用程序进行通信和发送查询。
感谢那些花时间阅读本文 post 并试图帮助我的人。
我目前正在学习 Java EE，我被要求开发一个后端 RESTful Java API 将与存储在云解决方案上的数据库进行通信（IBM Bluemix）。
我目前使用 Eclipse Photon 作为 IDE，我不是计算机的管理员用户。
我被要求使用 IBM Was Liberty 服务器插件测试我的代码，但我在设置服务器时遇到了一些问题。我想我可能不明白插件是如何工作的，不能让它像我想要的那样工作。
问题是我无法访问存储在该服务器上的数据库，无论是我的 api 还是管理中心（甚至无法登录管理中心）。
这是我使用（修改过）并在 this site
上找到的 java 代码package connection;
//STEP 1. Import required packages
import java.sql.*;
public class FirstExample {
// JDBC driver name and database URL
static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3306/ibm/api/validator/dataSource/SAMPLEDB";
// Database credentials
static final String USER = "admin";
static final String PASS = "admin";
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try{
//STEP 2: Register JDBC driver
Class.forName(JDBC_DRIVER);
//STEP 3: Open a connection
System.out.println("Connecting to database...");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
//STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql;
sql = "SELECT * FROM *";
ResultSet rs = stmt.executeQuery(sql);
//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
String data = rs.getString("last");
//Display values
System.out.println("Data Retreived " + data);
}
//STEP 6: Clean-up environment
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
//Handle errors for JDBC
System.out.println("\nJDBC ERROR ! \n");
se.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
System.out.println("\nClass.forName ERROR ! \n");
e.printStackTrace();
}finally{
//finally block used to close resources
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){
System.out.println("\nSQL ERROR ! NOTHING TO DO \n");
}// nothing we can do
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
System.out.println("\nJDBC ERROR ! MAYBE SOMETHING TO DO \n");
se.printStackTrace();
}//end finally try
}//end try
System.out.println("\nGoodbye!");
}//end main
}//end FirstExample
至于我的 Server.xml 这是更新后的代码：
<server description="Liberty beta">
<featureManager>
<feature>webProfile-8.0</feature>
<feature>adminCenter-1.0</feature>
<feature>restConnector-2.0</feature>
<feature>transportSecurity-1.0</feature>
<feature>logstashCollector-1.1</feature>
<feature>validator-1.0</feature>
<feature>mpConfig-1.3</feature>
<feature>mpFaultTolerance-1.1</feature>
<feature>mpHealth-1.0</feature>
<feature>mpJwt-1.0</feature>
<feature>mpMetrics-1.1</feature>
<feature>mpOpenAPI-1.0</feature>
<feature>mpOpenTracing-1.0</feature>
<feature>mpRestClient-1.0</feature>
<feature>localConnector-1.0</feature>
<feature>jdbc-4.2</feature>
</featureManager>
<httpEndpoint id="defaultHttpEndpoint"
host="*"
httpPort="9080"
httpsPort="9443" />
<applicationManager autoExpand="true"/>
<keyStore id="defaultKeyStore"
password="Liberty" />
<basicRegistry id="userReg">
<user password="admin"
name="admin"
id="admin"></user>
</basicRegistry>
<administrator-role>
<user>admin</user>
</administrator-role>
<remoteFileAccess>
<writeDir>${server.config.dir}</writeDir>
</remoteFileAccess>
<dataSource id="DefaultDataSource" jndiName="jdbc/mySQL">
<jdbcDriver libraryRef="MySQLLib" />
<properties.microsoft.sqlserver databaseName="SAMPLEDB" serverName="localhost" portNumber="3306" user="admin" password="admin"/>
<connectionManager></connectionManager>
</dataSource>
<library id="MySQLLib">
<file name="C:/PUBLIC/tools/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12.jar" />
</library>
</server>
我现在遇到的问题是我似乎无法与我的服务器通信。
这是控制台错误：
Connecting to database...
JDBC ERROR !
Goodbye!
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:832)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at connection.FirstExample.main(FirstExample.java:23)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91)
at com.mysql.cj.NativeSession.connect(NativeSession.java:152)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:952)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:822)
... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:173)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65)
... 9 more
作为初学者，我试图盲目地遵循网上找到的教程，并没有想太多我到底在做什么。
我不明白 Was Liberty 不像设置一个包含您想要的服务的 VM，而且在 Liberty 中设置一个数据源 不是设置一个数据库。 由于缺乏信息、指导和严谨性，我在创建数据源时认为 Liberty 服务器实际上是 运行 一个 mySQL 服务器。事实上（如果我错了请纠正我）这部分代码，
<dataSource id="DefaultDataSource" jndiName="jdbc/mySQL">
<jdbcDriver libraryRef="MySQLLib" />
<properties.microsoft.sqlserver databaseName="SAMPLEDB"
serverName="localhost"
portNumber="3306"
user="admin"
password="admin"/>
<connectionManager></connectionManager>
</dataSource>
<library id="MySQLLib">
<file name="C:/PUBLIC/tools/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12/mysql-connector-java-8.0.12.jar" />
</library>
旨在使用足够的驱动程序在服务器中设置服务以连接到您的远程数据库。在这种情况下，我设置了一个带有 mySQL 驱动程序的数据源。
当我使用 运行 本地 mySQL 服务器时，我能够通过我的 java 应用程序进行通信和发送查询。
感谢那些花时间阅读本文 post 并试图帮助我的人。