我正在努力让我的数据库与我的Java程序对话.
有人可以使用JDBC给我一个快速而又脏的示例程序吗？
我收到了一个相当惊人的错误:
Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.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 sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2260)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:787)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:49)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:357)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:207)
at SqlTest.main(SqlTest.java:22)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The …java.net.SocketException: Invalid argument: connect当我运行以下基本代码时,我的新笔记本电脑(Alienware m17x)会抛出一个:
Server.java:
public static void main (String[] args) throws Exception {
ServerSocket serverSocket = new ServerSocket (8888);
Socket socket = serverSocket.accept();
}
Client.java:
public static void main (String[] args) throws Exception {
Socket socket = new Socket ("localhost", 8888);
}
每次我运行Client.java(在启动Server.java之后),我都会收到此套接字异常.以下是异常的完整描述:
Exception in thread "main" java.net.SocketException: Invalid argument: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
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 java.net.Socket.connect(Unknown …我在尝试使用以下代码获取数据库连接时遇到问题:
try {
Class.forName("com.mysql.jdbc.Driver");
Properties p = new Properties();
p.put("user", user_name);
p.put("password", password);
connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1/jsp_test", p);
} catch (SQLException ex) {
// handle any errors
ex.printStackTrace();
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
return false;
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
输出的错误消息是:
/ usr/lib/jvm/java-6-openjdk/bin/java -Didea.launcher.port = 7532 -Didea.launcher.bin.path =/usr/bin/idea/bin -Dfile.encoding = UTF-8 - classpath /usr/lib/jvm/java-6-openjdk/jre/lib/jce.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/about.jar:/usr/lib/jvm/的java -6-的openjdk/JRE/LIB/resources.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/management-agent.jar:/ usr/lib中/ JVM/JAVA -6-的openjdk/JRE/lib目录/ jsse.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/charsets.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/rt.jar: /usr/lib/jvm/java-6-openjdk/jre/lib/ext/localedata.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/ext/sunjce_provider.jar:/usr/lib /jvm/java-6-openjdk/jre/lib/ext/sunpkcs11.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/ext/dnsns.jar:/home/bedtimes/Java Projects/db_demo/out/production/db_demo:/opt/java/jre/lib/ext/mysql-connector-java-5.1.10-bin.jar:/usr/bin/idea/lib/idea_rt.jar com.intellij.rt.execution.application.AppMain Main com.mysql.jdbc.exceptions.jdbc4.CommunicationsException:通信链路故障
成功发送到服务器的最后一个数据包是0毫秒前.驱动程序未收到来自服务器的任何数据包.at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)at java.lang.reflect.Constructor .newInstance(Constructor.java:532)位于com.mysql.jdbc.Util.handleNewInstance(Util.java:406)的com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)com.mysql.jdbc. …