java - JDBC 的难倒 SQL 异常

Question

我正在尽我所能让 JDBC 工作，现在唯一让我难过的是这个异常，我不知道:

com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '????????????????' at line 1
    com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1049)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3593)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3525)
    com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1986)
    com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2140)
    com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2620)
    com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1890)
    com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3523)
    com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2386)
    com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163)
    com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
    com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:374)
    com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
    java.sql.DriverManager.getConnection(libgcj.so.10)
    java.sql.DriverManager.getConnection(libgcj.so.10)

我正在使用它来连接...

Class.forName("com.mysql.jdbc.Driver");
DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql", "username", "password");

非常感谢!

Answer 1

那些是相关的部分:

com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL
syntax; check the manual that corresponds to your MySQL server version for the 
right syntax to use near '????????????????' at line 1
    ...
    com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1890)
    ...
    java.sql.DriverManager.getConnection(libgcj.so.10)

这些问号表示在配置客户端字符集的查询过程中存在严重的字符编码问题。

第一次尝试，打开 my.cnf文件并确保存在以下两个条目:

character_set_server=utf8
collation_server=utf8_general_ci

作为第二次尝试，将 GCJ 替换为 OpenJDK或 Oracle (Sun) JDK哪个更健壮。众所周知，GCJ 有其古怪之处。