Unknown initial character set index ‘255‘ received from server. Initial client character set can be

spring5遇到的问题及解决方法

学链接池jdbc 的时候遇到的一下这个异常，看了一下是bean1.xml配置文件的url地址遇到的问题

//这个是出问题的代码
<!-- 数据库连接池 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
          destroy-method="close">
        <property name="url" value="jdbc:mysql:///user_db"/>
        <property name="username" value="root"/>
        <property name="password" value="******"/>
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    </bean>

7月 20, 2021 4:16:45 下午 com.alibaba.druid.support.logging.JakartaCommonsLoggingImpl error
严重: create connection SQLException, url: jdbc:mysql:///user_db, errorCode 0, state S1000
java.sql.SQLException: Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
	at com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1689)
	at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3444)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2062)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:723)
	at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:64)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1513)
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1578)
	at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2466)

解决办法
在url地址表后添加了一行?characterEncoding=utf8把字符编码转换为utf8的格式，就好了
修改后的代码

    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
          destroy-method="close">
        <property name="url" value="jdbc:mysql:///user_db?characterEncoding=utf8"/>
        <property name="username" value="root"/>
        <property name="password" value="******"/>
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    </bean>