看之前有童鞋出了这问题，然后说在Dao中trim()了，我试了，没效果。代码如下：

Dao层：

//获取message表中数据

public List<Message> messagelist(String command,String description){

List<Message> messagelist = null;

//调用Dao操作方法

//messagelist = this.dbaccess(command,description);

//调用Mybatis方式操作方法

SqlSession sqlSession = null;

Message message = new Message();

//检索数据处理

if(command !=null&&!"".equals(command.trim())){

message.setCommand(command.trim());

}

if(description !=null&&!"".equals(description.trim())){

message.setDescription(description.trim());

}

try {

//获取sqlSession

sqlSession = this.dbaccess.mybatis();

//查询messagelist

messagelist = sqlSession.selectList("Message.messagelist",message);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

finally{

//关闭数据库连接会话

if(sqlSession != null){

sqlSession.close();

}

}

mappersql.xml配置文件:

 <select id="messagelist" parameterType="blue.java.model.Message" resultMap="MessageResult">

    select id,command,description,content from message where 1=1

    <if test="command != null ">

    and command = #{command}

    </if>

    <if test="description != null">

    and description like '%' #{description} '%'

    </if>

  </select>

日志打印如下:

DEBUG [http-8080-2] - Opening JDBC Connection

DEBUG [http-8080-2] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@1dc696e]

DEBUG [http-8080-2] - ==>  Preparing: select id,command,description,content from message where 1=1 and command = ? 

DEBUG [http-8080-2] - ==> Parameters: 查看(String)

DEBUG [http-8080-2] - <==      Total: 0

DEBUG [http-8080-2] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@1dc696e]

DEBUG [http-8080-2] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@1dc696e]