mybatis杂记

mybatis学习官网：

1、如果项目中使用maven管理，又引用 了mybatis框架，

下面是mybatis官网给出的 mybatis在maven中央仓库的坐标原文

详情见连接：https://code.google.com/p/mybatis/wiki/DocMavenTutorial

MyBatis & Maven

The following is the Maven group, artifact and version for MyBatis.

  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.1.1</version>
  </dependency>

If you are looking to try the latest and greatest you can use our snapshot repository. Just add the following to your project's pom.xml or to a profile defined in your settings.xml.

<repository>
    <id>mybatis-snapshot</id>
    <name>MyBatis Snapshot Repository</name>
    <url>https://oss.sonatype.org/content/repositories/snapshots</url></repository>

2、What is the difference between #{...} and ${...}?

https://code.google.com/p/mybatis/wiki/faq

MyBatis interprets #{...} as a parameter marker in a JDBC prepared statement. MyBatis interprets ${...} as string substitution. It is important to know the difference because parameter markers cannot be used in certain places in SQL statements. For example, you cannot use a parameter marker to specify a table name. Given the following code:

Map<String,Object> parms =newHashMap<String,Object>();
parms.put("table","foo");
parms.put("criteria",37);List<Object> rows = mapper.generalSelect(parms);

<selectid="generalSelect"parameterType="map">
  select * from ${table} where col1 = #{criteria}
</select>

MyBatis will generate the following prepared statement:

select*from foo where col1 =?

Important: note that use of ${...} (string substitution) presents a risk for SQL injection attacks. Also, string substitution can be problematical for complex types like dates. For these reasons, we recommend using the #{...} form whenever possible.