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环境配置
新建一个名称为SSM工程
new ->module 选择MAVEN
然后在pom.xml中添加
<packaging>jar</packaging>
<!-- Mybatis核心 -->
<dependency> <groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.7</version>
</dependency> <!-- junit测试 --> <dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version> <scope>test</scope>
</dependency> <!-- MySQL驱动 --> <dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.3</version> </dependency> </dependencies>
创建mapper接口
MyBatis中的mapper接口相当于以前的dao。但是区别在于，mapper仅仅是接口，我们不需要提供实现类。
导入log4j
添加依赖
将log4j.properties放入resources中
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
mybatis执行过程
mybatis的底层源码
public Object execute(SqlSession sqlSession, Object[] args) {
Object result;
Object param;
switch(this.command.getType()) {
case INSERT:
param = this.method.convertArgsToSqlCommandParam(args);
result = this.rowCountResult(sqlSession.insert(this.command.getName(), param));
break;
case UPDATE:
param = this.method.convertArgsToSqlCommandParam(args);
result = this.rowCountResult(sqlSession.update(this.command.getName(), param));
break;
case DELETE:
param = this.method.convertArgsToSqlCommandParam(args);
result = this.rowCountResult(sqlSession.delete(this.command.getName(), param));
break;
case SELECT:
if (this.method.returnsVoid() && this.method.hasResultHandler()) {
this.executeWithResultHandler(sqlSession, args);
result = null;
} else if (this.method.returnsMany()) {
result = this.executeForMany(sqlSession, args);
} else if (this.method.returnsMap()) {
result = this.executeForMap(sqlSession, args);
} else if (this.method.returnsCursor()) {
result = this.executeForCursor(sqlSession, args);
} else {
param = this.method.convertArgsToSqlCommandParam(args);
result = sqlSession.selectOne(this.command.getName(), param);
if (this.method.returnsOptional() && (result == null || !this.method.getReturnType().equals(result.getClass()))) {
result = Optional.ofNullable(result);
}
}
break;
case FLUSH:
result = sqlSession.flushStatements();
break;
default:
throw new BindingException("Unknown execution method for: " + this.command.getName());
}
if (result == null && this.method.getReturnType().isPrimitive() && !this.method.returnsVoid()) {
throw new BindingException("Mapper method '" + this.command.getName() + " attempted to return null from a method with a primitive return type (" + this.method.getReturnType() + ").");
} else {
return result;
}
}
command中包含
通过command.getName得到mapper中的唯一标识进行增删改查通过sqlsession得到代理实现类去重写方法
