spring替代方法

　　总结spring替代方法的使用

　　MyValueCalculator类中的computerValue方法将会被替代

public class MyValueCalculator {

public String computeValue(String input) {
// some real code...
}

// some other methods...

}

替代类实现接口MethodReplacer

/**
* meant to be used to override the existing computeValue(String)
* implementation in MyValueCalculator
*/
public class ReplacementComputeValue implements MethodReplacer {

public Object reimplement(Object o, Method m, Object[] args) throws Throwable {
// get the input value, work with it, and return a computed result
String input = (String) args[0];
...
return ...;
}
}

bean配置

<bean id="myValueCalculator" class="x.y.z.MyValueCalculator">
<!-- arbitrary method replacement -->
<replaced-method name="computeValue" replacer="replacementComputeValue">
<arg-type>String</arg-type>
</replaced-method>
</bean>

<bean id="replacementComputeValue" class="a.b.c.ReplacementComputeValue"/>

　　　　总结：这样就可以将computeValue方法交给类ReplacementComputeValue来完成。这是一种动态代理模式。由此想到了mybatis通过使用动态代理将自定义的dao接口的实现通过代理方法实现。