我有这个类，它包含四个私有方法，每个方法具有相同的两个参数，以及一个在它们之间进行选择的公共方法。 可能的方法存储在 Map 中，可以添加更多方法。 我想动态调用正确的方法，删除开关。箱。 有没有礼貌的方法可以做到这一点，即没有getMethod/invoke？
public class PlayerClass {
private MediaSource customPlayFunction1(Channel chn, OtherParam other) {
}
private MediaSource customPlayFunction2(Channel chn, OtherParam other) {
}
private MediaSource customPlayFunction3(Channel chn, OtherParam other) {
}
private MediaSource defauPlayFunction(Channel chn, OtherParam other) {
}
public void playChannel(Activity activity, Channel chn) {
//do something
switch (chn.customFunction) {
case ("CustomPlayFunction1"): {
videoSource = customPlayFunction1(chn,other);
break;
}
case ("CustomPlayFunction2"): {
videoSource = customPlayFunction2(chn,other);
break;
}
case ("CustomPlayFunction3"): {
videoSource = customPlayFunction3(chn,other);
break;
}
default: {
videoSource = defaultPlayFunction(chn,other);
break;
}
}
//do something else
}
}
您可以将Map与java.util.function中的BiFunction<Channel, OtherParam, MediaSource>结合起来。您需要做的就是根据字符串键填充地图：
private Map<String, BiFunction<Channel, OtherParam, MediaSource>> myMap;
public void setup() {
myMap = new HashMap<>();
myMap.put("CustomPlayFunction1", this::customPlayFunction1);
myMap.put("CustomPlayFunction2", this::customPlayFunction2);
myMap.put("CustomPlayFunction3", this::customPlayFunction3);
}
public void playChannel(Activity activity, Channel chn) {
videoSource = myMap.getOrDefault(chn.customFunction, this::defaultPlayFunction).apply(chn, other);
}
apply将使用适当的参数调用接收到的函数。
getOrDefault将捕获地图中找不到键的任何情况，并自动调用defaultPlayFunction。
好吧，如果它们是有限的并且使用有意义，您可以使用Enums(取决于上下文，但目前您尚未提供任何信息)：
public enum Channel{
CUSTOM_1 {
@Override
public abstract MediaSource perform(Other other){
// customPlayFunction1
}
},
CUSTOM_2{
@Override
public abstract MediaSource perform(Other other){
// customPlayFunction2
}
},
CUSTOM_3{
@Override
public abstract MediaSource perform(Other other){
// customPlayFunction3
}
},
DEFAULT{
@Override
public abstract MediaSource perform(Other other){
// defaultPlayFunction
}
};
public abstract MediaSource perform(Other other);
}
否则，您必须将责任分离到Strategy：
public interface PlayStrategy{
public MediaSource perform(Channel chn, Other other);
}
public class Custom1Strategy implements PlayStrategy{
public MediaSource perform(Channel chn, Other other){
// customPlayFunction1
}
}
// same fore 2, 3 and default
在Channel中，您可以存储一个PlayStrategy对象，该对象将传递给将执行以下操作的PlayerClass：
chn.getPlay().perform(chn, other);
最后但最不建议的方法是使用这样的Map<String, BiFunction<Channel, Other, MediaSource>>：
public class PlayerClass {
private BiFunction<Channel, Other, MediaSource>> map = new HashMap<>();
public PlayerClass(){
map.put("CustomPlayFunction1", this::customPlayFunction1)
map.put("CustomPlayFunction2", this::customPlayFunction2)
map.put("CustomPlayFunction3", this::customPlayFunction3)
}
private MediaSource customPlayFunction1(Channel chn, OtherParam other) {}
private MediaSource customPlayFunction2(Channel chn, OtherParam other) {}
private MediaSource customPlayFunction3(Channel chn, OtherParam other) {}
private MediaSource defauPlayFunction(Channel chn, OtherParam other) {}
public void playChannel(Activity activity, Channel chn) {
map.getOrDefault(chn.customFunction, this::defauPlayFunction).apply(chn, other);
}
}