如何使用反射从POJO获得值

Question

我只是使用方法反射API创建一个通用方法。在这种方法中，我试图获得一个微粒方法(getter方法/setter方法)值，但我被卡住了，我不知道如何做到这一点。我是Abel使用方法反射API获得所有方法名称，但不是Abel获得该方法的值。所以请帮帮我。

这是我的代码......

/*
propertyNames List包含两条记录

   and that records are two different EntityName(Variable Name)
   ex. in my class i have declared two Entity(Variable)
   private Integer productId;
   private Integer bomBucket;
   so propertyNames List is contain [productId ,  bomBucket] this two records.

*/

 public <T>void fillList(List<String> propertyNames , T clas){
    try{
        for(Object entity : entities.keySet()){
            if(propertyNames != null && propertyNames.size() > 0){  
                Method[] methodList = clas.getClass().getMethods(); 
                Method methodName;
                for (String propertyName : propertyNames) {
                    for(Method method : methodList){
                        if(method.getName().trim().startsWith("set")){
                           if(propertyName.trim().equalsIgnoreCase(method.getName().substring(3, method.getName().trim().length()))){
                               methodName = clas.getClass().getMethod(method.getName().trim(),new Class[]{Integer.class});
                               System.out.println("HERE I GET METHOD NAME ::: " + methodName.getName());
                               /*
                                * here one by one i am getting all the Setter methods name from the class .
                                * but i want a that Setter methods values. Not return type.  
                                */
                           }
                       } 
                   }   
                }
            }
        }   
    }catch (Exception e) {
        e.printStackTrace();
    }
}

Answer 1

你的意思是"方法的值"你是指方法的返回类型，还是你想调用那个方法，在它的父类的某个实例上，也许有一些参数，然后得到它返回的值?在这种情况下，如果你的方法不是公共的，你必须在调用方法对象之前先调用setAccessible(true):

//get instance of the class that has your method
    DsrProcessor dsrProcessor = DsrProcessor.class.newInstance();
    //get method object (by passing in it's name and the list of argument types he's accepting - echo(String):
    Method m = DsrProcessor.class.getMethod("echo", String.class);
    //use reflection to invoke the method passing the instance of it's class and a list of arguments :
    String methodReturnValue = (String) m.invoke(dsrProcessor, "Hello");
    //do something with what the method returned
    System.out.println(methodReturnValue);//prints: "echo:hello"

Answer 2

您还可以使用java.beans.Introspector类及其getBeanInfo方法之一。它返回一个BeanInfo实例，该实例引用了所有的属性描述符。