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使用java反射显示java类中可用的方法注释

suppress-warnings annotations reflection methods java

Nayantara Jeyaraj · 技术社区 · 7 年前

我有以下课程

package labsheet;

public class Employee {

    private String eid = "E001";
    String ename = "Anura";
    public String address = "Batticaloa";
    protected double salary = 60_000.00;

    public String getEid() {
        return eid;
    }
    public void setEid(String eid) {
        this.eid = eid;
    }
    String getEname() {
        return ename;
    }
    void setEname(String ename) {
        this.ename = ename;
    }
    protected String getAddress() {
        return address;
    }
    protected void setAddress(String address) {
        this.address = address;
    }
    @SuppressWarnings("unused")
    private double getSalary() {
        return salary;
    }
    @SuppressWarnings("unused")
    private void setSalary(double salary) {
        this.salary = salary;
    }

    public String display(String eid, String ename, String address, double salary){
        System.out.println("Method invoked successfully");
        return eid+" , "+ename+" , "+address+" , "+salary;
    }


}

我试图显示中可用的注释 Employee.java @SuppressWarnings("unused") 使用Java反射的getSalary()和setSalary()方法的详细信息。

任务3.java 如下所示。

package labsheet;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Parameter;

public class Task3 {
    public static void main(String[] args) {
        try {
            Class<?> clazz = Class.forName("labsheet.Employee");
            Method[] methods = clazz.getDeclaredMethods();

            for(int m =0; m<methods.length;m++){
                System.out.println("Modifier=> "+ Modifier.toString(methods[m].getModifiers()));
                Annotation [] annotations = methods[m].getAnnotations();
                System.out.println("Annotation count: "+annotations.length);
                for(int o =0; o<annotations.length;o++){
                    System.out.println("Annotation "+(o+1)+": "+annotations[o]);
                }
                System.out.print("|| Return Type=> "+ methods[m].getReturnType());
                System.out.print("|| Method Name=> "+ methods[m].getName());
                Parameter[] parameters = methods[m].getParameters();
                if(parameters.length != 0){
                    System.out.print("|| Method Parameters=> ");
                    for(int u = 0; u<parameters.length;u++){
                        if(u== parameters.length-1){
                            System.out.print(parameters[u].getType().getSimpleName());
                        }
                        else{
                            System.out.print(parameters[u].getType().getSimpleName()+" ");
                        }
                    }
                }

                System.out.println();
                System.out.println();
            }
            System.out.println("*******************************");
            executeMethod();
            System.out.println("*******************************");
            executeMethodWithDefault();
        } 

        catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

    }

...
//Methods declaration for executeMethod() and executeMethodWithDefault()

}

但是我得到了一个输出,其中表示getSalary()和setSalary()方法也没有注释,而我需要

输出

Modifier=> protected
Annotation count: 0
|| Return Type=> class java.lang.String|| Method Name=> getAddress

Modifier=> public
Annotation count: 0
|| Return Type=> class java.lang.String|| Method Name=> display|| Method Parameters=> String String String double

Modifier=> private
Annotation count: 0
|| Return Type=> void|| Method Name=> setSalary|| Method Parameters=> double

Modifier=> 
Annotation count: 0
|| Return Type=> class java.lang.String|| Method Name=> getEname

Modifier=> protected
Annotation count: 0
|| Return Type=> void|| Method Name=> setAddress|| Method Parameters=> String

Modifier=> 
Annotation count: 0
|| Return Type=> void|| Method Name=> setEname|| Method Parameters=> String

Modifier=> private
Annotation count: 0
|| Return Type=> double|| Method Name=> getSalary

Modifier=> public
Annotation count: 0
|| Return Type=> class java.lang.String|| Method Name=> getEid

Modifier=> public
Annotation count: 0
|| Return Type=> void|| Method Name=> setEid|| Method Parameters=> String

1 回复 | 直到 7 年前

Vadym Pechenoha 7 年前

看看 java.lang.SuppressWarnings 类别:

@Retention(RetentionPolicy.SOURCE)
public @interface SuppressWarnings {
  // code...
}

它有 SOURCE java.lang.annotation.RetentionPolicy 类别):

public enum RetentionPolicy {
    /**
     * Annotations are to be discarded by the compiler.
     */
    SOURCE,
    // code...
}

这意味着不可能在运行时获得有关注释的信息,因为编译器不会将其放入类文件中。