java - 从纯文本中检测 Java 类名

Question

假设您有以下 Java 代码:

public class Test {
    public Test() {
        string name = "Robot";
        Robot aRobot = new Robot();
        List<String> aList = new List<String>();
    }
}

您将如何检测 Test、string、List 和 Robot 是类名以及它们在文本文件中的位置？

Answer 1

You can use Refelction API for finding the type of the field in your java file.

import java.lang.reflect.Field;
import java.util.List;

public class FieldSpy<T> {
    public boolean[][] b = {{ false, false }, { true, true } };
    public String name  = "Alice";
    public List<Integer> list;
    public T val;

    public static void main(String... args) {
    try {
        Class<?> c = Class.forName(args[0]);
        Field f = c.getField(args[1]);
        System.out.format("Type: %s%n", f.getType());
        System.out.format("GenericType: %s%n", f.getGenericType());

        // production code should handle these exceptions more gracefully
    } catch (ClassNotFoundException x) {
        x.printStackTrace();
    } catch (NoSuchFieldException x) {
        x.printStackTrace();
    }
    }
}
Sample output to retrieve the type of the three public fields in this class (b, name, and the parameterized type list), follows. User input is in italics.

$ java FieldSpy FieldSpy b
Type: class [[Z
GenericType: class [[Z
$ java FieldSpy FieldSpy name
Type: class java.lang.String
GenericType: class java.lang.String
$ java FieldSpy FieldSpy list
Type: interface java.util.List
GenericType: java.util.List<java.lang.Integer>
$ java FieldSpy FieldSpy val
Type: class java.lang.Object
GenericType: T