1. 獲取類名

// 1. 靜態方法
Class c = Class.forName("類的路徑, 帶類包名");
// 2. 任何類都有 getName() 方法 返回類的名字
// 3. 類的class屬性

2. 獲取類中的屬性(反射屬性)

package com.fmg.restudy;
​
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
​
public class FieldTest {
  public static void main(String[] args) throws Exception {
    // 1. 屬性都有class
    Class c = Class.forName("com.fmg.restudy.study");
    Field[] fields = c.getDeclaredFields();
    StringBuffer str = new StringBuffer();
    str.append("public class study {");
    for (Field filed : fields) {
      // 修飾符屬性
      // System.out.println(Modifier.toString(filed.getModifiers()));
      // 修飾符
      // System.out.println(filed.getType().getSimpleName());
      // 獲取屬性名
      // System.out.println(filed.getName());
      str.append("\n");
      str.append(" ");
      str.append(Modifier.toString(filed.getModifiers()));
      if (filed.getModifiers() > 0) str.append(" ");
      str.append(filed.getType().getSimpleName());
      str.append(" ");
      str.append(filed.getName());
      str.append(";");
     }
    str.append("\n}");
    System.out.println(str);
   }
}
​
 

3. 反射方法

package com.fmg.restudy;
​
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
​
public class ReflectMethods {
  public static void main(String[] args) throws Exception {
    Class c = Class.forName("java.lang.String");
    Method[] methods = c.getDeclaredMethods();
    StringBuffer sbf = new StringBuffer();
    for (Method method: methods) {
      // 修飾符列表  結果 public
      // System.out.println(Modifier.toString(method.getModifiers()));
      sbf.append(Modifier.toString(method.getModifiers()));
      sbf.append(" ");
      // 返回結果 Boolean
      // System.out.println(method.getReturnType());
      sbf.append(method.getReturnType());
      sbf.append(" ");
      // 返回方法名
      // System.out.println(method.getName());
      sbf.append(method.getName());
      sbf.append(" (");
      // 獲取方法引數
      Class[] cl = method.getParameterTypes();
      for (Class cla : cl) {
        // System.out.println(cla.getSimpleName());
        sbf.append(cla.getSimpleName() + ",");
       }
      sbf.deleteCharAt(sbf.length() - 1);
      sbf.append(") {}");
      sbf.append("\n");
     }
    System.out.println(sbf);
   }
}
​
 

4. 反射構造器

package com.fmg.restudy;
​
import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
​
public class ReflectConstructor {
  public static void main(String[] args) throws Exception {
    Class c = Class.forName("com.fmg.restudy.study");
    // 獲取構造方法陣列
    Constructor[] ct = c.getDeclaredConstructors();
    // 遍歷構造方法陣列
    for (Constructor cr : ct) {
      Class[] s = cr.getParameterTypes();
      for (Class s2 : s) {
        // 拿構造器方法的名字
        System.out.println(s2.getSimpleName());
       }
     }
​
   }
}
​
 

5. 通過反射呼叫方法

package com.fmg.restudy;
​
import java.lang.reflect.Method;
​
public class UseMethod {
  public static void main(String[] args) throws Exception {
    Class c = Class.forName("com.fmg.restudy.study");
    Object obj = c.newInstance();
    Method method = c.getDeclaredMethod("soSome", int.class, int.class);
    method.invoke(obj, 3, 9);
   }
}
​

6. 通過反射呼叫構造方法

package com.fmg.restudy;
​
import java.lang.reflect.Constructor;
​
public class UseConstructor {
  public static void main(String[] args) throws Exception {
    Class c = Class.forName("com.fmg.restudy.study");
    Constructor ct = c.getDeclaredConstructor(String.class, String.class);
    ct.newInstance("fmg", "123456");
   }
}
​

7. 通過反射機制設定屬性值

package com.fmg.restudy;
​
import java.lang.reflect.Field;
import java.lang.reflect.Method;
​
public class ReflectSetField {
  public static void main(String[] args) throws Exception {
    Class c = Class.forName("com.fmg.restudy.study");
    Object obj = c.newInstance();
    Field num = c.getDeclaredField("num");
    num.set(obj, 1000);
    System.out.println(obj);
   }
}
​

做測試用的java study 程式碼

package com.fmg.restudy;

public class study {
    String username = "fmg";
    private String password = "123";
    int num;
    public boolean check(String username, String password) {
        return this.username.equals(username) && this.password.equals(password);
    }

    public study() {
    }

    public study(String username) {
        this.username = username;
    }

    public study(String username, String password) {
        this.username = username;
        this.password = password;
        System.out.println(this.username + "---------" + this.password);
    }

    public void soSome(int a, int b) {
        System.out.println(a + "+" + b + "=" + (a + b));
    }

    @Override
    public String toString() {
        return "study{" +
                "username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", num=" + num +
                '}';
    }
}