反射相關的API

1.獲取clazz

clazz = Class.forName("xxx.Maple");
clazz= new Maple().getClass();
clazz= Maple.class;

2.獲取父類

Class<?> parentClass = clazz.getSuperclass();

3.獲取介面

Class<?> intes[] = clazz.getInterfaces();

System.out.println("clazz實現的介面有：");

for (int i = 0; i < intes.length; i++) {
System.out.println((i + 1) + "：" + intes[i].getName());
}

4. 例項化預設構造方法，呼叫set賦值

User user = (User) clazz.newInstance();
user.setName("maple");
System.out.println(user);

5.取得全部的建構函式 使用建構函式賦值

Constructor<?> cons[] = clazz.getConstructors();

檢視每個構造方法需要的引數

for (int i = 0; i < cons.length; i++) {
Class<?> parClazzs[] = cons[i].getParameterTypes();
System.out.print("cons[" + i + "] (");
for (int j = 0; j < parClazzs.length; j++) {
parClazzs[j].getName()
}

6.獲取某個類的全部屬性

Class<?> clazz = Class.forName("net.xsoftlab.baike.TestReflect");
System.out.println("===============本類屬性===============");
// 取得本類的全部屬性
Field[] field = clazz.getDeclaredFields();
for (int i = 0; i < field.length; i++) {
// 許可權修飾符
int mo = field[i].getModifiers();
String priv = Modifier.toString(mo);
// 屬性型別
Class<?> type = field[i].getType();
System.out.println(priv + " " + type.getName() + " " + field[i].getName() + ";");
}

System.out.println("==========實現的介面或者父類的屬性==========");
// 取得實現的介面或者父類的屬性
Field[] filed1 = clazz.getFields();
for (int j = 0; j < filed1.length; j++) {
// 許可權修飾符
int mo = filed1[j].getModifiers();
String priv = Modifier.toString(mo);
// 屬性型別
Class<?> type = filed1[j].getType();
System.out.println(priv + " " + type.getName() + " " + filed1[j].getName() + ";");
}

7.獲取某個類的全部方法

package net.xsoftlab.baike;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
public class TestReflect implements Serializable {
private static final long serialVersionUID = -2862585049955236662L;
public static void main(String[] args) throws Exception {
Class<?> clazz = Class.forName("net.xsoftlab.baike.TestReflect");
Method method[] = clazz.getMethods();
for (int i = 0; i < method.length; ++i) {
Class<?> returnType = method[i].getReturnType();
Class<?> para[] = method[i].getParameterTypes();
int temp = method[i].getModifiers();
System.out.print(Modifier.toString(temp) + " ");
System.out.print(returnType.getName() + " ");
System.out.print(method[i].getName() + " ");
System.out.print("(");
for (int j = 0; j < para.length; ++j) {
System.out.print(para[j].getName() + " " + "arg" + j);
if (j < para.length - 1) {
System.out.print(",");
}
}
Class<?> exce[] = method[i].getExceptionTypes();
if (exce.length > 0) {
System.out.print(") throws ");
for (int k = 0; k < exce.length; ++k) {
System.out.print(exce[k].getName() + " ");
if (k < exce.length - 1) {
System.out.print(",");
}
}
} else {
System.out.print(")");
}
System.out.println();
}
}
}

8.通過反射機制呼叫某個類的方法

9.通過反射機制操作某個類的屬性

package net.xsoftlab.baike;
import java.lang.reflect.Field;
public class TestReflect {
private String proprety = null;
public static void main(String[] args) throws Exception {
Class<?> clazz = Class.forName("net.xsoftlab.baike.TestReflect");
Object obj = clazz.newInstance();
// 可以直接對 private 的屬性賦值
Field field = clazz.getDeclaredField("proprety");
field.setAccessible(true);
field.set(obj, "Java反射機制");
System.out.println(field.get(obj));
}
}