Java Reflect

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1. 反射无参构造函数

Class clazz =Class.forName("com.test.reflect.Person");

Constructor c =clazz.getConstructor(null);

Person person = (Person)c.newInstance(null);

Class clazz = Class.forName("com.test.reflect.Person");

Person p = (Person)clazz.newInstance();

2. 反射带有参数的构造函数(简单类型)

Class clazz =Class.forName("com.test.reflect.Person");

Constructor c =clazz.getConstructor(String.class);

Person p = (Person) c.newInstance("xxx");

例如：

public static UserHandle newUserHandle(intuserId) {

UserHandle userHandle =null;

try {

Constructor<UserHandle>constructor = UserHandle.class.getConstructor(int.class);

userHandle =(UserHandle) constructor.newInstance(userId);

} catch (Exception e) {

e.printStackTrace();

}

return userHandle;

}

3. 反射带有参数的构造函数(复杂类型)

Class clazz =Class.forName("com.test.reflect.Person");

Constructor c =clazz.getDeclaredConstructor(List.class);

c.setAccessible(true);

Person p = (Person) c.newInstance(new ArrayList());

4. 反射函数(非static函数)

public static voidgrantRuntimePermission(PackageManager pm,

StringpackageName, String permissionName, UserHandle user) {

try{

Methodmethod = PackageManager.class.getMethod("grantRuntimePermission",

String.class,String.class, UserHandle.class);

method.invoke(pm,packageName, permissionName, user);

}catch (Exception e) {

e.printStackTrace();

}

5. 反射static函数

// AppOpsManager

public static int permissionToOpCode(Stringpermission) {

try{

Methodmethod = AppOpsManager.class.getMethod("permissionToOpCode",

String.class);

return(Integer) method.invoke(null, permission);

}catch (Exception e) {

e.printStackTrace();

}

return-1;

}

6. 反射成员变量

例如：反射ApplicationInfo下的int类型变量flagsEx(info为ApplicationInfo类型对象)

ApplicationInfo.class.getField("flagsEx").getInt(info)

package org.local;

public class ReflectTest {

/**

* @param args

privateint x;

publicint y;

publicString str1 = "abc";

publicString str2 = "access";

publicReflectTest(int x, int y) {

this.x= x;

this.y= y;

}

@Override

publicString toString() {

return"ReflectTest [str1=" + str1 + ", str2=" + str2 +"]";

}

ReflectTest test = new ReflectTest(3,5);

//取得对象字节码

Class cls = test.getClass();

//getField只能得到可见的变量

Field fd1 = cls.getField("y");//返回的值不是test对象的变量，而是Field对象。所以下面必须通过get方法传入指定的ReflectTest对象，获取值

System.out.println("value1:" +fd1.get(test));

//getDeclaredField能够得到私有的变量

Field fd2 = cls.getDeclaredField("x");

fd2.setAccessible(true);

参考：http://blog.csdn.net/howlaa/article/details/8606071

http://blog.sina.com.cn/s/blog_620b085d0100hcam.html

http://blog.csdn.net/a600423444/article/details/6448844

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