java反射(3)--反射的调用方法

来源：互联网发布：搜狗打字软件编辑：程序博客网时间：2024/05/01 23:33

1.通过发射调用类中的方法

1.调用没有返回值没有参数的方法

package org.sh.reflect2;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.lang.reflect.Modifier;public class InvokeDemo {public static void main(String[] args) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, InstantiationException {Class<?> c = null;try {c = Class.forName("org.sh.reflect2.Person");} catch (ClassNotFoundException e) {e.printStackTrace();}Method met = null;try {met = c.getMethod("sayHello");} catch (SecurityException e) {e.printStackTrace();} catch (NoSuchMethodException e) {e.printStackTrace();}met.invoke(c.newInstance());}}

1.调用有返回值没有参数的方法

package org.sh.reflect2;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.lang.reflect.Modifier;public class InvokeDemo02 {public static void main(String[] args) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, InstantiationException {Class<?> c = null;try {c = Class.forName("org.sh.reflect2.Person");} catch (ClassNotFoundException e) {e.printStackTrace();}Method met = null;try {met = c.getMethod("getInfo");} catch (SecurityException e) {e.printStackTrace();} catch (NoSuchMethodException e) {e.printStackTrace();}String val = (String)met.invoke(c.newInstance());System.out.println(val);}}

1.调用有返回值有参数的方法

package org.sh.reflect2;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.lang.reflect.Modifier;public class InvokeDemo03 {public static void main(String[] args) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, InstantiationException {Class<?> c = null;try {c = Class.forName("org.sh.reflect2.Person");} catch (ClassNotFoundException e) {e.printStackTrace();}Method met = null;try {met = c.getMethod("say",String.class,String.class);} catch (SecurityException e) {e.printStackTrace();} catch (NoSuchMethodException e) {e.printStackTrace();}String val = (String)met.invoke(c.newInstance(),"suhao","欢迎你");System.out.println(val);}}

2.通过发射调用类中的setter和getter方法

package org.sh.reflect2;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.lang.reflect.Modifier;public class InvokeDemo04 {public static void main(String[] args) throws Exception {Class<?> c = null;c = Class.forName("org.sh.reflect2.Person");Object o = c.newInstance();set("name","suhao",o,String.class);set("age",30,o,int.class);System.out.println(get("name",o));System.out.println(get("age",o));}/** *  * @param name 属性名称 * @param value 属性值 * @param obj 对象 */public static void set(String name,Object value,Object obj,Class<?> type) throws Exception{Method met = obj.getClass().getMethod("set"+initStr(name), type);met.invoke(obj, value);}public static Object get(String name,Object obj) throws Exception{Method met = obj.getClass().getMethod("get"+initStr(name));Object value =  met.invoke(obj);return value;}public static String initStr(String name){StringBuffer buf = new StringBuffer();buf.append(name.substring(0,1).toUpperCase()).append(name.substring(1));return buf.toString();}}

3.通过发射直接操作类的属性

package org.sh.reflect2;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.lang.reflect.Modifier;public class InvokeDemo05 {public static void main(String[] args) throws Exception {Class<?> c = null;c = Class.forName("org.sh.reflect2.Person");Object obj = c.newInstance();Field nameField = c.getDeclaredField("name");nameField.setAccessible(true);//让属性可见nameField.set(obj, "suhao");System.out.println(nameField.get(obj));}}

属性也可以直接操作，但不建议这么做因为不安全最好使用上面的setter和getter方法

0 0