1. 寰楀埌鏌愪釜瀵硅薄鐨勫睘鎬?br />
2 Class ownerClass = owner.getClass();
3
4 Field field = ownerClass.getField(fieldName);
5
6 Object property = field.get(owner);
7
8 return property;
9 }
Class ownerClass = owner.getClass()錛氬緱鍒拌瀵硅薄鐨凜lass銆?br />
Field field = ownerClass.getField(fieldName)錛氶氳繃Class寰楀埌綾誨０鏄庣殑灞炴с?br />
Object property = field.get(owner)錛氶氳繃瀵硅薄寰楀埌璇ュ睘鎬х殑瀹炰緥錛屽鏋滆繖涓睘鎬ф槸闈炲叕鏈夌殑錛岃繖閲屼細鎶llegalAccessException銆?br />
2. 寰楀埌鏌愪釜綾葷殑闈欐佸睘鎬?br />
2 throws Exception {
3 Class ownerClass = Class.forName(className);
4
5 Field field = ownerClass.getField(fieldName);
6
7 Object property = field.get(ownerClass);
8
9 return property;
10 }
Class ownerClass = Class.forName(className) 錛氶鍏堝緱鍒拌繖涓被鐨凜lass銆?br />
Field field = ownerClass.getField(fieldName)錛氬拰涓婇潰涓鏍鳳紝閫氳繃Class寰楀埌綾誨０鏄庣殑灞炴с?br />
Object property = field.get(ownerClass) 錛氳繖閲屽拰涓婇潰鏈変簺涓嶅悓錛屽洜涓鴻灞炴ф槸闈欐佺殑錛屾墍浠ョ洿鎺ヤ粠綾葷殑Class閲屽彇銆?br />
3. 鎵ц鏌愬璞＄殑鏂規(guī)硶
2
3 Class ownerClass = owner.getClass();
4
5 Class[] argsClass = new Class[args.length];
6
7 for (int i = 0, j = args.length; i < j; i++) {
8 argsClass[i] = args[i].getClass();
9 }
10
11 Method method = ownerClass.getMethod(methodName, argsClass);
12
13 return method.invoke(owner, args);
14 }
Class owner_class = owner.getClass() 錛氶鍏堣繕鏄繀欏誨緱鍒拌繖涓璞＄殑Class銆?br />
5锝?琛岋細閰嶇疆鍙傛暟鐨凜lass鏁扮粍錛屼綔涓哄鎵綧ethod鐨勬潯浠躲?br />
Method method = ownerClass.getMethod(methodName, argsClass)錛氶氳繃Method鍚嶅拰鍙傛暟鐨凜lass鏁扮粍寰楀埌瑕佹墽琛岀殑Method銆?br />
method.invoke(owner, args)錛氭墽琛岃Method錛宨nvoke鏂規(guī)硶鐨勫弬鏁版槸鎵ц榪欎釜鏂規(guī)硶鐨勫璞★紝鍜屽弬鏁版暟緇勩傝繑鍥炲兼槸Object錛屼篃鏃㈡槸璇ユ柟娉曠殑榪斿洖鍊箋?br />
4. 鎵ц鏌愪釜綾葷殑闈欐佹柟娉?br />
2 Object[] args) throws Exception {
3 Class ownerClass = Class.forName(className);
4
5 Class[] argsClass = new Class[args.length];
6
7 for (int i = 0, j = args.length; i < j; i++) {
8 argsClass[i] = args[i].getClass();
9 }
10
11 Method method = ownerClass.getMethod(methodName, argsClass);
12
13 return method.invoke(null, args);
14 }
鍩烘湰鐨勫師鐞嗗拰瀹炰緥3鐩稿悓錛屼笉鍚岀偣鏄渶鍚庝竴琛岋紝invoke鐨勪竴涓弬鏁版槸null錛屽洜涓鴻繖鏄潤鎬佹柟娉曪紝涓嶉渶瑕佸熷姪瀹炰緥榪愯銆?br />
5. 鏂板緩瀹炰緥
2 public Object newInstance(String className, Object[] args) throws Exception {
3 Class newoneClass = Class.forName(className);
4
5 Class[] argsClass = new Class[args.length];
6
7 for (int i = 0, j = args.length; i < j; i++) {
8 argsClass[i] = args[i].getClass();
9 }
10
11 Constructor cons = newoneClass.getConstructor(argsClass);
12
13 return cons.newInstance(args);
14
15 }
榪欓噷璇寸殑鏂規(guī)硶鏄墽琛屽甫鍙傛暟鐨勬瀯閫犲嚱鏁版潵鏂板緩瀹炰緥鐨勬柟娉曘傚鏋滀笉闇瑕佸弬鏁幫紝鍙互鐩存帴浣跨敤newoneClass.newInstance()鏉ュ疄鐜般?br />
Class newoneClass = Class.forName(className)錛氱涓姝ワ紝寰楀埌瑕佹瀯閫犵殑瀹炰緥鐨凜lass銆?br />
絎?锝炵9琛岋細寰楀埌鍙傛暟鐨凜lass鏁扮粍銆?br />
Constructor cons = newoneClass.getConstructor(argsClass)錛氬緱鍒版瀯閫犲瓙銆?br />
cons.newInstance(args)錛氭柊寤哄疄渚嬨?br />
6. 鍒ゆ柇鏄惁涓烘煇涓被鐨勫疄渚?br />
2 return cls.isInstance(obj);
3 }
7. 寰楀埌鏁扮粍涓殑鏌愪釜鍏冪礌
2 return Array.get(array,index);
3 }
闄勫畬鏁存簮鐮侊細
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
/**
* Java Reflection Cookbook
*
* @author Michael Lee
* @since 2006-8-23
* @version 0.1a
*/
public class Reflection {
/**
* 寰楀埌鏌愪釜瀵硅薄鐨勫叕鍏卞睘鎬?br /> *
* @param owner, fieldName
* @return 璇ュ睘鎬у璞?br /> * @throws Exception
*
*/
public Object getProperty(Object owner, String fieldName) throws Exception {
Class ownerClass = owner.getClass();
Field field = ownerClass.getField(fieldName);
Object property = field.get(owner);
return property;
}
/**
* 寰楀埌鏌愮被鐨勯潤鎬佸叕鍏卞睘鎬?br /> *
* @param className 綾誨悕
* @param fieldName 灞炴у悕
* @return 璇ュ睘鎬у璞?br /> * @throws Exception
*/
public Object getStaticProperty(String className, String fieldName)
throws Exception {
Class ownerClass = Class.forName(className);
Field field = ownerClass.getField(fieldName);
Object property = field.get(ownerClass);
return property;
}
/**
* 鎵ц鏌愬璞℃柟娉?br /> *
* @param owner
* 瀵硅薄
* @param methodName
* 鏂規(guī)硶鍚?br /> * @param args
* 鍙傛暟
* @return 鏂規(guī)硶榪斿洖鍊?br /> * @throws Exception
*/
public Object invokeMethod(Object owner, String methodName, Object[] args)
throws Exception {
Class ownerClass = owner.getClass();
Class[] argsClass = new Class[args.length];
for (int i = 0, j = args.length; i < j; i++) {
argsClass[i] = args[i].getClass();
}
Method method = ownerClass.getMethod(methodName, argsClass);
return method.invoke(owner, args);
}
/**
* 鎵ц鏌愮被鐨勯潤鎬佹柟娉?br /> *
* @param className
* 綾誨悕
* @param methodName
* 鏂規(guī)硶鍚?br /> * @param args
* 鍙傛暟鏁扮粍
* @return 鎵ц鏂規(guī)硶榪斿洖鐨勭粨鏋?br /> * @throws Exception
*/
public Object invokeStaticMethod(String className, String methodName,
Object[] args) throws Exception {
Class ownerClass = Class.forName(className);
Class[] argsClass = new Class[args.length];
for (int i = 0, j = args.length; i < j; i++) {
argsClass[i] = args[i].getClass();
}
Method method = ownerClass.getMethod(methodName, argsClass);
return method.invoke(null, args);
}
/**
* 鏂板緩瀹炰緥
*
* @param className
* 綾誨悕
* @param args
* 鏋勯犲嚱鏁扮殑鍙傛暟
* @return 鏂板緩鐨勫疄渚?br /> * @throws Exception
*/
public Object newInstance(String className, Object[] args) throws Exception {
Class newoneClass = Class.forName(className);
Class[] argsClass = new Class[args.length];
for (int i = 0, j = args.length; i < j; i++) {
argsClass[i] = args[i].getClass();
}
Constructor cons = newoneClass.getConstructor(argsClass);
return cons.newInstance(args);
}
/**
* 鏄笉鏄煇涓被鐨勫疄渚?br /> * @param obj 瀹炰緥
* @param cls 綾?br /> * @return 濡傛灉 obj 鏄綾葷殑瀹炰緥錛屽垯榪斿洖 true
*/
public boolean isInstance(Object obj, Class cls) {
return cls.isInstance(obj);
}
/**
* 寰楀埌鏁扮粍涓殑鏌愪釜鍏冪礌
* @param array 鏁扮粍
* @param index 绱㈠紩
* @return 榪斿洖鎸囧畾鏁扮粍瀵硅薄涓儲寮曠粍浠剁殑鍊?br /> */
public Object getByArray(Object array, int index) {
return Array.get(array,index);
}
}
]]>
1. 涓涓畝鍗曠殑渚嬪瓙
鑰冭檻涓嬮潰榪欎釜綆鍗曠殑渚嬪瓙錛岃鎴戜滑鐪嬬湅 reflection 鏄浣曞伐浣滅殑銆?br /> import java.lang.reflect.*;
public class DumpMethods {
public static void main(String args[]) {
try {
Class c = Class.forName(args[0]);
Method m[] = c.getDeclaredMethods();
for (int i = 0; i < m.length; i++)
System.out.println(m[i].toString());
} catch (Throwable e) {
System.err.println(e);
}
}
}
鎸夊涓嬭鍙ユ墽琛岋細
java DumpMethods java.util.Stack
瀹冪殑緇撴灉杈撳嚭涓猴細
public java.lang.Object java.util.Stack.push(java.lang.Object)
public synchronized java.lang.Object java.util.Stack.pop()
public synchronized java.lang.Object java.util.Stack.peek()
public boolean java.util.Stack.empty()
public synchronized int java.util.Stack.search(java.lang.Object)
榪欐牱灝卞垪鍑轟簡java.util.Stack 綾葷殑鍚勬柟娉曞悕浠ュ強瀹冧滑鐨勯檺鍒剁鍜岃繑鍥炵被鍨嬨?/p>
榪欎釜紼嬪簭浣跨敤 Class.forName 杞藉叆鎸囧畾鐨勭被錛岀劧鍚庤皟鐢?getDeclaredMethods 鏉ヨ幏鍙栬繖涓被涓畾涔変簡鐨勬柟娉曞垪琛ㄣ俲ava.lang.reflect.Methods 鏄敤鏉ユ弿榪版煇涓被涓崟涓柟娉曠殑涓涓被銆?/p>
2.寮濮嬩嬌鐢?Reflection
鐢?
浜?reflection 鐨勭被錛屽 Method錛屽彲浠ュ湪 java.lang.relfect
鍖呬腑鎵懼埌銆備嬌鐢ㄨ繖浜涚被鐨勬椂鍊欏繀欏昏閬靛驚涓変釜姝ラ錛氱涓姝ユ槸鑾峰緱浣犳兂鎿嶄綔鐨勭被鐨?java.lang.Class 瀵硅薄銆傚湪榪愯涓殑 Java
紼嬪簭涓紝鐢?java.lang.Class 綾繪潵鎻忚堪綾誨拰鎺ュ彛絳夈?/p>
涓嬮潰灝辨槸鑾峰緱涓涓?Class 瀵硅薄鐨勬柟娉曚箣涓錛?br />
Class c = Class.forName("java.lang.String");
榪欐潯璇彞寰楀埌涓涓?String 綾葷殑綾誨璞°傝繕鏈夊彟涓縐嶆柟娉曪紝濡備笅闈㈢殑璇彞錛?br />
Class c = int.class; 鎴栬?nbsp; Class c = Integer.TYPE;
瀹冧滑鍙幏寰楀熀鏈被鍨嬬殑綾諱俊鎭傚叾涓悗涓縐嶆柟娉曚腑璁塊棶鐨勬槸鍩烘湰綾誨瀷鐨勫皝瑁呯被 (濡?Integer) 涓鍏堝畾涔夊ソ鐨?TYPE 瀛楁銆?br />
絎簩姝ユ槸璋冪敤璇稿 getDeclaredMethods 鐨勬柟娉曪紝浠ュ彇寰楄綾諱腑瀹氫箟鐨勬墍鏈夋柟娉曠殑鍒楄〃銆?br />
涓鏃﹀彇寰楄繖涓俊鎭紝灝卞彲浠ヨ繘琛岀涓夋浜嗏斺斾嬌鐢?reflection API 鏉ユ搷浣滆繖浜涗俊鎭紝濡備笅闈㈣繖孌典唬鐮侊細
Class c = Class.forName("java.lang.String");
Method m[] = c.getDeclaredMethods();
System.out.println(m[0].toString());
瀹冨皢浠ユ枃鏈柟寮忔墦鍗板嚭 String 涓畾涔夌殑絎竴涓柟娉曠殑鍘熷瀷銆?br />
鍦ㄤ笅闈㈢殑渚嬪瓙涓紝榪欎笁涓楠ゅ皢涓轟嬌鐢?reflection 澶勭悊鐗規(guī)畩搴旂敤紼嬪簭鎻愪緵渚嬭瘉銆?/p>
妯℃嫙 instanceof 鎿嶄綔絎?br />
寰楀埌綾諱俊鎭箣鍚庯紝閫氬父涓嬩竴涓楠ゅ氨鏄В鍐沖叧浜?Class 瀵硅薄鐨勪竴浜涘熀鏈殑闂銆備緥濡傦紝Class.isInstance 鏂規(guī)硶鍙互鐢ㄤ簬妯℃嫙 instanceof 鎿嶄綔絎︼細
class A {
}
public class instance1 {
public static void main(String args[]) {
try {
Class cls = Class.forName("A");
boolean b1 = cls.isInstance(new Integer(37));
System.out.println(b1);
boolean b2 = cls.isInstance(new A());
System.out.println(b2);
} catch (Throwable e) {
System.err.println(e);
}
}
}
鍦ㄨ繖涓緥瀛愪腑鍒涘緩浜嗕竴涓?A 綾葷殑 Class 瀵硅薄錛岀劧鍚庢鏌ヤ竴浜涘璞℃槸鍚︽槸 A 鐨勫疄渚嬨侷nteger(37) 涓嶆槸錛屼絾 new A() 鏄?/p>
3.鎵懼嚭綾葷殑鏂規(guī)硶
鎵懼嚭涓涓被涓畾涔変簡浜涗粈涔堟柟娉曪紝榪欐槸涓涓潪甯告湁浠峰間篃闈炲父鍩虹鐨?reflection 鐢ㄦ硶銆備笅闈㈢殑浠ｇ爜灝卞疄鐜頒簡榪欎竴鐢ㄦ硶錛?br />
import java.lang.reflect.*;
public class method1 {
private int f1(Object p, int x) throws NullPointerException {
if (p == null)
throw new NullPointerException();
return x;
}
public static void main(String args[]) {
try {
Class cls = Class.forName("method1");
Method methlist[] = cls.getDeclaredMethods();
for (int i = 0; i < methlist.length; i++) {
Method m = methlist[i];
System.out.println("name = " + m.getName());
System.out.println("decl class = " + m.getDeclaringClass());
Class pvec[] = m.getParameterTypes();
for (int j = 0; j < pvec.length; j++)
System.out.println("param #" + j + " " + pvec[j]);
Class evec[] = m.getExceptionTypes();
for (int j = 0; j < evec.length; j++)
System.out.println("exc #" + j + " " + evec[j]);
System.out.println("return type = " + m.getReturnType());
System.out.println("-----");
}
} catch (Throwable e) {
System.err.println(e);
}
}
}
榪?
涓▼搴忛鍏堝彇寰?method1 綾葷殑鎻忚堪錛岀劧鍚庤皟鐢?getDeclaredMethods 鏉ヨ幏鍙栦竴緋誨垪鐨?Method
瀵硅薄錛屽畠浠垎鍒弿榪頒簡瀹氫箟鍦ㄧ被涓殑姣忎竴涓柟娉曪紝鍖呮嫭 public 鏂規(guī)硶銆乸rotected 鏂規(guī)硶銆乸ackage 鏂規(guī)硶鍜?private
鏂規(guī)硶絳夈傚鏋滀綘鍦ㄧ▼搴忎腑浣跨敤 getMethods 鏉ヤ唬鏇?getDeclaredMethods錛屼綘榪樿兘鑾峰緱緇ф壙鏉ョ殑鍚勪釜鏂規(guī)硶鐨勪俊鎭?br />
鍙栧緱浜?Method 瀵硅薄鍒楄〃涔嬪悗錛岃鏄劇ず榪欎簺鏂規(guī)硶鐨勫弬鏁扮被鍨嬨佸紓甯哥被鍨嬪拰榪斿洖鍊肩被鍨嬬瓑灝變笉闅句簡銆傝繖浜涚被鍨嬫槸鍩烘湰綾誨瀷榪樻槸綾葷被鍨嬶紝閮藉彲浠ョ敱鎻忚堪綾葷殑瀵硅薄鎸夐『搴忕粰鍑恒?br />
杈撳嚭鐨勭粨鏋滃涓嬶細
name = f1
decl class = class method1
param #0 class java.lang.Object
param #1 int
exc #0 class java.lang.NullPointerException
return type = int
-----
name = main
decl class = class method1
param #0 class [Ljava.lang.String;
return type = void
-----
4.鑾峰彇鏋勯犲櫒淇℃伅
鑾峰彇綾繪瀯閫犲櫒鐨勭敤娉曚笌涓婅堪鑾峰彇鏂規(guī)硶鐨勭敤娉曠被浼鹼紝濡傦細
import java.lang.reflect.*;
public class constructor1 {
public constructor1() {
}
protected constructor1(int i, double d) {
}
public static void main(String args[]) {
try {
Class cls = Class.forName("constructor1");
Constructor ctorlist[] = cls.getDeclaredConstructors();
for (int i = 0; i < ctorlist.length; i++) {
Constructor ct = ctorlist[i];
System.out.println("name = " + ct.getName());
System.out.println("decl class = " + ct.getDeclaringClass());
Class pvec[] = ct.getParameterTypes();
for (int j = 0; j < pvec.length; j++)
System.out.println("param #" + j + " " + pvec[j]);
Class evec[] = ct.getExceptionTypes();
for (int j = 0; j < evec.length; j++)
System.out.println("exc #" + j + " " + evec[j]);
System.out.println("-----");
}
} catch (Throwable e) {
System.err.println(e);
}
}
}
榪欎釜渚嬪瓙涓病鑳借幏寰楄繑鍥炵被鍨嬬殑鐩稿叧淇℃伅錛岄偅鏄洜涓烘瀯閫犲櫒娌℃湁榪斿洖綾誨瀷銆?br />
榪欎釜紼嬪簭榪愯鐨勭粨鏋滄槸錛?br />
name = constructor1
decl class = class constructor1
-----
name = constructor1
decl class = class constructor1
param #0 int
param #1 double
-----
5.鑾峰彇綾葷殑瀛楁(鍩?
鎵懼嚭涓涓被涓畾涔変簡鍝簺鏁版嵁瀛楁涔熸槸鍙兘鐨勶紝涓嬮潰鐨勪唬鐮佸氨鍦ㄥ共榪欎釜浜嬫儏錛?br />
import java.lang.reflect.*;
public class field1 {
private double d;
public static final int i = 37;
String s = "testing";
public static void main(String args[]) {
try {
Class cls = Class.forName("field1");
Field fieldlist[] = cls.getDeclaredFields();
for (int i = 0; i < fieldlist.length; i++) {
Field fld = fieldlist[i];
System.out.println("name = " + fld.getName());
System.out.println("decl class = " + fld.getDeclaringClass());
System.out.println("type = " + fld.getType());
int mod = fld.getModifiers();
System.out.println("modifiers = " + Modifier.toString(mod));
System.out.println("-----");
}
} catch (Throwable e) {
System.err.println(e);
}
}
}
榪?
涓緥瀛愬拰鍓嶉潰閭ｄ釜渚嬪瓙闈炲父鐩鎬技銆備緥涓嬌鐢ㄤ簡涓涓柊涓滆タ Modifier錛屽畠涔熸槸涓涓?reflection
綾伙紝鐢ㄦ潵鎻忚堪瀛楁鎴愬憳鐨勪慨楗拌錛屽“private int”銆傝繖浜涗慨楗拌鑷韓鐢辨暣鏁版弿榪幫紝鑰屼笖浣跨敤 Modifier.toString
鏉ヨ繑鍥炰互“瀹樻柟”欏哄簭鎺掑垪鐨勫瓧絎︿覆鎻忚堪 (濡?#8220;static”鍦?#8220;final”涔嬪墠)銆傝繖涓▼搴忕殑杈撳嚭鏄細
name = d
decl class = class field1
type = double
modifiers = private
-----
name = i
decl class = class field1
type = int
modifiers = public static final
-----
name = s
decl class = class field1
type = class java.lang.String
modifiers =
-----
鍜岃幏鍙栨柟娉曠殑鎯呭喌涓涓嬶紝鑾峰彇瀛楁鐨勬椂鍊欎篃鍙互鍙彇寰楀湪褰撳墠綾諱腑鐢蟲槑浜嗙殑瀛楁淇℃伅 (getDeclaredFields)錛屾垨鑰呬篃鍙互鍙栧緱鐖剁被涓畾涔夌殑瀛楁 (getFields) 銆?/p>
6.鏍規(guī)嵁鏂規(guī)硶鐨勫悕縐版潵鎵ц鏂規(guī)硶
鏂囨湰鍒拌繖閲岋紝鎵涓劇殑渚嬪瓙鏃犱竴渚嬪閮戒笌濡備綍鑾峰彇綾葷殑淇℃伅鏈夊叧銆傛垜浠篃鍙互鐢?reflection 鏉ュ仛涓浜涘叾瀹冪殑浜嬫儏錛屾瘮濡傛墽琛屼竴涓寚瀹氫簡鍚嶇О鐨勬柟娉曘備笅闈㈢殑紺轟緥婕旂ず浜嗚繖涓鎿嶄綔錛?br />
import java.lang.reflect.*;
public class method2 {
public int add(int a, int b) {
return a + b;
}
public static void main(String args[]) {
try {
Class cls = Class.forName("method2");
Class partypes[] = new Class[2];
partypes[0] = Integer.TYPE;
partypes[1] = Integer.TYPE;
Method meth = cls.getMethod("add", partypes);
method2 methobj = new method2();
Object arglist[] = new Object[2];
arglist[0] = new Integer(37);
arglist[1] = new Integer(47);
Object retobj = meth.invoke(methobj, arglist);
Integer retval = (Integer) retobj;
System.out.println(retval.intValue());
} catch (Throwable e) {
System.err.println(e);
}
}
}
鍋囧涓涓▼搴忓湪鎵ц鐨勬煇澶勭殑鏃跺欐墠鐭ラ亾闇瑕佹墽琛屾煇涓柟娉曪紝榪欎釜鏂規(guī)硶鐨勫悕縐版槸鍦ㄧ▼搴忕殑榪愯榪囩▼涓寚瀹氱殑 (渚嬪錛孞avaBean 寮鍙戠幆澧冧腑灝變細鍋氳繖鏍風殑浜?錛岄偅涔堜笂闈㈢殑紼嬪簭婕旂ず浜嗗浣曞仛鍒般?/p>
涓?
渚嬩腑錛実etMethod 鐢ㄤ簬鏌ユ壘涓涓叿鏈変袱涓暣鍨嬪弬鏁頒笖鍚嶄負 add 鐨勬柟娉曘傛壘鍒拌鏂規(guī)硶騫跺垱寤轟簡鐩稿簲鐨?Method
瀵硅薄涔嬪悗錛屽湪姝ｇ‘鐨勫璞″疄渚嬩腑鎵ц瀹冦傛墽琛岃鏂規(guī)硶鐨勬椂鍊欙紝闇瑕佹彁渚涗竴涓弬鏁板垪琛紝榪欏湪涓婁緥涓槸鍒嗗埆鍖呰浜嗘暣鏁?37 鍜?47 鐨勪袱涓?Integer
瀵硅薄銆傛墽琛屾柟娉曠殑榪斿洖鐨勫悓鏍鋒槸涓涓?Integer 瀵硅薄錛屽畠?yōu)畞瑁呬簡杩斿洖鍊?84銆?/p>
7.鍒涘緩鏂扮殑瀵硅薄
瀵逛簬鏋勯犲櫒錛屽垯涓嶈兘鍍忔墽琛屾柟娉曢偅鏍瘋繘琛岋紝鍥犱負鎵ц涓涓瀯閫犲櫒灝辨剰鍛崇潃鍒涘緩浜嗕竴涓柊鐨勫璞?(鍑嗙‘鐨勮錛屽垱寤轟竴涓璞＄殑榪囩▼鍖呮嫭鍒嗛厤鍐呭瓨鍜屾瀯閫犲璞?銆傛墍浠ワ紝涓庝笂渚嬫渶鐩鎬技鐨勪緥瀛愬涓嬶細
import java.lang.reflect.*;
public class constructor2 {
public constructor2() {
}
public constructor2(int a, int b) {
System.out.println("a = " + a + " b = " + b);
}
public static void main(String args[]) {
try {
Class cls = Class.forName("constructor2");
Class partypes[] = new Class[2];
partypes[0] = Integer.TYPE;
partypes[1] = Integer.TYPE;
Constructor ct = cls.getConstructor(partypes);
Object arglist[] = new Object[2];
arglist[0] = new Integer(37);
arglist[1] = new Integer(47);
Object retobj = ct.newInstance(arglist);
} catch (Throwable e) {
System.err.println(e);
}
}
}
鏍規(guī)嵁鎸囧畾鐨勫弬鏁扮被鍨嬫壘鍒扮浉搴旂殑鏋勯犲嚱鏁板茍鎵ц瀹冿紝浠ュ垱寤轟竴涓柊鐨勫璞″疄渚嬨備嬌鐢ㄨ繖縐嶆柟娉曞彲浠ュ湪紼嬪簭榪愯鏃跺姩鎬佸湴鍒涘緩瀵硅薄錛岃屼笉鏄湪緙栬瘧鐨勬椂鍊欏垱寤哄璞★紝榪欎竴鐐歸潪甯告湁浠峰箋?/p>
8.鏀瑰彉瀛楁(鍩?鐨勫?br />
reflection 鐨勮繕鏈変竴涓敤澶勫氨鏄敼鍙樺璞℃暟鎹瓧孌電殑鍊箋俽eflection 鍙互浠庢鍦ㄨ繍琛岀殑紼嬪簭涓牴鎹悕縐版壘鍒板璞＄殑瀛楁騫舵敼鍙樺畠錛屼笅闈㈢殑渚嬪瓙鍙互璇存槑榪欎竴鐐癸細
import java.lang.reflect.*;
public class field2 {
public double d;
public static void main(String args[]) {
try {
Class cls = Class.forName("field2");
Field fld = cls.getField("d");
field2 f2obj = new field2();
System.out.println("d = " + f2obj.d);
fld.setDouble(f2obj, 12.34);
System.out.println("d = " + f2obj.d);
} catch (Throwable e) {
System.err.println(e);
}
}
}
榪欎釜渚嬪瓙涓紝瀛楁 d 鐨勫艱鍙樹負浜?12.34銆?br />
9.浣跨敤鏁扮粍
鏈枃浠嬬粛鐨?reflection 鐨勬渶鍚庝竴縐嶇敤娉曟槸鍒涘緩鐨勬搷浣滄暟緇勩傛暟緇勫湪 Java 璇█涓槸涓縐嶇壒孌婄殑綾葷被鍨嬶紝涓涓暟緇勭殑寮曠敤鍙互璧嬬粰 Object 寮曠敤銆傝瀵熶笅闈㈢殑渚嬪瓙鐪嬬湅鏁扮粍鏄庝箞宸ヤ綔鐨勶細
import java.lang.reflect.*;
public class array1 {
public static void main(String args[]) {
try {
Class cls = Class.forName("java.lang.String");
Object arr = Array.newInstance(cls, 10);
Array.set(arr, 5, "this is a test");
String s = (String) Array.get(arr, 5);
System.out.println(s);
} catch (Throwable e) {
System.err.println(e);
}
}
}
渚嬩腑鍒涘緩浜?10 涓崟浣嶉暱搴︾殑 String 鏁扮粍錛屼負絎?5 涓綅緗殑瀛楃涓茶祴浜嗗鹼紝鏈鍚庡皢榪欎釜瀛楃涓蹭粠鏁扮粍涓彇寰楀茍鎵撳嵃浜嗗嚭鏉ャ?br />
涓嬮潰榪欐浠ｇ爜鎻愪緵浜嗕竴涓洿澶嶆潅鐨勪緥瀛愶細
import java.lang.reflect.*;
public class array2 {
public static void main(String args[]) {
int dims[] = new int[]{5, 10, 15};
Object arr = Array.newInstance(Integer.TYPE, dims);
Object arrobj = Array.get(arr, 3);
Class cls = arrobj.getClass().getComponentType();
System.out.println(cls);
arrobj = Array.get(arrobj, 5);
Array.setInt(arrobj, 10, 37);
int arrcast[][][] = (int[][][]) arr;
System.out.println(arrcast[3][5][10]);
}
}
渚?
涓垱寤轟簡涓涓?5 x 10 x 15 鐨勬暣鍨嬫暟緇勶紝騫朵負澶勪簬 [3][5][10] 鐨勫厓绱犺祴浜嗗間負
37銆傛敞鎰忥紝澶氱淮鏁扮粍瀹為檯涓婂氨鏄暟緇勭殑鏁扮粍錛屼緥濡傦紝絎竴涓?Array.get 涔嬪悗錛宎rrobj 鏄竴涓?10 x 15
鐨勬暟緇勩傝繘鑰屽彇寰楀叾涓殑涓涓厓绱狅紝鍗抽暱搴︿負 15 鐨勬暟緇勶紝騫朵嬌鐢?Array.setInt 涓哄畠鐨勭 10 涓厓绱犺祴鍊箋?br />
娉ㄦ剰鍒涘緩鏁扮粍鏃剁殑綾誨瀷鏄姩鎬佺殑錛屽湪緙栬瘧鏃跺茍涓嶇煡閬撳叾綾誨瀷銆?/p>
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Iterator;
public class ProcessFileObject {
聽protected String filename = "";
聽protected ProcessFileObject(String filename) {
聽聽this.filename = filename;
聽}
聽public ObjectOutputStream oos = null;
聽public ObjectInputStream ios = null;
聽public synchronized boolean insertAssignInfo(String assignid,
聽聽聽String assigncode, String assignname) {
聽聽ArrayList alist = new ArrayList();
聽聽Assign assign = new Assign();
聽聽assign.setAssigncode(assigncode);
聽聽assign.setAssignid(assignid);
聽聽assign.setAssignname(assignname);
聽聽/*try {
聽聽聽System.out.println(filename);
聽聽聽ios = new ObjectInputStream(new FileInputStream(new File(filename)));
聽聽聽alist = (ArrayList) ios.readObject();
聽聽聽ios.close();
聽聽} catch (IOException ioe) {
聽聽聽ioe.printStackTrace();
聽聽} catch (ClassNotFoundException cnfe) {
聽聽}*/
聽聽if (!alist.add(assign)) {
聽聽聽return false;
聽聽}
聽聽try {
聽聽聽oos = new ObjectOutputStream(new FileOutputStream(new File(filename)));
聽聽聽oos.writeObject(alist);
聽聽聽oos.close();
聽聽} catch (IOException ioe) {
聽聽聽ioe.printStackTrace();
聽聽}
聽聽return true;
聽}
聽public synchronized boolean existAssignInfo(String assignid,
聽聽聽String assigncode, String assignname) {
聽聽ArrayList alist = null;
聽聽Assign assign = null;
聽聽try {
聽聽聽ios = new ObjectInputStream(new FileInputStream(filename));
聽聽聽alist = (ArrayList) ios.readObject();
聽聽聽ios.close();
聽聽} catch (IOException ioe) {
聽聽} catch (ClassNotFoundException cnfe) {
聽聽}
聽聽Iterator iter = alist.iterator();
聽聽while (iter.hasNext()) {
聽聽聽assign = (Assign) iter.next();
聽聽聽if (assign.getAssigncode().equals(assigncode)
聽聽聽聽聽&& assign.getAssignid().equals(assignid)
聽聽聽聽聽&& assign.getAssignname().equals(assignname)) {
聽聽聽聽return true;
聽聽聽}
聽聽}
聽聽return false;
聽}
聽public synchronized boolean removebyAssigncode(String assigncode) {
聽聽ArrayList alist = null;
聽聽Assign assign = null;
聽聽try {
聽聽聽ios = new ObjectInputStream(new FileInputStream(filename));
聽聽聽alist = (ArrayList) ios.readObject();
聽聽聽ios.close();
聽聽} catch (IOException ioe) {
聽聽} catch (ClassNotFoundException cnfe) {
聽聽}
聽聽for (int i = 0, j = alist.size(); i < j; i++) {
聽聽聽assign = (Assign) alist.get(i);
聽聽聽if (assign.getAssigncode().equals(assigncode)) {
聽聽聽聽alist.remove(i);
聽聽聽}
聽聽}
聽聽try {
聽聽聽oos = new ObjectOutputStream(new FileOutputStream(filename));
聽聽聽oos.writeObject(alist);
聽聽聽oos.close();
聽聽} catch (IOException ioe) {
聽聽}
聽聽return true;
聽}
聽public synchronized boolean removeAll() {
聽聽ArrayList alist = null;
聽聽try {
聽聽聽oos = new ObjectOutputStream(new FileOutputStream(filename));
聽聽聽oos.writeObject(alist);
聽聽聽oos.close();
聽聽} catch (IOException ioe) {
聽聽}
聽聽return true;
聽}
聽public class Assign implements Serializable {
聽聽public String assignid;
聽聽public String assigncode;
聽聽public String assignname;
聽聽public Assign() {
聽聽}
聽聽public String getAssigncode() {
聽聽聽return assigncode;
聽聽}
聽聽public void setAssigncode(String assigncode) {
聽聽聽this.assigncode = assigncode;
聽聽}
聽聽public String getAssignid() {
聽聽聽return assignid;
聽聽}
聽聽public void setAssignid(String assignid) {
聽聽聽this.assignid = assignid;
聽聽}
聽聽public String getAssignname() {
聽聽聽return assignname;
聽聽}
聽聽public void setAssignname(String assignname) {
聽聽聽this.assignname = assignname;
聽聽}
聽}
}
]]>
<!--[if !supportLists]-->涓銆?/span><!--[endif]-->Log4j鐨勭畝鍗曟濇兂
Log4j 鐪熺殑寰堢畝鍗曪紝綆鍗曞埌浠や漢鍙戞寚鐨勫湴姝ャ備笉鏄璁板綍鏃ュ織鍚楋紵閭ｅ氨緇欎綘涓涓?/span> Log 錛岀劧鍚庝綘鐢?/span> Log 鏉ュ啓涓滆タ灝辮浜嗭紝鍏堟潵涓涓畬鏁寸被紺轟緥錛?/span>
package
test;
import
org.apache.commons.logging.Log;
import
org.apache.commons.logging.LogFactory;
public
class
Test {
聽聽聽
聽聽聽
static
Log
log
= LogFactory.getLog(Test.
class
);
聽聽聽聽聽聽聽聽//protected final Log log = LogFactory.getLog(this.getClass());
聽聽聽
聽聽聽
public
void
log(){
聽聽聽聽聽聽
聽聽聽
log
.debug(
"Debug info."
);
聽聽聽聽聽聽
聽聽聽
log
.info(
"Info info"
);
聽聽聽聽聽聽
聽聽聽
log
.warn(
"Warn info"
);
聽聽聽聽聽聽
聽聽聽
log
.error(
"Error info"
);
聽聽聽聽聽聽
聽聽聽
log
.fatal(
"Fatal info"
);
聽聽聽
聽聽聽 }
聽聽聽
聽聽聽
/**
聽聽聽
聽
聽聽
聽
*
@param
args
聽聽聽
聽
聽聽
聽
*/
聽聽聽
聽聽聽
public
static
void
main(String[] args) {
聽聽聽聽聽聽
聽聽聽 Test test =
new
Test();
聽聽聽聽聽聽
聽聽聽
test.log();
聽聽聽
聽聽聽 }
}
鍒曪紝鐪嬪畬榪欑瘒鏂囩珷浣犲氨浼氳寰楀緢綆鍗曚簡銆?/span>
聽聽聽 聽聽聽 Log4j 榛樿鎶婃棩蹇椾俊鎭垎涓轟簲涓瓑綰?/span>
聽聽聽 聽聽聽 debug < info < warn < error < fatal
铏界劧鍙互鑷繁娣誨姞絳夌駭錛屼絾鏄垜瑙夊緱娌℃湁蹇呰錛屼簲涓鐢ㄤ簡鍚э紒浣犺鍐欏叆淇℃伅鐨勬椂鍊欏氨鎶婁俊鎭綊涓轟簲涓瓑綰т腑鐨勪竴涓紝鐒跺悗璋冪敤鐩稿簲鐨勫嚱鏁板嵆鍙?/span>
聽聽聽 鍒嗕簲涓瓑綰у埌搴曟湁浠涔堢敤鍛紵鏃ュ織淇℃伅鍒板簳鍐欏埌鍝噷鍘諱簡錛?/span>
聽聽聽 鈥?/span> LogFactory.getLog(Test. class ) 鈥濆張鏄粈涔堟剰鎬濇崗錛熸帴鐫寰涓嬬湅鍚э紒
Log4j 鐨勫叧閿箣澶勫湪浜庡畠鐨勭戶鎵挎濇兂銆備篃灝辨槸涓涓?/span> Log 鍙互緇ф壙鍙﹀涓涓?/span> Log 鐨勫睘鎬э紙杈撳嚭鍒板摢閲岋紝鏃ュ織絳夌駭錛屾棩蹇楁牸寮忕瓑絳夛級銆傛庝箞緇ф壙錛?/span>
Log4j 鏄牴鎹?/span> Log 鐨勫悕瀛楁潵鍒ゆ柇緇ф壙鍏崇郴鐨勶紝姣斿錛?/span>
鍚嶅瓧涓衡?/span> com.zhlmmc.lib 鈥濈殑 Log 灝辨槸鈥?/span> com.zhlmmc.lib.log 鈥濈殑 parent 錛屾槑鐧戒簡鍚э紒 Log4j 榪樻湁涓涓?/span> rootLogger 錛岀浉褰撲簬 Java 鐨?/span> Object 銆?/span>
鍥炶繃澶存潵鐪嬧?/span> LogFactory.getLog(Test. class ) 鈥濊繖閲岀殑鈥?/span> Test. class 鈥濅簨瀹炰笂浼犺繘鍘葷殑鏄?/span> Test 榪欎釜綾葷殑瀹屾暣璺緞錛堝寘鍚?/span> + 綾誨悕錛夛紝鈥?/span> test.Test 鈥濄傝繖鏍峰鏋滃瓨鍦ㄢ?/span> test 鈥濊繖涓?/span> Log 閭ｄ箞 Test 榪欎釜 Log 灝辯戶鎵垮畠錛屽惁鍒欏氨緇ф壙 rootLogger 銆?/span>
聽聽聽 閭ｅ叿浣撶殑 Log 灞炴ф槸鍦ㄥ摢閲屽畾涔夌殑鍛紵
<!--[if !supportLists]-->浜屻?/span><!--[endif]-->甯歌鐨勯厤緗枃浠?/span>
铏界劧鍙互鐢?/span> xml 鎴栬呭湪榪愯鏃剁敤 Java 鏉ラ厤緗?/span> Log4j 錛屼絾榪樻槸 properties 鏂囦歡濂界敤鍟婏紒
log4j.rootLogger=
info,
stdout
log4j.appender.stdout=
org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=
org.apache.log4j.PatternLayout
# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=
%5p
[%t]
(%F
:
%L)
-
%m%n
鍒嗘瀽涓涓嬶細
絎竴琛岋紝閰嶇疆 log4j.rootLogger 浣犳槑鐧藉惂銆傚簲涓哄畠鏄牴錛屾誨緱閰嶇疆涓涓嬶紝鍚﹀垯鍒殑 Log 緇ф壙浠涔堝晩銆傚叾浠栫殑 Log 鍙互閰嶇疆涔熷彲浠ヤ笉閰嶇疆銆傜瓑鍙峰悗闈㈢殑絎竴涓弬鏁拌〃紺烘棩蹇楃駭鍒紝鍙互濉簲涓駭鍒腑鐨勪竴縐嶏紝鍚庨潰鐨勫弬鏁伴兘鏄 Log 鐭ラ亾杈撳嚭鍒板摢閲岋紝濡傛灉浣犳兂璁╂棩蹇楄緭鍑哄埌涓や釜鍦版柟灝卞姞涓や釜杈撳嚭鍙傛暟錛屾瘮濡傦細
log4j.rootLogger= info, stdout, file
榪欓噷鐨?/span> info 琛ㄧず錛岃 Log 鐨勬棩蹇楃駭鍒負 info 錛屾墍鏈夌駭鍒皬浜?/span> info 鐨勬棩蹇楅兘涓嶄細琚褰曘傛瘮濡備嬌鐢ㄨ繖涓厤緗枃浠剁殑璇濓紝鎴戝垰寮濮嬩婦鐨勯偅涓被涓?/span>
log
.debug(
"Debug info."
);
榪欏彞璇濇槸涓嶈搗浣滅敤鐨勶紝鍥犱負 debug 鐨勭駭鍒皬浜?/span> info 銆傝繖鏍峰氨寰堝鏄撴帶鍒朵粈涔堜俊鎭湪璋冭瘯鐨勬椂鍊欒鏄劇ず錛屼粈涔堜俊鎭湪鍙戝竷鐨勬椂鍊欒鍘繪帀銆傝繖浜涢兘涓嶇敤鏀逛唬鐮侊紝寰堟柟渚垮惂銆?/span>
浣嗭紝 stdout 鍜?/span> file 鍙堟槸浠涔堝憿錛?/span>
鎺ョ潃寰涓嬬湅錛屽氨鏄厤緗?/span> stdout 浜嗭紝榪欎釜鍚嶅瓧鏄殢渚垮彇鐨勶紝浣犲彲浠ュ彨瀹?/span> A 錛?/span>
log4j.appender.A= org.apache.log4j.ConsoleAppender
閭ｄ箞涓婇潰鐨?/span> rootLogger 鐨勫弬鏁?/span> stdout 涔熻鏀規(guī)垚 A 錛屽叾浠栫敤鍒扮殑鍦版柟褰撶劧涔熻鏀廣傝繖閲岀殑鍏抽敭涓嶆槸鍚嶅瓧錛岃屾槸 appender 綾誨瀷錛屾瘮濡傝繖閲岀殑鈥?/span> ConsoleAppender 鈥濓紝鐪嬫槑鐧戒簡鍚э紝杈撳嚭鍒?/span> Console 銆傚悗闈袱琛岄兘鏄緗棩蹇楁牸寮忕殑錛屼竴鑸儏鍐典笅浣犲氨鐓ф妱鍚с傛棦鐒舵槸鏈綆鍏ラ棬鍏蟲敞浜庣悊瑙?/span> Log4j 鐨勫伐浣滃師鐞嗭紝鎴戝氨涓嶄粙緇?/span> file 綾誨瀷鐨?/span> appender 浜嗭紝涓鎼滀竴澶ф妸銆?/span>
鍦ㄥ疄闄呯殑欏圭洰寮鍙戜腑錛屽緢鍙兘閬囧埌鎵寮曠敤鐨勫寘鐢?/span> Log4j 鏉ヨ褰曟棩蹇楋紝姣斿 Hibernate 銆傞偅涔堝湪榪欓噷浣犲彲浠ュ緢瀹規(guī)槗鐨勬帶鍒惰繖涓寘濡備綍璁板綍鏃ュ織銆傛瘮濡傚湪涓婇潰鐨勯厤緗枃浠朵腑鍔犱竴琛岋細
log4j.logger.org.hibernate= fatal
聽聽聽 閭ｄ箞鎵鏈?/span> org.hibernate 鍖呬笅闈㈢殑綾誨氨鍙細鏄劇ず寰堝皯鐨勪俊鎭紝鍥犱負 fatal 鐨勭駭鍒渶楂樺晩銆?/span>
<!--[if !supportLists]-->涓夈?/span><!--[endif]-->閮ㄧ講
鍒曪紝榪欏彲涓嶆槸閮ㄧ講 Tomcat 銆傛妸 log4j 鐨勫寘鍜?/span> commons-logging 鐨勫寘錛堝姞鍦ㄤ竴璧鋒墠涓や釜錛夋斁鍒?/span> classpath 涓嬮潰銆傜劧鍚庢妸閰嶇疆鏂囦歡淇濆瓨涓?/span> log4j.properties 錛屼篃鏀懼湪 classpath 涓嬮潰錛堝鏋滅敤 Eclipse 鐨勮瘽錛屾斁鍦?/span> src 鐩綍涓嬪嵆鍙級銆傜劧鍚庝綘灝卞彲浠ヨ窇浜嗐?/span>
]]>
]]>