java反射的一些應用，望各大神給予指正
阿新 • • 發佈：2019-01-24
第一次寫，很緊張，值得紀念的日子 2016-04-01（竟然是愚人節，我是個小白）
首先，這個是在專案裡的一個功能，因為之前專案裡都是寫死的值，每個人寫的時候都寫一堆一堆的程式碼，一堆一堆的if,else.所以就自己寫了個公共的方式，今天開始用，寫不太好，望大神們給點指導建議。
話不多說，上正文。
需求背景：
在系統中需要做使用者與統一使用者系統同步的功能，對於待更新和刪除操作的使用者，不能直接同步，需要由業務人員作業系統同步使用者和組織。最最主要的是，同步時可能不同步所有欄位，感覺這個需求停尷尬的，但是業務上需要這樣，所以默認了。
解決方案：
頁面在選中待更新專案後，彈出dialog，選擇要更新的欄位。傳到後臺，向正式表中更新選中的欄位。
公共類：
public class DesignUtils<D> { private final static String SET_HEAD = "set"; private final static String GET_HEAD = "get"; public D get(D newDomain,D originDomain, String ids[]) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException{ //建立class物件 Class<? extends Object> clazzNew = newDomain.getClass(); // 欄位陣列 Field[] fields = clazzNew.getDeclaredFields(); for(int i = 0; i < ids.length; i++){ for(int j = 0; j < fields.length; j++){ if(fields[j].getName().equals(ids[i])){ getMethod(clazzNew, SET_HEAD, fields[j]).invoke(newDomain, new Object[]{getMethod(clazzNew, GET_HEAD, fields[j]).invoke(originDomain, new Object[]{})}); } } } return newDomain; } /** * 獲取實體對應的get和set方法 * @param clazzOrigin * @param methodHead * @param fieldName * @return */ public Method getMethod(Class<? extends Object> clazz,String methodHead, Field field){ if(field.getName() == null || "".equals(field.getName())){ return null; } Method method = null; try { if(methodHead.equals(GET_HEAD)){ method = clazz.getMethod(getMethodName(methodHead, field.getName()), new Class[]{}); }else if(methodHead.equals(SET_HEAD)){ method = clazz.getMethod(getMethodName(methodHead, field.getName()), new Class[]{field.getType()}); } } catch (NoSuchMethodException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } return method; } /** * 獲取get或者set方法名 * @param methodHead * @param fieldName * @return */ public String getMethodName(String methodHead, String fieldName){ return methodHead + getFirstLetterStr(fieldName); } /** * 將字串首字母轉換成大寫 * @param str * @return */ public String getFirstLetterStr(String str){ return getFirstLetter(str) + str.substring(1); } /** * 獲取字串第一個字母，並且轉換成大寫 * @param str * @return */ public String getFirstLetter(String str){ return str.substring(0, 1).toUpperCase(); } }
user工具類（感覺可有可無）：
import java.lang.reflect.InvocationTargetException; public class UserDesign extends DesignUtils<User>{ public User getNewUser(User newUser, User originUser, String[] ids) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException{ return get(newUser, originUser, ids); } }
depart工具類（同上）：
import java.lang.reflect.InvocationTargetException;
public class DepartDesign extends DesignUtils<Depart>{
public Depart getNewDepart(Depart newDepart, Depart originDepart, String[] ids) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException{
return get(newDepart, originDepart, ids);
}
}user實體：
public class User {
private String userId;
private String userName;
private String userAge;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserAge() {
return userAge;
}
public void setUserAge(String userAge) {
this.userAge = userAge;
}
}public class Depart {
private String departId;
private String departName;
private String departParent;
public String getDepartId() {
return departId;
}
public void setDepartId(String departId) {
this.departId = departId;
}
public String getDepartName() {
return departName;
}
public void setDepartName(String departName) {
this.departName = departName;
}
public String getDepartParent() {
return departParent;
}
public void setDepartParent(String departParent) {
this.departParent = departParent;
}
}Test類：
import java.lang.reflect.InvocationTargetException;
public class Test extends DesignUtils<User>{
public static void main(String[] args) {
/**
* 使用者類 User
*/
UserDesign ud = new UserDesign();
//DesignUtils<User> user = new DesignUtils<User>();
//根據前臺選定的使用者資訊(臨時表)
User originUser = new User();
originUser.setUserId("1001");;
originUser.setUserName("張三");
originUser.setUserAge("20");
//通過前臺傳遞過來（需要向更新的欄位）
String[] idsUser = {"userName"};
//需要插入正是表的實體類
User newUser = new User();
try {
//user.get(newUser, originUser, idsUser);
//user.getNewUser(newUser, originUser, idsUser);
ud.get(newUser, originUser, idsUser);
System.out.println(newUser.getUserId());
System.out.println(newUser.getUserName());
System.out.println(newUser.getUserAge());
//TODO
//對正是表進行操作
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//=============================================
/**
* 部門Depart 與人員同理，只是方式不同
*/
//DepartDesign dd = new DepartDesign();
DesignUtils<Depart> departUtil = new DesignUtils<Depart>();
Depart originDepart = new Depart();
originDepart.setDepartId("000201");
originDepart.setDepartName("部門一");
originDepart.setDepartParent("000000");
Depart newDepart = new Depart();
String[] idsDepart = {"departId", "departName"};
try {
//dd.getNewDepart(newDepart, originDepart, idsDepart);
//dd.get(newDepart, originDepart, idsDepart);
departUtil.get(newDepart, originDepart, idsDepart);
System.out.println(newDepart.getDepartId());
System.out.println(newDepart.getDepartName());
System.out.println(newDepart.getDepartParent());
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}