ST

TLoi li M t li Cch x l Code v d x l Priority

1

Li

common

Khng focus vo trng li onFocus = function(componentId){

dojo.byId(componentId).focus();

}

high

2

Li

common

Khng validate maxlength cc control input Thm thuc tnh

maxlength ti tng

control hoc vit hm

javascript validate

ti client.

Validate thm

maxlength ti server.

client :

Thm maxlength='10' :

TextArea trong framework 1 : Thm vo hm validate

var abc = document.getElementById("abc");

if (abc != undefined && abc!= null){

if (abc.length >10){

alert("Trng abc khng c vt qu 10 k t")

abc.focus();

}

}

server :

+Nu truyn theo form :

String abc = frm.getAbc();

if (abc != null && !abc.trim().isEmpty() &&

abc.trim().length()>10){

request.setAttribute("errorCode","abcxyz");

return "errorPage"

}

high

3

Li

common

Khng validate cc trng bt buc nhp (required) Vit hm javascript

validate nhng

trng no bt buc

nhp m khng nhp

th thng bo cho

ngi dng bit v

setFocus vo trng

var target=dojo.byId("badKpiCfgFormOnDialog.target").value;

if(target.toString().trim()==""){

msg.error('notFill

key.target',onFocus("badKpiCfgForm

OnDialog.target"));

return false;

}

high

4Li

common

Khng ct (trim) khong trng trong d liu nhp vo - client: Thm thuc

tnh trim="true" cho

cc control.

- server: Trim d liu

trc khi thao tc

Ex: Trng name kiu String cn trim d liu

- Client :

Jsp thm :

Hoc s dng hm trimFormById(Id) trim ton b form theo

Id:

function trimFormById(formId){

var formObject = document.getElementById(formId);

var formElements = formObject.elements;

for (var i = 0; i < formElements.length; i++) {

var e = formElements[i];

if (e.type != undefined) {

var fieldType = e.type.toLowerCase();

switch (fieldType) {

case "text":

case "textarea":

e.value = e.value.trim();

break;

default:

break;

}

}

}

}

- Server :

String name= ;

If(form.getName() != null){

name = form.getName().trim();

}

high

5

Li

common

Khng validate d liu nhp vo kiu number Thm validate kiu

number ti client v

server

Client :

Framework 3: thm mask="digit"(mask="0-9" ..)

ex :

Server :

S dng hm :

public static boolean isNumber(String s) {

return s == null ? true: s.matches("\\d*");

}

high

6Li

common

- Li v b cc, font ch, chnh t, mu ch

- Li v trng bt buc phi c du * hoc tam gic

mu

Fix trang code hin

th giao din:

1. Cc label, textbox,

combo c di,

rng v khong cch

bng nhau, khng x

lch

2. Cc label s dng

cng 1 loi font, c

ch, cn l

3. Cc trng hp

bt buc nhp phi

c du * hoc tam

gic : t thuc

tnh required="true"

high

7

Li

common

Hin th sai nh dng thi gian control DatePicker t li format cho

control theo nh

dng mong mun:

dd/MM/yyyy hoc

dd/MM/yyyy

hh:mm:ss

high

8

Li

common

Code khng h tr multi language Phi khai bo key

trong file Language

Trong jsp : dng th

key

Trong java : dng

hm

LanguageBundleUtils.

getString(key) hoc

vit hm tng t ...

high

9Li

common

Khng tm kim c vi cc k t c bit nh %,

_ , !

Ex:

String name = formSearch.getName();

String sql = "select price from abc where 1=1 ";

SQLQuery q = getSession().createSQLQuery(sql);

if (name != null && !name.trim().isEmpty()){

q.app("and lower(name) like :name");

q.setParameter("name", "%"+name+"%");

}

q.addScalar("name",Hibernate.STRING);

q.setResultTransformer(Transformer.aliasToBean(A

bcBO.class));

List resultList = (List)query.list();

=> Khng search c khi truyn % , _ ....

S dng t kha

Escape trong SQL String name = formSearch.getName();

String sql = "select price from abc where 1=1 ";

SQLQuery q = getSession().createSQLQuery(sql);

if (name != null && !name.trim().isEmpty()){

q.app("and lower(name) like :name escape '\\'");

q.setParameter("name", "%" +

name.trim().toLowerCase().replace("\\", "\\\\").replaceAll("%",

"\\\\%").replaceAll("_", "\\\\_").replaceAll("!", "\\\\!") + "%");

}

q.addScalar("name",Hibernate.STRING);

q.setResultTransformer(Transformer.aliasToBean(AbcBO.class));

List resultList = (List)query.list();

high

10

Li

common

Qun khng break sau lnh switch-case

switch (temp){

case 1 :

System.out.print("1");

case 2 :

System.out.print("2");

switch (temp){

case 1 :

System.out.print("1");

break;

case 2 :

System.out.print("2");

break;

Medium

11

Li

common

Code tm kim ngay sau code insert -> khng th

select bn ghi va save do cha commit

EX:

code java :

// Dung hibernate

save(abcBO);

//Dung sql thuan

SQLQuery query =

getSession().createSQLQuery("select * from abc");

List temp = query.list();

-> khng ly c kt qu va thay i

Thm on code cp

nht gi tr va thay

i t Hibernate

xung DB:

session.flush()

Gii php :

code java :

// Dung hibernate

save(abcBO);

sess.flush();

//Dung sql thuan

SQLQuery query = getSession().createSQLQuery("select * from

abc");

List temp = query.list();

Medium

12

Li

common

Hin th sai nh dng thi gian datagrid Vit thm hm

formatter cho column

page.getTimeBegin = function(inRow) {

try{

var row = dijit.byId("gridId").getItem(inRow-1);

var timeBegin = row.timeBegin + "";

var split1 = timeBegin.split("-");

var split2 = split1[2].split("T",2);

return split2[0] + "/" + split1[1] + "/" + split1[0] + " " +

split2[1];

} catch(err){

return "";

};

}

Medium

13

Li

common

Trong DB2 khi to view bo li: The specification

ORDER BY or FETCH FIRST n ROWS ONLY is

invalid. SQLCODE=-20211, SQLSTATE=428FJ

DB2 khng chp

nhn lnh ORDER

BY trong view --> B

lnh order by trong

view i v s dng

order by trong cu

lnh select t view

Medium

14

Li

common

Cc form giao din b v mc d cn chnh trong

cc th div hoc table

Thm thuc tnh

theme="simple" vo

th s:form bao trn

vng giao din

Medium

15

Li

common

Khng post c gi tr trn cc control b set thuc

tnh disable=true, v d:

--> Khi submit form gi tr stockModelForm.code

post gi tr = null ln server.

Thm th hidden

lu thng tin b

disable

Medium

16

Li

common

Li map sai kiu d liu Sa li kiu d liu

cho ph hp

1. Trn Form l Text :

Nhng trong form java :

class FormSearch{

Long abc;

........

}

2. Hoc khi get list trng abc kiu String -> add scalar kiu Date

addScalar("abc", Hibernate.DATE);

3. Hoc statement gi hm

CallableStatement cs = conn.prepareCall("{ call proc_test(?) }");

String abc = "ss";

cs.setString(1, abc);

cs.execute();

Trong khi trong proc_test : bin cn truyn l Long -> Li

Medium

17

Li

common

Khng Validate trng d liu trong file excel V d bn cnh l 1

phng php gii

quyt :

1. a tt c cc

cell u tin khng b

trng lp vo

HashMap + Km

thng tin cell nh

row, column

2. Duyt li d liu

ct pht hin cc

bn ghi tn ti

trong HashMap

Ex: Validate trng ct ISDN trong file Excel ---- ng vi trng

vipId trong bng Vip

public List validateDuplicateVIPInExcel(List

exportError, List isdnList) {

HashMap base = new HashMap();

VipBO temp;

int isdnListSize = isdnList == null ? 0 : isdnList.size();

for (int i = isdnListSize - 1; i > -1; i--) {

temp = isdnList.get(i);

base.put(temp.getVipId(), temp.getRowIndex());

}

List result = new ArrayList();

ErrorImport errImport = null;

Long index = null;

int row = 0;

for (VipBO isdn : isdnList) {

row = isdn.getRowIndex().intValue();

index = base.get(isdn.getVipId());

if (index != null && index != row) {

errImport = new ErrorImport(isdn.getVipId(),

Constants.IMPORT.DUPLICATE_ISDN + (index.intValue() + 1),

row, isdn.getColumnIndex().intValue());

exportError.add(errImport);

} else {

result.add(isdn);

}

}

return result;

}

Medium

18Li

common

i vi cc hm b ng, trong khi lnh catch

khng thc hin throw exception ln

Thm throw

exception vo trong

cc hm b ng hoc

khai bo hm b ng

lun throws Exception

Code chun :

try{

// Do something here

}catch(Exception ex){

throw ex;

}

Medium

19Li

common

Khng th dng gotoaction trn popup submit

trn FW2

Dng tag submit hoc

dng

setaction("formID",

"contextpath + url

submit");

Low

20Li

common

Khi s dng hibernate save object mc d trn

java set gi tr ID cho object l A nhng gi tr ID lu

vo trong DB li khng phi l A

V d:

StockTransSerial stock = new

StockStockTransSerial();

stock.setID(100L);

stock.setName("abc");

stock.save();

--> Kim tra Database gi tr stock_id khng phi l

100.

Kim tra file mapping

hibernate (xml) trong

th c on set

sequence th b on

set sequence i

STOCK_TRANS_SERIAL_SEQ

--> X l bng cch b on generator (bi ) i

Low

21

Li khng

xc thc

i

tng/

d liu

trc khi

s dng

Khng check null i tng trc khi gi method

hoc truy cp thuc tnh ca i tng.VD:

public void setVariable(String name, Object value) {

...

logger.debug("add variable (" + name + "="

+ value.toString() + ")");

...

}

Phi check null trc

khi gi method hoc

truy cp vo thuc

tnh ca i tng

public void setVariable(String name, Object value) {

if(value != null)

logger.debug("add variable (" + name + "=" + value.toString()

+ ")");

...

}

high

22

Li khng

xc thc

i

tng/

d liu

trc khi

s dng

Li khng kim tra kch thc ca Danh sch hoc

Mng. VD:

deptToken = vsaUserToken.getDeptTokens().get(0);

Trc khi truy cp

n phn t ca

Mng hoc Danh

sch, cn check kch

thc trc

if (vsaUserToken.getDeptTokens().isEmpty()) {

return null;

} else {

deptToken = vsaUserToken.getDeptTokens().get(0);

}

high

23

Li khng

xc thc

i

tng/

d liu

trc khi

s dng

Khng kim tra mu s (khc 0) khi thc hin php

chia V d

public int A (int x, int y) {

int z = x/y;

...

}

on code ny b li runtime nu y =0

Kim tra mu s

trc khi thc hin

php chia

public int A (int x, int y) {

int z =0;

if (y ==0 ){

// Thng bo li

} else {

z = x/y;

}

...

}

Medium

24

Li qun

l kt ni

M nhng khng ng kt ni trong trng hp

exception. VD:

try {

logout();

disconnect();

} catch (IOException ex) {

logger.error(hlr + " close transport error: " + ex);

} finally {

logged = false;

connected = false;

}

- logout fail s vng exception v nhy qua

disconnect

Kim tra y cc

trng hp sao cho

vi bt k iu kin

no on code ng

kt ni lun lun

c thc hin, nh

VD y l t trong

khi finally.

try {

logout();

} catch (IOException ex) {

logger.error(hlr + " close transport error: " + ex);

}

//dong socket

try {

disconnect();

} catch (IOException ex) {

logger.error(hlr + " close transport error: " + ex);

}

//set cac bien trang thai

logged = false;

connected = false;

high

25

Li qun

l ti

nguyn

S dng Statement, PrepareStatement, resultset

nhng khng ng. VD:

try {

String strSQL = "Update ......";

stmt = conn.prepareStatement(strSQL);

//execute query

stmt.executeUpdate();

} catch (Exception e) {

logger.error(e, e);

}

Tin hnh ng ti

khi lnh finally

try {

String strSQL = "Update ......";

stmt = conn.prepareStatement(strSQL);

//execute query

stmt.executeUpdate();

} catch (Exception e) {

logger.error(e, e);

} finally {

if(stmt != null && !stmt.isClosed()){

this.closeResource(stmt);

}

}

high

26

Li qun

l ti

nguyn

Giao tip gia cc h thng qua webservices, lib

khng set thi gian timeout. VD:

String serverIp = resource.getString("ip");

int serverPort =

Integer.parseInt(resource.getString("port"));

String userName = resource.getString("username");

String password = resource.getString("password");

Client client = new ObjectClientChannel(serverIp,

serverPort, userName, password, true);

client.connect();

ViettelMsg response = client.send(request);

on code ny c th chim ti nguyn gy treo ng

dng nu pha server khng phn hi response

Set timeout khi h

thng thc hin giao

tip vi cc h thng

bn ngoi.

String serverIp = resource.getString("ip");

int serverPort = Integer.parseInt(resource.getString("port"));

String userName = resource.getString("username");

String password = resource.getString("password");

Client client = new ObjectClientChannel(serverIp, serverPort,

userName, password, true);

client.setReceiverTimeout(ReportConstant.REPORT_MESSAGE_

TIME_OUT);

client.connect();

ViettelMsg response = client.send(request);

high

27

Li qun

l ti

nguyn

Li khng ng li file khi dng ng file sau khi thao

tc ti khi lnh

Finally

V d: try {

byte[] bFile = new byte[(int) fileUpload.length()];

fileInputStream = new FileInputStream(fileUpload);

fileInputStream.read(bFile);

String fileOutput =

getRequest().getRealPath(Constant.EXPORT.TEMPLATE_SOUR

CE_LOCATION + "/checklistNSS/") + File.separator +

fileUploadName;

fos = new FileOutputStream(fileOutput);

fos.write(bFile);

fos.flush();

getRequest().setAttribute("message", "Upload file

success");

getRequest().setAttribute("reload", "true");

} catch (Exception ex) {

ex.printStackTrace();

getRequest().setAttribute("message", "Upload file fail");

} finally {

if (fileInputStream != null) {

fileInputStream.close();

}

if (fos != null) {

fos.close();

}

}

high

28

Li qun

l ti

nguyn

Khng ng cursor khi gp li exception

VD: on PLSQL

declare

cursor c_data

is

select * from table_a;

v_data c_data%rowtype;

begin

open c_data;

fetch c_data into v_task;

if c_data%NOTFOUND then

insert into table_a values (1);

end if;

close c_data;

commit;

exception when others

then

rollback;

end;

- on code ny khi cu lnh insert chy ok th s

ng cursor c_data, tuy nhin nu cu lnh insert b

li exception, cursor s ko c ng.

- B sung thm code

ng cursor trong

on exception:

exception when others

then

rollback;

if c_data%ISOPEN then

close c_data;

end if;

end;

high

29

Li qun

l ti

nguyn

NioSocketConnector ch cn to mt ln lc u,

nu to lin tc s tht thot ti nguyn --> sau mt

thi gian chy gy li.

public void connect() throws IOException {

...

connector = new NioSocketConnector();

...

}

Ch to 1 ln, check

truc khi s dng

to cha - nu cha

th to mi nu ri th

ly i tng to

ra s dng

public void connect() throws IOException {

//neu chua tao connector thi tao lai

if (connector == null) {

connector = new NioSocketConnector();

}

}

Low

30

Li cu

hnh

Li xy ra khi cha add action Authentication.do v

error.do vo allowurl dn n b redirect lin tc

(Viettel Web Framework + Viettel Passport)

Cu hinh gi tr

allowURL trong file

cu hnh

cas.properties

AllowUrl=${contextPath}/Authentication.do,${contextPath}/error.do

.

Medium

31

Li cu

hnh

Khi cu hnh wrapper phn cu hnh load th vin

wrapper.java.classpath.1 thng l *.jar. Khi

upcode mi backup th vin c li ch i tn file c

thnh file bk (v d abc_bk.jar) --> li vn dng th

vin c khi trin khai

C 2 hng khc

phc:

1/ Khi cu hnh

classpath th ch

tng minh tng th

vin s dng

2/ Khi upcode mi th

xa hn th vin c

i hoc i ui file

c (v d abc.jar_bk)

Medium

32

Li trin

khai

ng dng b trn b nh, xy ra li

java.lang.OutOfMemoryError: heap space

Ch yu xut pht t

2 nguyn nhn:

- Cu hnh b nh

JVM khng cho

nhu cu ca ng

dng. Thng

thng khi khng cu

hnh th b nh JVM

ly mc nh

thp(64m)

- Qun l b nh

khng tt , xy ra

memory leak, gc

khng gii phng

c b nh. Cn

qun l tt nhng

bin static hay shared

c s dng vi

mc ch lu tr d

liu cho nhiu thread

-Cu hnh li file catalina.sh trong tomcat:

JAVA_OPTS="-Xmx1024m"

- Cu hnh li file wrapper.sh trong tin trnh(JSW):

wrapper.java.maxmemory=3000

high

33

Li trin

khai

ng dng tomcat xy ra li

java.lang.OutOfMemoryError: PermGen space

B nh PermGen

mc nh(64m) ca

JVM thp hn so vi

nhu cu ca ng

dng.Tng b nh

permGen bng cch

cu hnh tng b nh

PermGen cho JVM.

-

XX:MaxPermSize=12

8m

-Cu hnh li file catalina.sh trong tomcat:

JAVA_OPTS="-XX:MaxPermSize=128m"

- Cu hnh li file wrapper.sh trong tin trnh(JSW):

wrapper.java.command=java --XX:MaxPermSize=128m

high

34

Li trin

khai

- Khi trin khai 1 yu cu mi cho h thng c, i

vi cc h thng ln a s dng cch up class. Vic

ny thng gy li do khi up class, nhiu class dev

ngh l ko thay i nn ko up nhng thc cht li gy

li cho chng trnh:

V d 1:

'- Trong class Constant.java khai bo 1 bin:

public static Integer TEST_1 = 1;

- Trong class ABC.java s dng bin TEST_1 ny:

int TEST = Constant.TEST_1;

- Khi trin khai mi 1 yu cu cn sa gi tr

TEST_1 = 2, dev build li project v ch up li file

Constant.java ln server

- Kt qu: bin TEST trong file ABC.java vn c gi

tr = 1.

V d 2:

- C class A1 extends class A

- Class B.java c method:

public static int TEST(A1 a1)

- Class C.java c on code gi hm TEST:

int C1 = B.TEST(a1);

- Khi trin khai mi 1 yu cu cn sa method

TEST, sa thnh:

public static int TEST(A a);

- Build project success.

- Dev upcode ch up li file B.java ln server

- Kt qu: khi gi n hm TEST, h thng tr v li

NoSuchMethodError

Khi trin khai cn up

li tt c cc class c

gi n hm b thay

i, c th s dng

tool find usage ca

netbean tm kim.

VD1: Do java bin

dch on int TEST =

Constant.TEST_1

thnh int TEST = 1.

V vy khi thay i gi

tr file Constant cn

up li cc class s

dng gi tr b thay i

high

35

Li trin

khai

y file code ln server test nhng b file b cache ->

khng apply c thay i

Dng SSH kt ni

n server cn

deploy -> browse n

th mc ci tomcat ->

work -> catalina ->

localhost -> tn ng

dng y ln ->

browse n th mc

tng ng vi file

y ln -> xa ht

cc file c ui

_jsp.class , _jsp.java

ng vi file y ln

high

36Li trin

khai

- Khi trin khai 1 yu cu mi cho h thng c, i

vi cc h thng ln a s dng cch up class. Vic

ny thng gy li do khi up class, nhiu class dev

ngh l ko thay i nn ko up nhng thc cht li gy

li cho chng trnh:

V d 1:

'- Trong class Constant.java khai bo 1 bin:

public static Integer TEST_1 = 1;

- Trong class ABC.java s dng bin TEST_1 ny:

int TEST = Constant.TEST_1;

- Khi trin khai mi 1 yu cu cn sa gi tr

TEST_1 = 2, dev build li project v ch up li file

Constant.java ln server

- Kt qu: bin TEST trong file ABC.java vn c gi

tr = 1.

V d 2:

- C class A1 extends class A

- Class B.java c method:

public static int TEST(A1 a1)

- Class C.java c on code gi hm TEST:

int C1 = B.TEST(a1);

- Khi trin khai mi 1 yu cu cn sa method

TEST, sa thnh:

public static int TEST(A a);

- Build project success.

- Dev upcode ch up li file B.java ln server

- Kt qu: khi gi n hm TEST, h thng tr v li

NoSuchMethodError

Khi trin khai cn up

li tt c cc class c

gi n hm b thay

i, c th s dng

tool find usage ca

netbean tm kim.

VD1: Do java bin

dch on int TEST =

Constant.TEST_1

thnh int TEST = 1.

V vy khi thay i gi

tr file Constant cn

up li cc class s

dng gi tr b thay i

Medium