第詳解Spring不同數據庫異常如何抽象的//SQLErrorCodesFactory構造方法中，生成的errorCodesMap，map的內容來自org/springframework/jdbc/support/sql-error-codes.xml文件

protectedSQLErrorCodesFactory(){

MaperrorCodes;

try{

DefaultListableBeanFactorylbf=newDefaultListableBeanFactory();

lbf.setBeanClassLoader(this.getClass().getClassLoader());

XmlBeanDefinitionReaderbdr=newXmlBeanDefinitionReader(lbf);

Resourceresource=this.loadResource("org/springframework/jdbc/support/sql-error-codes.xml");

if(resource!=nullresource.exists()){

bdr.loadBeanDefinitions(resource);

}else{

("Defaultsql-error-codes.xmlnotfound(shouldbeincludedinspring-jdbcjar)");

resource=this.loadResource("sql-error-codes.xml");

if(resource!=nullresource.exists()){

bdr.loadBeanDefinitions(resource);

logger.debug("Foundcustomsql-error-codes.xmlfileattherootoftheclasspath");

errorCodes=lbf.getBeansOfType(SQLErrorCodes.class,true,false);

if(logger.isTraceEnabled()){

logger.trace("SQLErrorCodesloaded:"+errorCodes.keySet());

}catch(BeansExceptionvar5){

logger.warn("ErrorloadingSQLerrorcodesfromconfigfile",var5);

errorCodes=Collections.emptyMap();

this.errorCodesMap=errorCodes;

}

sql-error-codes.xml文件中配置了各個數據庫的主要的錯誤碼

這里列舉了MYSQL部分，當然還有其他部分，我們可以看到唯一性約束錯誤碼是1062，就可以翻譯成DuplicateKeyException異常了

beanid="MySQL"

propertyname="databaseProductNames"

list

valueMySQL/value

valueMariaDB/value

/list

/property

propertyname="badSqlGrammarCodes"

value1054,1064,1146/value

/property

propertyname="duplicateKeyCodes"

value1062/value

/property

propertyname="dataIntegrityViolationCodes"

value630,839,840,893,1169,1215,1216,1217,1364,1451,1452,1557/value

/property

propertyname="dataAccessResourceFailureCodes"

value1/value

/property

propertyname="cannotAcquireLockCodes"

value1205,3572/value

/property

propertyname="deadlockLoserCodes"

value1213/value

/property

/bean

你已經看到，比如上面的錯誤碼值列舉了一部分，如果出現了一個不在其中的錯誤碼肯定是匹配不到，Spring當然能想到這種情況了

*@公-眾-號：程序員阿牛

*在AbstractFallbackSQLExceptionTranslator中，看到如果查找失敗會獲取下一個后續轉換器

@Nullable

publicDataAccessExceptiontranslate(Stringtask,@NullableStringsql,SQLExceptionex){

Assert.notNull(ex,"CannottranslateanullSQLException");

DataAccessExceptiondae=this.doTranslate(task,sql,ex);

if(dae!=null){

returndae;

}else{

SQLExceptionTranslatorfallback=this.getFallbackTranslator();

returnfallback!=nullfallback.translate(task,sql,ex):null;

}

SQLErrorCodeSQLExceptionTranslator的后置轉換器是什么？

//構造方法中已經指定，SQLExceptionSubclassTranslator

publicSQLErrorCodeSQLExceptionTranslator(){

this.setFallbackTranslator(newSQLExceptionSubclassTranslator());

}

SQLExceptionSubclassTranslator的轉換方法邏輯如下：

*@公-眾-號：程序員阿牛

*可以看出實際按照子類類型來判斷，返回相應的錯誤類，如果匹配不到，則找到下一個處理器，這里的處理其我們可以根據構造方法青松找到*SQLStateSQLExceptionTranslator

@Nullable

protectedDataAccessExceptiondoTranslate(Stringtask,@NullableStringsql,SQLExceptionex){

if(exinstanceofSQLTransientException){

if(exinstanceofSQLTransientConnectionException){

returnnewTransientDataAccessResourceException(this.buildMessage(task,sql,ex),ex);

if(exinstanceofSQLTransactionRollbackException){

returnnewConcurrencyFailureException(this.buildMessage(task,sql,ex),ex);

if(exinstanceofSQLTimeoutException){

returnnewQueryTimeoutException(this.buildMessage(task,sql,ex),ex);

}elseif(exinstanceofSQLNonTransientException){

if(exinstanceofSQLNonTransientConnectionException){

returnnewDataAccessResourceFailureException(this.buildMessage(task,sql,ex),ex);

if(exinstanceofSQLDataException){

returnnewDataIntegrityViolationException(this.buildMessage(task,sql,ex),ex);

if(exinstanceofSQLIntegrityConstraintViolationException){

returnnewDataIntegrityViolationException(this.buildMessage(task,sql,ex),ex);

if(exinstanceofSQLInvalidAuthorizationSpecException){

returnnewPermissionDeniedDataAccessException(this.buildMessage(task,sql,ex),ex);

if(exinstanceofSQLSyntaxErrorException){

returnnewBadSqlGrammarException(task,sql!=nullsql:"",ex);

if(exinstanceofSQLFeatureNotSupportedException){

returnnewInvalidDataAccessApiUsageException(this.buildMessage(task,sql,ex),ex);

}elseif(exinstanceofSQLRecoverableException){

returnnewRecoverableDataAccessException(this.buildMessage(task,sql,ex),ex);

returnnull;

}

SQLStateSQLExceptionTranslator的轉換方法：

*@公-眾-號：程序員阿牛

*可以看出根據SQLState的前兩位來判斷異常，根據匹配結果返回相應的異常信息

@Nullable

protectedDataAccessExceptiondoTranslate(Stringtask,@NullableStringsql,SQLExceptionex){

StringsqlState=this.getSqlState(ex);

if(sqlState!=nullsqlState.length()=2){

StringclassCode=sqlState.substring(0,2);

if(this.logger.isDebugEnabled()){

this.logger.debug("ExtractedSQLstateclass'"+classCode+"'fromvalue'"+sqlState+"'");

if(BAD_SQL_GRAMMAR_CODES.contains(classCode)){

returnnewBadSqlGrammarException(task,sql!=nullsql:"",ex);

if(DATA_INTEGRITY_VIOLATION_CODES.contains(classCode)){

returnnewDataIntegrityViolationException(this.buildMessage(task,sql,ex),ex);

if(DATA_ACCESS_RESOURCE_FAILURE_CODES.contains(classCode)){

returnnewDataAccessResourceFailureException(this.buildMessage(task,sql,ex),ex);

if(TRANSIENT_DATA_ACCESS_RESOURCE_CODES.contains(classCode)){

returnnewTransientDataAccessResourceException(this.buildMessage(task,sql,ex),ex);

if(CONCURRENCY_FAILURE_CODES.contains(classCode)){

returnnewConcurrencyFailureException(this.buildMessage(task,sql,ex),ex);

returnex.getClass().getName().contains("Timeout")newQueryTimeoutException(this.buildMessage(task,sq