<strong>package</strong> com.ibm.dw.sample.exception;
/**
 * 自定義 RuntimeException
 * 添加錯(cuò)誤代碼屬性
 */
<strong>public</strong> <strong>class</strong> <strong>RuntimeException</strong> <strong>extends</strong> <strong>java</strong>.<strong>lang</strong>.<strong>RuntimeException</strong> { 
  //默認(rèn)錯(cuò)誤代碼 
 <strong>public</strong> <strong>static</strong> <strong>final</strong> Integer GENERIC = 1000000; 
 //錯(cuò)誤代碼
 <strong>private</strong> Integer errorCode; 
  <strong>public</strong> <strong>RuntimeException</strong>(Integer errorCode, Throwable cause) {
   <strong>this</strong>(errorCode, <strong>null</strong>, cause);
  }
  <strong>public</strong> <strong>RuntimeException</strong>(String message, Throwable cause) {
   //利用通用錯(cuò)誤代碼
   <strong>this</strong>(GENERIC, message, cause);
  }
  <strong>public</strong> <strong>RuntimeException</strong>(Integer errorCode, String message, Throwable cause) {
   <strong>super</strong>(message, cause);
   <strong>this</strong>.errorCode = errorCode;
  }
  <strong>public</strong> Integer <strong>getErrorCode</strong>() {
   <strong>return</strong> errorCode;
  } 
}

<strong>public</strong> Customer <strong>retrieveCustomerById</strong>(Long id) <strong>throw</strong> SQLException {
 //根據(jù) ID 查詢數(shù)據(jù)庫
}

<strong>public</strong> Customer <strong>retrieveCustomerById</strong>(Long id) {
  <strong>try</strong>{
   //根據(jù) ID 查詢數(shù)據(jù)庫
  }<strong>catch</strong>(SQLException e){
   //利用非檢測(cè)異常封裝檢測(cè)異常，降低層次耦合
   <strong>throw</strong> <strong>new</strong> RuntimeException(SQLErrorCode, e);
  }<strong>finally</strong>{
   //關(guān)閉連接，清理資源
  }
}

<strong>public</strong> <strong>void</strong> <strong>retrieveObjectById</strong>(Long id){
 <strong>try</strong>{
  //..some code that throws SQLException
 }<strong>catch</strong>(SQLException ex){
  /**
  *了解的人都知道，這里的異常打印毫無意義，僅僅是將錯(cuò)誤堆棧輸出到控制臺(tái)。
  * 而在 Production 環(huán)境中，需要將錯(cuò)誤堆棧輸出到日志。
  * 而且這里 catch 處理之后程序繼續(xù)執(zhí)行，會(huì)導(dǎo)致進(jìn)一步的問題*/
   ex.printStacktrace();
  }
}

<strong>public</strong> <strong>void</strong> <strong>retrieveObjectById</strong>(Long id){
 <strong>try</strong>{
 //..some code that throws SQLException
 }
 <strong>catch</strong>(SQLException ex){
 <strong>throw</strong> <strong>new</strong> RuntimeException(“Exception <strong>in</strong> retieveObjectById”, ex);
 }
 <strong>finally</strong>{
 //clean up resultset, statement, connection etc
 }
}

<strong>for</strong>(<strong>int</strong> i=0; i<100; i++){
 <strong>try</strong>{
 }<strong>catch</strong>(XXXException e){
   //….
 }
}

<strong>public</strong> <strong>void</strong> <strong>retrieveObjectById</strong>(Long id){
 <strong>try</strong>{
  //…拋出 IOException 的代碼調(diào)用
  //…拋出 SQLException 的代碼調(diào)用
 }<strong>catch</strong>(Exception e){
  //這里利用基類 Exception 捕捉的所有潛在的異常，如果多個(gè)層次這樣捕捉，會(huì)丟失原始異常的有效信息
  <strong>throw</strong> <strong>new</strong> RuntimeException(“Exception <strong>in</strong> retieveObjectById”, e);
 }
}

<strong>public</strong> <strong>void</strong> <strong>retrieveObjectById</strong>(Long id){
 <strong>try</strong>{
  //..some code that throws RuntimeException, IOException, SQLException
 }<strong>catch</strong>(IOException e){
  //僅僅捕捉 IOException
  <strong>throw</strong> <strong>new</strong> RuntimeException(/*指定這里 IOException 對(duì)應(yīng)的錯(cuò)誤代碼*/code,“Exception <strong>in</strong> retieveObjectById”, e);
 }<strong>catch</strong>(SQLException e){
  //僅僅捕捉 SQLException
  <strong>throw</strong> <strong>new</strong> RuntimeException(/*指定這里 SQLException 對(duì)應(yīng)的錯(cuò)誤代碼*/code,“Exception <strong>in</strong> retieveObjectById”, e);
 }
}

<strong>try</strong>{
 //可能拋出 RuntimeException、IOExeption 或者其它；
 //注意這里和誤區(qū)六的區(qū)別，這里是一段代碼拋出多種異常。以上是多段代碼，各自拋出不同的異常
}<strong>catch</strong>(<strong>Exception</strong> e){
 //一如既往的將 Exception 轉(zhuǎn)換成 RuntimeException，但是這里的 e 其實(shí)是 RuntimeException 的實(shí)例，已經(jīng)在前段代碼中封裝過
 <strong>throw</strong> <strong>new</strong> RuntimeException(/**/code, /**/, e);
}

<strong>public</strong> <strong>class</strong> <strong>A</strong> {
 <strong>private</strong> <strong>static</strong> Logger logger = LoggerFactory.getLogger(A.class);
 <strong>public</strong> <strong>void</strong> <strong>process</strong>(){
  <strong>try</strong>{
  //實(shí)例化 B 類，可以換成其它注入等方式
  B b = <strong>new</strong> B();
  b.process();
  //other code might cause exception
 } <strong>catch</strong>(XXXException e){
  //如果 B 類 process 方法拋出異常，異常會(huì)在 B 類中被打印，在這里也會(huì)被打印，從而會(huì)打印 2 次
  logger.error(e);
  <strong>throw</strong> <strong>new</strong> RuntimeException(/* 錯(cuò)誤代碼 */ errorCode, /*異常信息*/msg, e);
  }
 }
}
<strong>public</strong> <strong>class</strong> <strong>B</strong>{
 <strong>private</strong> <strong>static</strong> Logger logger = LoggerFactory.getLogger(B.class);
 <strong>public</strong> <strong>void</strong> <strong>process</strong>(){
  <strong>try</strong>{
   //可能拋出異常的代碼
  }
  <strong>catch</strong>(XXXException e){
   logger.error(e);
   <strong>throw</strong> <strong>new</strong> RuntimeException(/* 錯(cuò)誤代碼 */ errorCode, /*異常信息*/msg, e);
  }
 }
}

public <strong>void</strong> retieveObjectById(Long id){
 <strong>try</strong>{
  //..some code that throws SQLException
 }<strong>catch</strong>(SQLException ex){
  //將參數(shù)信息添加到異常信息中
  <strong>throw</strong> <strong>new</strong> RuntimeException(“Exception <strong>in</strong> retieveObjectById <strong>with</strong> Object Id :”+ id, ex);
 }
}