獲得hibernate的sql語句(2.1.6)

獲得hibernate的sql語句

我們知道hibernate會將hql解析成sql，也許在某些時候，我們需要這些sql。
不過hibernate的介面中沒有公開的api，看來我們得自己行動了。

1.開始前的工作
  1.1 知道如何閱讀javadoc api
  1.2 知道如何使用ant編譯hibernate源碼包
  1.3 hibernate源碼包在hibernate壓縮包的src目錄,api文檔在doc目錄

2.在執行Query.list()方法時，hibernate在控制台輸出sql。從api文檔中我們知道， Query介面有個實作類別是net.sf.hibernate.impl.AbstractQueryImpl，但這個虛類中並沒有實現list方法，繼續查該類的子類net.sf.hibernate.impl.QueryImpl，呵呵，找到了。

list public List list() throws HibernateException Description copied from interface: Query Return the query results as a List. If the query contains multiple results pre row, the results are returned in an instance of Object[]. Returns: the result list Throws: HibernateException

3.查看net.sf.hibernate.impl.QueryImpl原始碼，發現這裡吧實現丟給了Session介面，看來我們得去找Session介面的麻煩。

public List list() throws HibernateException {     verifyParameters();     Map namedParams = getNamedParams();     return getSession().find( bindParameterLists(namedParams), getQueryParameters(namedParams) ); }

4.介面是沒有實現代碼的，因此我們直接看實作類別net.sf.hibernate.impl.SessionImple的原始碼

public List find(String query, QueryParameters queryParameters) throws HibernateException {     if ( log.isTraceEnabled() ) {         log.trace( "find: " + query );         queryParameters.traceParameters(factory);     }     queryParameters.validateParameters();     QueryTranslator[] q = getQueries(query, false);     List results = Collections.EMPTY_LIST;     dontFlushFromFind++; //stops flush being called multiple times if this method is recursively called     //execute the queries and return all result lists as a single list     try {         for ( int i=0; i<q.length; i++ ) {             List currentResults;             try {                 currentResults = q[i].list(this, queryParameters); // 原來list是由這個類做的             }             catch (SQLException sqle) {                 throw new JDBCException("Could not execute query", sqle);             }             currentResults.addAll(results);             results = currentResults;         }     }     finally {         dontFlushFromFind--;     }     return results; }

5. 在api文檔左下角All Classes架構搜尋QueryTranslator，查到後點擊查看api，嗯，有料。

getSQLString public String getSQLString() Description copied from class: Loader The SQL query string to be called; implemented by all subclasses Specified by: getSQLString in class Loader

6.但是我們並不想處理第4步中找到的find方法的QueryParameters參數，怎麼辦捏？參考一下其他find方法

private static final Object[] NO_ARGS = ArrayHelper.EMPTY_STRING_ARRAY; private static final Type[] NO_TYPES = ArrayHelper.EMPTY_TYPE_ARRAY; /** * Retrieve a list of persistent objects using a hibernate query */ public List find(String query) throws HibernateException {     return find(query, NO_ARGS, NO_TYPES); // 他交給了三個參數的介面 } public List find(String query, Object value, Type type) throws HibernateException {     return find( query, new Object[] { value }, new Type[] { type } ); // 又丟給另一個介面處理 } public List find(String query, Object[] values, Type[] types) throws HibernateException {     return find(query, new QueryParameters(types, values) ); // 回到2參數的介面手裡了 }

7.開始修改，將第4步找到的代碼複製出來更改如下，然後添加回SessionImpl類

public String[] getSQLStrings(String query) throws HibernateException {     // 採用單參數介面處理queryParameters的方法     QueryParameters queryParameters = new QueryParameters(NO_ARGS, NO_TYPES);     if ( log.isTraceEnabled() ) {         log.trace( "find: " + query );         queryParameters.traceParameters(factory);     }     queryParameters.validateParameters();     QueryTranslator[] q = getQueries(query, false);     String[] results = new String[q.length]; // 建立傳回值     dontFlushFromFind++; //stops flush being called multiple times if this method is recursively called     //execute the queries and return all result lists as a single list     try {         for ( int i=0; i<q.length; i++ ) {             try {                 results[i] = q[i].getSQLString(); // 獲得sql語句             }             catch (SQLException sqle) {                 throw new JDBCException("Could not execute query", sqle);             }         }     }     finally {         dontFlushFromFind--;     }     return results; }

8.給Session介面增加一個方法

public String[] getSQLStrings(String query) throws HibernateException;

9.編譯之後大功告成，我們可以使用Session.getSQLStrings(query)獲得sql語句數組