动态加载HQL

  1 public class ReloadableDynamicHibernate{
  2     private final Map<String, XmlHolder> cachedXmls = new HashMap<String, XmlHolder>();
  3     private org.springframework.beans.factory.xml.DocumentLoader documentLoader = new org.springframework.beans.factory.xml.DefaultDocumentLoader();
  4     
  5     public void afterPropertiesSet() throws Exception {
  6         refreshLoad2Cache(true);
  7     };
  8 
  9     protected String getSqlByName(String queryKey) {
 10         refreshLoad2Cache(false);
 11         Collection<XmlHolder> xmlHolders = cachedXmls.values();
 12         for (XmlHolder holder : xmlHolders) {
 13             String qlString = holder.getQl(queryKey);
 14             if (StringUtils.isNotEmpty(qlString)) {
 15                 return qlString;
 16             }
 17         }
 18         throw new RuntimeException("can not find ql in xml.");
 19     };
 20 
 21     private void refreshLoad2Cache(boolean isForce) {
 22         for (int i = 0; i < fileNames.size(); i++) {
 23             String fileName = ((String) fileNames.get(i)).trim();
 24             if (resourceLoader instanceof ResourcePatternResolver) {
 25                 try {
 26                     Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(fileName);
 27                     for (Resource resource : resources) {
 28                         getXmls(resource,isForce);
 29                     }
 30                 } catch (IOException ex) {
 31                     throw new RuntimeException("Could not resolve sql definition resource pattern [" + fileName + "]", ex);
 32                 }
 33             } else {
 34                 Resource resource = resourceLoader.getResource(fileName);
 35                 getXmls(resource,isForce);
 36             }
 37         }
 38     };
 39 
 40     protected XmlHolder getXmls(Resource resource, boolean isForce) {
 41         synchronized (this.cachedXmls) {
 42             String filename = resource.getFilename();
 43             XmlHolder cachedXmls = this.cachedXmls.get(filename);
 44             if (cachedXmls != null && (cachedXmls.getRefreshTimestamp() < 0 || cachedXmls.getRefreshTimestamp() > System.currentTimeMillis())) {
 45                 return cachedXmls;
 46             }
 47             return refreshXmls(resource, cachedXmls, isForce);
 48         }
 49     };
 50 
 51     protected XmlHolder refreshXmls(Resource resource, XmlHolder xmlHolder, boolean isForce) {
 52         String filename = resource.getFilename();
 53         long refreshTimestamp = System.currentTimeMillis();
 54         if (resource.exists()) {
 55             long fileTimestamp = -1;
 56             try {
 57                 fileTimestamp = resource.lastModified();
 58                 if (!isForce && xmlHolder != null && xmlHolder.getFileTimestamp() == fileTimestamp) {
 59                     if (LOGGER.isDebugEnabled()) {
 60                         LOGGER.debug("Re-caching properties for filename [" + filename + "] - file hasn't been modified");
 61                     }
 62                     xmlHolder.setRefreshTimestamp(refreshTimestamp);
 63                     return xmlHolder;
 64                 }
 65             } catch (IOException ex) {
 66                 if (LOGGER.isDebugEnabled()) {
 67                     LOGGER.debug(resource + " could not be resolved in the file system - assuming that is hasn't changed", ex);
 68                 }
 69                 fileTimestamp = -1;
 70             }
 71             try {
 72                 Map qlMap = loadQlMap(resource);
 73                 xmlHolder = new XmlHolder(qlMap, fileTimestamp);
 74             } catch (Exception ex) {
 75                 if (LOGGER.isWarnEnabled()) {
 76                     LOGGER.warn("Could not parse properties file [" + resource.getFilename() + "]", ex);
 77                 }
 78                 xmlHolder = new XmlHolder();
 79             }
 80         } else {
 81             if (LOGGER.isDebugEnabled()) {
 82                 LOGGER.debug("No properties file found for [" + filename + "] - neither plain properties nor XML");
 83             }
 84             xmlHolder = new XmlHolder();
 85         }
 86         xmlHolder.setRefreshTimestamp(refreshTimestamp);
 87         this.cachedXmls.put(filename, xmlHolder);
 88         return xmlHolder;
 89     };
 90 
 91     protected Map<String,String> buildHQLMap(Resource resource) throws Exception {
 92         Map<String, String> qlMap = new HashMap<String, String>();
 93         try {
 94             InputSource inputSource = new InputSource(resource.getInputStream());
 95             org.w3c.dom.Document doc = this.documentLoader.loadDocument(inputSource, null, null, org.springframework.util.xml.XmlValidationModeDetector.VALIDATION_NONE, false);
 96             Element root = doc.getDocumentElement();
 97             List<Element> querys = DomUtils.getChildElements(root);
 98             for(Element query:querys){
 99                 String queryName = query.getAttribute("name");
100                 if (StringUtils.isEmpty(queryName)) {
101                     throw new Exception("DynamicHibernate Service : name is essential attribute in a <query>.");
102                 }
103                 if(qlMap.containsKey(queryName)){
104                     throw new Exception("DynamicHibernate Service : duplicated query in a <query>.");
105                 }
106                 qlMap.put(queryName, DomUtils.getTextValue(query));
107             }
108         } catch (Exception ioe) {
109             throw ioe;
110         }
111         return qlMap;
112     };
113 
114     protected Map loadQlMap(Resource resource) {
115         Map qlMap = new HashMap<String, String>();
116         InputStream is = null;
117         try {
118             is = resource.getInputStream();
119             return buildHQLMap(resource);
120         } catch (Exception e) {
121             e.printStackTrace();
122         } finally {
123             try {
124                 if (null != is) {
125                     is.close();
126                 }
127             } catch (Exception e) {
128                 e.printStackTrace();
129             }
130         }
131         return qlMap;
132     };
133 
134     protected class XmlHolder {
135         private Map<String, String> qlMap;                //查询的映射
136         private long                fileTimestamp    = -1;
137         private long                refreshTimestamp = -1;
138         public String getQl(String key) {
139             if (null != qlMap) {
140                 return qlMap.get(key);
141             } else {
142                 if (LOGGER.isErrorEnabled()) {
143                     LOGGER.debug("error is occured in getQl.");
144                 }
145                 return "";
146             }
147         }
148 
149         public XmlHolder(Map<String, String> qlMap, long fileTimestamp) {
150             this.qlMap = qlMap;
151             this.fileTimestamp = fileTimestamp;
152         }
153         public XmlHolder() {
154         }
155         public Map<String, String> getQlMap() {
156             return qlMap;
157         }
158         public long getFileTimestamp() {
159             return fileTimestamp;
160         }
161         public void setRefreshTimestamp(long refreshTimestamp) {
162             this.refreshTimestamp = refreshTimestamp;
163         }
164         public long getRefreshTimestamp() {
165             return refreshTimestamp;
166         }
167     }
168 }        

Spring 配置如下：

<bean id="dynamicHibernate" class="com.company.ReloadableDynamicHibernate">
        <property name="sessionFactory" ref="sessionFactory" />
        <property name="simpleTemplate" ref="simpleTemplate" />
        <property name="fileNames">
            <list>
                <value>classpath*:hibernate/dynamic/dynamic-hibernate-*.xml</value>
            </list>
        </property>
    </bean>

这样就实现了每次修改SQL or HQL语句后不用重启服务器，立刻看到结果，加快了开发速度。