Improve a logic for closing an external resource

* Close an external resource reliably if occurred exception
* Use try-with-resources

Author: kazuki43zoo

src/main/java/org/apache/ibatis/cache/decorators/SerializedCache.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2017 the original author or authors.
+ *    Copyright 2009-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -91,12 +91,10 @@ public boolean equals(Object obj) {
   }
 
   private byte[] serialize(Serializable value) {
-    try {
-      ByteArrayOutputStream bos = new ByteArrayOutputStream();
-      ObjectOutputStream oos = new ObjectOutputStream(bos);
+    try (ByteArrayOutputStream bos = new ByteArrayOutputStream();
+         ObjectOutputStream oos = new ObjectOutputStream(bos)) {
       oos.writeObject(value);
       oos.flush();
-      oos.close();
       return bos.toByteArray();
     } catch (Exception e) {
       throw new CacheException("Error serializing object.  Cause: " + e, e);
@@ -105,11 +103,9 @@ private byte[] serialize(Serializable value) {
 
   private Serializable deserialize(byte[] value) {
     Serializable result;
-    try {
-      ByteArrayInputStream bis = new ByteArrayInputStream(value);
-      ObjectInputStream ois = new CustomObjectInputStream(bis);
+    try (ByteArrayInputStream bis = new ByteArrayInputStream(value);
+         ObjectInputStream ois = new CustomObjectInputStream(bis)) {
       result = (Serializable) ois.readObject();
-      ois.close();
     } catch (Exception e) {
       throw new CacheException("Error deserializing object.  Cause: " + e, e);
     }

src/main/java/org/apache/ibatis/datasource/pooled/PooledDataSource.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2017 the original author or authors.
+ *    Copyright 2009-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -523,10 +523,9 @@ protected boolean pingConnection(PooledConnection conn) {
               log.debug("Testing connection " + conn.getRealHashCode() + " ...");
             }
             Connection realConn = conn.getRealConnection();
-            Statement statement = realConn.createStatement();
-            ResultSet rs = statement.executeQuery(poolPingQuery);
-            rs.close();
-            statement.close();
+            try (Statement statement = realConn.createStatement()) {
+              statement.executeQuery(poolPingQuery).close();
+            }
             if (!realConn.getAutoCommit()) {
               realConn.rollback();
             }

src/main/java/org/apache/ibatis/io/DefaultVFS.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2015 the original author or authors.
+ *    Copyright 2009-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -73,17 +73,17 @@ public List<String> list(URL url, String path) throws IOException {
             // Some versions of JBoss VFS might give a JAR stream even if the resource
             // referenced by the URL isn't actually a JAR
             is = url.openStream();
-            JarInputStream jarInput = new JarInputStream(is);
-            if (log.isDebugEnabled()) {
-              log.debug("Listing " + url);
-            }
-            for (JarEntry entry; (entry = jarInput.getNextJarEntry()) != null;) {
+            try (JarInputStream jarInput = new JarInputStream(is)) {
               if (log.isDebugEnabled()) {
-                log.debug("Jar entry: " + entry.getName());
+                log.debug("Listing " + url);
+              }
+              for (JarEntry entry; (entry = jarInput.getNextJarEntry()) != null; ) {
+                if (log.isDebugEnabled()) {
+                  log.debug("Jar entry: " + entry.getName());
+                }
+                children.add(entry.getName());
               }
-              children.add(entry.getName());
             }
-            jarInput.close();
           }
           else {
             /*

src/main/java/org/apache/ibatis/io/Resources.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2015 the original author or authors.
+ *    Copyright 2009-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -125,9 +125,9 @@ public static InputStream getResourceAsStream(ClassLoader loader, String resourc
    */
   public static Properties getResourceAsProperties(String resource) throws IOException {
     Properties props = new Properties();
-    InputStream in = getResourceAsStream(resource);
-    props.load(in);
-    in.close();
+    try (InputStream in = getResourceAsStream(resource)) {
+      props.load(in);
+    }
     return props;
   }
 
@@ -141,9 +141,9 @@ public static Properties getResourceAsProperties(String resource) throws IOExcep
    */
   public static Properties getResourceAsProperties(ClassLoader loader, String resource) throws IOException {
     Properties props = new Properties();
-    InputStream in = getResourceAsStream(loader, resource);
-    props.load(in);
-    in.close();
+    try (InputStream in = getResourceAsStream(loader, resource)) {
+      props.load(in);
+    }
     return props;
   }
 
@@ -244,9 +244,9 @@ public static Reader getUrlAsReader(String urlString) throws IOException {
    */
   public static Properties getUrlAsProperties(String urlString) throws IOException {
     Properties props = new Properties();
-    InputStream in = getUrlAsStream(urlString);
-    props.load(in);
-    in.close();
+    try (InputStream in = getUrlAsStream(urlString)) {
+      props.load(in);
+    }
     return props;
   }
 

src/main/java/org/apache/ibatis/session/SqlSessionManager.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2017 the original author or authors.
+ *    Copyright 2009-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -352,16 +352,15 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
           throw ExceptionUtil.unwrapThrowable(t);
         }
       } else {
-        final SqlSession autoSqlSession = openSession();
-        try {
-          final Object result = method.invoke(autoSqlSession, args);
-          autoSqlSession.commit();
-          return result;
-        } catch (Throwable t) {
-          autoSqlSession.rollback();
-          throw ExceptionUtil.unwrapThrowable(t);
-        } finally {
-          autoSqlSession.close();
+        try (SqlSession autoSqlSession = openSession()) {
+          try {
+            final Object result = method.invoke(autoSqlSession, args);
+            autoSqlSession.commit();
+            return result;
+          } catch (Throwable t) {
+            autoSqlSession.rollback();
+            throw ExceptionUtil.unwrapThrowable(t);
+          }
         }
       }
     }