#919 - io.ebean package initial

src/main/java/io/ebeaninternal/server/query/CQueryFetchSingleAttribute.java

@@ -0,0 +1,172 @@
+package io.ebeaninternal.server.query;
+
+import io.ebeaninternal.api.SpiQuery;
+import io.ebeaninternal.api.SpiTransaction;
+import io.ebeaninternal.server.core.OrmQueryRequest;
+import io.ebeaninternal.server.deploy.BeanDescriptor;
+import io.ebeaninternal.server.type.RsetDataReader;
+import io.ebeaninternal.server.type.ScalarType;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Base compiled query request for single attribute queries.
+ */
+class CQueryFetchSingleAttribute {
+
+  private static final Logger logger = LoggerFactory.getLogger(CQueryFetchSingleAttribute.class);
+
+  /**
+   * The overall find request wrapper object.
+   */
+  private final OrmQueryRequest<?> request;
+
+  private final BeanDescriptor<?> desc;
+
+  private final SpiQuery<?> query;
+
+  /**
+   * Where clause predicates.
+   */
+  private final CQueryPredicates predicates;
+
+  /**
+   * The final sql that is generated.
+   */
+  private final String sql;
+
+  private RsetDataReader dataReader;
+
+  /**
+   * The statement used to create the resultSet.
+   */
+  private PreparedStatement pstmt;
+
+  private String bindLog;
+
+  private int executionTimeMicros;
+
+  private int rowCount;
+
+  private final ScalarType<Object> scalarType;
+
+  /**
+   * Create the Sql select based on the request.
+   */
+  CQueryFetchSingleAttribute(OrmQueryRequest<?> request, CQueryPredicates predicates, CQueryPlan plan) {
+    this.request = request;
+    this.query = request.getQuery();
+    this.sql = plan.getSql();
+    this.desc = request.getBeanDescriptor();
+    this.predicates = predicates;
+    this.scalarType = plan.getSingleProperty().getScalarType();
+
+    query.setGeneratedSql(sql);
+  }
+
+  /**
+   * Return a summary description of this query.
+   */
+  protected String getSummary() {
+    StringBuilder sb = new StringBuilder(80);
+    sb.append("FindAttr exeMicros[").append(executionTimeMicros)
+      .append("] rows[").append(rowCount)
+      .append("] type[").append(desc.getName())
+      .append("] predicates[").append(predicates.getLogWhereSql())
+      .append("] bind[").append(bindLog).append("]");
+
+    return sb.toString();
+  }
+
+  /**
+   * Execute the query returning the row count.
+   */
+  protected List<Object> findList() throws SQLException {
+
+    long startNano = System.nanoTime();
+    try {
+
+      prepareExecute();
+
+      List<Object> result = new ArrayList<>();
+
+      while (dataReader.next()) {
+        result.add(scalarType.read(dataReader));
+        dataReader.resetColumnPosition();
+        rowCount++;
+      }
+
+      long exeNano = System.nanoTime() - startNano;
+      executionTimeMicros = (int) exeNano / 1000;
+
+      return result;
+
+    } finally {
+      close();
+    }
+  }
+
+  /**
+   * Return the bind log.
+   */
+  protected String getBindLog() {
+    return bindLog;
+  }
+
+  /**
+   * Return the generated sql.
+   */
+  protected String getGeneratedSql() {
+    return sql;
+  }
+
+  private void prepareExecute() throws SQLException {
+
+    SpiTransaction t = request.getTransaction();
+    Connection conn = t.getInternalConnection();
+    pstmt = conn.prepareStatement(sql);
+
+    if (query.getBufferFetchSizeHint() > 0) {
+      pstmt.setFetchSize(query.getBufferFetchSizeHint());
+    }
+    if (query.getTimeout() > 0) {
+      pstmt.setQueryTimeout(query.getTimeout());
+    }
+
+    bindLog = predicates.bind(pstmt, conn);
+    dataReader = new RsetDataReader(request.getDataTimeZone(), pstmt.executeQuery());
+  }
+
+  /**
+   * Close the resources.
+   * <p>
+   * The jdbc resultSet and statement need to be closed. Its important that
+   * this method is called.
+   * </p>
+   */
+  private void close() {
+    try {
+      if (dataReader != null) {
+        dataReader.close();
+        dataReader = null;
+      }
+    } catch (SQLException e) {
+      logger.error("Error closing DataReader", e);
+    }
+    try {
+      if (pstmt != null) {
+        pstmt.close();
+        pstmt = null;
+      }
+    } catch (SQLException e) {
+      logger.error("Error closing PreparedStatement", e);
+    }
+  }
+
+}