[CALCITE-591] Drop support for Java 1.6 (and JDBC 4.0)

.travis.yml

@@ -20,7 +20,6 @@ language: java
 jdk:
   - oraclejdk8
   - oraclejdk7
-  - openjdk6
 branches:
   only:
     - master

avatica/src/main/java/org/apache/calcite/avatica/UnregisteredDriver.java

@@ -86,9 +86,9 @@ protected Handler createHandler() {
   protected String getFactoryClassName(JdbcVersion jdbcVersion) {
     switch (jdbcVersion) {
     case JDBC_30:
-      return "org.apache.calcite.avatica.AvaticaFactoryJdbc3Impl";
     case JDBC_40:
-      return "org.apache.calcite.avatica.AvaticaJdbc40Factory";
+      throw new IllegalArgumentException("JDBC version not supported: "
+          + jdbcVersion);
     case JDBC_41:
     default:
       return "org.apache.calcite.avatica.AvaticaJdbc41Factory";

core/src/main/java/org/apache/calcite/jdbc/Driver.java

@@ -65,9 +65,9 @@ protected Function0<CalcitePrepare> createPrepareFactory() {
   @Override protected String getFactoryClassName(JdbcVersion jdbcVersion) {
     switch (jdbcVersion) {
     case JDBC_30:
-      return "org.apache.calcite.jdbc.CalciteJdbc3Factory";
     case JDBC_40:
-      return "org.apache.calcite.jdbc.CalciteJdbc40Factory";
+      throw new IllegalArgumentException("JDBC version not supported: "
+          + jdbcVersion);
     case JDBC_41:
     default:
       return "org.apache.calcite.jdbc.CalciteJdbc41Factory";

core/src/main/java/org/apache/calcite/util/Compatible.java

@@ -57,6 +57,7 @@ public interface Compatible {
    *
    * <p>This method is available in JDK 1.7 and above, and in
    * {@link org.apache.calcite.jdbc.CalciteConnection} in all JDK versions. */
+  @Deprecated // to be removed before 2.0
   void setSchema(Connection connection, String schema);
 
   /** Creates the implementation of Compatible suitable for the

core/src/test/java/org/apache/calcite/test/CalciteAssert.java

@@ -33,7 +33,6 @@
 import org.apache.calcite.schema.SchemaPlus;
 import org.apache.calcite.schema.impl.AbstractSchema;
 import org.apache.calcite.schema.impl.ViewTable;
-import org.apache.calcite.util.Compatible;
 import org.apache.calcite.util.JsonBuilder;
 import org.apache.calcite.util.Pair;
 import org.apache.calcite.util.Util;
@@ -972,7 +971,7 @@ public Connection apply(Connection connection) throws SQLException {
         SchemaPlus rootSchema = con.getRootSchema();
         rootSchema.add(name, schema);
       }
-      Compatible.INSTANCE.setSchema(connection, name);
+      connection.setSchema(name);
       return connection;
     }
   }

doc/HOWTO.md

@@ -6,7 +6,7 @@ adapters.
 ## Building from a source distribution
 
 Prerequisites are maven (3.2.1 or later)
-and Java (JDK 1.6 or later, 1.8 preferred) on your path.
+and Java (JDK 1.7 or later, 1.8 preferred) on your path.
 
 Unpack the source distribution `.tar.gz` or `.zip` file,
 `cd` to the root directory of the unpacked source,
@@ -24,7 +24,7 @@ tests.
 ## Building from git
 
 Prerequisites are git, maven (3.2.1 or later)
-and Java (JDK 1.6 or later, 1.8 preferred) on your path.
+and Java (JDK 1.7 or later, 1.8 preferred) on your path.
 
 Create a local copy of the github repository,
 `cd` to its root directory,
@@ -283,7 +283,7 @@ the `KEYS` file.
 
 Before you start:
 * Set up signing keys as described above.
-* Make sure you are using JDK 1.7 (not 1.6 or 1.8).
+* Make sure you are using JDK 1.7 (not 1.8).
 * Make sure build and tests succeed with `-Dcalcite.test.db=hsqldb` (the default)
 
 ```bash
@@ -303,7 +303,7 @@ When the dry-run has succeeded, change `install` to `deploy`.
 
 Before you start:
 * Set up signing keys as described above.
-* Make sure you are using JDK 1.7 (not 1.6 or 1.8).
+* Make sure you are using JDK 1.7 (not 1.8).
 * Check that `README`, `README.md` and `HOWTO.md` have the correct version number.
 * Make sure build and tests succeed, including with
   -Dcalcite.test.db={mysql,hsqldb}, -Dcalcite.test.slow=true,

pom.xml

@@ -272,8 +272,8 @@ limitations under the License.
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
         <configuration>
-          <source>1.5</source>
-          <target>1.5</target>
+          <source>1.7</source>
+          <target>1.7</target>
         </configuration>
       </plugin>
       <plugin>