feat: implement UpdatableAdapter and add tests (#73)

Author: Muluo-cyan

src/main/java/org/casbin/adapter/JDBCBaseAdapter.java

@@ -24,6 +24,7 @@
 import org.casbin.jcasbin.persist.Adapter;
 import org.casbin.jcasbin.persist.BatchAdapter;
 import org.casbin.jcasbin.persist.Helper;
+import org.casbin.jcasbin.persist.UpdatableAdapter;
 
 import javax.sql.DataSource;
 import java.sql.*;
@@ -49,7 +50,7 @@ public String[] toStringArray() {
  * JDBCAdapter is the JDBC adapter for jCasbin.
  * It can load policy from JDBC supported database or save policy to it.
  */
-abstract class JDBCBaseAdapter implements Adapter, BatchAdapter {
+abstract class JDBCBaseAdapter implements Adapter, BatchAdapter, UpdatableAdapter {
     protected static final String DEFAULT_TABLE_NAME = "casbin_rule";
     protected static final boolean DEFAULT_REMOVE_POLICY_FAILED = false;
     protected static final boolean DEFAULT_AUTO_CREATE_TABLE = true;
@@ -480,6 +481,47 @@ public void removeFilteredPolicy(String sec, String ptype, int fieldIndex, Strin
         });
     }
 
+    /**
+     * updatePolicy updates a policy rule from the current policy.
+     */
+    @Override
+    public void updatePolicy(String sec, String ptype, List<String> oldRule, List<String> newRule) {
+        if (CollectionUtils.isEmpty(oldRule) || CollectionUtils.isEmpty(newRule)) {
+            return;
+        }
+
+        String sql = renderActualSql("INSERT INTO casbin_rule (ptype,v0,v1,v2,v3,v4,v5) VALUES(?,?,?,?,?,?,?)");
+
+
+        Failsafe.with(retryPolicy).run(ctx -> {
+            if (ctx.isRetry()) {
+                retry(ctx);
+            }
+            conn.setAutoCommit(false);
+            removePolicy(sec, ptype, oldRule);
+            try (PreparedStatement ps = conn.prepareStatement(sql)) {
+                CasbinRule line = this.savePolicyLine(ptype, newRule);
+
+                ps.setString(1, line.ptype);
+                ps.setString(2, line.v0);
+                ps.setString(3, line.v1);
+                ps.setString(4, line.v2);
+                ps.setString(5, line.v3);
+                ps.setString(6, line.v4);
+                ps.setString(7, line.v5);
+                ps.executeUpdate();
+                conn.commit();
+            } catch (SQLException e) {
+                conn.rollback();
+
+                e.printStackTrace();
+                throw e;
+            } finally {
+                conn.setAutoCommit(true);
+            }
+        });
+    }
+
     /**
      * Close the Connection.
      */

src/test/java/org/casbin/adapter/JDBCAdapterTest.java

@@ -257,4 +257,37 @@ public void testRemovePolicy() throws Exception {
                 asList("data2_admin", "data2", "read"),
                 asList("data2_admin", "data2", "write")));
     }
+
+    @Test
+    public void testUpdatePolicy() throws Exception {
+        JDBCAdapter adapter = new MySQLAdapterCreator().create();
+
+        // Because the DB is empty at first,
+        // so we need to load the policy from the file adapter (.CSV) first.
+        Enforcer e = new Enforcer("examples/rbac_model.conf", "examples/rbac_policy.csv");
+
+        // This is a trick to save the current policy to the DB.
+        // We can't call e.savePolicy() because the adapter in the enforcer is still the file adapter.
+        // The current policy means the policy in the jCasbin enforcer (aka in memory).
+        adapter.savePolicy(e.getModel());
+
+        e.clearPolicy();
+        testGetPolicy(e, asList());
+
+        e = new Enforcer("examples/rbac_model.conf", adapter);
+        testGetPolicy(e, asList(
+                asList("alice", "data1", "read"),
+                asList("bob", "data2", "write"),
+                asList("data2_admin", "data2", "read"),
+                asList("data2_admin", "data2", "write")));
+
+        adapter.updatePolicy("p", "p", asList("bob", "data2", "write"), asList("alice", "data2", "read"));
+        e = new Enforcer("examples/rbac_model.conf", adapter);
+        testGetPolicy(e, asList(
+                asList("alice", "data1", "read"),
+                asList("data2_admin", "data2", "read"),
+                asList("data2_admin", "data2", "write"),
+                asList("alice", "data2", "read")));
+
+    }
 }