Add improvements to certificate component

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.cert.admin.api/src/main/java/io/entgra/device/mgt/core/certificate/mgt/cert/admin/api/CertificateManagementAdminService.java

@@ -311,20 +311,17 @@ public interface CertificateManagementAdminService {
             @ApiParam(
                     name = "serialNumber",
                     value = "The serial number of the certificates",
-                    required = false,
+                    required = false)
-                    defaultValue = "0")
             @QueryParam("serialNumber") String serialNumber,
             @ApiParam(
                     name = "deviceIdentifier",
                     value = "The device identifier of the certificates",
-                    required = false,
+                    required = false)
-                    defaultValue = "0")
             @QueryParam("deviceIdentifier") String deviceIdentifier,
             @ApiParam(
                     name = "username",
-                    value = "User name of the certificate added user" ,
+                    value = "User name of the certificate added user",
-                    required = false,
+                    required = false)
-                    defaultValue = "0")
             @QueryParam("username") String username,
             @ApiParam(
                     name = "If-Modified-Since",

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.cert.admin.api/src/main/java/io/entgra/device/mgt/core/certificate/mgt/cert/admin/api/impl/CertificateManagementAdminServiceImpl.java

@@ -27,6 +27,7 @@ import javax.ws.rs.PathParam;
 import javax.ws.rs.QueryParam;
 
 import io.entgra.device.mgt.core.device.mgt.common.CertificatePaginationRequest;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import io.entgra.device.mgt.core.certificate.mgt.cert.admin.api.CertificateManagementAdminService;
@@ -138,20 +139,23 @@ public class CertificateManagementAdminServiceImpl implements CertificateManagem
      */
     @GET
     public Response getAllCertificates(
-            @QueryParam("serialNumber") String serialNumber, @QueryParam("deviceIdentifier") String deviceIdentifier,
+            @QueryParam("serialNumber") String serialNumber,
-            @QueryParam("username") String username, @HeaderParam("If-Modified-Since") String ifModifiedSince, @QueryParam("offset") int offset,
+            @QueryParam("deviceIdentifier") String deviceIdentifier,
+            @QueryParam("username") String username,
+            @HeaderParam("If-Modified-Since") String ifModifiedSince,
+            @QueryParam("offset") int offset,
             @QueryParam("limit") int limit) {
         RequestValidationUtil.validatePaginationInfo(offset, limit);
         CertificateManagementService certificateService = CertificateMgtAPIUtils.getCertificateManagementService();
         CertificatePaginationRequest request = new CertificatePaginationRequest(offset, limit);
 
-        if (serialNumber != null && !serialNumber.isEmpty()) {
+        if (StringUtils.isNotEmpty(serialNumber)) {
             request.setSerialNumber(serialNumber);
         }
-        if (deviceIdentifier != null){
+        if (StringUtils.isNotEmpty(deviceIdentifier)){
             request.setDeviceIdentifier(deviceIdentifier);
         }
-        if (username != null){
+        if (StringUtils.isNotEmpty(username)){
             request.setUsername(username);
         }
         try {
@@ -188,18 +192,19 @@ public class CertificateManagementAdminServiceImpl implements CertificateManagem
                                         serialNumber + "' has been removed").build();
                     }
                 } catch (CertificateManagementException e) {
-                    String msg = "Error occurred while converting PEM file to X509Certificate";
+                    String msg = "Error occurred while removing certificate with the given " +
+                            "serial number '" + serialNumber + "'";
                     log.error(msg, e);
                     return Response.serverError().entity(
                             new ErrorResponse.ErrorResponseBuilder().setMessage(msg).build()).build();
                 }
             } else {
-                return Response.status(Response.Status.NOT_FOUND).entity(
+                return Response.status(Response.Status.UNAUTHORIZED).entity(
-                        "User not have to access delete certificate " +
+                        "User unauthorized to delete certificate with " +
                                 "serial number '" + serialNumber + "'").build();
             }
         } catch (CertificateManagementException e) {
-            String msg = "Error occurred while converting PEM file to X509Certificate";
+            String msg = "Error occurred while getting the metadata entry for certificate deletion.";
             log.error(msg, e);
             return Response.serverError().entity(
                     new ErrorResponse.ErrorResponseBuilder().setMessage(msg).build()).build();

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/pom.xml

@@ -56,6 +56,7 @@
                         <Import-Package>
                             org.osgi.framework.*;version="${imp.package.version.osgi.framework}",
                             org.osgi.service.*;version="${imp.package.version.osgi.service}",
+                            org.apache.commons.lang,
                             org.apache.commons.logging,
                             org.apache.commons.collections.map,
                             javax.security.auth.x500,

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/dao/impl/GenericCertificateDAOImpl.java

@@ -21,11 +21,11 @@ package io.entgra.device.mgt.core.certificate.mgt.core.dao.impl;
 import io.entgra.device.mgt.core.device.mgt.common.CertificatePaginationRequest;
 import io.entgra.device.mgt.core.certificate.mgt.core.dto.CertificateResponse;
 import io.entgra.device.mgt.core.certificate.mgt.core.impl.CertificateGenerator;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOException;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOFactory;
-import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOUtil;
 import io.entgra.device.mgt.core.certificate.mgt.core.service.PaginationResult;
 import org.wso2.carbon.context.PrivilegedCarbonContext;
 
@@ -55,66 +55,58 @@ public class GenericCertificateDAOImpl extends AbstractCertificateDAOImpl {
         String serialNumber = request.getSerialNumber();
         String deviceIdentifier = request.getDeviceIdentifier();
         String username = request.getUsername();
-        PreparedStatement stmt = null;
-        ResultSet rs = null;
 
         try {
             Connection conn = this.getConnection();
-            StringBuilder queryBuilder = new StringBuilder("SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT FROM DM_DEVICE_CERTIFICATE WHERE TENANT_ID = ?");
+            String sql = "SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT " +
+                            "FROM DM_DEVICE_CERTIFICATE " +
+                            "WHERE TENANT_ID = ?";
 
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+            if (StringUtils.isNotEmpty(serialNumber)) {
-                queryBuilder.append(" AND SERIAL_NUMBER = ?");
+                sql += " AND SERIAL_NUMBER = ?";
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
-                queryBuilder.append(" AND DEVICE_IDENTIFIER = ?");
+                sql += " AND DEVICE_IDENTIFIER = ?";
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
-                queryBuilder.append(" AND USERNAME LIKE ?");
+                sql += " AND USERNAME LIKE ?";
             }
 
-            String sql = queryBuilder.toString();
+            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
-
-            stmt = conn.prepareStatement(sql);
                 stmt.setInt(1, tenantId);
 
                 int paramIdx = 2;
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+                if (StringUtils.isNotEmpty(serialNumber)) {
                     stmt.setString(paramIdx++, serialNumber);
                 }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+                if (StringUtils.isNotEmpty(deviceIdentifier)) {
                     stmt.setString(paramIdx++, deviceIdentifier);
                 }
 
-            if (username != null && !username.isEmpty()) {
+                if (StringUtils.isNotEmpty(username)) {
                     stmt.setString(paramIdx, "%" + username + "%");
                 }
-
+                try (ResultSet rs = stmt.executeQuery()) {
-            rs = stmt.executeQuery();
-
                     if (rs.next()) {
                         certificateCount = rs.getInt("DEVICE_CERTIFICATE_COUNT");
                     }
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificate count.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, rs);
         }
-
         return certificateCount;
     }
 
 
-
     @Override
     public PaginationResult getAllCertificates(CertificatePaginationRequest request) throws CertificateManagementDAOException {
         int tenantId = PrivilegedCarbonContext.getThreadLocalCarbonContext().getTenantId();
-        PreparedStatement stmt = null;
-        ResultSet resultSet = null;
         CertificateResponse certificateResponse;
         List<CertificateResponse> certificates = new ArrayList<>();
         PaginationResult paginationResult;
@@ -130,24 +122,25 @@ public class GenericCertificateDAOImpl extends AbstractCertificateDAOImpl {
             String query = "SELECT * " +
                     "FROM DM_DEVICE_CERTIFICATE " +
                     "WHERE TENANT_ID = ? ";
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+
+            if (StringUtils.isNotEmpty(serialNumber)) {
                 query += "AND SERIAL_NUMBER = ? ";
                 isCertificateSerialNumberProvided = true;
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
                 query += "AND DEVICE_IDENTIFIER = ? ";
                 isCertificateDeviceIdentifierProvided = true;
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
                 query += "AND USERNAME LIKE ? ";
                 isCertificateUsernameProvided = true;
             }
 
             query += "ORDER BY ID LIMIT ?,?";
 
-            stmt = conn.prepareStatement(query);
+            try (PreparedStatement stmt = conn.prepareStatement(query)) {
                 int paramIdx = 1;
                 stmt.setInt(paramIdx++, tenantId);
                 if (isCertificateSerialNumberProvided) {
@@ -161,7 +154,7 @@ public class GenericCertificateDAOImpl extends AbstractCertificateDAOImpl {
                 }
                 stmt.setInt(paramIdx++, request.getStartIndex());
                 stmt.setInt(paramIdx++, request.getRowCount());
-            resultSet = stmt.executeQuery();
+                try (ResultSet resultSet = stmt.executeQuery()) {
                     while (resultSet.next()) {
                         certificateResponse = new CertificateResponse();
                         byte[] certificateBytes = resultSet.getBytes("CERTIFICATE");
@@ -176,13 +169,12 @@ public class GenericCertificateDAOImpl extends AbstractCertificateDAOImpl {
                     paginationResult = new PaginationResult();
                     paginationResult.setData(certificates);
                     paginationResult.setRecordsTotal(this.getCertificateCount(request));
-
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificates.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, resultSet);
         }
         return paginationResult;
     }

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/dao/impl/OracleCertificateDAOImpl.java

@@ -21,11 +21,11 @@ package io.entgra.device.mgt.core.certificate.mgt.core.dao.impl;
 import io.entgra.device.mgt.core.device.mgt.common.CertificatePaginationRequest;
 import io.entgra.device.mgt.core.certificate.mgt.core.dto.CertificateResponse;
 import io.entgra.device.mgt.core.certificate.mgt.core.impl.CertificateGenerator;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOException;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOFactory;
-import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOUtil;
 import io.entgra.device.mgt.core.certificate.mgt.core.service.PaginationResult;
 import org.wso2.carbon.context.PrivilegedCarbonContext;
 
@@ -47,8 +47,6 @@ public class OracleCertificateDAOImpl extends AbstractCertificateDAOImpl {
     @Override
     public PaginationResult getAllCertificates(CertificatePaginationRequest request) throws CertificateManagementDAOException {
         int tenantId = PrivilegedCarbonContext.getThreadLocalCarbonContext().getTenantId();
-        PreparedStatement stmt = null;
-        ResultSet resultSet = null;
         CertificateResponse certificateResponse;
         List<CertificateResponse> certificates = new ArrayList<>();
         PaginationResult paginationResult;
@@ -64,24 +62,24 @@ public class OracleCertificateDAOImpl extends AbstractCertificateDAOImpl {
             String query = "SELECT * " +
                     "FROM DM_DEVICE_CERTIFICATE " +
                     "WHERE TENANT_ID = ? ";
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+            if (StringUtils.isNotEmpty(serialNumber)) {
                 query += "AND SERIAL_NUMBER = ? ";
                 isCertificateSerialNumberProvided = true;
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
                 query += "AND DEVICE_IDENTIFIER = ? ";
                 isCertificateDeviceIdentifierProvided = true;
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
                 query += "AND USERNAME LIKE ? ";
                 isCertificateUsernameProvided = true;
             }
 
             query += "ORDER BY ID OFFSET ? ROWS FETCH NEXT ? ROWS ONLY";
 
-            stmt = conn.prepareStatement(query);
+            try (PreparedStatement stmt = conn.prepareStatement(query)) {
                 int paramIdx = 1;
                 stmt.setInt(paramIdx++, tenantId);
                 if (isCertificateSerialNumberProvided) {
@@ -95,7 +93,7 @@ public class OracleCertificateDAOImpl extends AbstractCertificateDAOImpl {
                 }
                 stmt.setInt(paramIdx++, request.getStartIndex());
                 stmt.setInt(paramIdx++, request.getRowCount());
-            resultSet = stmt.executeQuery();
+                try (ResultSet resultSet = stmt.executeQuery()) {
                     while (resultSet.next()) {
                         certificateResponse = new CertificateResponse();
                         byte[] certificateBytes = resultSet.getBytes("CERTIFICATE");
@@ -110,12 +108,12 @@ public class OracleCertificateDAOImpl extends AbstractCertificateDAOImpl {
                     paginationResult = new PaginationResult();
                     paginationResult.setData(certificates);
                     paginationResult.setRecordsTotal(this.getCertificateCount(request));
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificates.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, resultSet);
         }
         return paginationResult;
     }
@@ -130,56 +128,52 @@ public class OracleCertificateDAOImpl extends AbstractCertificateDAOImpl {
         String serialNumber = request.getSerialNumber();
         String deviceIdentifier = request.getDeviceIdentifier();
         String username = request.getUsername();
-        PreparedStatement stmt = null;
-        ResultSet rs = null;
 
         try {
             Connection conn = this.getConnection();
-            StringBuilder queryBuilder = new StringBuilder("SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT FROM DM_DEVICE_CERTIFICATE WHERE TENANT_ID = ?");
+            String sql = "SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT " +
+                    "FROM DM_DEVICE_CERTIFICATE " +
+                    "WHERE TENANT_ID = ?";
 
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+            if (StringUtils.isNotEmpty(serialNumber)) {
-                queryBuilder.append(" AND SERIAL_NUMBER = ?");
+                sql += " AND SERIAL_NUMBER = ?";
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
-                queryBuilder.append(" AND DEVICE_IDENTIFIER = ?");
+                sql += " AND DEVICE_IDENTIFIER = ?";
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
-                queryBuilder.append(" AND USERNAME LIKE ?");
+                sql += " AND USERNAME LIKE ?";
             }
 
-            String sql = queryBuilder.toString();
+            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
-
-            stmt = conn.prepareStatement(sql);
                 stmt.setInt(1, tenantId);
 
                 int paramIdx = 2;
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+                if (StringUtils.isNotEmpty(serialNumber)) {
                     stmt.setString(paramIdx++, serialNumber);
                 }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+                if (StringUtils.isNotEmpty(deviceIdentifier)) {
                     stmt.setString(paramIdx++, deviceIdentifier);
                 }
 
-            if (username != null && !username.isEmpty()) {
+                if (StringUtils.isNotEmpty(username)) {
                     stmt.setString(paramIdx, "%" + username + "%");
                 }
 
-            rs = stmt.executeQuery();
+                try (ResultSet rs = stmt.executeQuery()) {
-
                     if (rs.next()) {
                         certificateCount = rs.getInt("DEVICE_CERTIFICATE_COUNT");
                     }
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificate count.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, rs);
         }
-
         return certificateCount;
     }
 

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/dao/impl/PostgreSQLCertificateDAOImpl.java

@@ -21,11 +21,11 @@ package io.entgra.device.mgt.core.certificate.mgt.core.dao.impl;
 import io.entgra.device.mgt.core.device.mgt.common.CertificatePaginationRequest;
 import io.entgra.device.mgt.core.certificate.mgt.core.dto.CertificateResponse;
 import io.entgra.device.mgt.core.certificate.mgt.core.impl.CertificateGenerator;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOException;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOFactory;
-import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOUtil;
 import io.entgra.device.mgt.core.certificate.mgt.core.service.PaginationResult;
 import org.wso2.carbon.context.PrivilegedCarbonContext;
 
@@ -47,8 +47,6 @@ public class PostgreSQLCertificateDAOImpl extends AbstractCertificateDAOImpl {
     @Override
     public PaginationResult getAllCertificates(CertificatePaginationRequest request) throws CertificateManagementDAOException {
         int tenantId = PrivilegedCarbonContext.getThreadLocalCarbonContext().getTenantId();
-        PreparedStatement stmt = null;
-        ResultSet resultSet = null;
         CertificateResponse certificateResponse;
         List<CertificateResponse> certificates = new ArrayList<>();
         PaginationResult paginationResult;
@@ -64,24 +62,24 @@ public class PostgreSQLCertificateDAOImpl extends AbstractCertificateDAOImpl {
             String query = "SELECT * " +
                     "FROM DM_DEVICE_CERTIFICATE " +
                     "WHERE TENANT_ID = ? ";
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+            if (StringUtils.isNotEmpty(serialNumber)) {
                 query += "AND SERIAL_NUMBER = ? ";
                 isCertificateSerialNumberProvided = true;
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
                 query += "AND DEVICE_IDENTIFIER = ? ";
                 isCertificateDeviceIdentifierProvided = true;
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
                 query += "AND USERNAME LIKE ? ";
                 isCertificateUsernameProvided = true;
             }
 
             query += "ORDER BY ID LIMIT ? OFFSET ?";
 
-            stmt = conn.prepareStatement(query);
+            try (PreparedStatement stmt = conn.prepareStatement(query)) {
                 int paramIdx = 1;
                 stmt.setInt(paramIdx++, tenantId);
                 if (isCertificateSerialNumberProvided) {
@@ -95,7 +93,7 @@ public class PostgreSQLCertificateDAOImpl extends AbstractCertificateDAOImpl {
                 }
                 stmt.setInt(paramIdx++, request.getStartIndex());
                 stmt.setInt(paramIdx++, request.getRowCount());
-            resultSet = stmt.executeQuery();
+                try (ResultSet resultSet = stmt.executeQuery()) {
                     while (resultSet.next()) {
                         certificateResponse = new CertificateResponse();
                         byte[] certificateBytes = resultSet.getBytes("CERTIFICATE");
@@ -110,13 +108,12 @@ public class PostgreSQLCertificateDAOImpl extends AbstractCertificateDAOImpl {
                     paginationResult = new PaginationResult();
                     paginationResult.setData(certificates);
                     paginationResult.setRecordsTotal(this.getCertificateCount(request));
-
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificates.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, resultSet);
         }
         return paginationResult;
     }
@@ -131,56 +128,52 @@ public class PostgreSQLCertificateDAOImpl extends AbstractCertificateDAOImpl {
         String serialNumber = request.getSerialNumber();
         String deviceIdentifier = request.getDeviceIdentifier();
         String username = request.getUsername();
-        PreparedStatement stmt = null;
-        ResultSet rs = null;
 
         try {
             Connection conn = this.getConnection();
-            StringBuilder queryBuilder = new StringBuilder("SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT FROM DM_DEVICE_CERTIFICATE WHERE TENANT_ID = ?");
+            String sql = "SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT " +
+                    "FROM DM_DEVICE_CERTIFICATE " +
+                    "WHERE TENANT_ID = ?";
 
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+            if (StringUtils.isNotEmpty(serialNumber)) {
-                queryBuilder.append(" AND SERIAL_NUMBER = ?");
+                sql += " AND SERIAL_NUMBER = ?";
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
-                queryBuilder.append(" AND DEVICE_IDENTIFIER = ?");
+                sql += " AND DEVICE_IDENTIFIER = ?";
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
-                queryBuilder.append(" AND USERNAME ILIKE ?");
+                sql += " AND USERNAME ILIKE ?";
             }
 
-            String sql = queryBuilder.toString();
+            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
-
-            stmt = conn.prepareStatement(sql);
                 stmt.setInt(1, tenantId);
 
                 int paramIdx = 2;
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+                if (StringUtils.isNotEmpty(serialNumber)) {
                     stmt.setString(paramIdx++, serialNumber);
                 }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+                if (StringUtils.isNotEmpty(deviceIdentifier)) {
                     stmt.setString(paramIdx++, deviceIdentifier);
                 }
 
-            if (username != null && !username.isEmpty()) {
+                if (StringUtils.isNotEmpty(username)) {
                     stmt.setString(paramIdx, "%" + username + "%");
                 }
 
-            rs = stmt.executeQuery();
+                try (ResultSet rs = stmt.executeQuery()) {
-
                     if (rs.next()) {
                         certificateCount = rs.getInt("DEVICE_CERTIFICATE_COUNT");
                     }
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificate count.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, rs);
         }
-
         return certificateCount;
     }
 

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/dao/impl/SQLServerCertificateDAOImpl.java

@@ -21,11 +21,11 @@ package io.entgra.device.mgt.core.certificate.mgt.core.dao.impl;
 import io.entgra.device.mgt.core.device.mgt.common.CertificatePaginationRequest;
 import io.entgra.device.mgt.core.certificate.mgt.core.dto.CertificateResponse;
 import io.entgra.device.mgt.core.certificate.mgt.core.impl.CertificateGenerator;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOException;
 import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOFactory;
-import io.entgra.device.mgt.core.certificate.mgt.core.dao.CertificateManagementDAOUtil;
 import io.entgra.device.mgt.core.certificate.mgt.core.service.PaginationResult;
 import org.wso2.carbon.context.PrivilegedCarbonContext;
 
@@ -47,8 +47,6 @@ public class SQLServerCertificateDAOImpl extends AbstractCertificateDAOImpl {
     @Override
     public PaginationResult getAllCertificates(CertificatePaginationRequest request) throws CertificateManagementDAOException {
         int tenantId = PrivilegedCarbonContext.getThreadLocalCarbonContext().getTenantId();
-        PreparedStatement stmt = null;
-        ResultSet resultSet = null;
         CertificateResponse certificateResponse;
         List<CertificateResponse> certificates = new ArrayList<>();
         PaginationResult paginationResult;
@@ -64,24 +62,24 @@ public class SQLServerCertificateDAOImpl extends AbstractCertificateDAOImpl {
             String query = "SELECT * " +
                     "FROM DM_DEVICE_CERTIFICATE " +
                     "WHERE TENANT_ID = ? ";
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+            if (StringUtils.isNotEmpty(serialNumber)) {
                 query += "AND SERIAL_NUMBER = ? ";
                 isCertificateSerialNumberProvided = true;
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
                 query += "AND DEVICE_IDENTIFIER = ? ";
                 isCertificateDeviceIdentifierProvided = true;
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
                 query += "AND USERNAME LIKE ? ";
                 isCertificateUsernameProvided = true;
             }
 
             query += "ORDER BY ID OFFSET ? ROWS FETCH NEXT ? ROWS ONLY";
 
-            stmt = conn.prepareStatement(query);
+            try (PreparedStatement stmt = conn.prepareStatement(query)) {
                 int paramIdx = 1;
                 stmt.setInt(paramIdx++, tenantId);
                 if (isCertificateSerialNumberProvided) {
@@ -95,7 +93,7 @@ public class SQLServerCertificateDAOImpl extends AbstractCertificateDAOImpl {
                 }
                 stmt.setInt(paramIdx++, request.getStartIndex());
                 stmt.setInt(paramIdx++, request.getRowCount());
-            resultSet = stmt.executeQuery();
+                try (ResultSet resultSet =  stmt.executeQuery()) {
                     while (resultSet.next()) {
                         certificateResponse = new CertificateResponse();
                         byte[] certificateBytes = resultSet.getBytes("CERTIFICATE");
@@ -110,13 +108,12 @@ public class SQLServerCertificateDAOImpl extends AbstractCertificateDAOImpl {
                     paginationResult = new PaginationResult();
                     paginationResult.setData(certificates);
                     paginationResult.setRecordsTotal(this.getCertificateCount(request));
-
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificates.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, resultSet);
         }
         return paginationResult;
     }
@@ -131,56 +128,52 @@ public class SQLServerCertificateDAOImpl extends AbstractCertificateDAOImpl {
         String serialNumber = request.getSerialNumber();
         String deviceIdentifier = request.getDeviceIdentifier();
         String username = request.getUsername();
-        PreparedStatement stmt = null;
-        ResultSet rs = null;
 
         try {
             Connection conn = this.getConnection();
-            StringBuilder queryBuilder = new StringBuilder("SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT FROM DM_DEVICE_CERTIFICATE WHERE TENANT_ID = ?");
+            String sql = "SELECT COUNT(*) AS DEVICE_CERTIFICATE_COUNT " +
+                    "FROM DM_DEVICE_CERTIFICATE " +
+                    "WHERE TENANT_ID = ?";
 
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+            if (StringUtils.isNotEmpty(serialNumber)) {
-                queryBuilder.append(" AND SERIAL_NUMBER = ?");
+                sql += " AND SERIAL_NUMBER = ?";
             }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+            if (StringUtils.isNotEmpty(deviceIdentifier)) {
-                queryBuilder.append(" AND DEVICE_IDENTIFIER = ?");
+                sql += " AND DEVICE_IDENTIFIER = ?";
             }
 
-            if (username != null && !username.isEmpty()) {
+            if (StringUtils.isNotEmpty(username)) {
-                queryBuilder.append(" AND USERNAME LIKE ?");
+                sql += " AND USERNAME LIKE ?";
             }
 
-            String sql = queryBuilder.toString();
+            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
-
-            stmt = conn.prepareStatement(sql);
                 stmt.setInt(1, tenantId);
 
                 int paramIdx = 2;
-            if (serialNumber != null && !serialNumber.isEmpty()) {
+                if (StringUtils.isNotEmpty(serialNumber)) {
                     stmt.setString(paramIdx++, serialNumber);
                 }
 
-            if (deviceIdentifier != null && !deviceIdentifier.isEmpty()) {
+                if (StringUtils.isNotEmpty(deviceIdentifier)) {
                     stmt.setString(paramIdx++, deviceIdentifier);
                 }
 
-            if (username != null && !username.isEmpty()) {
+                if (StringUtils.isNotEmpty(username)) {
                     stmt.setString(paramIdx, "%" + username + "%");
                 }
 
-            rs = stmt.executeQuery();
+                try (ResultSet rs = stmt.executeQuery()) {
-
                     if (rs.next()) {
                         certificateCount = rs.getInt("DEVICE_CERTIFICATE_COUNT");
                     }
+                }
+            }
         } catch (SQLException e) {
             String errorMsg = "SQL error occurred while retrieving the certificate count.";
             log.error(errorMsg, e);
             throw new CertificateManagementDAOException(errorMsg, e);
-        } finally {
-            CertificateManagementDAOUtil.cleanupResources(stmt, rs);
         }
-
         return certificateCount;
     }
 

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/service/CertificateManagementServiceImpl.java

@@ -17,8 +17,6 @@
  */
 package io.entgra.device.mgt.core.certificate.mgt.core.service;
 
-
-
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParseException;
 import com.google.gson.JsonParser;
@@ -38,6 +36,7 @@ import io.entgra.device.mgt.core.certificate.mgt.core.impl.KeyStoreReader;
 
 import io.entgra.device.mgt.core.device.mgt.common.exceptions.MetadataManagementException;
 import io.entgra.device.mgt.core.device.mgt.common.metadata.mgt.Metadata;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.bouncycastle.pkcs.PKCS10CertificationRequest;
@@ -210,7 +209,7 @@ public class CertificateManagementServiceImpl implements CertificateManagementSe
             metadata = CertificateManagerUtil.getMetadataManagementService().retrieveMetadata(CertificateManagementConstants.CERTIFICATE_DELETE);
             if (metadata != null) {
                 String metaValue = metadata.getMetaValue();
-                if (metaValue != null && !metaValue.isEmpty()) {
+                if (StringUtils.isNotEmpty(metaValue)) {
                     JsonParser parser = new JsonParser();
                     JsonObject jsonObject = parser.parse(metaValue).getAsJsonObject();
                     return jsonObject.get(CertificateManagementConstants.IS_CERTIFICATE_DELETE_ENABLE).getAsBoolean();