Improve JdbcJobExecutionDao::getJobExecution

spring-batch-core/src/main/java/org/springframework/batch/core/repository/dao/jdbc/JdbcJobExecutionDao.java

@@ -90,18 +90,17 @@ SELECT COUNT(*)
 			WHERE JOB_EXECUTION_ID = ? AND VERSION = ?
 			""";
 
-	private static final String GET_JOB_EXECUTIONS = """
-			SELECT JOB_EXECUTION_ID, START_TIME, END_TIME, STATUS, EXIT_CODE, EXIT_MESSAGE, CREATE_TIME, LAST_UPDATED, VERSION
-			FROM %PREFIX%JOB_EXECUTION
-			""";
-
 	private static final String GET_LAST_JOB_EXECUTION_ID = """
 			SELECT JOB_EXECUTION_ID
 			FROM %PREFIX%JOB_EXECUTION
 			WHERE JOB_INSTANCE_ID = ? AND JOB_EXECUTION_ID IN (SELECT MAX(JOB_EXECUTION_ID) FROM %PREFIX%JOB_EXECUTION E2 WHERE E2.JOB_INSTANCE_ID = ?)
 			""";
 
-	private static final String GET_EXECUTION_BY_ID = GET_JOB_EXECUTIONS + " WHERE JOB_EXECUTION_ID = ?";
+	private static final String GET_EXECUTION_BY_ID = """
+			SELECT JOB_EXECUTION_ID, JOB_INSTANCE_ID, START_TIME, END_TIME, STATUS, EXIT_CODE, EXIT_MESSAGE, CREATE_TIME, LAST_UPDATED, VERSION
+			FROM %PREFIX%JOB_EXECUTION
+			WHERE JOB_EXECUTION_ID = ?
+			""";
 
 	private static final String GET_RUNNING_EXECUTION_FOR_INSTANCE = """
 			SELECT E.JOB_EXECUTION_ID
@@ -136,12 +135,6 @@ SELECT COUNT(*)
 			WHERE JOB_EXECUTION_ID = ?
 			""";
 
-	private static final String GET_JOB_INSTANCE_ID_FROM_JOB_EXECUTION_ID = """
-			SELECT JI.JOB_INSTANCE_ID
-			FROM %PREFIX%JOB_INSTANCE JI, %PREFIX%JOB_EXECUTION JE
-			WHERE JOB_EXECUTION_ID = ? AND JI.JOB_INSTANCE_ID = JE.JOB_INSTANCE_ID
-			""";
-
 	private static final String GET_JOB_EXECUTION_IDS_BY_INSTANCE_ID = """
 			SELECT JOB_EXECUTION_ID FROM %PREFIX%JOB_EXECUTION WHERE JOB_INSTANCE_ID = ?
 			ORDER BY JOB_EXECUTION_ID DESC
@@ -321,23 +314,15 @@ public JobExecution getLastJobExecution(JobInstance jobInstance) {
 
 	@Override
 	public JobExecution getJobExecution(long jobExecutionId) {
-		long jobInstanceId = getJobInstanceId(jobExecutionId);
-		JobInstance jobInstance = jobInstanceDao.getJobInstance(jobInstanceId);
-		JobParameters jobParameters = getJobParameters(jobExecutionId);
 		try {
 			return getJdbcTemplate().queryForObject(getQuery(GET_EXECUTION_BY_ID),
-					new JobExecutionRowMapper(jobInstance, jobParameters), jobExecutionId);
+					new JobExecutionRowMapper(jobInstanceDao::getJobInstance, this::getJobParameters), jobExecutionId);
 		}
 		catch (EmptyResultDataAccessException e) {
 			return null;
 		}
 	}
 
-	private long getJobInstanceId(long jobExecutionId) {
-		return getJdbcTemplate().queryForObject(getQuery(GET_JOB_INSTANCE_ID_FROM_JOB_EXECUTION_ID), Long.class,
-				jobExecutionId);
-	}
-
 	@Override
 	public Set<JobExecution> findRunningJobExecutions(String jobName) {
 		final Set<JobExecution> result = new HashSet<>();

spring-batch-core/src/main/java/org/springframework/batch/core/repository/dao/jdbc/JobExecutionRowMapper.java

@@ -2,6 +2,7 @@
 
 import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.util.function.Function;
 
 import org.springframework.batch.core.BatchStatus;
 import org.springframework.batch.core.ExitStatus;
@@ -13,11 +14,13 @@
 /**
  * @author Dave Syer
  * @author Mahmoud Ben Hassine
+ * @author Yanming Zhou
  * <p>
  * Expects a result set with the following columns: *
  * <ul>
  * *
  * <li>JOB_EXECUTION_ID</li> *
+ * <li>JOB_INSTANCE_ID</li> *
  * <li>START_TIME</li> *
  * <li>END_TIME</li> *
  * <li>STATUS</li> *
@@ -31,19 +34,21 @@
  */
 class JobExecutionRowMapper implements RowMapper<JobExecution> {
 
-	private final JobInstance jobInstance;
+	private final Function<Long, JobInstance> jobInstanceMapper;
 
-	private final JobParameters jobParameters;
+	private final Function<Long, JobParameters> jobParametersMapper;
 
-	public JobExecutionRowMapper(JobInstance jobInstance, JobParameters jobParameters) {
-		this.jobInstance = jobInstance;
-		this.jobParameters = jobParameters;
+	public JobExecutionRowMapper(Function<Long, JobInstance> jobInstanceMapper,
+			Function<Long, JobParameters> jobParametersMapper) {
+		this.jobInstanceMapper = jobInstanceMapper;
+		this.jobParametersMapper = jobParametersMapper;
 	}
 
 	@Override
 	public JobExecution mapRow(ResultSet rs, int rowNum) throws SQLException {
 		long id = rs.getLong("JOB_EXECUTION_ID");
-		JobExecution jobExecution = new JobExecution(id, this.jobInstance, this.jobParameters);
+		JobExecution jobExecution = new JobExecution(id, this.jobInstanceMapper.apply(rs.getLong("JOB_INSTANCE_ID")),
+				this.jobParametersMapper.apply(id));
 		jobExecution.setStartTime(
 				rs.getTimestamp("START_TIME") == null ? null : rs.getTimestamp("START_TIME").toLocalDateTime());
 		jobExecution

spring-batch-core/src/test/java/org/springframework/batch/core/repository/dao/jdbc/JdbcJobExecutionDaoTests.java

@@ -39,6 +39,7 @@
 /**
  * @author Parikshit Dutta
  * @author Mahmoud Ben Hassine
+ * @author Yanming Zhou
  */
 public class JdbcJobExecutionDaoTests {
 
@@ -90,6 +91,20 @@ void testCreateJobExecution() {
 		Assertions.assertEquals(1, batchJobExecutionsCount);
 	}
 
+	@Test
+	void testGetJobExecution() {
+		// given
+		JobParameters jobParameters = new JobParameters();
+		JobInstance jobInstance = jdbcJobInstanceDao.createJobInstance("job", jobParameters);
+
+		// when
+		JobExecution createdJobExecution = jdbcJobExecutionDao.createJobExecution(jobInstance, jobParameters);
+		JobExecution retrievedJobExecution = jdbcJobExecutionDao.getJobExecution(createdJobExecution.getId());
+
+		// then
+		Assertions.assertEquals(createdJobExecution, retrievedJobExecution);
+	}
+
 	@Test
 	void testDeleteJobExecution() {
 		// given