将 find 方法的返回值改为 Optional<T>。

plusone-basic/plusone-basic-infrastructure/src/main/java/xyz/zhouxy/plusone/jdbc/JdbcEntityDaoSupport.java

@@ -4,6 +4,7 @@ import java.io.Serializable;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Stream;
 
 import javax.annotation.Nonnull;
@@ -20,23 +21,23 @@ public abstract class JdbcEntityDaoSupport<T extends Entity<ID>, ID extends Seri
         extends PlusoneJdbcDaoSupport {
 
     protected RowMapper<T> rowMapper;
-    protected ResultSetExtractor<T> resultSetExtractor;
+    protected ResultSetExtractor<Optional<T>> resultSetExtractor;
 
     protected JdbcEntityDaoSupport(@Nonnull NamedParameterJdbcTemplate namedParameterJdbcTemplate) {
         super(namedParameterJdbcTemplate);
         this.rowMapper = (ResultSet rs, int rowNum) -> mapRow(rs);
-        this.resultSetExtractor = (ResultSet rs) -> rs.next() ? mapRow(rs) : null;
+        this.resultSetExtractor = (ResultSet rs) -> rs.next() ? Optional.of(mapRow(rs)) : Optional.empty();
     }
 
-    protected final T queryForObject(String sql) {
+    protected final Optional<T> queryForObject(String sql) {
         return queryForObject(sql, this.resultSetExtractor);
     }
 
-    protected final T queryForObject(String sql, SqlParameterSource paramSource) {
+    protected final Optional<T> queryForObject(String sql, SqlParameterSource paramSource) {
         return queryForObject(sql, paramSource, this.resultSetExtractor);
     }
 
-    protected final T queryForObject(String sql, String paramName, Object value) {
+    protected final Optional<T> queryForObject(String sql, String paramName, Object value) {
         return queryForObject(sql, new MapSqlParameterSource(paramName, value), this.resultSetExtractor);
     }
 
@@ -66,7 +67,7 @@ public abstract class JdbcEntityDaoSupport<T extends Entity<ID>, ID extends Seri
         this.rowMapper = rowMapper;
     }
 
-    protected void setResultSetExtractor(@Nonnull ResultSetExtractor<T> resultSetExtractor) {
+    protected void setResultSetExtractor(@Nonnull ResultSetExtractor<Optional<T>> resultSetExtractor) {
         this.resultSetExtractor = resultSetExtractor;
     }
 }

plusone-basic/plusone-basic-infrastructure/src/main/java/xyz/zhouxy/plusone/jdbc/JdbcRepositorySupport.java

@@ -1,6 +1,7 @@
 package xyz.zhouxy.plusone.jdbc;
 
 import java.io.Serializable;
+import java.util.Optional;
 
 import javax.annotation.Nonnull;
 
@@ -20,7 +21,7 @@ public abstract class JdbcRepositorySupport<T extends AggregateRoot<ID>, ID exte
 
     protected abstract void doDelete(@Nonnull T entity);
 
-    protected abstract T doFindById(@Nonnull ID id);
+    protected abstract Optional<T> doFindById(@Nonnull ID id);
 
     protected abstract T doInsert(@Nonnull T entity);
 
@@ -35,7 +36,7 @@ public abstract class JdbcRepositorySupport<T extends AggregateRoot<ID>, ID exte
     }
 
     @Override
-    public final T find(ID id) {
+    public final Optional<T> find(ID id) {
         if (id == null) {
             throw new IllegalArgumentException("Id cannot be null.");
         }