Java 8引入了大量的增強，其中lambda表達式和新的 java.util.stream.Stream.。這些新的構造與Jooq流利的API對齊得很好，可以從下面的例子中看到：
jOOQ and lambda 表達式
JOOQ官方網站：https://www.jooq.org
jOOQ的RecordMapper API是完全Java-8-ready，這基本上意味著它是SAM（單一抽象方法）類型，可以使用lambda表達式進行初始化。考慮這個例子：
try (Connection c = getConnection()) {
String sql = "select schema_name, is_default " +
"from information_schema.schemata " +
"order by schema_name";
DSL.using(c)
.fetch(sql)
// We can use lambda expressions to map jOOQ Records
.map(rs -> new Schema(
rs.getValue("SCHEMA_NAME", String.class),
rs.getValue("IS_DEFAULT", boolean.class)
))
// ... and then profit from the new Collection methods
.forEach(System.out::println);
}
DSL.using(c)
.select(
COUNTRIES.YEAR,
COUNTRIES.CODE,
COUNTRIES.GOVT_DEBT)
.from(COUNTRIES)
.join(
table(
select(COUNTRIES.CODE, avg(COUNTRIES.GOVT_DEBT).as("avg"))
.from(COUNTRIES)
.groupBy(COUNTRIES.CODE)
).as("c1")
)
.on(COUNTRIES.CODE.eq(field(name("c1", COUNTRIES.CODE.getName()), String.class)))
// order countries by their average projected value
.orderBy(
field(name("avg")),
COUNTRIES.CODE,
COUNTRIES.YEAR)
上面的示例顯示了jOOQ的Ressult.map()方法如何接收lambda表達式，該表達式實現RecordMapper以將jOOQ記錄映射到定製類型。
jOOQ and the Streams API
Jooq的 Result類型擴展了java.util.List，它打開了Java 8中各種新Java特性的訪問。下面的示例顯示了轉換一個包含INFORMATION_SCHEMA元數據的jOOQ Result以產生DDL語句：
DSL.using(c)
.select(
COLUMNS.TABLE_NAME,
COLUMNS.COLUMN_NAME,
COLUMNS.TYPE_NAME
)
.from(COLUMNS)
.orderBy(
COLUMNS.TABLE_CATALOG,
COLUMNS.TABLE_SCHEMA,
COLUMNS.TABLE_NAME,
COLUMNS.ORDINAL_POSITION
)
.fetch() // jOOQ ends here
.stream() // JDK 8 Streams start here
.collect(groupingBy(
r -> r.getValue(COLUMNS.TABLE_NAME),
LinkedHashMap::new,
mapping(
r -> new Column(
r.getValue(COLUMNS.COLUMN_NAME),
r.getValue(COLUMNS.TYPE_NAME)
),
toList()
)
))
.forEach(
(table, columns) -> {
// Just emit a CREATE TABLE statement
System.out.println(
"CREATE TABLE " + table + " (");
// Map each "Column" type into a String
// containing the column specification,
// and join them using comma and
// newline. Done!
System.out.println(
columns.stream()
.map(col -> " " + col.name +
" " + col.type)
.collect(Collectors.joining(",\n"))
);
System.out.println(");");
}
);
上面的示例在本博客文章中進行了更深入的解釋：http://blog.jooq.org/2014/04/11/java-8-friday-no-more-.-for-orms/。
Java 8 is the future, and with jOOQ, Java 8, and the Streams API, you can write powerful data transformation APIs. I hope we got you as excited as we are!
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