{"id":131971,"date":"2020-07-06T23:51:24","date_gmt":"2020-07-06T15:51:24","guid":{"rendered":"http:\/\/4563.org\/?p=131971"},"modified":"2020-07-06T23:51:24","modified_gmt":"2020-07-06T15:51:24","slug":"scala%e8%af%ad%e8%a8%80%e5%ad%a6%e4%b9%a0%ef%bc%88%e5%9b%9b%ef%bc%89%e3%80%81%e5%87%bd%e6%95%b0%e5%bc%8f%e7%bc%96%e7%a8%8b","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=131971","title":{"rendered":"scala\u8bed\u8a00\u5b66\u4e60\uff08\u56db\uff09\u3001\u51fd\u6570\u5f0f\u7f16\u7a0b"},"content":{"rendered":"

<\/a>\u51fd\u6570\u5f0f\u7f16\u7a0b<\/h2>\n

\u6211\u4eec\u5c06\u6765\u4f7f\u7528Spark\/Flink\u7684\u5927\u91cf\u4e1a\u52a1\u4ee3\u7801\u90fd\u4f1a\u4f7f\u7528\u5230\u51fd\u6570\u5f0f\u7f16\u7a0b\u3002
\u4e0b\u9762\u7684\u8fd9\u4e9b\u64cd\u4f5c\u662f\u5b66\u4e60\u7684\u91cd\u70b9\uff0c\u5148\u6765\u611f\u53d7\u4e0b\u5982\u4f55\u8fdb\u884c\u51fd\u6570\u5f0f\u7f16\u7a0b\u4ee5\u53ca\u5b83\u7684\u5f3a\u5927<\/p>\n

<\/a>\u904d\u5386 – foreach<\/h2>\n

<\/a>\u65b9\u6cd5\u63cf\u8ff0<\/h3>\n
\n\n\n
\n
1<\/span>
<\/pre>\n<\/td>\n
\n
foreach(f: (A<\/span>) \u21d2 Unit<\/span>): Unit<\/span><\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u65b9\u6cd5\u8bf4\u660e<\/h3>\n\n\n\n\n\n\n
foreach<\/th>\nAPI<\/th>\n\u8bf4\u660e<\/th>\n<\/tr>\n<\/thead>\n
\u53c2\u6570<\/td>\nf: (A) \u21d2 Unit<\/td>\n\u63a5\u6536\u4e00\u4e2a\u51fd\u6570\u5bf9\u8c61\u4f5c\u4e3a\u53c2\u6570
\u51fd\u6570\u7684\u8f93\u5165\u53c2\u6570\u4e3a\u96c6\u5408\u7684\u5143\u7d20
\u8fd4\u56de\u503c\u4e3a\u7a7a<\/td>\n<\/tr>\n
\u8fd4\u56de\u503c<\/td>\nUnit<\/td>\n\u7a7a<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
<\/a>\u65b9\u6cd5\u5b9e\u64cd<\/h3>\n
\n\n\n
\n
1<\/span>
2<\/span>
3<\/span>
4<\/span>
5<\/span>
6<\/span>
7<\/span>
8<\/span>
9<\/span>
10<\/span>
11<\/span>
12<\/span>
13<\/span>
14<\/span>
15<\/span>
16<\/span>
17<\/span>
18<\/span>
19<\/span>
20<\/span>
21<\/span>
22<\/span>
23<\/span>
24<\/span>
25<\/span>
26<\/span>
27<\/span>
28<\/span>
29<\/span>
30<\/span>
31<\/span>
32<\/span>
<\/pre>\n<\/td>\n
\n
scala> val<\/span> list = List<\/span>(1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>)<\/span>
list: List<\/span>[Int<\/span>] = List<\/span>(1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>)<\/span>
<\/span>
\/\/\u5b9a\u4e49\u4e00\u4e2a\u533f\u540d\u51fd\u6570\u4f20\u5165\u5230foreach\u65b9\u6cd5\u4e2d<\/span><\/span>
scala> list.foreach((x: Int<\/span>) => println(x))<\/span>
1<\/span><\/span>
2<\/span><\/span>
3<\/span><\/span>
4<\/span><\/span>
<\/span>
\/\/\u533f\u540d\u51fd\u6570\u7684\u8f93\u5165\u53c2\u6570\u7c7b\u578b\u53ef\u4ee5\u7701\u7565\uff0c\u7531\u7f16\u8bd1\u5668\u81ea\u52a8\u63a8\u65ad<\/span><\/span>
scala> list.foreach(x => println(x))<\/span>
1<\/span><\/span>
2<\/span><\/span>
3<\/span><\/span>
4<\/span><\/span>
<\/span>
\/\/\u5f53\u51fd\u6570\u53c2\u6570\uff0c\u53ea\u5728\u51fd\u6570\u4f53\u4e2d\u51fa\u73b0\u4e00\u6b21\uff0c\u800c\u4e14\u51fd\u6570\u4f53\u6ca1\u6709\u5d4c\u5957\u8c03\u7528\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u4e0b\u5212\u7ebf\u6765\u7b80\u5316\u51fd\u6570\u5b9a\u4e49<\/span><\/span>
scala> list.foreach(println(_))<\/span>
1<\/span><\/span>
2<\/span><\/span>
3<\/span><\/span>
4<\/span><\/span>
<\/span>
\/\/\u6700\u7b80\u5199\uff0c\u76f4\u63a5\u7ed9\u5b9aprintln<\/span><\/span>
scala> list.foreach(println)<\/span>
1<\/span><\/span>
2<\/span><\/span>
3<\/span><\/span>
4<\/span><\/span>
<\/span>
\/\/\u5f88\u795e\u5947\u7684\u8bed\u6cd5\uff0c\u522b\u5bb3\u6015\uff0c\u76d8\u5b83\u5c31\u53ef\u4ee5\u4e86\uff0c\u540e\u671f\u901a\u8fc7scala\u8bed\u8a00\u5f00\u53d1spark\u3001Flink\u7a0b\u5e8f\u975e\u5e38\u7b80\u6d01\u65b9\u4fbf<\/span><\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u6620\u5c04 – map<\/h2>\n
\u96c6\u5408\u7684\u6620\u5c04\u64cd\u4f5c\u662f\u5c06\u6765\u5728\u7f16\u5199Spark\/Flink\u7528\u5f97\u6700\u591a\u7684\u64cd\u4f5c\uff0c\u662f\u6211\u4eec\u5fc5\u987b\u8981\u638c\u63e1\u3002<\/p>\n
<\/a>\u65b9\u6cd5\u63cf\u8ff0<\/h3>\n
\n\n\n
\n
1<\/span>
<\/pre>\n<\/td>\n
\n
def<\/span> map<\/span><\/span>[B<\/span>](f: (A<\/span>) \u21d2 B<\/span>): TraversableOnce<\/span>[B<\/span>]<\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u65b9\u6cd5\u8bf4\u660e<\/h3>\n\n\n\n\n\n\n\n
map\u65b9\u6cd5<\/th>\nAPI<\/th>\n\u8bf4\u660e<\/th>\n<\/tr>\n<\/thead>\n
\u6cdb\u578b<\/td>\n[B]<\/td>\n\u6307\u5b9amap\u65b9\u6cd5\u6700\u7ec8\u8fd4\u56de\u7684\u96c6\u5408\u6cdb\u578b<\/td>\n<\/tr>\n
\u53c2\u6570<\/td>\nf: (A) \u21d2 B<\/td>\n\u4f20\u5165\u4e00\u4e2a\u51fd\u6570\u5bf9\u8c61\u4f5c\u4e3a\u53c2\u6570
\u8be5\u51fd\u6570\u63a5\u6536\u4e00\u4e2a\u7c7b\u578bA\uff08\u8981\u8f6c\u6362\u7684\u96c6\u5408\u7684\u5143\u7d20\u7c7b\u578b\uff09
\u8fd4\u56de\u503c\u4e3a\u7c7b\u578bB<\/td>\n<\/tr>\n
\u8fd4\u56de\u503c<\/td>\nTraversableOnce[B]<\/td>\nB\u7c7b\u578b\u7684\u96c6\u5408<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
<\/a>\u65b9\u6cd5\u5b9e\u64cd<\/h3>\n
\n\n\n
\n
1<\/span>
2<\/span>
3<\/span>
4<\/span>
5<\/span>
6<\/span>
7<\/span>
8<\/span>
9<\/span>
10<\/span>
11<\/span>
12<\/span>
13<\/span>
14<\/span>
15<\/span>
<\/pre>\n<\/td>\n
\n
\/\/\u5b9a\u4e49\u4e00\u4e2alist\u96c6\u5408\uff0c\u5b9e\u73b0\u628a\u5185\u90e8\u6bcf\u4e00\u4e2a\u5143\u7d20\u505a\u4e58\u4ee510\uff0c\u751f\u6210\u4e00\u4e2a\u65b0\u7684list\u96c6\u5408<\/span><\/span>
scala> val<\/span> list = List<\/span>(1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>)<\/span>
list: List<\/span>[Int<\/span>] = List<\/span>(1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>)<\/span>
<\/span>
\/\/\u5b9a\u4e49\u4e00\u4e2a\u533f\u540d\u51fd\u6570<\/span><\/span>
scala> list.map((x: Int<\/span>) => x * 10<\/span>)<\/span>
res21: List<\/span>[Int<\/span>] = List<\/span>(10<\/span>, 20<\/span>, 30<\/span>, 40<\/span>)<\/span>
<\/span>
\/\/\u7701\u7565\u533f\u540d\u51fd\u6570\u53c2\u6570\u7c7b\u578b<\/span><\/span>
scala> list.map(x => x * 10<\/span>)<\/span>
res22: List<\/span>[Int<\/span>] = List<\/span>(10<\/span>, 20<\/span>, 30<\/span>, 40<\/span>)<\/span>
<\/span>
\/\/\u6700\u7b80\u5199\u7528\u4e0b\u5212\u7ebf<\/span><\/span>
scala> list.map(_ * 10<\/span>)<\/span>
res23: List<\/span>[Int<\/span>] = List<\/span>(10<\/span>, 20<\/span>, 30<\/span>, 40<\/span>)<\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u6241\u5e73\u5316\u6620\u5c04 – flatmap<\/h2>\n
\u6620\u5c04\u6241\u5e73\u5316\u4e5f\u662f\u5c06\u6765\u7528\u5f97\u975e\u5e38\u591a\u7684\u64cd\u4f5c\uff0c\u4e5f\u662f\u5fc5\u987b\u8981\u638c\u63e1\u7684\u3002<\/p>\n
<\/a>\u65b9\u6cd5\u63cf\u8ff0<\/h3>\n
\n\n\n
\n
1<\/span>
<\/pre>\n<\/td>\n
\n
def<\/span> flatMap<\/span><\/span>[B<\/span>](f: (A<\/span>) \u21d2 GenTraversableOnce<\/span>[B<\/span>]): TraversableOnce<\/span>[B<\/span>]<\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u65b9\u6cd5\u8bf4\u660e<\/h3>\n\n\n\n\n\n\n\n
flatmap\u65b9\u6cd5<\/th>\nAPI<\/th>\n\u8bf4\u660e<\/th>\n<\/tr>\n<\/thead>\n
\u6cdb\u578b<\/td>\n[B]<\/td>\n\u6700\u7ec8\u8981\u8f6c\u6362\u7684\u96c6\u5408\u5143\u7d20\u7c7b\u578b<\/td>\n<\/tr>\n
\u53c2\u6570<\/td>\nf: (A) \u21d2 GenTraversableOnce[B]<\/td>\n\u4f20\u5165\u4e00\u4e2a\u51fd\u6570\u5bf9\u8c61\u4f5c\u4e3a\u53c2\u6570
\u51fd\u6570\u7684\u53c2\u6570\u662f\u96c6\u5408\u7684\u5143\u7d20
\u51fd\u6570\u7684\u8fd4\u56de\u503c\u662f\u4e00\u4e2a\u96c6\u5408<\/td>\n<\/tr>\n
\u8fd4\u56de\u503c<\/td>\nTraversableOnce[B]<\/td>\nB\u7c7b\u578b\u7684\u96c6\u5408<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
<\/a>\u65b9\u6cd5\u5b9e\u64cd<\/h3>\n
\n\n\n
\n
1<\/span>
2<\/span>
3<\/span>
4<\/span>
5<\/span>
6<\/span>
7<\/span>
8<\/span>
9<\/span>
10<\/span>
11<\/span>
12<\/span>
13<\/span>
14<\/span>
15<\/span>
<\/pre>\n<\/td>\n
\n
\/\/\u5b9a\u4e49\u4e00\u4e2aList\u96c6\u5408,\u6bcf\u4e00\u4e2a\u5143\u7d20\u4e2d\u5c31\u662f\u4e00\u884c\u6570\u636e\uff0c\u6709\u5f88\u591a\u4e2a\u5355\u8bcd<\/span><\/span>
scala>  val<\/span> list = List<\/span>(\"hadoop hive spark flink\"<\/span>, \"hbase spark\"<\/span>)<\/span>
list: List<\/span>[String<\/span>] = List<\/span>(hadoop hive spark flink, hbase spark)<\/span>
<\/span>
\/\/\u4f7f\u7528flatMap\u8fdb\u884c\u504f\u5e73\u5316\u5904\u7406\uff0c\u83b7\u53d6\u5f97\u5230\u6240\u6709\u7684\u5355\u8bcd<\/span><\/span>
scala> list.flatMap(x => x.split(\" \"<\/span>))<\/span>
res24: List<\/span>[String<\/span>] = List<\/span>(hadoop, hive, spark, flink, hbase, spark)<\/span>
<\/span>
\/\/\u7b80\u5199<\/span><\/span>
scala> list.flatMap(_.split(\" \"<\/span>))<\/span>
res25: List<\/span>[String<\/span>] = List<\/span>(hadoop, hive, spark, flink, hbase, spark)<\/span>
<\/span>
\/\/ flatMap\u8be5\u65b9\u6cd5\u5176\u672c\u8d28\u662f\u5148\u8fdb\u884c\u4e86map \u7136\u540e\u53c8\u8c03\u7528\u4e86flatten<\/span><\/span>
scala> list.map(_.split(\" \"<\/span>)).flatten<\/span>
res26: List<\/span>[String<\/span>] = List<\/span>(hadoop, hive, spark, flink, hbase, spark)<\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u8fc7\u6ee4 – filter<\/h2>\n
\u8fc7\u6ee4\u7b26\u5408\u4e00\u5b9a\u6761\u4ef6\u7684\u5143\u7d20<\/p>\n
<\/a>\u65b9\u6cd5\u63cf\u8ff0<\/h3>\n
\n\n\n
\n
1<\/span>
<\/pre>\n<\/td>\n
\n
def<\/span> filter<\/span><\/span>(p: (A<\/span>) \u21d2 Boolean<\/span>): TraversableOnce<\/span>[A<\/span>]<\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u65b9\u6cd5\u8bf4\u660e<\/h3>\n\n\n\n\n\n\n
filter\u65b9\u6cd5<\/th>\nAPI<\/th>\n\u8bf4\u660e<\/th>\n<\/tr>\n<\/thead>\n
\u53c2\u6570<\/td>\np: (A) \u21d2 Boolean<\/td>\n\u4f20\u5165\u4e00\u4e2a\u51fd\u6570\u5bf9\u8c61\u4f5c\u4e3a\u53c2\u6570
\u51fd\u6570\u7684\u53c2\u6570\u662f\u96c6\u5408\u4e2d\u7684\u5143\u7d20
\u6b64\u51fd\u6570\u8fd4\u56de\u5e03\u5c14\u7c7b\u578b\uff0c\u6ee1\u8db3\u6761\u4ef6\u8fd4\u56detrue, \u4e0d\u6ee1\u8db3\u8fd4\u56defalse<\/td>\n<\/tr>\n
\u8fd4\u56de\u503c<\/td>\nTraversableOnce[A]<\/td>\n\u5217\u8868<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
<\/a>\u65b9\u6cd5\u5b9e\u64cd<\/h3>\n
\n\n\n
\n
1<\/span>
2<\/span>
3<\/span>
4<\/span>
5<\/span>
6<\/span>
7<\/span>
8<\/span>
9<\/span>
10<\/span>
11<\/span>
12<\/span>
13<\/span>
<\/pre>\n<\/td>\n
\n
\/\/\u5b9a\u4e49\u4e00\u4e2alist\u96c6\u5408<\/span><\/span>
scala> val<\/span> list = List<\/span>(1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>, 5<\/span>, 6<\/span>, 7<\/span>, 8<\/span>, 9<\/span>, 10<\/span>)<\/span>
list: List<\/span>[Int<\/span>] = List<\/span>(1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>, 5<\/span>, 6<\/span>, 7<\/span>, 8<\/span>, 9<\/span>, 10<\/span>)<\/span>
<\/span>
\/\/\u8fc7\u6ee4\u51fa\u96c6\u5408\u4e2d\u5927\u4e8e5\u7684\u5143\u7d20<\/span><\/span>
scala> list.filter(x => x > 5<\/span>)<\/span>
res27: List<\/span>[Int<\/span>] = List<\/span>(6<\/span>, 7<\/span>, 8<\/span>, 9<\/span>, 10<\/span>)<\/span>
<\/span>
\/\/\u628a\u96c6\u5408\u4e2d\u5927\u4e8e5\u7684\u5143\u7d20\u53d6\u51fa\u6765\u4e58\u4ee510\u751f\u6210\u4e00\u4e2a\u65b0\u7684list\u96c6\u5408<\/span><\/span>
scala> list.filter(_ > 5<\/span>).map(_ * 10<\/span>)<\/span>
res29: List<\/span>[Int<\/span>] = List<\/span>(60<\/span>, 70<\/span>, 80<\/span>, 90<\/span>, 100<\/span>)<\/span>
<\/span>
\/\/\u901a\u8fc7\u8fd9\u4e2a\u6848\u4f8b\uff0c\u5e94\u8be5\u662f\u53ef\u4ee5\u611f\u53d7\u5230scala\u6bd4java\u7684\u5f3a\u5927\u4e86...<\/span><\/span>
<\/pre>\n<\/td>\n<\/tr>\n<\/table>\n<\/figure>\n
<\/a>\u6392\u5e8f – sort<\/h2>\n
\u5728scala\u96c6\u5408\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u51e0\u79cd\u65b9\u5f0f\u6765\u8fdb\u884c\u6392\u5e8f<\/p>\n