csharp复制代码> setnx lock:codehole true
OK
... do something critical ...
> del lock:codehole
(integer) 1

csharp复制代码> setnx lock:codehole true
OK
> expire lock:codehole 5
... do something critical ...
> del lock:codehole
(integer) 1

csharp复制代码> set lock:codehole true ex 5 nx
OK
... do something critical ...
> del lock:codehole

lua复制代码if redis.call("get",KEYS[1]) == ARGV[1] then
    return redis.call("del",KEYS[1])
else
    return 0
end

markdown复制代码> cl.throttle laoqian:reply 15 30 60 1
                      ▲     ▲  ▲  ▲  ▲
                      |     |  |  |  └───── need 1 quota (可选参数，默认值也是1)
                      |     |  └──┴─────── 30 operations / 60 seconds 这是漏水速率
                      |     └───────────── 15 capacity 这是漏斗容量
                      └─────────────────── key laoqian

go复制代码type Reader interface {
    Read(p []byte) (n int, err error)
}

go复制代码var r io.Reader
log.Println(r)
// 2021/11/28 12:27:52 <nil>

go复制代码type Human struct {
    Firstname string
    Lastname string
    Age int
    Country string
}

type DomesticAnimal interface {
    ReceiveAffection(from Human)
    GiveAffection(to Human)
}

go复制代码type Cat struct {
    Name string
}

type Dog struct {
    Name string
}

go复制代码func (c Cat) ReceiveAffection(from Human) {
    fmt.Printf("The cat named %s has received affection from Human named %s\n", c.Name, from.Firstname)
}

func (c Cat) GiveAffection(to Human) {
    fmt.Printf("The cat named %s has given affection to Human named %s\n", c.Name, to.Firstname)
}

go复制代码func (d Dog) ReceiveAffection(from Human) {
    fmt.Printf("The dog named %s has received affection from Human named %s\n", d.Name, from.Firstname)
}

func (d Dog) GiveAffection(to Human) {
    fmt.Printf("The dog named %s has given affection to Human named %s\n", d.Name, to.Firstname)
}

go复制代码func Pet(animal DomesticAnimal, human Human) {
    animal.GiveAffection(human)
    animal.ReceiveAffection(human)
}

go复制代码func main() {

    // Create the Human
    var john Human
    john.Firstname = "John"


    // Create a Cat
    var c Cat
    c.Name = "Maru"

    // then a dog
    var d Dog
    d.Name = "Medor"

    Pet(c, john)
    Pet(d,john)
}

go复制代码// ...
// let's create a concrete type Snake
type Snake struct {
    Name string
}
// we do not implement the methods ReceiveAffection and GiveAffection intentionally
//...


func main(){

    var snake Snake
    snake.Name = "Joe"

    Pet(snake, john)
}

shell复制代码./main.go:70:5: cannot use snake (type Snake) as type DomesticAnimal in argument to Pet:
    Snake does not implement DomesticAnimal (missing GiveAffection method)

go复制代码type Driver interface {
    Open(name string) (Conn, error)
}

go复制代码// the Stringer type interface from the standard library
type Stringer interface {
    String() string
}
// A homemade interface
type DomesticAnimal interface {
    ReceiveAffection(from Human)
    GiveAffection(to Human)
    // embed the interface Stringer into the DomesticAnimal interface
    Stringer
}

go复制代码type error interface {
    Error() string
}

go复制代码func (c *Communicator) SendEmailAsynchronously(email *Email) error {
    //...
}

go复制代码type Stringer interface {
    String() string
}

go复制代码type Human struct {
    Firstname string
    Lastname string
    Age int
    Country string
}

func (h Human) String() string {
    return fmt.Sprintf("human named %s %s of age %d living in %s",h.Firstname,h.Lastname,h.Age,h.Country)
}

go复制代码package main

func main() {
    var john Human
    john.Firstname = "John"
    john.Lastname = "Doe"
    john.Country = "USA"
    john.Age = 45

    fmt.Println(john)
}

shell复制代码human named John Doe of age 45 living in the USA

go复制代码type Interface interface {
    Len() int
    Less(i, j int) bool
    Swap(i, j int)
}

go复制代码type Person struct {
    Name string
    Age int
}
// ByAge implements sort.Interface for []Person based on
// the Age field.
type ByAge []Person

func (a ByAge) Len() int           { return len(a) }
func (a ByAge) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a ByAge) Less(i, j int) bool { return a[i].Age < a[j].Age }

go复制代码func main() {
    people := []Person{
        {"Bob", 31},
        {"John", 42},
        {"Michael", 17},
        {"Jenny", 26},
    }

    sort.Sort(ByAge(people))
}

java复制代码// JAVA
public class Cat implements DomesticAnimal{
    public void receiveAffection(){
        //...
    }
    public void giveAffection(){
        //..
    }
}

PHP复制代码//PHP
<?php

class Cat implements DomesticAnimal {
    public function receiveAffection():void {
        // ...
    }
    public function giveAffection():void {
        // ...
    }
}
?>

go复制代码interface{}

go复制代码func (l *Logger) Fatal(v ...interface{}) { }

go复制代码func Printf(format string, a ...interface{}) (n int, err error) { }

go复制代码// printany prints an argument passed to panic.
// If panic is called with a value that has a String or Error method,
// it has already been converted into a string by preprintpanics.
func printany(i interface{}) {
    switch v := i.(type) {
    case nil:
        print("nil")
    case bool:
        print(v)
    case int:
        print(v)
    case int8:
        print(v)
    case int16:
        print(v)
    case int32:
        print(v)
    case int64:
        print(v)
    case uint:
        print(v)
    case uint8:
        print(v)
    case uint16:
        print(v)
    case uint32:
        print(v)
    case uint64:
        print(v)
    case uintptr:
        print(v)
    case float32:
        print(v)
    case float64:
        print(v)
    case complex64:
        print(v)
    case complex128:
        print(v)
    case string:
        print(v)
    default:
        printanycustomtype(i)
    }
}

go复制代码func (c Cart) ApplyCoupon(coupon Coupon) error  {
    //...
}

func (c Cart) ApplyCoupon2(coupon interface{}) (interface{},interface{}) {
    //...
}

go复制代码type CartStore interface {
    GetById(ID string) (*cart.Cart, error)
    Put(cart *cart.Cart) (*cart.Cart, error)
}

go复制代码type CartStoreMySQL struct{}

func (c *CartStoreMySQL) GetById(ID string) (*cart.Cart, error) {
    // implement me
}

func (c *CartStoreMySQL) Put(cart *cart.Cart) (*cart.Cart, error) {
    // implement me
}

go复制代码type CartStorePostgres struct{}

func (c *CartStorePostgres) GetById(ID string) (*cart.Cart, error) {
    // implement me
}

func (c *CartStorePostgres) Put(cart *cart.Cart) (*cart.Cart, error) {
    // implement me
}

go复制代码// go v.1.10.1
package sort
//..

type Interface interface {
    // Len is the number of elements in the collection.
    Len() int
    // Less reports whether the element with
    // index i should sort before the element with index j.
    Less(i, j int) bool
    // Swap swaps the elements with indexes i and j.
    Swap(i, j int)
}

// Sort sorts data.
// It makes one call to data.Len to determine n, and O(n*log(n)) calls to
// data.Less and data.Swap. The sort is not guaranteed to be stable.
func Sort(data Interface) {
    n := data.Len()
    quickSort(data, 0, n, maxDepth(n))
}

go复制代码type User struct {
    firstname string
    lastname string
    totalTurnover float64
}

go复制代码type Users []User

go复制代码user0 := User{firstname:"John", lastname:"Doe", totalTurnover:1000}
user1 := User{firstname:"Dany", lastname:"Boyu", totalTurnover:20000}
user2 := User{firstname:"Elisa", lastname:"Smith Brown", totalTurnover:70}

users := make([]Users,3)
users[0] = user0
users[1] = user1
users[2] = user2

go复制代码// Compute the length of the array. Easy...
func (users Users) Len() int {
  return len(users)
}

// decide which instance is bigger than the other one
func (users Users) Less(i, j int) bool {
  return users[i].totalTurnover < users[j].totalTurnover
}

// swap two elements of the array
func (users Users) Swap(i, j int) {
    users[i], users[j] = users[j], users[i]
}

go复制代码sort.Sort(users)
fmt.Println(users)
// will output :
[{Elisa Smith Brown 70} {John Doe 1000} {Dany Boyu 20000}]

go复制代码type ReadWriter interface {
    Reader
    Writer
}

go复制代码type Cart interface {
    GetById(ID string) (*cart.Cart, error)
    Put(cart *cart.Cart) (*cart.Cart, error)
}

go复制代码switch v := i.(type) {
    case nil:
        print("nil")
    case bool:
        print(v)
    case int:
        print(v)
}

bash复制代码exec java -Duser.home="$JENKINS_HOME" -Dhudson.security.csrf.GlobalCrumbIssuerConfiguration.DISABLE_CSRF_PROTECTION=true "${java_opts_array[@]}" -jar ${JENKINS_WAR} "${jenkins_opts_array[@]}" "$@

复制代码 Hook executed successfully but returned HTTP 403

vbnet复制代码This configuration is unavailable because the System property hudson.security.csrf.GlobalCrumbIssuerConfiguration.DISABLE_CSRF_PROTECTION is set to true.

arduino复制代码Process leaked file descriptors. See https://www.jenkins.io/redirect/troubleshooting/process-leaked-file-descriptors for more information

css复制代码To reliably kill processes spawned by a job during a build, Jenkins contains a bit of native code to list up such processes and kill them.

java复制代码public class HDFSDemo {

    private FileSystem fs;

    final String HADOOP_URI_ADDRESS = "hdfs://192.168.10.102:8020";

    final String HADOOP_USER = "root";

    @Before
    public void init() throws URISyntaxException, IOException, InterruptedException {
        // 获取文件系统
        fs = FileSystem.get(new URI(HADOOP_URI_ADDRESS), 
                            new Configuration(), 
                            HADOOP_USER);
    }

    @After
    public void after() throws IOException {
        // 关闭资源
        fs.close();
    }
}

java复制代码@Test
public void downloadFile() throws IOException {
    fs.copyToLocalFile(false,//是否删除源文件
                       new Path("/input/word.txt"),//hdfs中的文件地址
                       new Path("d:/word_down.txt"),//本地的文件地址
                       true);//是否开启校验
}

java复制代码@Test
public void uploadFile() throws IOException {
    fs.copyFromLocalFile(new Path("d:/word_down.txt"), new Path("/input/"));
}

shell复制代码mvn clean install

xml复制代码<dependency>
    <groupId>danran.rpc</groupId>
    <artifactId>danran-rpc-spring-boot-starter</artifactId>
    <version>1.0.1</version>
    <!--排除日志冲突-->
    <exclusions>
        <exclusion>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
        </exclusion>
    </exclusions>
</dependency>

properties复制代码danran.rpc.register-address=121.4.195.203:2181 # zk的地址
danran.rpc.protocol=danran
danran.rpc.server-port=6666

java复制代码package provider.service;

import common.api.BookService;
import common.entity.Book;
import danran.rpc.annotation.RPCService;
import org.springframework.beans.factory.annotation.Autowired;
import provider.mapper.BookMapper;

import java.util.List;

/**
 * @Classname BookServiceImpl
 * @Description TODO
 * @Date 2021/8/24 15:50
 * @Created by ASUS
 */
@RPCService
public class BookServiceImpl implements BookService {

    @Autowired
    private BookMapper bookMapper;

    /**
     * @return 所有的书籍信息
     */
    @Override
    public List<Book> getAllBooks() {
        return bookMapper.getAllBooks();
    }
}

java复制代码package consumer.controller;

import common.api.BookService;
import common.entity.Book;
import danran.rpc.annotation.InjectService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * @Classname ConsumerController
 * @Description TODO
 * @Date 2021/8/24 19:04
 * @Created by ASUS
 */
@RestController
@RequestMapping("/consumer")
public class ConsumerController {

    @InjectService
    private BookService bookService;

    @GetMapping("/get_all_books")
    public List<Book> getAllBooks() {
        return bookService.getAllBooks();
    }
}

java复制代码public byte[] sendRequest(byte[] data, Service service) throws InterruptedException {
    String[] ip_port = service.getAddress().split(":");
    String ip = ip_port[0];
    int port = Integer.parseInt(ip_port[1]);

    SendHandler sendHandler = new SendHandler(data);
    byte[] rsp;
    // 配置客户端
    EventLoopGroup group = new NioEventLoopGroup();
    try {
        Bootstrap bootstrap = new Bootstrap();
        // 初始化通道
        bootstrap.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true).handler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) {
                ChannelPipeline pipeline = ch.pipeline();
                pipeline.addLast(sendHandler);
            }
        });
        // 启动连接
        bootstrap.connect(ip, port).sync();
        rsp = (byte[]) sendHandler.rspData();
        logger.info("Send Request and get the response: {}", rsp);
    } finally {
        // 释放线程组资源
        group.shutdownGracefully();
    }
    return rsp;
}

java复制代码return (T) this.objectCache.computeIfAbsent(
    clazz, 
    cls -> newProxyInstance(
        cls.getClassLoader(), 
        new Class<?>[]{cls}, 
        new ClientInvocationHandler(cls)));

java复制代码List<Service> services = serviceDiscovery.getServices(serviceName);

java复制代码/***
 * 服务暴露
 *
 * @param service 需要暴露的服务
 */
private void exportService(Service service) {
    String serviceName = service.getName();
    String uri = JSON.toJSONString(service);
    try {
        uri = URLEncoder.encode(uri, "UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    // 抽象的服务定位节点
    String servicePath = "/rpc/" + serviceName + "/service";
    logger.info("抽象服务[" + serviceName + "]注册地址 == " + servicePath);

    if (!zkClient.exists(servicePath)) {
        zkClient.createPersistent(servicePath, true);
    }
    // 具体的服务实例地址
    String uriPath = servicePath + "/" + uri;
    logger.info("具体服务实例注册节点 == " + uriPath);

    if (zkClient.exists(uriPath)) zkClient.delete(uriPath);// 如果存在，删除更新
    zkClient.createEphemeral(uriPath);// 创建一个短暂的节点
}

bash复制代码➜  cd prometheus
➜  prometheus docker run -d --rm \
    -v $(pwd)/receive-data:/receive/data \
    --net=host \
    --name receive \
    quay.io/thanos/thanos:v0.23.1 \
    receive \
    --tsdb.path "/receive/data" \
    --grpc-address 127.0.0.1:10907 \
    --http-address 127.0.0.1:10909 \
    --label "receive_replica=\"0\"" \
    --label "receive_cluster=\"moelove\"" \
    --remote-write.address 127.0.0.1:10908
59498d43291b705709b3f360d28af81d5a8daba11f5629bb11d6e07532feb8b6
➜  prometheus docker ps -l
CONTAINER ID   IMAGE                           COMMAND                  CREATED          STATUS          PORTS     NAMES
59498d43291b   quay.io/thanos/thanos:v0.23.1   "/bin/thanos receive…"   21 seconds ago   Up 20 seconds             receive

bash复制代码➜  prometheus docker run -d --rm \
--net=host \
--name query \
quay.io/thanos/thanos:v0.23.1 \
query \
--http-address "0.0.0.0:39090" \
--store "127.0.0.1:10907"
10c2b1bf2375837dbda16d09cee43d95787243f6dcbee73f4159a21b12d36019
➜  prometheus docker ps -l
CONTAINER ID   IMAGE                           COMMAND                  CREATED         STATUS         PORTS     NAMES
10c2b1bf2375   quay.io/thanos/thanos:v0.23.1   "/bin/thanos query -…"   4 seconds ago   Up 3 seconds             query

yaml复制代码global:
  scrape_interval: 15s
  external_labels:
    cluster: moelove
    replica: 0

scrape_configs:
  - job_name: "prometheus"
    static_configs:
      - targets: ["localhost:9090"]

remote_write:
- url: 'http://127.0.0.1:10908/api/v1/receive'

bash复制代码➜  ./prometheus --enable-feature=agent --log.level=debug --config.file="prometheus.yml" 
ts=2021-11-27T19:03:15.861Z caller=main.go:195 level=info msg="Experimental agent mode enabled."
ts=2021-11-27T19:03:15.861Z caller=main.go:515 level=info msg="Starting Prometheus" version="(version=2.32.0-beta.0, branch=HEAD, revision=c32725ba7873dbaa39c223410043430ffa5a26c0)"
ts=2021-11-27T19:03:15.861Z caller=main.go:520 level=info build_context="(go=go1.17.3, user=root@da630543d231, date=20211116-11:23:14)"
ts=2021-11-27T19:03:15.861Z caller=main.go:521 level=info host_details="(Linux 5.14.18-200.fc34.x86_64 #1 SMP Fri Nov 12 16:48:10 UTC 2021 x86_64 moelove (none))"
ts=2021-11-27T19:03:15.861Z caller=main.go:522 level=info fd_limits="(soft=1024, hard=524288)"
ts=2021-11-27T19:03:15.861Z caller=main.go:523 level=info vm_limits="(soft=unlimited, hard=unlimited)"
ts=2021-11-27T19:03:15.862Z caller=web.go:546 level=info component=web msg="Start listening for connections" address=0.0.0.0:9090
ts=2021-11-27T19:03:15.862Z caller=main.go:980 level=info msg="Starting WAL storage ..."
ts=2021-11-27T19:03:15.863Z caller=tls_config.go:195 level=info component=web msg="TLS is disabled." http2=false
ts=2021-11-27T19:03:15.864Z caller=db.go:306 level=info msg="replaying WAL, this may take a while" dir=data-agent/wal
ts=2021-11-27T19:03:15.864Z caller=db.go:357 level=info msg="WAL segment loaded" segment=0 maxSegment=0
ts=2021-11-27T19:03:15.864Z caller=main.go:1001 level=info fs_type=9123683e
ts=2021-11-27T19:03:15.864Z caller=main.go:1004 level=info msg="Agent WAL storage started"
ts=2021-11-27T19:03:15.864Z caller=main.go:1005 level=debug msg="Agent WAL storage options" WALSegmentSize=0B WALCompression=true StripeSize=0 TruncateFrequency=0s MinWALTime=0s MaxWALTime=0s
ts=2021-11-27T19:03:15.864Z caller=main.go:1129 level=info msg="Loading configuration file" filename=prometheus.yml
ts=2021-11-27T19:03:15.865Z caller=dedupe.go:112 component=remote level=info remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="Starting WAL watcher" queue=e6fa2a
ts=2021-11-27T19:03:15.865Z caller=dedupe.go:112 component=remote level=info remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="Starting scraped metadata watcher"
ts=2021-11-27T19:03:15.865Z caller=dedupe.go:112 component=remote level=info remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="Replaying WAL" queue=e6fa2a
ts=2021-11-27T19:03:15.865Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="Tailing WAL" lastCheckpoint= checkpointIndex=0 currentSegment=0 lastSegment=0
ts=2021-11-27T19:03:15.865Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="Processing segment" currentSegment=0
ts=2021-11-27T19:03:15.877Z caller=manager.go:196 level=debug component="discovery manager scrape" msg="Starting provider" provider=static/0 subs=[prometheus]
ts=2021-11-27T19:03:15.877Z caller=main.go:1166 level=info msg="Completed loading of configuration file" filename=prometheus.yml totalDuration=12.433099ms db_storage=361ns remote_storage=323.413µs web_handler=247ns query_engine=157ns scrape=11.609215ms scrape_sd=248.024µs notify=3.216µs notify_sd=6.338µs rules=914ns
ts=2021-11-27T19:03:15.877Z caller=main.go:897 level=info msg="Server is ready to receive web requests."
ts=2021-11-27T19:03:15.877Z caller=manager.go:214 level=debug component="discovery manager scrape" msg="Discoverer channel closed" provider=static/0
ts=2021-11-27T19:03:28.196Z caller=dedupe.go:112 component=remote level=info remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="Done replaying WAL" duration=12.331255772s
ts=2021-11-27T19:03:30.867Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="runShard timer ticked, sending buffered data" samples=230 exemplars=0 shard=0
ts=2021-11-27T19:03:35.865Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg=QueueManager.calculateDesiredShards dataInRate=23 dataOutRate=23 dataKeptRatio=1 dataPendingRate=0 dataPending=0 dataOutDuration=0.0003201718 timePerSample=1.3920513043478261e-05 desiredShards=0.0003201718 highestSent=1.638039808e+09 highestRecv=1.638039808e+09
ts=2021-11-27T19:03:35.865Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg=QueueManager.updateShardsLoop lowerBound=0.7 desiredShards=0.0003201718 upperBound=1.3
ts=2021-11-27T19:03:45.866Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg=QueueManager.calculateDesiredShards dataInRate=23.7 dataOutRate=18.4 dataKeptRatio=1 dataPendingRate=5.300000000000001 dataPending=355.5 dataOutDuration=0.00025613744 timePerSample=1.3920513043478263e-05 desiredShards=0.00037940358300000006 highestSent=1.638039808e+09 highestRecv=1.638039823e+09
ts=2021-11-27T19:03:45.866Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg=QueueManager.updateShardsLoop lowerBound=0.7 desiredShards=0.00037940358300000006 upperBound=1.3
ts=2021-11-27T19:03:45.871Z caller=dedupe.go:112 component=remote level=debug remote_name=e6fa2a url=http://127.0.0.1:10908/api/v1/receive msg="runShard timer ticked, sending buffered data" samples=265 exemplars=0 shard=0

shell复制代码cd app/hadoop-2.6.0-cdh5.7.0/sbin/
./start-dfs.sh

bash复制代码sudo vim /etc/hosts

xml复制代码<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.neusoft</groupId>
    <artifactId>hadoopdemo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>hadoopdemo</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
        <hadoop.version>2.6.0-cdh5.7.0</hadoop.version>
    </properties>
    <repositories>
        <repository>
            <id>cloudera</id>
            <url>https://repository.cloudera.com/artifactory/cloudera-repos/</url>
        </repository>
    </repositories>

    <dependencies>
        <!--        添加hadoop依赖-->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>${hadoop.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
                <plugin>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>3.1.0</version>
                </plugin>
                <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
                <plugin>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>3.0.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.0</version>
                </plugin>
                <plugin>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>2.22.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-jar-plugin</artifactId>
                    <version>3.0.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-install-plugin</artifactId>
                    <version>2.5.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-deploy-plugin</artifactId>
                    <version>2.8.2</version>
                </plugin>
                <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
                <plugin>
                    <artifactId>maven-site-plugin</artifactId>
                    <version>3.7.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-project-info-reports-plugin</artifactId>
                    <version>3.0.0</version>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

java复制代码package com.neusoft.hdfs;

import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.apache.hadoop.conf.Configuration;

import java.net.URI;

public class HDFSApp {
    Configuration configuration = null;
    FileSystem fileSystem = null;
    public static final String HDFS_PATH = "hdfs://192.168.10.128:8020";

    @Test
    public void mkdir() throws Exception {
        fileSystem.mkdirs(new Path("/ruochen/test2"));
    }

    // Java 连接hdfs 需要先建立一个连接
    // 测试方法执行之前要执行的操作
    @Before
    public void setUp() throws Exception {
        System.out.println("开始建立与HDFS的连接");
        configuration = new Configuration();
        fileSystem = FileSystem.get(new URI(HDFS_PATH), configuration, "hadoop");
    }

    // 测试之后要执行的代码
    @After
    public void tearDown() {
        configuration = null;
        fileSystem = null;
        System.out.println("关闭与HDFS的连接");
    }
}

java复制代码    // 创建文件
    @Test
    public void create() throws Exception {
        Path path = new Path("/ruochen/test1/hello.txt");
        FSDataOutputStream outputStream = fileSystem.create(path);
        outputStream.write("hello world".getBytes());
        outputStream.flush();
        outputStream.close();
    }

java复制代码   // rename文件
   @Test
   public void rename() throws Exception {
       Path oldPath = new Path("/ruochen/test1/hello.txt");
       Path newPath = new Path("/ruochen/test1/xixi.txt");
       fileSystem.rename(oldPath, newPath);
   }

java复制代码    // 查看文件
    @Test
    public void cat() throws Exception {
        Path path = new Path("/ruochen/test1/xixi.txt");
        FSDataInputStream inputStream = fileSystem.open(path);
        IOUtils.copyBytes(inputStream, System.out, 1024);
        inputStream.close();
    }

java复制代码    // 上传文件
    @Test
    public void upload() throws Exception {
        Path localPath = new Path("cifar-10-python.tar.gz");
        Path hdfsPath = new Path("/");
        fileSystem.copyFromLocalFile(localPath, hdfsPath);
    }

java复制代码    // 下载文件
    @Test
    public void download() throws Exception {
        Path hdfsPath = new Path("/hadoop-2.6.0-cdh5.7.0.tar.gz");
        Path localPath = new Path("./down/hadoop-2.6.0-cdh5.7.0.tar.gz");
        fileSystem.copyToLocalFile(false, hdfsPath, localPath, true);
    }

java复制代码package com.neusoft;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

/**
 * 词频统计
 */
public class WordCountApp {
    /**
     * map 阶段
     */
    public static class MyMapper extends Mapper<LongWritable, Text, Text, LongWritable> {
        LongWritable one = new LongWritable(1);

        @Override
        protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            // 分
            String line = value.toString();
            // 拆分
            String[] s = line.split(" ");
            for (String word : s) {
                // 输出
                context.write(new Text(word), one);
            }
        }
    }

    /**
     * reduce 阶段
     */
    public static class MyReducer extends Reducer<Text, LongWritable, Text, LongWritable> {
        @Override
        protected void reduce(Text key, Iterable<LongWritable> values, Context context) throws IOException, InterruptedException {
            long sum = 0;
            // 合并统计
            for (LongWritable value : values) {
                // 求和
                sum += value.get();
            }
            context.write(key, new LongWritable(sum));
        }
    }

    public static void main(String[] args) throws Exception {
        Configuration configuration = new Configuration();
        Job job = Job.getInstance(configuration, "wordcount");
        job.setJarByClass(WordCountApp.class);

        // 设置 map 相关参数
        FileInputFormat.setInputPaths(job, new Path(args[0]));
        job.setMapperClass(MyMapper.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(LongWritable.class);

        // 设置 reduce 相关参数
        job.setReducerClass(MyReducer.class);
        job.setOutputKeyClass(MyReducer.class);
        job.setOutputValueClass(LongWritable.class);

        Path outPath = new Path(args[1]);
        FileSystem fileSystem = FileSystem.get(configuration);
        if (fileSystem.exists(outPath)) {
            // 删除文件
            fileSystem.delete(outPath, true);
            System.out.println("输出路径已存在, 已被删除");
        }
        FileOutputFormat.setOutputPath(job, outPath);

        // 控制台输出详细信息
        // 输出：1  不输出：0
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}

shell复制代码hadoop fs -rm -r /output/wc

shell复制代码hadoop jar hadoopdemo-1.0-SNAPSHOT.jar com.neusoft.WordCountApp hdfs://hadoop000:8020/ruochenchen.txt hdfs://hadoop000:8020/output/wc

shell复制代码hadoop fs -cat /output/wc/part-r-00000

go复制代码var c complex64 = 5 + 5i
// output: (5+5i)
fmt.Printf("Value is: %v", c)

go复制代码s := "hello"
c := []byte(s) // 将字符串 s 转换为 []byte 类型
c[0] = 'c'
s2 := string(c) // 再转换回 string 类型
fmt.Printf("%s\n", s2)

go复制代码var b bytes.Buffer
...
for condition {
    b.WriteString(str) // 将字符串 str 写入缓存 buffer
}
return b.String()

go复制代码var variable_name [SIZE] variable_type
var balance = [5]float32{1000.0, 2.0, 3.4, 7.0, 50.0}
balance := [...]float32{1000.0, 2.0, 3.4, 7.0, 50.0}
balance := [5]float32{1:2.0,3:7.0}

go复制代码var variable_name [SIZE1][SIZE2]...[SIZEN] variable_type

go复制代码func main() {
    // Step 1：创建数组
    values := [][]int{}

    // Step 2：使用 appped() 函数向空的二维数组添加两行一维数组
    row1 := []int{1, 2, 3}
    row2 := []int{4, 5, 6}
    values = append(values, row1)
    values = append(values, row2)

    // Step 3：显示两行数据
    fmt.Println("Row 1")
    fmt.Println(values[0])
    fmt.Println("Row 2")
    fmt.Println(values[1])

    // Step 4：访问第一个元素
    fmt.Println("第一个元素为：")
    fmt.Println(values[0][0])
}

go复制代码// 默认是 nil
var identifier []type
s := make([]int, len, cap)
y := s[low:high:max]

go复制代码func main() {
    s := []int{1, 2, 3}
    a := s[0:1]
    s[0] = 888
    fmt.Printf("a: %p\n", a)
    fmt.Println("a", a, len(a), cap(a))
    fmt.Printf("s: %p\n", s)
    fmt.Println("s", s, len(s), cap(s))
    s = append(s, 4)
    fmt.Println("扩容后")
    s[0] = 666
    fmt.Printf("a: %p\n", a)
    fmt.Println("a", a, len(a), cap(a))
    fmt.Printf("s: %p\n", s)
    fmt.Println("s", s, len(s), cap(s))
}

ini复制代码a: 0xc00011a000
a [888] 1 3
s: 0xc00011a000
s [888 2 3] 3 3
扩容后
a: 0xc00011a000
a [888] 1 3
s: 0xc000120000
s [666 2 3 4] 4 6

go复制代码func main() {
    var (
        arr   = [3]int{1, 2, 3}
        slice = []int{1, 2, 3}
    )

    changeArr(&arr)
    changeSlice(slice)

    fmt.Println("arr", arr)
    fmt.Println("slice", slice)
}

func changeArr(arr *[3]int) {
    arr[0] = 100
}

func changeSlice(slice []int) {
    slice[0] = 100
}

css复制代码arr [100 2 3]
slice [100 2 3]

go复制代码var digitRegexp = regexp.MustCompile("[0-9]+")

// 返回的 []byte 指向的底层是整个文件的数据，只要该返回的切片不被释放，垃圾回收器就不能释放整个文件所占用的内存
func FindDigits(filename string) []byte {
    b, _ := ioutil.ReadFile(filename)
    return digitRegexp.Find(b)
}

// 可以通过拷贝需要的部分到一个新的切片中
func FindFileDigits(filename string) []byte {
   fileBytes, _ := ioutil.ReadFile(filename)
   b := digitRegexp.FindAll(fileBytes, len(fileBytes))
   c := make([]byte, 0)
   for _, bytes := range b {
      c = append(c, bytes...)
   }
   return c
}

go复制代码// 默认是 nil，nil map 不能用来存放键值对
var map_variable map[key_data_type]value_data_type
map_variable := make(map[key_data_type]value_data_type)

go复制代码// OK
y := new(Bar)
(*y).thingOne = "hello"
(*y).thingTwo = 1

// NOT OK
z := make(Bar) // 编译错误：cannot make type Bar
(*z).thingOne = "hello"
(*z).thingTwo = 1

// OK
x := make(Foo)
x["x"] = "goodbye"
x["y"] = "world"

// NOT OK
u := new(Foo)
(*u)["x"] = "goodbye" // 运行时错误!! panic: assignment to entry in nil map
(*u)["y"] = "world"

go复制代码// 使用 new 创建一个 map 指针
ma := new(map[string]int)
// 第一种初始化方法
*ma = map[string]int{}
(*ma)["a"] = 44
fmt.Println(*ma)

// 第二种初始化方法
*ma = make(map[string]int, 0)
(*ma)["b"] = 55
fmt.Println(*ma)

// 第三种初始化方法
mb := make(map[string]int, 0)
mb["c"] = 66
*ma = mb
(*ma)["d"] = 77
fmt.Println(*ma)

go复制代码// 使用 make 来创建并使用 map
ma := make(map[string]int)
ma["a"] = 33
fmt.Println(ma)

go复制代码const (
    a = "abc"
    b = len(a)
    c = unsafe.Sizeof(a)
)

const (
    a = iota   // 0
    b          // 1
    c          // 2
    d = "ha"   // 独立值，iota += 1
    e          // "ha"，iota += 1
    f = 100    // iota += 1
    g          // 100，iota +=1
    h = iota   // 7，恢复计数
    i          // 8
)

const (
    h, i, j = iota, iota, iota // h = 0、i = 0、j = 0，因为 iota 在同一行
)

go复制代码err := errors.New("emit macho dwarf: elf header corrupted")
if err != nil {
    fmt.Print(err)
}

go复制代码type User struct {
    username string
    password string
}

func (p *User) init(username string, password string) (*User, string) {
    if "" == username || "" == password {
        return p, p.Error()
    }
    p.username = username
    p.password = password
    return p, ""
}

func (p *User) Error() string {
    return "Usernam or password shouldn't be empty!"
}

func main() {
    var user User
    user1, _ := user.init("", "")
    fmt.Println(user1)
}

rust复制代码Usernam or password shouldn't be empty!

go复制代码func main() {

    switch {
    case false:
            fmt.Println("1、case 条件语句为 false")
            fallthrough
    case true:
            fmt.Println("2、case 条件语句为 true")
            fallthrough
    case false:
            fmt.Println("3、case 条件语句为 false")
            fallthrough
    case true:
            fmt.Println("4、case 条件语句为 true")
    case false:
            fmt.Println("5、case 条件语句为 false")
            fallthrough
    default:
            fmt.Println("6、默认 case")
    }
}

arduino复制代码2、case 条件语句为 true
3、case 条件语句为 false
4、case 条件语句为 true

go复制代码sum := 1
for sum < 1000 {
    sum += sum
}

go复制代码func main() {

    // 不使用标记
    fmt.Println("---- break ----")
    for i := 1; i <= 3; i++ {
        fmt.Printf("i: %d\n", i)
        for i2 := 11; i2 <= 13; i2++ {
            fmt.Printf("i2: %d\n", i2)
            break
        }
    }

    // 使用标记
    fmt.Println("---- break label ----")
re:
    for i := 1; i <= 3; i++ {
        fmt.Printf("i: %d\n", i)
        for i2 := 11; i2 <= 13; i2++ {
            fmt.Printf("i2: %d\n", i2)
            break / continue re
        }
    }
}

go复制代码func main() {
    /* 定义局部变量 */
    var a int = 10

    /* 循环 */
LOOP:
    for a < 20 {
        if a == 15 {
            /* 跳过迭代 */
            a = a + 1
            goto LOOP
        }
        fmt.Printf("a的值为 : %d\n", a)
        a++
    }
}

less复制代码a的值为 : 10
a的值为 : 11
a的值为 : 12
a的值为 : 13
a的值为 : 14
a的值为 : 16
a的值为 : 17
a的值为 : 18
a的值为 : 19

go复制代码// 变量 arg 是一个 int 的 slice
func myfunc(arg ...int) {}

go复制代码func main() {
    /* 声明函数变量 */
    getSquareRoot := func(x float64) float64 {
        return math.Sqrt(x)
    }

    /* 使用函数 */
    fmt.Println(getSquareRoot(9))
}

复制代码2

go复制代码type testInt func(int) bool // 声明了一个函数类型

func isOdd(integer int) bool {
    if integer%2 == 0 {
        return false
    }
    return true
}

func isEven(integer int) bool {
    if integer%2 == 0 {
        return true
    }
    return false
}

// 声明的函数类型在这个地方当做了一个参数
func filter(slice []int, f testInt) []int {
    var result []int
    for _, value := range slice {
        if f(value) {
            result = append(result, value)
        }
    }
    return result
}

func main() {
    slice := []int{1, 2, 3, 4, 5, 7}
    fmt.Println("slice = ", slice)
    odd := filter(slice, isOdd) // 函数当做值来传递了
    fmt.Println("Odd elements of slice are: ", odd)
    even := filter(slice, isEven) // 函数当做值来传递了
    fmt.Println("Even elements of slice are: ", even)
}

ini复制代码slice = [1 2 3 4 5 7]
Odd elements of slice are: [1 3 5 7]
Even elements of slice are: [2 4]

go复制代码func getSequence() func() int {
    i := 0
    return func() int {
        i += 1
        return i
    }
}

func main() {
    /* nextNumber 为一个函数，函数 i 为 0 */
    nextNumber := getSequence()

    /* 调用 nextNumber 函数，i 变量自增 1 并返回 */
    fmt.Println(nextNumber())
    fmt.Println(nextNumber())
    fmt.Println(nextNumber())

    /* 创建新的函数 nextNumber1，并查看结果 */
    nextNumber1 := getSequence()
    fmt.Println(nextNumber1())
    fmt.Println(nextNumber1())
}

复制代码1
2
3
1
2

go复制代码func add(x1, x2 int) func(int, int) (int, int, int) {
    i := 0
    return func(x3, x4 int) (int, int, int) {
        i += 1
        return i, x1 + x2, x3 + x4
    }
}

func main() {
    add_func := add(1, 2)
    fmt.Println(add_func(1, 1))
    fmt.Println(add_func(0, 0))
    fmt.Println(add_func(2, 2))
}

复制代码1 3 2
2 3 0
3 3 4

go复制代码func main() {
    addBmp := MakeAddSuffix(".bmp")
    addJpeg := MakeAddSuffix(".jpeg")

    fmt.Println(addBmp("file"))
    fmt.Println(addJpeg("file"))
}

func MakeAddSuffix(suffix string) func(string) string {
    return func(name string) string {
        if !strings.HasSuffix(name, suffix) {
            return name + suffix
        }
        return name
    }
}

复制代码file.bmp
file.jpeg

go复制代码func trace(s string) string {
    fmt.Println("entering:", s)
    return s
}

func un(s string) {
    fmt.Println("leaving:", s)
}

func a() {
    defer un(trace("a"))
    fmt.Println("in a")
}

func b() {
    defer un(trace("b"))
    fmt.Println("in b")
    a()
}

func main() {
    b()
}

makefile复制代码entering: b
in b
entering: a
in a
leaving: a
leaving: b