HDFS调用JAVAapi

HDFS调用API

创建项目

pom.xml

<?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>Itcase</groupId>
<artifactId>HdfsApi</artifactId>
<version>1.0-SNAPSHOT</version>

    <repositories>
        <repository>
            <id>cloudera</id>
            <url>https://repository.cloudera.com/artifactory/cloudera-repos/</url>
        </repository>
    </repositories>
    <dependencies>
        <dependency>
            <groupId>org.apache.Hadoop</groupId>
            <artifactId>Hadoop-client</artifactId>
            <version>2.6.0-mr1-cdh5.14.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.Hadoop</groupId>
            <artifactId>Hadoop-common</artifactId>
            <version>2.6.0-cdh5.14.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.Hadoop</groupId>
            <artifactId>Hadoop-hdfs</artifactId>
            <version>2.6.0-cdh5.14.0</version>
        </dependency>

        <dependency>
            <groupId>org.apache.Hadoop</groupId>
            <artifactId>Hadoop-mapreduce-client-core</artifactId>
            <version>2.6.0-cdh5.14.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>RELEASE</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                    <!--    <verbal>true</verbal>-->
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.3</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <minimizeJar>true</minimizeJar>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <!--  <plugin>
                  <artifactId>maven-assembly-plugin </artifactId>
                  <configuration>
                      <descriptorRefs>
                          <descriptorRef>jar-with-dependencies</descriptorRef>
                      </descriptorRefs>
                      <archive>
                          <manifest>
                              <mainClass>cn.itcast.Hadoop.db.DBToHdfs2</mainClass>
                          </manifest>
                      </archive>
                  </configuration>
                  <executions>
                      <execution>
                          <id>make-assembly</id>
                          <phase>package</phase>
                          <goals>
                              <goal>single</goal>
                          </goals>
                      </execution>
                  </executions>
              </plugin>-->
        </plugins>
    </build>

</project>

代码
/**
* 创建文件夹
* @throws Exception
*/

   
    @Test
    public void mkdir01() throws Exception{
        Configuration cf = new Configuration();
        FileSystem fileSystem = FileSystem.get(new URI("hdfs://192.168.100.100:8020"), cf);
        boolean mkdirs = fileSystem.mkdirs(new Path("/airpods/one"));
        if (mkdirs){
            System.out.println("创建成功");
        }else{
            System.out.println("创建失败");
        }
    }

/**
* 获取根目录下的所有文件夹路径
* @throws Exception
*/

   
    @Test
    public void listStatus() throws Exception{
        Configuration cs = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://192.168.100.100:8020"), cs);
        FileStatus[] fileStatuses = fs.listStatus(new Path("/"));
        for (FileStatus fileStatus : fileStatuses) {
            System.out.println(fileStatus.getPath().toString());
        }

    }

/**
* 修改文件夹名字
* @throws Exception
*/

  
    @Test
    public void rename() throws Exception{
        Configuration configuration = new Configuration();
        FileSystem fileSystem = FileSystem.get(new URI("hdfs://192.168.100.100:8020"), configuration);
        Path path = new Path("/aaaaa");
        Path path1 = new Path("/FiveA");
        boolean rename = fileSystem.rename(path, path1);
        String s = rename ? "成功" : "失败";
        System.out.println(s);

    }

/**
 * 查看创建时间
 * @throws Exception
 */

    @Test
    public void getTime() throws Exception{
        Configuration configuration = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://192.168.100.100"), configuration);
        FileStatus fileStatus = fs.getFileStatus(new Path("/FiveA"));
        long modificationTime = fileStatus.getModificationTime();
        System.out.println(modificationTime);
    }

/**

• 删除文件夹
  */

  @Test
 
  public void deleteFile() throws Exception{
        Configuration configuration = new Configuration();
        FileSystem fileSystem = FileSystem.get(new URI("hdfs://192.168.100.100:8020"), configuration);
        boolean delete = fileSystem.delete(new Path("/sum"), true);
        System.out.println(delete);
    }

/**
* 创建一个文件 并写入文件
* @throws Exception
*/

    
    @Test
    public void addFile()throws Exception{
        Configuration configuration = new Configuration( );
        FileSystem fileSystem = FileSystem.get(new URI("hdfs://192.168.100.100:8020"), configuration);
        FSDataOutputStream outputStream = fileSystem.create(new Path("/airpods/one/后来.txt"));
        byte[] bytes = "后来,终于在眼泪中明白".getBytes();
        outputStream.write(bytes,0,bytes.length);
        outputStream.close();
    }

/**
* 上传本地文件
* @throws Exception
*/

  
    @Test
    public void put()throws Exception{
        Configuration configuration = new Configuration();
        FileSystem fileSystem = FileSystem.get(new URI("hdfs://192.168.100.100:8020"), configuration);
        Path path = new Path("C:\\Users\\Desktop\\pomAPI.txt");
        Path path1 = new Path("/aripods");
        fileSystem.copyFromLocalFile(path,path1);
    }

/**
* 判断该文件夹是否存在
* @throws Exception
*/

   
    @Test
    public void check()throws Exception{
        Configuration configuration = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://192.168.100.100"), configuration);
        boolean exists = fs.exists(new Path("/airpods"));
        if (exists){
            System.out.println("已存在");
        }else{
            System.out.println("不存在");
        }
    }

/**
* 读取本地文件内容之后在集群上创建新的文件吧内容写进去
* @throws Exception
*/

   
    @Test
    public void VimText() throws Exception{
        String line=null;
        Configuration configuration = new Configuration();
        FileSystem fileSystem = FileSystem.get(configuration);
        FSDataInputStream open = fileSystem.open(new Path("D:\\山丘.txt"));
        FileSystem fileSystem1 = FileSystem.get(new URI("hdfs://192.168.100.100:8020"), configuration);
        FSDataOutputStream fsDataOutputStream = fileSystem1.create(new Path("/airpods/sq.txt"));
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(open));
        while ((line=bufferedReader.readLine())!=null){
            System.out.println(line);
            fsDataOutputStream.write(line.getBytes(),0,line.getBytes().length);
        }
    }

强化练习

String uri=“hdfs://192.168.100.100:8020”;
//创建文件夹 — 如果该文件夹存在就删除 如果不存在就创建

    @Test
    public void mkdir() throws URISyntaxException, IOException {

        Configuration configuration = new Configuration();

        FileSystem fs = FileSystem.get(new URI(uri), configuration);
        boolean exists = fs.exists(new Path("/opt"));
        if (exists){
            fs.delete(new Path(uri+"/opt"));
            System.out.println("删除");
        }else{
            fs.mkdirs(new Path(uri+"/opt"));
            System.out.println("创建");
        }

    }

// //获取所有的文件路径

    @Test
    public void list() throws URISyntaxException, IOException {
        Configuration configuration = new Configuration();
        FileSystem fileSystem = FileSystem.get(new URI(uri ), configuration);
        FileStatus[] fileStatuses = fileSystem.listStatus(new Path("/"));
        for (FileStatus fileStatus : fileStatuses) {
            System.out.println(fileStatus.getPath().toString());
        }
    }

//创建一个新的文件并写入数据

 @Test
 public void write() throws Exception{
     Configuration configuration = new Configuration();
     FileSystem fileSystem = FileSystem.get(new URI(uri), configuration);
     FSDataOutputStream fsDataOutputStream = fileSystem.create(new Path("/opt/1.txt"));
     byte[] bytes = "李丽欣是一个大狼狗".getBytes();
     fsDataOutputStream.write(bytes,0,bytes.length);
     fsDataOutputStream.close();

 }

//查看一个文件的内容

    @Test
    public void read()throws Exception{
        String line=null;
        Configuration configuration = new Configuration();
        FileSystem fs = FileSystem.get(new URI(uri), configuration);
        FSDataInputStream open = fs.open(new Path("/sq.txt"));
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(open));
        while ((line=bufferedReader.readLine())!=null){
            System.out.println(line);
        }
    }

// 把本地文件的txt文件写入到集群上 集群的文件要新创建的 然后把本地的Txt文件内容写入到集群新的文件中 一边一边写

@Test
   public void readANDwrit() throws Exception {
   String line = null;
   Configuration configuration = new Configuration();
   FileSystem fileOpen = FileSystem.get(configuration);
   FSDataInputStream open = fileOpen.open(new Path("D:\\山丘.txt"));

   FileSystem fileCreate = FileSystem.get(new URI(uri), configuration);
   FSDataOutputStream fsDataOutputStream = fileCreate.create(new Path("/sq.txt"));

   BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(open));
   while ((line=bufferedReader.readLine())!=null){
       fsDataOutputStream.write(line.getBytes(),0,line.getBytes().length);
   }

//修改集群上文件夹名字 并且读取你修改后的文件内容

    @Test
    public void rename()throws Exception{
        Configuration configuration = new Configuration();
        FileSystem fileSystem = FileSystem.get(new URI(uri), configuration);

        boolean rename = fileSystem.rename(new Path("/sq.txt"), new Path("/山丘.txt"));
        if (rename){
            System.out.println("修改成功");
        }else{
            System.out.println("修改失败");
        }
        readThis("/山丘.txt");

    }

// //创建一个文件夹 如果这个文件夹已存在那么就创建一个旧的名称+随机100以内的数

   @Test
   public void mkdirRound() throws URISyntaxException, IOException {
       Configuration configuration = new Configuration();
       FileSystem fs = FileSystem.get(new URI(uri), configuration);
     if (fs.exists(new Path("/山丘"))){
         System.out.println("已存在");
         Random random = new Random();
         int i = random.nextInt(100);
       fs.mkdirs(new Path("/山丘"+i));
     }else{
    fs.mkdirs(new Path("/山丘"));
     }
   }

// //上传本地文件 如果已存在就把存在的给删除了

  @Test
  public  void put() throws Exception{
      Configuration configuration = new Configuration();
      FileSystem fs = FileSystem.get(new URI(uri), configuration);
      String Filename="aaa.txt";
      //这是我本地的路径
      Path bendi = new Path("D:\\"+Filename);
      //这是HDFS的根目录
      Path Hdfs = new Path("/");
      //判断的是HDFS上是否存在该文件
      boolean exists = fs.exists(new Path("/"+Filename));
      if (exists){
          //这是删除Hdfs上的文件而不是
          fs.delete(new Path("/"+Filename));
          System.out.println("已删除");
      }else{
          fs.copyFromLocalFile(bendi,Hdfs);
          System.out.println("以上传到本地");
      }
  }

//判断文件是否存在如果存在就删除 如果不存在就创建

    @Test
    public void readThis(String name)throws Exception{
        String line=null;
        Configuration configuration = new Configuration();
        FileSystem fs = FileSystem.get(new URI(uri), configuration);
        FSDataInputStream open = fs.open(new Path(name));
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(open));
        while ((line=bufferedReader.readLine())!=null){
            System.out.println(line);
        }
    }