mapreduce

code/Hadoop/hadoop-word-count/pom.xml

@@ -0,0 +1,55 @@
+<?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.heibaiying</groupId>
+    <artifactId>hadoop-word-count</artifactId>
+    <version>1.0</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>8</source>
+                    <target>8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <hadoop.version>2.6.0-cdh5.15.2</hadoop.version>
+    </properties>
+
+
+    <!---配置CDH仓库地址-->
+    <repositories>
+        <repository>
+            <id>cloudera</id>
+            <url>https://repository.cloudera.com/artifactory/cloudera-repos/</url>
+        </repository>
+    </repositories>
+
+
+    <dependencies>
+        <!--Hadoop-client-->
+        <dependency>
+            <groupId>org.apache.hadoop</groupId>
+            <artifactId>hadoop-client</artifactId>
+            <version>${hadoop.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>3.8.1</version>
+        </dependency>
+    </dependencies>
+
+
+</project>

code/Hadoop/hadoop-word-count/src/main/java/com/heibaiying/WordCountApp.java

@@ -0,0 +1,84 @@
+package com.heibaiying;
+
+import com.heibaiying.component.WordCountMapper;
+import com.heibaiying.component.WordCountReducer;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+
+import java.net.URI;
+
+/**
+ * 组装作业 并提交到集群运行
+ */
+public class WordCountApp {
+
+
+    // 这里为了直观显示参数 使用了硬编码，实际开发中可以通过外部传参
+    private static final String HDFS_URL = "hdfs://192.168.0.107:8020";
+    private static final String HADOOP_USER_NAME = "root";
+
+    public static void main(String[] args) throws Exception {
+
+
+        //  文件输入路径和输出路径由外部传参指定
+        if (args.length < 2) {
+            System.out.println("Input and output paths are necessary!");
+            return;
+        }
+
+        // 需要指明hadoop用户名，否则在HDFS上创建目录时可能会抛出权限不足的异常
+        System.setProperty("HADOOP_USER_NAME", HADOOP_USER_NAME);
+
+
+        Configuration configuration = new Configuration();
+        // 指明HDFS的地址
+        configuration.set("fs.defaultFS", HDFS_URL);
+
+
+        // 创建一个Job
+        Job job = Job.getInstance(configuration);
+
+        // 设置运行的主类
+        job.setJarByClass(WordCountApp.class);
+
+        // 设置Mapper和Reducer
+        job.setMapperClass(WordCountMapper.class);
+        job.setReducerClass(WordCountReducer.class);
+
+        // 设置Mapper输出key和value的类型
+        job.setMapOutputKeyClass(Text.class);
+        job.setMapOutputValueClass(IntWritable.class);
+
+        // 设置Reducer输出key和value的类型
+        job.setOutputKeyClass(Text.class);
+        job.setOutputValueClass(IntWritable.class);
+
+        // 如果输出目录已经存在，则必须先删除，否则重复运行程序时会抛出异常
+        FileSystem fileSystem = FileSystem.get(new URI(HDFS_URL), configuration, HADOOP_USER_NAME);
+        Path outputPath = new Path(args[1]);
+        if (fileSystem.exists(outputPath)) {
+            fileSystem.delete(outputPath, true);
+        }
+
+
+        // 设置作业输入文件和输出文件的路径
+        FileInputFormat.setInputPaths(job, new Path(args[0]));
+        FileOutputFormat.setOutputPath(job, outputPath);
+
+        // 将作业提交到群集并等待它完成，参数设置为true代表打印显示对应的进度
+        boolean result = job.waitForCompletion(true);
+
+        // 关闭之前创建的fileSystem
+        fileSystem.close();
+
+        // 根据作业结果,终止当前运行的Java虚拟机,退出程序
+        System.exit(result ? 0 : -1);
+
+    }
+}

code/Hadoop/hadoop-word-count/src/main/java/com/heibaiying/WordCountCombinerApp.java

@@ -0,0 +1,87 @@
+package com.heibaiying;
+
+import com.heibaiying.component.WordCountMapper;
+import com.heibaiying.component.WordCountReducer;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+
+import java.net.URI;
+
+/**
+ * 组装作业 并提交到集群运行
+ */
+public class WordCountCombinerApp {
+
+
+    // 这里为了直观显示参数 使用了硬编码的形式，实际开发中可以通过外部传参
+    private static final String HDFS_URL = "hdfs://192.168.0.107:8020";
+    private static final String HADOOP_USER_NAME = "root";
+
+    public static void main(String[] args) throws Exception {
+
+
+        //  文件输入路径和输出路径由外部传参指定
+        if (args.length < 2) {
+            System.out.println("Input and output paths are necessary!");
+            return;
+        }
+
+        // 需要指明hadoop用户名，否则在HDFS上创建目录时可能会抛出权限不足的异常
+        System.setProperty("HADOOP_USER_NAME", HADOOP_USER_NAME);
+
+
+        Configuration configuration = new Configuration();
+        // 指明HDFS的地址
+        configuration.set("fs.defaultFS", HDFS_URL);
+
+
+        // 创建一个Job
+        Job job = Job.getInstance(configuration);
+
+        // 设置运行的主类
+        job.setJarByClass(WordCountCombinerApp.class);
+
+        // 设置Mapper和Reducer
+        job.setMapperClass(WordCountMapper.class);
+        job.setReducerClass(WordCountReducer.class);
+
+        // 设置Combiner
+        job.setCombinerClass(WordCountReducer.class);
+
+        // 设置Mapper输出key和value的类型
+        job.setMapOutputKeyClass(Text.class);
+        job.setMapOutputValueClass(IntWritable.class);
+
+        // 设置Reducer输出key和value的类型
+        job.setOutputKeyClass(Text.class);
+        job.setOutputValueClass(IntWritable.class);
+
+        // 如果输出目录已经存在，则必须先删除，否则重复运行程序时会抛出异常
+        FileSystem fileSystem = FileSystem.get(new URI(HDFS_URL), configuration, HADOOP_USER_NAME);
+        Path outputPath = new Path(args[1]);
+        if (fileSystem.exists(outputPath)) {
+            fileSystem.delete(outputPath, true);
+        }
+
+
+        // 设置作业输入文件和输出文件的路径
+        FileInputFormat.setInputPaths(job, new Path(args[0]));
+        FileOutputFormat.setOutputPath(job, outputPath);
+
+        // 将作业提交到群集并等待它完成，参数设置为true代表打印显示对应的进度
+        boolean result = job.waitForCompletion(true);
+
+        // 关闭之前创建的fileSystem
+        fileSystem.close();
+
+        // 根据作业结果,终止当前运行的Java虚拟机,退出程序
+        System.exit(result ? 0 : -1);
+
+    }
+}

code/Hadoop/hadoop-word-count/src/main/java/com/heibaiying/WordCountCombinerPartitionerApp.java

@@ -0,0 +1,95 @@
+package com.heibaiying;
+
+import com.heibaiying.component.CustomPartitioner;
+import com.heibaiying.component.WordCountMapper;
+import com.heibaiying.component.WordCountReducer;
+import com.heibaiying.utils.WordCountDataUtils;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+
+import java.net.URI;
+
+/**
+ * 组装作业 并提交到集群运行
+ */
+public class WordCountCombinerPartitionerApp {
+
+
+    // 这里为了直观显示参数 使用了硬编码的形式，实际开发中可以通过外部传参
+    private static final String HDFS_URL = "hdfs://192.168.0.107:8020";
+    private static final String HADOOP_USER_NAME = "root";
+
+    public static void main(String[] args) throws Exception {
+
+
+        //  文件输入路径和输出路径由外部传参指定
+        if (args.length < 2) {
+            System.out.println("Input and output paths are necessary!");
+            return;
+        }
+
+        // 需要指明hadoop用户名，否则在HDFS上创建目录时可能会抛出权限不足的异常
+        System.setProperty("HADOOP_USER_NAME", HADOOP_USER_NAME);
+
+
+        Configuration configuration = new Configuration();
+        // 指明HDFS的地址
+        configuration.set("fs.defaultFS", HDFS_URL);
+
+
+        // 创建一个Job
+        Job job = Job.getInstance(configuration);
+
+        // 设置运行的主类
+        job.setJarByClass(WordCountCombinerPartitionerApp.class);
+
+        // 设置Mapper和Reducer
+        job.setMapperClass(WordCountMapper.class);
+        job.setReducerClass(WordCountReducer.class);
+
+        // 设置Combiner
+        job.setCombinerClass(WordCountReducer.class);
+
+
+        // 设置自定义分区规则
+        job.setPartitionerClass(CustomPartitioner.class);
+        // 设置reduce个数
+        job.setNumReduceTasks(WordCountDataUtils.WORD_LIST.size());
+
+        // 设置Mapper输出key和value的类型
+        job.setMapOutputKeyClass(Text.class);
+        job.setMapOutputValueClass(IntWritable.class);
+
+        // 设置Reducer输出key和value的类型
+        job.setOutputKeyClass(Text.class);
+        job.setOutputValueClass(IntWritable.class);
+
+        // 如果输出目录已经存在，则必须先删除，否则重复运行程序时会抛出异常
+        FileSystem fileSystem = FileSystem.get(new URI(HDFS_URL), configuration, HADOOP_USER_NAME);
+        Path outputPath = new Path(args[1]);
+        if (fileSystem.exists(outputPath)) {
+            fileSystem.delete(outputPath, true);
+        }
+
+
+        // 设置作业输入文件和输出文件的路径
+        FileInputFormat.setInputPaths(job, new Path(args[0]));
+        FileOutputFormat.setOutputPath(job, outputPath);
+
+        // 将作业提交到群集并等待它完成，参数设置为true代表打印显示对应的进度
+        boolean result = job.waitForCompletion(true);
+
+        // 关闭之前创建的fileSystem
+        fileSystem.close();
+
+        // 根据作业结果,终止当前运行的Java虚拟机,退出程序
+        System.exit(result ? 0 : -1);
+
+    }
+}

code/Hadoop/hadoop-word-count/src/main/java/com/heibaiying/component/CustomPartitioner.java

@@ -0,0 +1,16 @@
+package com.heibaiying.component;
+
+import com.heibaiying.utils.WordCountDataUtils;
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Partitioner;
+
+/**
+ * 自定义partitioner,按照单词分区
+ */
+public class CustomPartitioner extends Partitioner<Text, IntWritable> {
+
+    public int getPartition(Text text, IntWritable intWritable, int numPartitions) {
+        return WordCountDataUtils.WORD_LIST.indexOf(text.toString());
+    }
+}

code/Hadoop/hadoop-word-count/src/main/java/com/heibaiying/component/WordCountMapper.java

@@ -0,0 +1,23 @@
+package com.heibaiying.component;
+
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.LongWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Mapper;
+
+import java.io.IOException;
+
+/**
+ * 将每行数据按照指定分隔符进行拆分
+ */
+public class WordCountMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
+
+    @Override
+    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
+        String[] words = value.toString().split("\t");
+        for (String word : words) {
+            context.write(new Text(word), new IntWritable(1));
+        }
+    }
+
+}

code/Hadoop/hadoop-word-count/src/main/java/com/heibaiying/component/WordCountReducer.java

@@ -0,0 +1,22 @@
+package com.heibaiying.component;
+
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Reducer;
+
+import java.io.IOException;
+
+/**
+ * 进行词频统计
+ */
+public class WordCountReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
+
+    @Override
+    protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
+        int count = 0;
+        for (IntWritable value : values) {
+            count += value.get();
+        }
+        context.write(key, new IntWritable(count));
+    }
+}

code/Hadoop/hadoop-word-count/src/main/java/com/heibaiying/utils/WordCountDataUtils.java

@@ -0,0 +1,91 @@
+package com.heibaiying.utils;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+
+import java.io.IOException;
+import java.net.URI;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Random;
+
+/**
+ * 产生词频统计模拟数据
+ */
+public class WordCountDataUtils {
+
+    public static final List<String> WORD_LIST = Arrays.asList("Spark", "Hadoop", "HBase", "Storm", "Flink", "Hive");
+
+
+    /**
+     * 模拟产生词频数据
+     *
+     * @return 词频数据
+     */
+    private static String generateData() {
+        StringBuilder builder = new StringBuilder();
+        for (int i = 0; i < 1000; i++) {
+            Collections.shuffle(WORD_LIST);
+            Random random = new Random();
+            int endIndex = random.nextInt(WORD_LIST.size()) % (WORD_LIST.size()) + 1;
+            String line = StringUtils.join(WORD_LIST.toArray(), "\t", 0, endIndex);
+            builder.append(line).append("\n");
+        }
+        return builder.toString();
+    }
+
+
+    /**
+     * 模拟产生词频数据并输出到本地
+     *
+     * @param outputPath 输出文件路径
+     */
+    private static void generateDataToLocal(String outputPath) {
+        try {
+            java.nio.file.Path path = Paths.get(outputPath);
+            if (Files.exists(path)) {
+                Files.delete(path);
+            }
+            Files.write(path, generateData().getBytes(), StandardOpenOption.CREATE);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * 模拟产生词频数据并输出到HDFS
+     *
+     * @param hdfsUrl          HDFS地址
+     * @param user             hadoop用户名
+     * @param outputPathString 存储到HDFS上的路径
+     */
+    private static void generateDataToHDFS(String hdfsUrl, String user, String outputPathString) {
+        FileSystem fileSystem = null;
+        try {
+            fileSystem = FileSystem.get(new URI(hdfsUrl), new Configuration(), user);
+            Path outputPath = new Path(outputPathString);
+            if (fileSystem.exists(outputPath)) {
+                fileSystem.delete(outputPath, true);
+            }
+            FSDataOutputStream out = fileSystem.create(outputPath);
+            out.write(generateData().getBytes());
+            out.flush();
+            out.close();
+            fileSystem.close();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static void main(String[] args) {
+       //generateDataToLocal("input.txt");
+       generateDataToHDFS("hdfs://192.168.0.107:8020", "root", "/wordcount/input.txt");
+    }
+}

code/Hadoop/hadoop-word-count/src/main/resources/log4j.properties

@@ -0,0 +1,9 @@
+log4j.rootLogger=INFO,CONSOLE
+log4j.addivity.org.apache=false
+
+log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
+log4j.appender.CONSOLE.Threshold=INFO
+log4j.appender.CONSOLE.layout.ConversionPattern=%d{yyyy-MM-dd HH\:mm\:ss} -%-4r [%t] %-5p  %x - %m%n
+log4j.appender.CONSOLE.Target=System.out
+log4j.appender.CONSOLE.Encoding=UTF-8
+log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout

code/Hadoop/hdfs-java-api/pom.xml

@@ -0,0 +1,42 @@
+<?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.heibaiying</groupId>
+    <artifactId>hdfs-java-api</artifactId>
+    <version>1.0</version>
+
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <hadoop.version>2.6.0-cdh5.15.2</hadoop.version>
+    </properties>
+
+
+    <!---配置CDH仓库地址-->
+    <repositories>
+        <repository>
+            <id>cloudera</id>
+            <url>https://repository.cloudera.com/artifactory/cloudera-repos/</url>
+        </repository>
+    </repositories>
+
+
+    <dependencies>
+        <!--Hadoop-client-->
+        <dependency>
+            <groupId>org.apache.hadoop</groupId>
+            <artifactId>hadoop-client</artifactId>
+            <version>${hadoop.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

code/Hadoop/hdfs-java-api/src/main/java/com/heibaiying/utils/HdfsUtils.java

@@ -0,0 +1,180 @@
+package com.heibaiying.utils;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.*;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.URI;
+import java.net.URISyntaxException;
+
+/**
+ * HDFS 工具类
+ */
+public class HdfsUtils {
+
+
+    private static final String HDFS_PATH = "hdfs://192.168.0.107:8020";
+    private static final String HDFS_USER = "root";
+    private static FileSystem fileSystem;
+
+    static {
+
+        try {
+            Configuration configuration = new Configuration();
+            configuration.set("dfs.replication", "1");
+            fileSystem = FileSystem.get(new URI(HDFS_PATH), configuration, HDFS_USER);
+        } catch (IOException e) {
+            e.printStackTrace();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        } catch (URISyntaxException e) {
+            e.printStackTrace();
+        }
+    }
+
+
+    public static FileSystem getFileSystem() {
+        return fileSystem;
+    }
+
+    /**
+     * 创建目录 支持递归创建
+     *
+     * @param path 路径地址
+     * @return 创建是否成功
+     */
+    public static boolean mkdir(String path) throws Exception {
+        return fileSystem.mkdirs(new Path(path));
+    }
+
+    /**
+     * 查看文件内容
+     *
+     * @param path 路径地址
+     * @return 返回文件内容字符串
+     */
+    public static String text(String path, String encode) throws Exception {
+        FSDataInputStream inputStream = fileSystem.open(new Path(path));
+        return inputStreamToString(inputStream, encode);
+    }
+
+
+    /**
+     * 创建文件并写入内容
+     *
+     * @param path 路径地址
+     * @param context    文件内容
+     */
+    public void createAndWrite(String path, String context) throws Exception {
+        FSDataOutputStream out = fileSystem.create(new Path(path));
+        out.writeUTF(context);
+        out.flush();
+        out.close();
+    }
+
+    /**
+     * 文件重命名
+     *
+     * @param oldPath 旧文件路径
+     * @param newPath 新文件路径
+     * @return 重命名是否成功
+     */
+    public boolean rename(String oldPath, String newPath) throws Exception {
+        return fileSystem.rename(new Path(oldPath), new Path(newPath));
+
+    }
+
+
+    /**
+     * 拷贝文件到HDFS
+     *
+     * @param localPath 本地文件路径
+     * @param hdfsPath  存储到hdfs上的路径
+     */
+    public void copyFromLocalFile(String localPath, String hdfsPath) throws Exception {
+        fileSystem.copyFromLocalFile(new Path(localPath), new Path(hdfsPath));
+    }
+
+
+    /**
+     * 从HDFS下载文件
+     *
+     * @param hdfsPath  文件在hdfs上的路径
+     * @param localPath 存储到本地的路径
+     */
+    public void copyToLocalFile(String hdfsPath, String localPath) throws Exception {
+        fileSystem.copyToLocalFile(new Path(hdfsPath), new Path(localPath));
+    }
+
+
+    /**
+     * 查询给定路径中文件/目录的状态
+     *
+     * @param path 目录路径
+     * @return 文件信息的数组
+     */
+    public FileStatus[] listFiles(String path) throws Exception {
+        return fileSystem.listStatus(new Path(path));
+    }
+
+
+    /**
+     * 查询给定路径中文件的状态和块位置
+     *
+     * @param path 路径可以是目录路径也可以是文件路径
+     * @return 文件信息的数组
+     */
+    public RemoteIterator<LocatedFileStatus> listFilesRecursive(String path, boolean recursive) throws Exception {
+        return fileSystem.listFiles(new Path(path), recursive);
+    }
+
+
+    /**
+     * 查看文件块信息
+     *
+     * @param path 文件路径
+     * @return 块信息数组
+     */
+    public BlockLocation[] getFileBlockLocations(String path) throws Exception {
+        FileStatus fileStatus = fileSystem.getFileStatus(new Path(path));
+        return fileSystem.getFileBlockLocations(fileStatus, 0, fileStatus.getLen());
+    }
+
+    /**
+     * 删除文件
+     *
+     * @param path 文件路径
+     * @return 删除是否成功
+     */
+    public boolean delete(String path) throws Exception {
+        return fileSystem.delete(new Path(path), true);
+    }
+
+
+    /**
+     * 把输入流转换为指定字符
+     *
+     * @param inputStream 输入流
+     * @param encode      指定编码类型
+     */
+    private static String inputStreamToString(InputStream inputStream, String encode) {
+        try {
+            if (encode == null || ("".equals(encode))) {
+                encode = "utf-8";
+            }
+            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, encode));
+            StringBuilder builder = new StringBuilder();
+            String str = "";
+            while ((str = reader.readLine()) != null) {
+                builder.append(str).append("\n");
+            }
+            return builder.toString();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+}